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1 //===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
8 //
9 //  This file implements semantic analysis for C++ templates.
10 //===----------------------------------------------------------------------===//
11 
12 #include "TreeTransform.h"
13 #include "clang/AST/ASTConsumer.h"
14 #include "clang/AST/ASTContext.h"
15 #include "clang/AST/DeclFriend.h"
16 #include "clang/AST/DeclTemplate.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/RecursiveASTVisitor.h"
20 #include "clang/AST/TypeVisitor.h"
21 #include "clang/Basic/Builtins.h"
22 #include "clang/Basic/LangOptions.h"
23 #include "clang/Basic/PartialDiagnostic.h"
24 #include "clang/Basic/TargetInfo.h"
25 #include "clang/Sema/DeclSpec.h"
26 #include "clang/Sema/Lookup.h"
27 #include "clang/Sema/ParsedTemplate.h"
28 #include "clang/Sema/Scope.h"
29 #include "clang/Sema/SemaInternal.h"
30 #include "clang/Sema/Template.h"
31 #include "clang/Sema/TemplateDeduction.h"
32 #include "llvm/ADT/SmallBitVector.h"
33 #include "llvm/ADT/SmallString.h"
34 #include "llvm/ADT/StringExtras.h"
35 
36 #include <iterator>
37 using namespace clang;
38 using namespace sema;
39 
40 // Exported for use by Parser.
41 SourceRange
getTemplateParamsRange(TemplateParameterList const * const * Ps,unsigned N)42 clang::getTemplateParamsRange(TemplateParameterList const * const *Ps,
43                               unsigned N) {
44   if (!N) return SourceRange();
45   return SourceRange(Ps[0]->getTemplateLoc(), Ps[N-1]->getRAngleLoc());
46 }
47 
48 /// \brief Determine whether the declaration found is acceptable as the name
49 /// of a template and, if so, return that template declaration. Otherwise,
50 /// returns NULL.
isAcceptableTemplateName(ASTContext & Context,NamedDecl * Orig,bool AllowFunctionTemplates)51 static NamedDecl *isAcceptableTemplateName(ASTContext &Context,
52                                            NamedDecl *Orig,
53                                            bool AllowFunctionTemplates) {
54   NamedDecl *D = Orig->getUnderlyingDecl();
55 
56   if (isa<TemplateDecl>(D)) {
57     if (!AllowFunctionTemplates && isa<FunctionTemplateDecl>(D))
58       return nullptr;
59 
60     return Orig;
61   }
62 
63   if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
64     // C++ [temp.local]p1:
65     //   Like normal (non-template) classes, class templates have an
66     //   injected-class-name (Clause 9). The injected-class-name
67     //   can be used with or without a template-argument-list. When
68     //   it is used without a template-argument-list, it is
69     //   equivalent to the injected-class-name followed by the
70     //   template-parameters of the class template enclosed in
71     //   <>. When it is used with a template-argument-list, it
72     //   refers to the specified class template specialization,
73     //   which could be the current specialization or another
74     //   specialization.
75     if (Record->isInjectedClassName()) {
76       Record = cast<CXXRecordDecl>(Record->getDeclContext());
77       if (Record->getDescribedClassTemplate())
78         return Record->getDescribedClassTemplate();
79 
80       if (ClassTemplateSpecializationDecl *Spec
81             = dyn_cast<ClassTemplateSpecializationDecl>(Record))
82         return Spec->getSpecializedTemplate();
83     }
84 
85     return nullptr;
86   }
87 
88   return nullptr;
89 }
90 
FilterAcceptableTemplateNames(LookupResult & R,bool AllowFunctionTemplates)91 void Sema::FilterAcceptableTemplateNames(LookupResult &R,
92                                          bool AllowFunctionTemplates) {
93   // The set of class templates we've already seen.
94   llvm::SmallPtrSet<ClassTemplateDecl *, 8> ClassTemplates;
95   LookupResult::Filter filter = R.makeFilter();
96   while (filter.hasNext()) {
97     NamedDecl *Orig = filter.next();
98     NamedDecl *Repl = isAcceptableTemplateName(Context, Orig,
99                                                AllowFunctionTemplates);
100     if (!Repl)
101       filter.erase();
102     else if (Repl != Orig) {
103 
104       // C++ [temp.local]p3:
105       //   A lookup that finds an injected-class-name (10.2) can result in an
106       //   ambiguity in certain cases (for example, if it is found in more than
107       //   one base class). If all of the injected-class-names that are found
108       //   refer to specializations of the same class template, and if the name
109       //   is used as a template-name, the reference refers to the class
110       //   template itself and not a specialization thereof, and is not
111       //   ambiguous.
112       if (ClassTemplateDecl *ClassTmpl = dyn_cast<ClassTemplateDecl>(Repl))
113         if (!ClassTemplates.insert(ClassTmpl).second) {
114           filter.erase();
115           continue;
116         }
117 
118       // FIXME: we promote access to public here as a workaround to
119       // the fact that LookupResult doesn't let us remember that we
120       // found this template through a particular injected class name,
121       // which means we end up doing nasty things to the invariants.
122       // Pretending that access is public is *much* safer.
123       filter.replace(Repl, AS_public);
124     }
125   }
126   filter.done();
127 }
128 
hasAnyAcceptableTemplateNames(LookupResult & R,bool AllowFunctionTemplates)129 bool Sema::hasAnyAcceptableTemplateNames(LookupResult &R,
130                                          bool AllowFunctionTemplates) {
131   for (LookupResult::iterator I = R.begin(), IEnd = R.end(); I != IEnd; ++I)
132     if (isAcceptableTemplateName(Context, *I, AllowFunctionTemplates))
133       return true;
134 
135   return false;
136 }
137 
isTemplateName(Scope * S,CXXScopeSpec & SS,bool hasTemplateKeyword,UnqualifiedId & Name,ParsedType ObjectTypePtr,bool EnteringContext,TemplateTy & TemplateResult,bool & MemberOfUnknownSpecialization)138 TemplateNameKind Sema::isTemplateName(Scope *S,
139                                       CXXScopeSpec &SS,
140                                       bool hasTemplateKeyword,
141                                       UnqualifiedId &Name,
142                                       ParsedType ObjectTypePtr,
143                                       bool EnteringContext,
144                                       TemplateTy &TemplateResult,
145                                       bool &MemberOfUnknownSpecialization) {
146   assert(getLangOpts().CPlusPlus && "No template names in C!");
147 
148   DeclarationName TName;
149   MemberOfUnknownSpecialization = false;
150 
151   switch (Name.getKind()) {
152   case UnqualifiedId::IK_Identifier:
153     TName = DeclarationName(Name.Identifier);
154     break;
155 
156   case UnqualifiedId::IK_OperatorFunctionId:
157     TName = Context.DeclarationNames.getCXXOperatorName(
158                                               Name.OperatorFunctionId.Operator);
159     break;
160 
161   case UnqualifiedId::IK_LiteralOperatorId:
162     TName = Context.DeclarationNames.getCXXLiteralOperatorName(Name.Identifier);
163     break;
164 
165   default:
166     return TNK_Non_template;
167   }
168 
169   QualType ObjectType = ObjectTypePtr.get();
170 
171   LookupResult R(*this, TName, Name.getLocStart(), LookupOrdinaryName);
172   LookupTemplateName(R, S, SS, ObjectType, EnteringContext,
173                      MemberOfUnknownSpecialization);
174   if (R.empty()) return TNK_Non_template;
175   if (R.isAmbiguous()) {
176     // Suppress diagnostics;  we'll redo this lookup later.
177     R.suppressDiagnostics();
178 
179     // FIXME: we might have ambiguous templates, in which case we
180     // should at least parse them properly!
181     return TNK_Non_template;
182   }
183 
184   TemplateName Template;
185   TemplateNameKind TemplateKind;
186 
187   unsigned ResultCount = R.end() - R.begin();
188   if (ResultCount > 1) {
189     // We assume that we'll preserve the qualifier from a function
190     // template name in other ways.
191     Template = Context.getOverloadedTemplateName(R.begin(), R.end());
192     TemplateKind = TNK_Function_template;
193 
194     // We'll do this lookup again later.
195     R.suppressDiagnostics();
196   } else {
197     TemplateDecl *TD = cast<TemplateDecl>((*R.begin())->getUnderlyingDecl());
198 
199     if (SS.isSet() && !SS.isInvalid()) {
200       NestedNameSpecifier *Qualifier = SS.getScopeRep();
201       Template = Context.getQualifiedTemplateName(Qualifier,
202                                                   hasTemplateKeyword, TD);
203     } else {
204       Template = TemplateName(TD);
205     }
206 
207     if (isa<FunctionTemplateDecl>(TD)) {
208       TemplateKind = TNK_Function_template;
209 
210       // We'll do this lookup again later.
211       R.suppressDiagnostics();
212     } else {
213       assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD) ||
214              isa<TypeAliasTemplateDecl>(TD) || isa<VarTemplateDecl>(TD) ||
215              isa<BuiltinTemplateDecl>(TD));
216       TemplateKind =
217           isa<VarTemplateDecl>(TD) ? TNK_Var_template : TNK_Type_template;
218     }
219   }
220 
221   TemplateResult = TemplateTy::make(Template);
222   return TemplateKind;
223 }
224 
DiagnoseUnknownTemplateName(const IdentifierInfo & II,SourceLocation IILoc,Scope * S,const CXXScopeSpec * SS,TemplateTy & SuggestedTemplate,TemplateNameKind & SuggestedKind)225 bool Sema::DiagnoseUnknownTemplateName(const IdentifierInfo &II,
226                                        SourceLocation IILoc,
227                                        Scope *S,
228                                        const CXXScopeSpec *SS,
229                                        TemplateTy &SuggestedTemplate,
230                                        TemplateNameKind &SuggestedKind) {
231   // We can't recover unless there's a dependent scope specifier preceding the
232   // template name.
233   // FIXME: Typo correction?
234   if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
235       computeDeclContext(*SS))
236     return false;
237 
238   // The code is missing a 'template' keyword prior to the dependent template
239   // name.
240   NestedNameSpecifier *Qualifier = (NestedNameSpecifier*)SS->getScopeRep();
241   Diag(IILoc, diag::err_template_kw_missing)
242     << Qualifier << II.getName()
243     << FixItHint::CreateInsertion(IILoc, "template ");
244   SuggestedTemplate
245     = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
246   SuggestedKind = TNK_Dependent_template_name;
247   return true;
248 }
249 
LookupTemplateName(LookupResult & Found,Scope * S,CXXScopeSpec & SS,QualType ObjectType,bool EnteringContext,bool & MemberOfUnknownSpecialization)250 void Sema::LookupTemplateName(LookupResult &Found,
251                               Scope *S, CXXScopeSpec &SS,
252                               QualType ObjectType,
253                               bool EnteringContext,
254                               bool &MemberOfUnknownSpecialization) {
255   // Determine where to perform name lookup
256   MemberOfUnknownSpecialization = false;
257   DeclContext *LookupCtx = nullptr;
258   bool isDependent = false;
259   if (!ObjectType.isNull()) {
260     // This nested-name-specifier occurs in a member access expression, e.g.,
261     // x->B::f, and we are looking into the type of the object.
262     assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
263     LookupCtx = computeDeclContext(ObjectType);
264     isDependent = ObjectType->isDependentType();
265     assert((isDependent || !ObjectType->isIncompleteType() ||
266             ObjectType->castAs<TagType>()->isBeingDefined()) &&
267            "Caller should have completed object type");
268 
269     // Template names cannot appear inside an Objective-C class or object type.
270     if (ObjectType->isObjCObjectOrInterfaceType()) {
271       Found.clear();
272       return;
273     }
274   } else if (SS.isSet()) {
275     // This nested-name-specifier occurs after another nested-name-specifier,
276     // so long into the context associated with the prior nested-name-specifier.
277     LookupCtx = computeDeclContext(SS, EnteringContext);
278     isDependent = isDependentScopeSpecifier(SS);
279 
280     // The declaration context must be complete.
281     if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
282       return;
283   }
284 
285   bool ObjectTypeSearchedInScope = false;
286   bool AllowFunctionTemplatesInLookup = true;
287   if (LookupCtx) {
288     // Perform "qualified" name lookup into the declaration context we
289     // computed, which is either the type of the base of a member access
290     // expression or the declaration context associated with a prior
291     // nested-name-specifier.
292     LookupQualifiedName(Found, LookupCtx);
293     if (!ObjectType.isNull() && Found.empty()) {
294       // C++ [basic.lookup.classref]p1:
295       //   In a class member access expression (5.2.5), if the . or -> token is
296       //   immediately followed by an identifier followed by a <, the
297       //   identifier must be looked up to determine whether the < is the
298       //   beginning of a template argument list (14.2) or a less-than operator.
299       //   The identifier is first looked up in the class of the object
300       //   expression. If the identifier is not found, it is then looked up in
301       //   the context of the entire postfix-expression and shall name a class
302       //   or function template.
303       if (S) LookupName(Found, S);
304       ObjectTypeSearchedInScope = true;
305       AllowFunctionTemplatesInLookup = false;
306     }
307   } else if (isDependent && (!S || ObjectType.isNull())) {
308     // We cannot look into a dependent object type or nested nme
309     // specifier.
310     MemberOfUnknownSpecialization = true;
311     return;
312   } else {
313     // Perform unqualified name lookup in the current scope.
314     LookupName(Found, S);
315 
316     if (!ObjectType.isNull())
317       AllowFunctionTemplatesInLookup = false;
318   }
319 
320   if (Found.empty() && !isDependent) {
321     // If we did not find any names, attempt to correct any typos.
322     DeclarationName Name = Found.getLookupName();
323     Found.clear();
324     // Simple filter callback that, for keywords, only accepts the C++ *_cast
325     auto FilterCCC = llvm::make_unique<CorrectionCandidateCallback>();
326     FilterCCC->WantTypeSpecifiers = false;
327     FilterCCC->WantExpressionKeywords = false;
328     FilterCCC->WantRemainingKeywords = false;
329     FilterCCC->WantCXXNamedCasts = true;
330     if (TypoCorrection Corrected = CorrectTypo(
331             Found.getLookupNameInfo(), Found.getLookupKind(), S, &SS,
332             std::move(FilterCCC), CTK_ErrorRecovery, LookupCtx)) {
333       Found.setLookupName(Corrected.getCorrection());
334       if (auto *ND = Corrected.getFoundDecl())
335         Found.addDecl(ND);
336       FilterAcceptableTemplateNames(Found);
337       if (!Found.empty()) {
338         if (LookupCtx) {
339           std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
340           bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
341                                   Name.getAsString() == CorrectedStr;
342           diagnoseTypo(Corrected, PDiag(diag::err_no_member_template_suggest)
343                                     << Name << LookupCtx << DroppedSpecifier
344                                     << SS.getRange());
345         } else {
346           diagnoseTypo(Corrected, PDiag(diag::err_no_template_suggest) << Name);
347         }
348       }
349     } else {
350       Found.setLookupName(Name);
351     }
352   }
353 
354   FilterAcceptableTemplateNames(Found, AllowFunctionTemplatesInLookup);
355   if (Found.empty()) {
356     if (isDependent)
357       MemberOfUnknownSpecialization = true;
358     return;
359   }
360 
361   if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope &&
362       !getLangOpts().CPlusPlus11) {
363     // C++03 [basic.lookup.classref]p1:
364     //   [...] If the lookup in the class of the object expression finds a
365     //   template, the name is also looked up in the context of the entire
366     //   postfix-expression and [...]
367     //
368     // Note: C++11 does not perform this second lookup.
369     LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
370                             LookupOrdinaryName);
371     LookupName(FoundOuter, S);
372     FilterAcceptableTemplateNames(FoundOuter, /*AllowFunctionTemplates=*/false);
373 
374     if (FoundOuter.empty()) {
375       //   - if the name is not found, the name found in the class of the
376       //     object expression is used, otherwise
377     } else if (!FoundOuter.getAsSingle<ClassTemplateDecl>() ||
378                FoundOuter.isAmbiguous()) {
379       //   - if the name is found in the context of the entire
380       //     postfix-expression and does not name a class template, the name
381       //     found in the class of the object expression is used, otherwise
382       FoundOuter.clear();
383     } else if (!Found.isSuppressingDiagnostics()) {
384       //   - if the name found is a class template, it must refer to the same
385       //     entity as the one found in the class of the object expression,
386       //     otherwise the program is ill-formed.
387       if (!Found.isSingleResult() ||
388           Found.getFoundDecl()->getCanonicalDecl()
389             != FoundOuter.getFoundDecl()->getCanonicalDecl()) {
390         Diag(Found.getNameLoc(),
391              diag::ext_nested_name_member_ref_lookup_ambiguous)
392           << Found.getLookupName()
393           << ObjectType;
394         Diag(Found.getRepresentativeDecl()->getLocation(),
395              diag::note_ambig_member_ref_object_type)
396           << ObjectType;
397         Diag(FoundOuter.getFoundDecl()->getLocation(),
398              diag::note_ambig_member_ref_scope);
399 
400         // Recover by taking the template that we found in the object
401         // expression's type.
402       }
403     }
404   }
405 }
406 
407 /// ActOnDependentIdExpression - Handle a dependent id-expression that
408 /// was just parsed.  This is only possible with an explicit scope
409 /// specifier naming a dependent type.
410 ExprResult
ActOnDependentIdExpression(const CXXScopeSpec & SS,SourceLocation TemplateKWLoc,const DeclarationNameInfo & NameInfo,bool isAddressOfOperand,const TemplateArgumentListInfo * TemplateArgs)411 Sema::ActOnDependentIdExpression(const CXXScopeSpec &SS,
412                                  SourceLocation TemplateKWLoc,
413                                  const DeclarationNameInfo &NameInfo,
414                                  bool isAddressOfOperand,
415                            const TemplateArgumentListInfo *TemplateArgs) {
416   DeclContext *DC = getFunctionLevelDeclContext();
417 
418   // C++11 [expr.prim.general]p12:
419   //   An id-expression that denotes a non-static data member or non-static
420   //   member function of a class can only be used:
421   //   (...)
422   //   - if that id-expression denotes a non-static data member and it
423   //     appears in an unevaluated operand.
424   //
425   // If this might be the case, form a DependentScopeDeclRefExpr instead of a
426   // CXXDependentScopeMemberExpr. The former can instantiate to either
427   // DeclRefExpr or MemberExpr depending on lookup results, while the latter is
428   // always a MemberExpr.
429   bool MightBeCxx11UnevalField =
430       getLangOpts().CPlusPlus11 && isUnevaluatedContext();
431 
432   if (!MightBeCxx11UnevalField && !isAddressOfOperand &&
433       isa<CXXMethodDecl>(DC) && cast<CXXMethodDecl>(DC)->isInstance()) {
434     QualType ThisType = cast<CXXMethodDecl>(DC)->getThisType(Context);
435 
436     // Since the 'this' expression is synthesized, we don't need to
437     // perform the double-lookup check.
438     NamedDecl *FirstQualifierInScope = nullptr;
439 
440     return CXXDependentScopeMemberExpr::Create(
441         Context, /*This*/ nullptr, ThisType, /*IsArrow*/ true,
442         /*Op*/ SourceLocation(), SS.getWithLocInContext(Context), TemplateKWLoc,
443         FirstQualifierInScope, NameInfo, TemplateArgs);
444   }
445 
446   return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
447 }
448 
449 ExprResult
BuildDependentDeclRefExpr(const CXXScopeSpec & SS,SourceLocation TemplateKWLoc,const DeclarationNameInfo & NameInfo,const TemplateArgumentListInfo * TemplateArgs)450 Sema::BuildDependentDeclRefExpr(const CXXScopeSpec &SS,
451                                 SourceLocation TemplateKWLoc,
452                                 const DeclarationNameInfo &NameInfo,
453                                 const TemplateArgumentListInfo *TemplateArgs) {
454   return DependentScopeDeclRefExpr::Create(
455       Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
456       TemplateArgs);
457 }
458 
459 /// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
460 /// that the template parameter 'PrevDecl' is being shadowed by a new
461 /// declaration at location Loc. Returns true to indicate that this is
462 /// an error, and false otherwise.
DiagnoseTemplateParameterShadow(SourceLocation Loc,Decl * PrevDecl)463 void Sema::DiagnoseTemplateParameterShadow(SourceLocation Loc, Decl *PrevDecl) {
464   assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
465 
466   // Microsoft Visual C++ permits template parameters to be shadowed.
467   if (getLangOpts().MicrosoftExt)
468     return;
469 
470   // C++ [temp.local]p4:
471   //   A template-parameter shall not be redeclared within its
472   //   scope (including nested scopes).
473   Diag(Loc, diag::err_template_param_shadow)
474     << cast<NamedDecl>(PrevDecl)->getDeclName();
475   Diag(PrevDecl->getLocation(), diag::note_template_param_here);
476 }
477 
478 /// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
479 /// the parameter D to reference the templated declaration and return a pointer
480 /// to the template declaration. Otherwise, do nothing to D and return null.
AdjustDeclIfTemplate(Decl * & D)481 TemplateDecl *Sema::AdjustDeclIfTemplate(Decl *&D) {
482   if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D)) {
483     D = Temp->getTemplatedDecl();
484     return Temp;
485   }
486   return nullptr;
487 }
488 
getTemplatePackExpansion(SourceLocation EllipsisLoc) const489 ParsedTemplateArgument ParsedTemplateArgument::getTemplatePackExpansion(
490                                              SourceLocation EllipsisLoc) const {
491   assert(Kind == Template &&
492          "Only template template arguments can be pack expansions here");
493   assert(getAsTemplate().get().containsUnexpandedParameterPack() &&
494          "Template template argument pack expansion without packs");
495   ParsedTemplateArgument Result(*this);
496   Result.EllipsisLoc = EllipsisLoc;
497   return Result;
498 }
499 
translateTemplateArgument(Sema & SemaRef,const ParsedTemplateArgument & Arg)500 static TemplateArgumentLoc translateTemplateArgument(Sema &SemaRef,
501                                             const ParsedTemplateArgument &Arg) {
502 
503   switch (Arg.getKind()) {
504   case ParsedTemplateArgument::Type: {
505     TypeSourceInfo *DI;
506     QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
507     if (!DI)
508       DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
509     return TemplateArgumentLoc(TemplateArgument(T), DI);
510   }
511 
512   case ParsedTemplateArgument::NonType: {
513     Expr *E = static_cast<Expr *>(Arg.getAsExpr());
514     return TemplateArgumentLoc(TemplateArgument(E), E);
515   }
516 
517   case ParsedTemplateArgument::Template: {
518     TemplateName Template = Arg.getAsTemplate().get();
519     TemplateArgument TArg;
520     if (Arg.getEllipsisLoc().isValid())
521       TArg = TemplateArgument(Template, Optional<unsigned int>());
522     else
523       TArg = Template;
524     return TemplateArgumentLoc(TArg,
525                                Arg.getScopeSpec().getWithLocInContext(
526                                                               SemaRef.Context),
527                                Arg.getLocation(),
528                                Arg.getEllipsisLoc());
529   }
530   }
531 
532   llvm_unreachable("Unhandled parsed template argument");
533 }
534 
535 /// \brief Translates template arguments as provided by the parser
536 /// into template arguments used by semantic analysis.
translateTemplateArguments(const ASTTemplateArgsPtr & TemplateArgsIn,TemplateArgumentListInfo & TemplateArgs)537 void Sema::translateTemplateArguments(const ASTTemplateArgsPtr &TemplateArgsIn,
538                                       TemplateArgumentListInfo &TemplateArgs) {
539  for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
540    TemplateArgs.addArgument(translateTemplateArgument(*this,
541                                                       TemplateArgsIn[I]));
542 }
543 
maybeDiagnoseTemplateParameterShadow(Sema & SemaRef,Scope * S,SourceLocation Loc,IdentifierInfo * Name)544 static void maybeDiagnoseTemplateParameterShadow(Sema &SemaRef, Scope *S,
545                                                  SourceLocation Loc,
546                                                  IdentifierInfo *Name) {
547   NamedDecl *PrevDecl = SemaRef.LookupSingleName(
548       S, Name, Loc, Sema::LookupOrdinaryName, Sema::ForRedeclaration);
549   if (PrevDecl && PrevDecl->isTemplateParameter())
550     SemaRef.DiagnoseTemplateParameterShadow(Loc, PrevDecl);
551 }
552 
553 /// ActOnTypeParameter - Called when a C++ template type parameter
554 /// (e.g., "typename T") has been parsed. Typename specifies whether
555 /// the keyword "typename" was used to declare the type parameter
556 /// (otherwise, "class" was used), and KeyLoc is the location of the
557 /// "class" or "typename" keyword. ParamName is the name of the
558 /// parameter (NULL indicates an unnamed template parameter) and
559 /// ParamNameLoc is the location of the parameter name (if any).
560 /// If the type parameter has a default argument, it will be added
561 /// later via ActOnTypeParameterDefault.
ActOnTypeParameter(Scope * S,bool Typename,SourceLocation EllipsisLoc,SourceLocation KeyLoc,IdentifierInfo * ParamName,SourceLocation ParamNameLoc,unsigned Depth,unsigned Position,SourceLocation EqualLoc,ParsedType DefaultArg)562 Decl *Sema::ActOnTypeParameter(Scope *S, bool Typename,
563                                SourceLocation EllipsisLoc,
564                                SourceLocation KeyLoc,
565                                IdentifierInfo *ParamName,
566                                SourceLocation ParamNameLoc,
567                                unsigned Depth, unsigned Position,
568                                SourceLocation EqualLoc,
569                                ParsedType DefaultArg) {
570   assert(S->isTemplateParamScope() &&
571          "Template type parameter not in template parameter scope!");
572 
573   SourceLocation Loc = ParamNameLoc;
574   if (!ParamName)
575     Loc = KeyLoc;
576 
577   bool IsParameterPack = EllipsisLoc.isValid();
578   TemplateTypeParmDecl *Param
579     = TemplateTypeParmDecl::Create(Context, Context.getTranslationUnitDecl(),
580                                    KeyLoc, Loc, Depth, Position, ParamName,
581                                    Typename, IsParameterPack);
582   Param->setAccess(AS_public);
583 
584   if (ParamName) {
585     maybeDiagnoseTemplateParameterShadow(*this, S, ParamNameLoc, ParamName);
586 
587     // Add the template parameter into the current scope.
588     S->AddDecl(Param);
589     IdResolver.AddDecl(Param);
590   }
591 
592   // C++0x [temp.param]p9:
593   //   A default template-argument may be specified for any kind of
594   //   template-parameter that is not a template parameter pack.
595   if (DefaultArg && IsParameterPack) {
596     Diag(EqualLoc, diag::err_template_param_pack_default_arg);
597     DefaultArg = nullptr;
598   }
599 
600   // Handle the default argument, if provided.
601   if (DefaultArg) {
602     TypeSourceInfo *DefaultTInfo;
603     GetTypeFromParser(DefaultArg, &DefaultTInfo);
604 
605     assert(DefaultTInfo && "expected source information for type");
606 
607     // Check for unexpanded parameter packs.
608     if (DiagnoseUnexpandedParameterPack(Loc, DefaultTInfo,
609                                         UPPC_DefaultArgument))
610       return Param;
611 
612     // Check the template argument itself.
613     if (CheckTemplateArgument(Param, DefaultTInfo)) {
614       Param->setInvalidDecl();
615       return Param;
616     }
617 
618     Param->setDefaultArgument(DefaultTInfo);
619   }
620 
621   return Param;
622 }
623 
624 /// \brief Check that the type of a non-type template parameter is
625 /// well-formed.
626 ///
627 /// \returns the (possibly-promoted) parameter type if valid;
628 /// otherwise, produces a diagnostic and returns a NULL type.
629 QualType
CheckNonTypeTemplateParameterType(QualType T,SourceLocation Loc)630 Sema::CheckNonTypeTemplateParameterType(QualType T, SourceLocation Loc) {
631   // We don't allow variably-modified types as the type of non-type template
632   // parameters.
633   if (T->isVariablyModifiedType()) {
634     Diag(Loc, diag::err_variably_modified_nontype_template_param)
635       << T;
636     return QualType();
637   }
638 
639   // C++ [temp.param]p4:
640   //
641   // A non-type template-parameter shall have one of the following
642   // (optionally cv-qualified) types:
643   //
644   //       -- integral or enumeration type,
645   if (T->isIntegralOrEnumerationType() ||
646       //   -- pointer to object or pointer to function,
647       T->isPointerType() ||
648       //   -- reference to object or reference to function,
649       T->isReferenceType() ||
650       //   -- pointer to member,
651       T->isMemberPointerType() ||
652       //   -- std::nullptr_t.
653       T->isNullPtrType() ||
654       // If T is a dependent type, we can't do the check now, so we
655       // assume that it is well-formed.
656       T->isDependentType()) {
657     // C++ [temp.param]p5: The top-level cv-qualifiers on the template-parameter
658     // are ignored when determining its type.
659     return T.getUnqualifiedType();
660   }
661 
662   // C++ [temp.param]p8:
663   //
664   //   A non-type template-parameter of type "array of T" or
665   //   "function returning T" is adjusted to be of type "pointer to
666   //   T" or "pointer to function returning T", respectively.
667   else if (T->isArrayType() || T->isFunctionType())
668     return Context.getDecayedType(T);
669 
670   Diag(Loc, diag::err_template_nontype_parm_bad_type)
671     << T;
672 
673   return QualType();
674 }
675 
ActOnNonTypeTemplateParameter(Scope * S,Declarator & D,unsigned Depth,unsigned Position,SourceLocation EqualLoc,Expr * Default)676 Decl *Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
677                                           unsigned Depth,
678                                           unsigned Position,
679                                           SourceLocation EqualLoc,
680                                           Expr *Default) {
681   TypeSourceInfo *TInfo = GetTypeForDeclarator(D, S);
682   QualType T = TInfo->getType();
683 
684   assert(S->isTemplateParamScope() &&
685          "Non-type template parameter not in template parameter scope!");
686   bool Invalid = false;
687 
688   T = CheckNonTypeTemplateParameterType(T, D.getIdentifierLoc());
689   if (T.isNull()) {
690     T = Context.IntTy; // Recover with an 'int' type.
691     Invalid = true;
692   }
693 
694   IdentifierInfo *ParamName = D.getIdentifier();
695   bool IsParameterPack = D.hasEllipsis();
696   NonTypeTemplateParmDecl *Param
697     = NonTypeTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
698                                       D.getLocStart(),
699                                       D.getIdentifierLoc(),
700                                       Depth, Position, ParamName, T,
701                                       IsParameterPack, TInfo);
702   Param->setAccess(AS_public);
703 
704   if (Invalid)
705     Param->setInvalidDecl();
706 
707   if (ParamName) {
708     maybeDiagnoseTemplateParameterShadow(*this, S, D.getIdentifierLoc(),
709                                          ParamName);
710 
711     // Add the template parameter into the current scope.
712     S->AddDecl(Param);
713     IdResolver.AddDecl(Param);
714   }
715 
716   // C++0x [temp.param]p9:
717   //   A default template-argument may be specified for any kind of
718   //   template-parameter that is not a template parameter pack.
719   if (Default && IsParameterPack) {
720     Diag(EqualLoc, diag::err_template_param_pack_default_arg);
721     Default = nullptr;
722   }
723 
724   // Check the well-formedness of the default template argument, if provided.
725   if (Default) {
726     // Check for unexpanded parameter packs.
727     if (DiagnoseUnexpandedParameterPack(Default, UPPC_DefaultArgument))
728       return Param;
729 
730     TemplateArgument Converted;
731     ExprResult DefaultRes =
732         CheckTemplateArgument(Param, Param->getType(), Default, Converted);
733     if (DefaultRes.isInvalid()) {
734       Param->setInvalidDecl();
735       return Param;
736     }
737     Default = DefaultRes.get();
738 
739     Param->setDefaultArgument(Default);
740   }
741 
742   return Param;
743 }
744 
745 /// ActOnTemplateTemplateParameter - Called when a C++ template template
746 /// parameter (e.g. T in template <template \<typename> class T> class array)
747 /// has been parsed. S is the current scope.
ActOnTemplateTemplateParameter(Scope * S,SourceLocation TmpLoc,TemplateParameterList * Params,SourceLocation EllipsisLoc,IdentifierInfo * Name,SourceLocation NameLoc,unsigned Depth,unsigned Position,SourceLocation EqualLoc,ParsedTemplateArgument Default)748 Decl *Sema::ActOnTemplateTemplateParameter(Scope* S,
749                                            SourceLocation TmpLoc,
750                                            TemplateParameterList *Params,
751                                            SourceLocation EllipsisLoc,
752                                            IdentifierInfo *Name,
753                                            SourceLocation NameLoc,
754                                            unsigned Depth,
755                                            unsigned Position,
756                                            SourceLocation EqualLoc,
757                                            ParsedTemplateArgument Default) {
758   assert(S->isTemplateParamScope() &&
759          "Template template parameter not in template parameter scope!");
760 
761   // Construct the parameter object.
762   bool IsParameterPack = EllipsisLoc.isValid();
763   TemplateTemplateParmDecl *Param =
764     TemplateTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
765                                      NameLoc.isInvalid()? TmpLoc : NameLoc,
766                                      Depth, Position, IsParameterPack,
767                                      Name, Params);
768   Param->setAccess(AS_public);
769 
770   // If the template template parameter has a name, then link the identifier
771   // into the scope and lookup mechanisms.
772   if (Name) {
773     maybeDiagnoseTemplateParameterShadow(*this, S, NameLoc, Name);
774 
775     S->AddDecl(Param);
776     IdResolver.AddDecl(Param);
777   }
778 
779   if (Params->size() == 0) {
780     Diag(Param->getLocation(), diag::err_template_template_parm_no_parms)
781     << SourceRange(Params->getLAngleLoc(), Params->getRAngleLoc());
782     Param->setInvalidDecl();
783   }
784 
785   // C++0x [temp.param]p9:
786   //   A default template-argument may be specified for any kind of
787   //   template-parameter that is not a template parameter pack.
788   if (IsParameterPack && !Default.isInvalid()) {
789     Diag(EqualLoc, diag::err_template_param_pack_default_arg);
790     Default = ParsedTemplateArgument();
791   }
792 
793   if (!Default.isInvalid()) {
794     // Check only that we have a template template argument. We don't want to
795     // try to check well-formedness now, because our template template parameter
796     // might have dependent types in its template parameters, which we wouldn't
797     // be able to match now.
798     //
799     // If none of the template template parameter's template arguments mention
800     // other template parameters, we could actually perform more checking here.
801     // However, it isn't worth doing.
802     TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
803     if (DefaultArg.getArgument().getAsTemplate().isNull()) {
804       Diag(DefaultArg.getLocation(), diag::err_template_arg_not_valid_template)
805         << DefaultArg.getSourceRange();
806       return Param;
807     }
808 
809     // Check for unexpanded parameter packs.
810     if (DiagnoseUnexpandedParameterPack(DefaultArg.getLocation(),
811                                         DefaultArg.getArgument().getAsTemplate(),
812                                         UPPC_DefaultArgument))
813       return Param;
814 
815     Param->setDefaultArgument(Context, DefaultArg);
816   }
817 
818   return Param;
819 }
820 
821 /// ActOnTemplateParameterList - Builds a TemplateParameterList, optionally
822 /// constrained by RequiresClause, that contains the template parameters in
823 /// Params.
824 TemplateParameterList *
ActOnTemplateParameterList(unsigned Depth,SourceLocation ExportLoc,SourceLocation TemplateLoc,SourceLocation LAngleLoc,ArrayRef<Decl * > Params,SourceLocation RAngleLoc,Expr * RequiresClause)825 Sema::ActOnTemplateParameterList(unsigned Depth,
826                                  SourceLocation ExportLoc,
827                                  SourceLocation TemplateLoc,
828                                  SourceLocation LAngleLoc,
829                                  ArrayRef<Decl *> Params,
830                                  SourceLocation RAngleLoc,
831                                  Expr *RequiresClause) {
832   if (ExportLoc.isValid())
833     Diag(ExportLoc, diag::warn_template_export_unsupported);
834 
835   // FIXME: store RequiresClause
836   return TemplateParameterList::Create(
837       Context, TemplateLoc, LAngleLoc,
838       llvm::makeArrayRef((NamedDecl *const *)Params.data(), Params.size()),
839       RAngleLoc);
840 }
841 
SetNestedNameSpecifier(TagDecl * T,const CXXScopeSpec & SS)842 static void SetNestedNameSpecifier(TagDecl *T, const CXXScopeSpec &SS) {
843   if (SS.isSet())
844     T->setQualifierInfo(SS.getWithLocInContext(T->getASTContext()));
845 }
846 
847 DeclResult
CheckClassTemplate(Scope * S,unsigned TagSpec,TagUseKind TUK,SourceLocation KWLoc,CXXScopeSpec & SS,IdentifierInfo * Name,SourceLocation NameLoc,AttributeList * Attr,TemplateParameterList * TemplateParams,AccessSpecifier AS,SourceLocation ModulePrivateLoc,SourceLocation FriendLoc,unsigned NumOuterTemplateParamLists,TemplateParameterList ** OuterTemplateParamLists,SkipBodyInfo * SkipBody)848 Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
849                          SourceLocation KWLoc, CXXScopeSpec &SS,
850                          IdentifierInfo *Name, SourceLocation NameLoc,
851                          AttributeList *Attr,
852                          TemplateParameterList *TemplateParams,
853                          AccessSpecifier AS, SourceLocation ModulePrivateLoc,
854                          SourceLocation FriendLoc,
855                          unsigned NumOuterTemplateParamLists,
856                          TemplateParameterList** OuterTemplateParamLists,
857                          SkipBodyInfo *SkipBody) {
858   assert(TemplateParams && TemplateParams->size() > 0 &&
859          "No template parameters");
860   assert(TUK != TUK_Reference && "Can only declare or define class templates");
861   bool Invalid = false;
862 
863   // Check that we can declare a template here.
864   if (CheckTemplateDeclScope(S, TemplateParams))
865     return true;
866 
867   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
868   assert(Kind != TTK_Enum && "can't build template of enumerated type");
869 
870   // There is no such thing as an unnamed class template.
871   if (!Name) {
872     Diag(KWLoc, diag::err_template_unnamed_class);
873     return true;
874   }
875 
876   // Find any previous declaration with this name. For a friend with no
877   // scope explicitly specified, we only look for tag declarations (per
878   // C++11 [basic.lookup.elab]p2).
879   DeclContext *SemanticContext;
880   LookupResult Previous(*this, Name, NameLoc,
881                         (SS.isEmpty() && TUK == TUK_Friend)
882                           ? LookupTagName : LookupOrdinaryName,
883                         ForRedeclaration);
884   if (SS.isNotEmpty() && !SS.isInvalid()) {
885     SemanticContext = computeDeclContext(SS, true);
886     if (!SemanticContext) {
887       // FIXME: Horrible, horrible hack! We can't currently represent this
888       // in the AST, and historically we have just ignored such friend
889       // class templates, so don't complain here.
890       Diag(NameLoc, TUK == TUK_Friend
891                         ? diag::warn_template_qualified_friend_ignored
892                         : diag::err_template_qualified_declarator_no_match)
893           << SS.getScopeRep() << SS.getRange();
894       return TUK != TUK_Friend;
895     }
896 
897     if (RequireCompleteDeclContext(SS, SemanticContext))
898       return true;
899 
900     // If we're adding a template to a dependent context, we may need to
901     // rebuilding some of the types used within the template parameter list,
902     // now that we know what the current instantiation is.
903     if (SemanticContext->isDependentContext()) {
904       ContextRAII SavedContext(*this, SemanticContext);
905       if (RebuildTemplateParamsInCurrentInstantiation(TemplateParams))
906         Invalid = true;
907     } else if (TUK != TUK_Friend && TUK != TUK_Reference)
908       diagnoseQualifiedDeclaration(SS, SemanticContext, Name, NameLoc);
909 
910     LookupQualifiedName(Previous, SemanticContext);
911   } else {
912     SemanticContext = CurContext;
913 
914     // C++14 [class.mem]p14:
915     //   If T is the name of a class, then each of the following shall have a
916     //   name different from T:
917     //    -- every member template of class T
918     if (TUK != TUK_Friend &&
919         DiagnoseClassNameShadow(SemanticContext,
920                                 DeclarationNameInfo(Name, NameLoc)))
921       return true;
922 
923     LookupName(Previous, S);
924   }
925 
926   if (Previous.isAmbiguous())
927     return true;
928 
929   NamedDecl *PrevDecl = nullptr;
930   if (Previous.begin() != Previous.end())
931     PrevDecl = (*Previous.begin())->getUnderlyingDecl();
932 
933   if (PrevDecl && PrevDecl->isTemplateParameter()) {
934     // Maybe we will complain about the shadowed template parameter.
935     DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
936     // Just pretend that we didn't see the previous declaration.
937     PrevDecl = nullptr;
938   }
939 
940   // If there is a previous declaration with the same name, check
941   // whether this is a valid redeclaration.
942   ClassTemplateDecl *PrevClassTemplate
943     = dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
944 
945   // We may have found the injected-class-name of a class template,
946   // class template partial specialization, or class template specialization.
947   // In these cases, grab the template that is being defined or specialized.
948   if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) &&
949       cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
950     PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
951     PrevClassTemplate
952       = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
953     if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
954       PrevClassTemplate
955         = cast<ClassTemplateSpecializationDecl>(PrevDecl)
956             ->getSpecializedTemplate();
957     }
958   }
959 
960   if (TUK == TUK_Friend) {
961     // C++ [namespace.memdef]p3:
962     //   [...] When looking for a prior declaration of a class or a function
963     //   declared as a friend, and when the name of the friend class or
964     //   function is neither a qualified name nor a template-id, scopes outside
965     //   the innermost enclosing namespace scope are not considered.
966     if (!SS.isSet()) {
967       DeclContext *OutermostContext = CurContext;
968       while (!OutermostContext->isFileContext())
969         OutermostContext = OutermostContext->getLookupParent();
970 
971       if (PrevDecl &&
972           (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
973            OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
974         SemanticContext = PrevDecl->getDeclContext();
975       } else {
976         // Declarations in outer scopes don't matter. However, the outermost
977         // context we computed is the semantic context for our new
978         // declaration.
979         PrevDecl = PrevClassTemplate = nullptr;
980         SemanticContext = OutermostContext;
981 
982         // Check that the chosen semantic context doesn't already contain a
983         // declaration of this name as a non-tag type.
984         Previous.clear(LookupOrdinaryName);
985         DeclContext *LookupContext = SemanticContext;
986         while (LookupContext->isTransparentContext())
987           LookupContext = LookupContext->getLookupParent();
988         LookupQualifiedName(Previous, LookupContext);
989 
990         if (Previous.isAmbiguous())
991           return true;
992 
993         if (Previous.begin() != Previous.end())
994           PrevDecl = (*Previous.begin())->getUnderlyingDecl();
995       }
996     }
997   } else if (PrevDecl &&
998              !isDeclInScope(Previous.getRepresentativeDecl(), SemanticContext,
999                             S, SS.isValid()))
1000     PrevDecl = PrevClassTemplate = nullptr;
1001 
1002   if (auto *Shadow = dyn_cast_or_null<UsingShadowDecl>(
1003           PrevDecl ? Previous.getRepresentativeDecl() : nullptr)) {
1004     if (SS.isEmpty() &&
1005         !(PrevClassTemplate &&
1006           PrevClassTemplate->getDeclContext()->getRedeclContext()->Equals(
1007               SemanticContext->getRedeclContext()))) {
1008       Diag(KWLoc, diag::err_using_decl_conflict_reverse);
1009       Diag(Shadow->getTargetDecl()->getLocation(),
1010            diag::note_using_decl_target);
1011       Diag(Shadow->getUsingDecl()->getLocation(), diag::note_using_decl) << 0;
1012       // Recover by ignoring the old declaration.
1013       PrevDecl = PrevClassTemplate = nullptr;
1014     }
1015   }
1016 
1017   if (PrevClassTemplate) {
1018     // Ensure that the template parameter lists are compatible. Skip this check
1019     // for a friend in a dependent context: the template parameter list itself
1020     // could be dependent.
1021     if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1022         !TemplateParameterListsAreEqual(TemplateParams,
1023                                    PrevClassTemplate->getTemplateParameters(),
1024                                         /*Complain=*/true,
1025                                         TPL_TemplateMatch))
1026       return true;
1027 
1028     // C++ [temp.class]p4:
1029     //   In a redeclaration, partial specialization, explicit
1030     //   specialization or explicit instantiation of a class template,
1031     //   the class-key shall agree in kind with the original class
1032     //   template declaration (7.1.5.3).
1033     RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
1034     if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind,
1035                                       TUK == TUK_Definition,  KWLoc, Name)) {
1036       Diag(KWLoc, diag::err_use_with_wrong_tag)
1037         << Name
1038         << FixItHint::CreateReplacement(KWLoc, PrevRecordDecl->getKindName());
1039       Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
1040       Kind = PrevRecordDecl->getTagKind();
1041     }
1042 
1043     // Check for redefinition of this class template.
1044     if (TUK == TUK_Definition) {
1045       if (TagDecl *Def = PrevRecordDecl->getDefinition()) {
1046         // If we have a prior definition that is not visible, treat this as
1047         // simply making that previous definition visible.
1048         NamedDecl *Hidden = nullptr;
1049         if (SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
1050           SkipBody->ShouldSkip = true;
1051           auto *Tmpl = cast<CXXRecordDecl>(Hidden)->getDescribedClassTemplate();
1052           assert(Tmpl && "original definition of a class template is not a "
1053                          "class template?");
1054           makeMergedDefinitionVisible(Hidden, KWLoc);
1055           makeMergedDefinitionVisible(Tmpl, KWLoc);
1056           return Def;
1057         }
1058 
1059         Diag(NameLoc, diag::err_redefinition) << Name;
1060         Diag(Def->getLocation(), diag::note_previous_definition);
1061         // FIXME: Would it make sense to try to "forget" the previous
1062         // definition, as part of error recovery?
1063         return true;
1064       }
1065     }
1066   } else if (PrevDecl) {
1067     // C++ [temp]p5:
1068     //   A class template shall not have the same name as any other
1069     //   template, class, function, object, enumeration, enumerator,
1070     //   namespace, or type in the same scope (3.3), except as specified
1071     //   in (14.5.4).
1072     Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
1073     Diag(PrevDecl->getLocation(), diag::note_previous_definition);
1074     return true;
1075   }
1076 
1077   // Check the template parameter list of this declaration, possibly
1078   // merging in the template parameter list from the previous class
1079   // template declaration. Skip this check for a friend in a dependent
1080   // context, because the template parameter list might be dependent.
1081   if (!(TUK == TUK_Friend && CurContext->isDependentContext()) &&
1082       CheckTemplateParameterList(
1083           TemplateParams,
1084           PrevClassTemplate ? PrevClassTemplate->getTemplateParameters()
1085                             : nullptr,
1086           (SS.isSet() && SemanticContext && SemanticContext->isRecord() &&
1087            SemanticContext->isDependentContext())
1088               ? TPC_ClassTemplateMember
1089               : TUK == TUK_Friend ? TPC_FriendClassTemplate
1090                                   : TPC_ClassTemplate))
1091     Invalid = true;
1092 
1093   if (SS.isSet()) {
1094     // If the name of the template was qualified, we must be defining the
1095     // template out-of-line.
1096     if (!SS.isInvalid() && !Invalid && !PrevClassTemplate) {
1097       Diag(NameLoc, TUK == TUK_Friend ? diag::err_friend_decl_does_not_match
1098                                       : diag::err_member_decl_does_not_match)
1099         << Name << SemanticContext << /*IsDefinition*/true << SS.getRange();
1100       Invalid = true;
1101     }
1102   }
1103 
1104   CXXRecordDecl *NewClass =
1105     CXXRecordDecl::Create(Context, Kind, SemanticContext, KWLoc, NameLoc, Name,
1106                           PrevClassTemplate?
1107                             PrevClassTemplate->getTemplatedDecl() : nullptr,
1108                           /*DelayTypeCreation=*/true);
1109   SetNestedNameSpecifier(NewClass, SS);
1110   if (NumOuterTemplateParamLists > 0)
1111     NewClass->setTemplateParameterListsInfo(
1112         Context, llvm::makeArrayRef(OuterTemplateParamLists,
1113                                     NumOuterTemplateParamLists));
1114 
1115   // Add alignment attributes if necessary; these attributes are checked when
1116   // the ASTContext lays out the structure.
1117   if (TUK == TUK_Definition) {
1118     AddAlignmentAttributesForRecord(NewClass);
1119     AddMsStructLayoutForRecord(NewClass);
1120   }
1121 
1122   ClassTemplateDecl *NewTemplate
1123     = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
1124                                 DeclarationName(Name), TemplateParams,
1125                                 NewClass, PrevClassTemplate);
1126   NewClass->setDescribedClassTemplate(NewTemplate);
1127 
1128   if (ModulePrivateLoc.isValid())
1129     NewTemplate->setModulePrivate();
1130 
1131   // Build the type for the class template declaration now.
1132   QualType T = NewTemplate->getInjectedClassNameSpecialization();
1133   T = Context.getInjectedClassNameType(NewClass, T);
1134   assert(T->isDependentType() && "Class template type is not dependent?");
1135   (void)T;
1136 
1137   // If we are providing an explicit specialization of a member that is a
1138   // class template, make a note of that.
1139   if (PrevClassTemplate &&
1140       PrevClassTemplate->getInstantiatedFromMemberTemplate())
1141     PrevClassTemplate->setMemberSpecialization();
1142 
1143   // Set the access specifier.
1144   if (!Invalid && TUK != TUK_Friend && NewTemplate->getDeclContext()->isRecord())
1145     SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
1146 
1147   // Set the lexical context of these templates
1148   NewClass->setLexicalDeclContext(CurContext);
1149   NewTemplate->setLexicalDeclContext(CurContext);
1150 
1151   if (TUK == TUK_Definition)
1152     NewClass->startDefinition();
1153 
1154   if (Attr)
1155     ProcessDeclAttributeList(S, NewClass, Attr);
1156 
1157   if (PrevClassTemplate)
1158     mergeDeclAttributes(NewClass, PrevClassTemplate->getTemplatedDecl());
1159 
1160   AddPushedVisibilityAttribute(NewClass);
1161 
1162   if (TUK != TUK_Friend) {
1163     // Per C++ [basic.scope.temp]p2, skip the template parameter scopes.
1164     Scope *Outer = S;
1165     while ((Outer->getFlags() & Scope::TemplateParamScope) != 0)
1166       Outer = Outer->getParent();
1167     PushOnScopeChains(NewTemplate, Outer);
1168   } else {
1169     if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
1170       NewTemplate->setAccess(PrevClassTemplate->getAccess());
1171       NewClass->setAccess(PrevClassTemplate->getAccess());
1172     }
1173 
1174     NewTemplate->setObjectOfFriendDecl();
1175 
1176     // Friend templates are visible in fairly strange ways.
1177     if (!CurContext->isDependentContext()) {
1178       DeclContext *DC = SemanticContext->getRedeclContext();
1179       DC->makeDeclVisibleInContext(NewTemplate);
1180       if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
1181         PushOnScopeChains(NewTemplate, EnclosingScope,
1182                           /* AddToContext = */ false);
1183     }
1184 
1185     FriendDecl *Friend = FriendDecl::Create(
1186         Context, CurContext, NewClass->getLocation(), NewTemplate, FriendLoc);
1187     Friend->setAccess(AS_public);
1188     CurContext->addDecl(Friend);
1189   }
1190 
1191   if (Invalid) {
1192     NewTemplate->setInvalidDecl();
1193     NewClass->setInvalidDecl();
1194   }
1195 
1196   ActOnDocumentableDecl(NewTemplate);
1197 
1198   return NewTemplate;
1199 }
1200 
1201 /// \brief Diagnose the presence of a default template argument on a
1202 /// template parameter, which is ill-formed in certain contexts.
1203 ///
1204 /// \returns true if the default template argument should be dropped.
DiagnoseDefaultTemplateArgument(Sema & S,Sema::TemplateParamListContext TPC,SourceLocation ParamLoc,SourceRange DefArgRange)1205 static bool DiagnoseDefaultTemplateArgument(Sema &S,
1206                                             Sema::TemplateParamListContext TPC,
1207                                             SourceLocation ParamLoc,
1208                                             SourceRange DefArgRange) {
1209   switch (TPC) {
1210   case Sema::TPC_ClassTemplate:
1211   case Sema::TPC_VarTemplate:
1212   case Sema::TPC_TypeAliasTemplate:
1213     return false;
1214 
1215   case Sema::TPC_FunctionTemplate:
1216   case Sema::TPC_FriendFunctionTemplateDefinition:
1217     // C++ [temp.param]p9:
1218     //   A default template-argument shall not be specified in a
1219     //   function template declaration or a function template
1220     //   definition [...]
1221     //   If a friend function template declaration specifies a default
1222     //   template-argument, that declaration shall be a definition and shall be
1223     //   the only declaration of the function template in the translation unit.
1224     // (C++98/03 doesn't have this wording; see DR226).
1225     S.Diag(ParamLoc, S.getLangOpts().CPlusPlus11 ?
1226          diag::warn_cxx98_compat_template_parameter_default_in_function_template
1227            : diag::ext_template_parameter_default_in_function_template)
1228       << DefArgRange;
1229     return false;
1230 
1231   case Sema::TPC_ClassTemplateMember:
1232     // C++0x [temp.param]p9:
1233     //   A default template-argument shall not be specified in the
1234     //   template-parameter-lists of the definition of a member of a
1235     //   class template that appears outside of the member's class.
1236     S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
1237       << DefArgRange;
1238     return true;
1239 
1240   case Sema::TPC_FriendClassTemplate:
1241   case Sema::TPC_FriendFunctionTemplate:
1242     // C++ [temp.param]p9:
1243     //   A default template-argument shall not be specified in a
1244     //   friend template declaration.
1245     S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
1246       << DefArgRange;
1247     return true;
1248 
1249     // FIXME: C++0x [temp.param]p9 allows default template-arguments
1250     // for friend function templates if there is only a single
1251     // declaration (and it is a definition). Strange!
1252   }
1253 
1254   llvm_unreachable("Invalid TemplateParamListContext!");
1255 }
1256 
1257 /// \brief Check for unexpanded parameter packs within the template parameters
1258 /// of a template template parameter, recursively.
DiagnoseUnexpandedParameterPacks(Sema & S,TemplateTemplateParmDecl * TTP)1259 static bool DiagnoseUnexpandedParameterPacks(Sema &S,
1260                                              TemplateTemplateParmDecl *TTP) {
1261   // A template template parameter which is a parameter pack is also a pack
1262   // expansion.
1263   if (TTP->isParameterPack())
1264     return false;
1265 
1266   TemplateParameterList *Params = TTP->getTemplateParameters();
1267   for (unsigned I = 0, N = Params->size(); I != N; ++I) {
1268     NamedDecl *P = Params->getParam(I);
1269     if (NonTypeTemplateParmDecl *NTTP = dyn_cast<NonTypeTemplateParmDecl>(P)) {
1270       if (!NTTP->isParameterPack() &&
1271           S.DiagnoseUnexpandedParameterPack(NTTP->getLocation(),
1272                                             NTTP->getTypeSourceInfo(),
1273                                       Sema::UPPC_NonTypeTemplateParameterType))
1274         return true;
1275 
1276       continue;
1277     }
1278 
1279     if (TemplateTemplateParmDecl *InnerTTP
1280                                         = dyn_cast<TemplateTemplateParmDecl>(P))
1281       if (DiagnoseUnexpandedParameterPacks(S, InnerTTP))
1282         return true;
1283   }
1284 
1285   return false;
1286 }
1287 
1288 /// \brief Checks the validity of a template parameter list, possibly
1289 /// considering the template parameter list from a previous
1290 /// declaration.
1291 ///
1292 /// If an "old" template parameter list is provided, it must be
1293 /// equivalent (per TemplateParameterListsAreEqual) to the "new"
1294 /// template parameter list.
1295 ///
1296 /// \param NewParams Template parameter list for a new template
1297 /// declaration. This template parameter list will be updated with any
1298 /// default arguments that are carried through from the previous
1299 /// template parameter list.
1300 ///
1301 /// \param OldParams If provided, template parameter list from a
1302 /// previous declaration of the same template. Default template
1303 /// arguments will be merged from the old template parameter list to
1304 /// the new template parameter list.
1305 ///
1306 /// \param TPC Describes the context in which we are checking the given
1307 /// template parameter list.
1308 ///
1309 /// \returns true if an error occurred, false otherwise.
CheckTemplateParameterList(TemplateParameterList * NewParams,TemplateParameterList * OldParams,TemplateParamListContext TPC)1310 bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
1311                                       TemplateParameterList *OldParams,
1312                                       TemplateParamListContext TPC) {
1313   bool Invalid = false;
1314 
1315   // C++ [temp.param]p10:
1316   //   The set of default template-arguments available for use with a
1317   //   template declaration or definition is obtained by merging the
1318   //   default arguments from the definition (if in scope) and all
1319   //   declarations in scope in the same way default function
1320   //   arguments are (8.3.6).
1321   bool SawDefaultArgument = false;
1322   SourceLocation PreviousDefaultArgLoc;
1323 
1324   // Dummy initialization to avoid warnings.
1325   TemplateParameterList::iterator OldParam = NewParams->end();
1326   if (OldParams)
1327     OldParam = OldParams->begin();
1328 
1329   bool RemoveDefaultArguments = false;
1330   for (TemplateParameterList::iterator NewParam = NewParams->begin(),
1331                                     NewParamEnd = NewParams->end();
1332        NewParam != NewParamEnd; ++NewParam) {
1333     // Variables used to diagnose redundant default arguments
1334     bool RedundantDefaultArg = false;
1335     SourceLocation OldDefaultLoc;
1336     SourceLocation NewDefaultLoc;
1337 
1338     // Variable used to diagnose missing default arguments
1339     bool MissingDefaultArg = false;
1340 
1341     // Variable used to diagnose non-final parameter packs
1342     bool SawParameterPack = false;
1343 
1344     if (TemplateTypeParmDecl *NewTypeParm
1345           = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
1346       // Check the presence of a default argument here.
1347       if (NewTypeParm->hasDefaultArgument() &&
1348           DiagnoseDefaultTemplateArgument(*this, TPC,
1349                                           NewTypeParm->getLocation(),
1350                NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
1351                                                        .getSourceRange()))
1352         NewTypeParm->removeDefaultArgument();
1353 
1354       // Merge default arguments for template type parameters.
1355       TemplateTypeParmDecl *OldTypeParm
1356           = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : nullptr;
1357       if (NewTypeParm->isParameterPack()) {
1358         assert(!NewTypeParm->hasDefaultArgument() &&
1359                "Parameter packs can't have a default argument!");
1360         SawParameterPack = true;
1361       } else if (OldTypeParm && hasVisibleDefaultArgument(OldTypeParm) &&
1362                  NewTypeParm->hasDefaultArgument()) {
1363         OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
1364         NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
1365         SawDefaultArgument = true;
1366         RedundantDefaultArg = true;
1367         PreviousDefaultArgLoc = NewDefaultLoc;
1368       } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
1369         // Merge the default argument from the old declaration to the
1370         // new declaration.
1371         NewTypeParm->setInheritedDefaultArgument(Context, OldTypeParm);
1372         PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
1373       } else if (NewTypeParm->hasDefaultArgument()) {
1374         SawDefaultArgument = true;
1375         PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
1376       } else if (SawDefaultArgument)
1377         MissingDefaultArg = true;
1378     } else if (NonTypeTemplateParmDecl *NewNonTypeParm
1379                = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
1380       // Check for unexpanded parameter packs.
1381       if (!NewNonTypeParm->isParameterPack() &&
1382           DiagnoseUnexpandedParameterPack(NewNonTypeParm->getLocation(),
1383                                           NewNonTypeParm->getTypeSourceInfo(),
1384                                           UPPC_NonTypeTemplateParameterType)) {
1385         Invalid = true;
1386         continue;
1387       }
1388 
1389       // Check the presence of a default argument here.
1390       if (NewNonTypeParm->hasDefaultArgument() &&
1391           DiagnoseDefaultTemplateArgument(*this, TPC,
1392                                           NewNonTypeParm->getLocation(),
1393                     NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
1394         NewNonTypeParm->removeDefaultArgument();
1395       }
1396 
1397       // Merge default arguments for non-type template parameters
1398       NonTypeTemplateParmDecl *OldNonTypeParm
1399         = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : nullptr;
1400       if (NewNonTypeParm->isParameterPack()) {
1401         assert(!NewNonTypeParm->hasDefaultArgument() &&
1402                "Parameter packs can't have a default argument!");
1403         if (!NewNonTypeParm->isPackExpansion())
1404           SawParameterPack = true;
1405       } else if (OldNonTypeParm && hasVisibleDefaultArgument(OldNonTypeParm) &&
1406                  NewNonTypeParm->hasDefaultArgument()) {
1407         OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
1408         NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
1409         SawDefaultArgument = true;
1410         RedundantDefaultArg = true;
1411         PreviousDefaultArgLoc = NewDefaultLoc;
1412       } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
1413         // Merge the default argument from the old declaration to the
1414         // new declaration.
1415         NewNonTypeParm->setInheritedDefaultArgument(Context, OldNonTypeParm);
1416         PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
1417       } else if (NewNonTypeParm->hasDefaultArgument()) {
1418         SawDefaultArgument = true;
1419         PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
1420       } else if (SawDefaultArgument)
1421         MissingDefaultArg = true;
1422     } else {
1423       TemplateTemplateParmDecl *NewTemplateParm
1424         = cast<TemplateTemplateParmDecl>(*NewParam);
1425 
1426       // Check for unexpanded parameter packs, recursively.
1427       if (::DiagnoseUnexpandedParameterPacks(*this, NewTemplateParm)) {
1428         Invalid = true;
1429         continue;
1430       }
1431 
1432       // Check the presence of a default argument here.
1433       if (NewTemplateParm->hasDefaultArgument() &&
1434           DiagnoseDefaultTemplateArgument(*this, TPC,
1435                                           NewTemplateParm->getLocation(),
1436                      NewTemplateParm->getDefaultArgument().getSourceRange()))
1437         NewTemplateParm->removeDefaultArgument();
1438 
1439       // Merge default arguments for template template parameters
1440       TemplateTemplateParmDecl *OldTemplateParm
1441         = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : nullptr;
1442       if (NewTemplateParm->isParameterPack()) {
1443         assert(!NewTemplateParm->hasDefaultArgument() &&
1444                "Parameter packs can't have a default argument!");
1445         if (!NewTemplateParm->isPackExpansion())
1446           SawParameterPack = true;
1447       } else if (OldTemplateParm &&
1448                  hasVisibleDefaultArgument(OldTemplateParm) &&
1449                  NewTemplateParm->hasDefaultArgument()) {
1450         OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
1451         NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
1452         SawDefaultArgument = true;
1453         RedundantDefaultArg = true;
1454         PreviousDefaultArgLoc = NewDefaultLoc;
1455       } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
1456         // Merge the default argument from the old declaration to the
1457         // new declaration.
1458         NewTemplateParm->setInheritedDefaultArgument(Context, OldTemplateParm);
1459         PreviousDefaultArgLoc
1460           = OldTemplateParm->getDefaultArgument().getLocation();
1461       } else if (NewTemplateParm->hasDefaultArgument()) {
1462         SawDefaultArgument = true;
1463         PreviousDefaultArgLoc
1464           = NewTemplateParm->getDefaultArgument().getLocation();
1465       } else if (SawDefaultArgument)
1466         MissingDefaultArg = true;
1467     }
1468 
1469     // C++11 [temp.param]p11:
1470     //   If a template parameter of a primary class template or alias template
1471     //   is a template parameter pack, it shall be the last template parameter.
1472     if (SawParameterPack && (NewParam + 1) != NewParamEnd &&
1473         (TPC == TPC_ClassTemplate || TPC == TPC_VarTemplate ||
1474          TPC == TPC_TypeAliasTemplate)) {
1475       Diag((*NewParam)->getLocation(),
1476            diag::err_template_param_pack_must_be_last_template_parameter);
1477       Invalid = true;
1478     }
1479 
1480     if (RedundantDefaultArg) {
1481       // C++ [temp.param]p12:
1482       //   A template-parameter shall not be given default arguments
1483       //   by two different declarations in the same scope.
1484       Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
1485       Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
1486       Invalid = true;
1487     } else if (MissingDefaultArg && TPC != TPC_FunctionTemplate) {
1488       // C++ [temp.param]p11:
1489       //   If a template-parameter of a class template has a default
1490       //   template-argument, each subsequent template-parameter shall either
1491       //   have a default template-argument supplied or be a template parameter
1492       //   pack.
1493       Diag((*NewParam)->getLocation(),
1494            diag::err_template_param_default_arg_missing);
1495       Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
1496       Invalid = true;
1497       RemoveDefaultArguments = true;
1498     }
1499 
1500     // If we have an old template parameter list that we're merging
1501     // in, move on to the next parameter.
1502     if (OldParams)
1503       ++OldParam;
1504   }
1505 
1506   // We were missing some default arguments at the end of the list, so remove
1507   // all of the default arguments.
1508   if (RemoveDefaultArguments) {
1509     for (TemplateParameterList::iterator NewParam = NewParams->begin(),
1510                                       NewParamEnd = NewParams->end();
1511          NewParam != NewParamEnd; ++NewParam) {
1512       if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*NewParam))
1513         TTP->removeDefaultArgument();
1514       else if (NonTypeTemplateParmDecl *NTTP
1515                                 = dyn_cast<NonTypeTemplateParmDecl>(*NewParam))
1516         NTTP->removeDefaultArgument();
1517       else
1518         cast<TemplateTemplateParmDecl>(*NewParam)->removeDefaultArgument();
1519     }
1520   }
1521 
1522   return Invalid;
1523 }
1524 
1525 namespace {
1526 
1527 /// A class which looks for a use of a certain level of template
1528 /// parameter.
1529 struct DependencyChecker : RecursiveASTVisitor<DependencyChecker> {
1530   typedef RecursiveASTVisitor<DependencyChecker> super;
1531 
1532   unsigned Depth;
1533   bool Match;
1534   SourceLocation MatchLoc;
1535 
DependencyChecker__anonbf9851720111::DependencyChecker1536   DependencyChecker(unsigned Depth) : Depth(Depth), Match(false) {}
1537 
DependencyChecker__anonbf9851720111::DependencyChecker1538   DependencyChecker(TemplateParameterList *Params) : Match(false) {
1539     NamedDecl *ND = Params->getParam(0);
1540     if (TemplateTypeParmDecl *PD = dyn_cast<TemplateTypeParmDecl>(ND)) {
1541       Depth = PD->getDepth();
1542     } else if (NonTypeTemplateParmDecl *PD =
1543                  dyn_cast<NonTypeTemplateParmDecl>(ND)) {
1544       Depth = PD->getDepth();
1545     } else {
1546       Depth = cast<TemplateTemplateParmDecl>(ND)->getDepth();
1547     }
1548   }
1549 
Matches__anonbf9851720111::DependencyChecker1550   bool Matches(unsigned ParmDepth, SourceLocation Loc = SourceLocation()) {
1551     if (ParmDepth >= Depth) {
1552       Match = true;
1553       MatchLoc = Loc;
1554       return true;
1555     }
1556     return false;
1557   }
1558 
VisitTemplateTypeParmTypeLoc__anonbf9851720111::DependencyChecker1559   bool VisitTemplateTypeParmTypeLoc(TemplateTypeParmTypeLoc TL) {
1560     return !Matches(TL.getTypePtr()->getDepth(), TL.getNameLoc());
1561   }
1562 
VisitTemplateTypeParmType__anonbf9851720111::DependencyChecker1563   bool VisitTemplateTypeParmType(const TemplateTypeParmType *T) {
1564     return !Matches(T->getDepth());
1565   }
1566 
TraverseTemplateName__anonbf9851720111::DependencyChecker1567   bool TraverseTemplateName(TemplateName N) {
1568     if (TemplateTemplateParmDecl *PD =
1569           dyn_cast_or_null<TemplateTemplateParmDecl>(N.getAsTemplateDecl()))
1570       if (Matches(PD->getDepth()))
1571         return false;
1572     return super::TraverseTemplateName(N);
1573   }
1574 
VisitDeclRefExpr__anonbf9851720111::DependencyChecker1575   bool VisitDeclRefExpr(DeclRefExpr *E) {
1576     if (NonTypeTemplateParmDecl *PD =
1577           dyn_cast<NonTypeTemplateParmDecl>(E->getDecl()))
1578       if (Matches(PD->getDepth(), E->getExprLoc()))
1579         return false;
1580     return super::VisitDeclRefExpr(E);
1581   }
1582 
VisitSubstTemplateTypeParmType__anonbf9851720111::DependencyChecker1583   bool VisitSubstTemplateTypeParmType(const SubstTemplateTypeParmType *T) {
1584     return TraverseType(T->getReplacementType());
1585   }
1586 
1587   bool
VisitSubstTemplateTypeParmPackType__anonbf9851720111::DependencyChecker1588   VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *T) {
1589     return TraverseTemplateArgument(T->getArgumentPack());
1590   }
1591 
TraverseInjectedClassNameType__anonbf9851720111::DependencyChecker1592   bool TraverseInjectedClassNameType(const InjectedClassNameType *T) {
1593     return TraverseType(T->getInjectedSpecializationType());
1594   }
1595 };
1596 } // end anonymous namespace
1597 
1598 /// Determines whether a given type depends on the given parameter
1599 /// list.
1600 static bool
DependsOnTemplateParameters(QualType T,TemplateParameterList * Params)1601 DependsOnTemplateParameters(QualType T, TemplateParameterList *Params) {
1602   DependencyChecker Checker(Params);
1603   Checker.TraverseType(T);
1604   return Checker.Match;
1605 }
1606 
1607 // Find the source range corresponding to the named type in the given
1608 // nested-name-specifier, if any.
getRangeOfTypeInNestedNameSpecifier(ASTContext & Context,QualType T,const CXXScopeSpec & SS)1609 static SourceRange getRangeOfTypeInNestedNameSpecifier(ASTContext &Context,
1610                                                        QualType T,
1611                                                        const CXXScopeSpec &SS) {
1612   NestedNameSpecifierLoc NNSLoc(SS.getScopeRep(), SS.location_data());
1613   while (NestedNameSpecifier *NNS = NNSLoc.getNestedNameSpecifier()) {
1614     if (const Type *CurType = NNS->getAsType()) {
1615       if (Context.hasSameUnqualifiedType(T, QualType(CurType, 0)))
1616         return NNSLoc.getTypeLoc().getSourceRange();
1617     } else
1618       break;
1619 
1620     NNSLoc = NNSLoc.getPrefix();
1621   }
1622 
1623   return SourceRange();
1624 }
1625 
1626 /// \brief Match the given template parameter lists to the given scope
1627 /// specifier, returning the template parameter list that applies to the
1628 /// name.
1629 ///
1630 /// \param DeclStartLoc the start of the declaration that has a scope
1631 /// specifier or a template parameter list.
1632 ///
1633 /// \param DeclLoc The location of the declaration itself.
1634 ///
1635 /// \param SS the scope specifier that will be matched to the given template
1636 /// parameter lists. This scope specifier precedes a qualified name that is
1637 /// being declared.
1638 ///
1639 /// \param TemplateId The template-id following the scope specifier, if there
1640 /// is one. Used to check for a missing 'template<>'.
1641 ///
1642 /// \param ParamLists the template parameter lists, from the outermost to the
1643 /// innermost template parameter lists.
1644 ///
1645 /// \param IsFriend Whether to apply the slightly different rules for
1646 /// matching template parameters to scope specifiers in friend
1647 /// declarations.
1648 ///
1649 /// \param IsExplicitSpecialization will be set true if the entity being
1650 /// declared is an explicit specialization, false otherwise.
1651 ///
1652 /// \returns the template parameter list, if any, that corresponds to the
1653 /// name that is preceded by the scope specifier @p SS. This template
1654 /// parameter list may have template parameters (if we're declaring a
1655 /// template) or may have no template parameters (if we're declaring a
1656 /// template specialization), or may be NULL (if what we're declaring isn't
1657 /// itself a template).
MatchTemplateParametersToScopeSpecifier(SourceLocation DeclStartLoc,SourceLocation DeclLoc,const CXXScopeSpec & SS,TemplateIdAnnotation * TemplateId,ArrayRef<TemplateParameterList * > ParamLists,bool IsFriend,bool & IsExplicitSpecialization,bool & Invalid)1658 TemplateParameterList *Sema::MatchTemplateParametersToScopeSpecifier(
1659     SourceLocation DeclStartLoc, SourceLocation DeclLoc, const CXXScopeSpec &SS,
1660     TemplateIdAnnotation *TemplateId,
1661     ArrayRef<TemplateParameterList *> ParamLists, bool IsFriend,
1662     bool &IsExplicitSpecialization, bool &Invalid) {
1663   IsExplicitSpecialization = false;
1664   Invalid = false;
1665 
1666   // The sequence of nested types to which we will match up the template
1667   // parameter lists. We first build this list by starting with the type named
1668   // by the nested-name-specifier and walking out until we run out of types.
1669   SmallVector<QualType, 4> NestedTypes;
1670   QualType T;
1671   if (SS.getScopeRep()) {
1672     if (CXXRecordDecl *Record
1673               = dyn_cast_or_null<CXXRecordDecl>(computeDeclContext(SS, true)))
1674       T = Context.getTypeDeclType(Record);
1675     else
1676       T = QualType(SS.getScopeRep()->getAsType(), 0);
1677   }
1678 
1679   // If we found an explicit specialization that prevents us from needing
1680   // 'template<>' headers, this will be set to the location of that
1681   // explicit specialization.
1682   SourceLocation ExplicitSpecLoc;
1683 
1684   while (!T.isNull()) {
1685     NestedTypes.push_back(T);
1686 
1687     // Retrieve the parent of a record type.
1688     if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
1689       // If this type is an explicit specialization, we're done.
1690       if (ClassTemplateSpecializationDecl *Spec
1691           = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
1692         if (!isa<ClassTemplatePartialSpecializationDecl>(Spec) &&
1693             Spec->getSpecializationKind() == TSK_ExplicitSpecialization) {
1694           ExplicitSpecLoc = Spec->getLocation();
1695           break;
1696         }
1697       } else if (Record->getTemplateSpecializationKind()
1698                                                 == TSK_ExplicitSpecialization) {
1699         ExplicitSpecLoc = Record->getLocation();
1700         break;
1701       }
1702 
1703       if (TypeDecl *Parent = dyn_cast<TypeDecl>(Record->getParent()))
1704         T = Context.getTypeDeclType(Parent);
1705       else
1706         T = QualType();
1707       continue;
1708     }
1709 
1710     if (const TemplateSpecializationType *TST
1711                                      = T->getAs<TemplateSpecializationType>()) {
1712       if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
1713         if (TypeDecl *Parent = dyn_cast<TypeDecl>(Template->getDeclContext()))
1714           T = Context.getTypeDeclType(Parent);
1715         else
1716           T = QualType();
1717         continue;
1718       }
1719     }
1720 
1721     // Look one step prior in a dependent template specialization type.
1722     if (const DependentTemplateSpecializationType *DependentTST
1723                           = T->getAs<DependentTemplateSpecializationType>()) {
1724       if (NestedNameSpecifier *NNS = DependentTST->getQualifier())
1725         T = QualType(NNS->getAsType(), 0);
1726       else
1727         T = QualType();
1728       continue;
1729     }
1730 
1731     // Look one step prior in a dependent name type.
1732     if (const DependentNameType *DependentName = T->getAs<DependentNameType>()){
1733       if (NestedNameSpecifier *NNS = DependentName->getQualifier())
1734         T = QualType(NNS->getAsType(), 0);
1735       else
1736         T = QualType();
1737       continue;
1738     }
1739 
1740     // Retrieve the parent of an enumeration type.
1741     if (const EnumType *EnumT = T->getAs<EnumType>()) {
1742       // FIXME: Forward-declared enums require a TSK_ExplicitSpecialization
1743       // check here.
1744       EnumDecl *Enum = EnumT->getDecl();
1745 
1746       // Get to the parent type.
1747       if (TypeDecl *Parent = dyn_cast<TypeDecl>(Enum->getParent()))
1748         T = Context.getTypeDeclType(Parent);
1749       else
1750         T = QualType();
1751       continue;
1752     }
1753 
1754     T = QualType();
1755   }
1756   // Reverse the nested types list, since we want to traverse from the outermost
1757   // to the innermost while checking template-parameter-lists.
1758   std::reverse(NestedTypes.begin(), NestedTypes.end());
1759 
1760   // C++0x [temp.expl.spec]p17:
1761   //   A member or a member template may be nested within many
1762   //   enclosing class templates. In an explicit specialization for
1763   //   such a member, the member declaration shall be preceded by a
1764   //   template<> for each enclosing class template that is
1765   //   explicitly specialized.
1766   bool SawNonEmptyTemplateParameterList = false;
1767 
1768   auto CheckExplicitSpecialization = [&](SourceRange Range, bool Recovery) {
1769     if (SawNonEmptyTemplateParameterList) {
1770       Diag(DeclLoc, diag::err_specialize_member_of_template)
1771         << !Recovery << Range;
1772       Invalid = true;
1773       IsExplicitSpecialization = false;
1774       return true;
1775     }
1776 
1777     return false;
1778   };
1779 
1780   auto DiagnoseMissingExplicitSpecialization = [&] (SourceRange Range) {
1781     // Check that we can have an explicit specialization here.
1782     if (CheckExplicitSpecialization(Range, true))
1783       return true;
1784 
1785     // We don't have a template header, but we should.
1786     SourceLocation ExpectedTemplateLoc;
1787     if (!ParamLists.empty())
1788       ExpectedTemplateLoc = ParamLists[0]->getTemplateLoc();
1789     else
1790       ExpectedTemplateLoc = DeclStartLoc;
1791 
1792     Diag(DeclLoc, diag::err_template_spec_needs_header)
1793       << Range
1794       << FixItHint::CreateInsertion(ExpectedTemplateLoc, "template<> ");
1795     return false;
1796   };
1797 
1798   unsigned ParamIdx = 0;
1799   for (unsigned TypeIdx = 0, NumTypes = NestedTypes.size(); TypeIdx != NumTypes;
1800        ++TypeIdx) {
1801     T = NestedTypes[TypeIdx];
1802 
1803     // Whether we expect a 'template<>' header.
1804     bool NeedEmptyTemplateHeader = false;
1805 
1806     // Whether we expect a template header with parameters.
1807     bool NeedNonemptyTemplateHeader = false;
1808 
1809     // For a dependent type, the set of template parameters that we
1810     // expect to see.
1811     TemplateParameterList *ExpectedTemplateParams = nullptr;
1812 
1813     // C++0x [temp.expl.spec]p15:
1814     //   A member or a member template may be nested within many enclosing
1815     //   class templates. In an explicit specialization for such a member, the
1816     //   member declaration shall be preceded by a template<> for each
1817     //   enclosing class template that is explicitly specialized.
1818     if (CXXRecordDecl *Record = T->getAsCXXRecordDecl()) {
1819       if (ClassTemplatePartialSpecializationDecl *Partial
1820             = dyn_cast<ClassTemplatePartialSpecializationDecl>(Record)) {
1821         ExpectedTemplateParams = Partial->getTemplateParameters();
1822         NeedNonemptyTemplateHeader = true;
1823       } else if (Record->isDependentType()) {
1824         if (Record->getDescribedClassTemplate()) {
1825           ExpectedTemplateParams = Record->getDescribedClassTemplate()
1826                                                       ->getTemplateParameters();
1827           NeedNonemptyTemplateHeader = true;
1828         }
1829       } else if (ClassTemplateSpecializationDecl *Spec
1830                      = dyn_cast<ClassTemplateSpecializationDecl>(Record)) {
1831         // C++0x [temp.expl.spec]p4:
1832         //   Members of an explicitly specialized class template are defined
1833         //   in the same manner as members of normal classes, and not using
1834         //   the template<> syntax.
1835         if (Spec->getSpecializationKind() != TSK_ExplicitSpecialization)
1836           NeedEmptyTemplateHeader = true;
1837         else
1838           continue;
1839       } else if (Record->getTemplateSpecializationKind()) {
1840         if (Record->getTemplateSpecializationKind()
1841                                                 != TSK_ExplicitSpecialization &&
1842             TypeIdx == NumTypes - 1)
1843           IsExplicitSpecialization = true;
1844 
1845         continue;
1846       }
1847     } else if (const TemplateSpecializationType *TST
1848                                      = T->getAs<TemplateSpecializationType>()) {
1849       if (TemplateDecl *Template = TST->getTemplateName().getAsTemplateDecl()) {
1850         ExpectedTemplateParams = Template->getTemplateParameters();
1851         NeedNonemptyTemplateHeader = true;
1852       }
1853     } else if (T->getAs<DependentTemplateSpecializationType>()) {
1854       // FIXME:  We actually could/should check the template arguments here
1855       // against the corresponding template parameter list.
1856       NeedNonemptyTemplateHeader = false;
1857     }
1858 
1859     // C++ [temp.expl.spec]p16:
1860     //   In an explicit specialization declaration for a member of a class
1861     //   template or a member template that ap- pears in namespace scope, the
1862     //   member template and some of its enclosing class templates may remain
1863     //   unspecialized, except that the declaration shall not explicitly
1864     //   specialize a class member template if its en- closing class templates
1865     //   are not explicitly specialized as well.
1866     if (ParamIdx < ParamLists.size()) {
1867       if (ParamLists[ParamIdx]->size() == 0) {
1868         if (CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
1869                                         false))
1870           return nullptr;
1871       } else
1872         SawNonEmptyTemplateParameterList = true;
1873     }
1874 
1875     if (NeedEmptyTemplateHeader) {
1876       // If we're on the last of the types, and we need a 'template<>' header
1877       // here, then it's an explicit specialization.
1878       if (TypeIdx == NumTypes - 1)
1879         IsExplicitSpecialization = true;
1880 
1881       if (ParamIdx < ParamLists.size()) {
1882         if (ParamLists[ParamIdx]->size() > 0) {
1883           // The header has template parameters when it shouldn't. Complain.
1884           Diag(ParamLists[ParamIdx]->getTemplateLoc(),
1885                diag::err_template_param_list_matches_nontemplate)
1886             << T
1887             << SourceRange(ParamLists[ParamIdx]->getLAngleLoc(),
1888                            ParamLists[ParamIdx]->getRAngleLoc())
1889             << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
1890           Invalid = true;
1891           return nullptr;
1892         }
1893 
1894         // Consume this template header.
1895         ++ParamIdx;
1896         continue;
1897       }
1898 
1899       if (!IsFriend)
1900         if (DiagnoseMissingExplicitSpecialization(
1901                 getRangeOfTypeInNestedNameSpecifier(Context, T, SS)))
1902           return nullptr;
1903 
1904       continue;
1905     }
1906 
1907     if (NeedNonemptyTemplateHeader) {
1908       // In friend declarations we can have template-ids which don't
1909       // depend on the corresponding template parameter lists.  But
1910       // assume that empty parameter lists are supposed to match this
1911       // template-id.
1912       if (IsFriend && T->isDependentType()) {
1913         if (ParamIdx < ParamLists.size() &&
1914             DependsOnTemplateParameters(T, ParamLists[ParamIdx]))
1915           ExpectedTemplateParams = nullptr;
1916         else
1917           continue;
1918       }
1919 
1920       if (ParamIdx < ParamLists.size()) {
1921         // Check the template parameter list, if we can.
1922         if (ExpectedTemplateParams &&
1923             !TemplateParameterListsAreEqual(ParamLists[ParamIdx],
1924                                             ExpectedTemplateParams,
1925                                             true, TPL_TemplateMatch))
1926           Invalid = true;
1927 
1928         if (!Invalid &&
1929             CheckTemplateParameterList(ParamLists[ParamIdx], nullptr,
1930                                        TPC_ClassTemplateMember))
1931           Invalid = true;
1932 
1933         ++ParamIdx;
1934         continue;
1935       }
1936 
1937       Diag(DeclLoc, diag::err_template_spec_needs_template_parameters)
1938         << T
1939         << getRangeOfTypeInNestedNameSpecifier(Context, T, SS);
1940       Invalid = true;
1941       continue;
1942     }
1943   }
1944 
1945   // If there were at least as many template-ids as there were template
1946   // parameter lists, then there are no template parameter lists remaining for
1947   // the declaration itself.
1948   if (ParamIdx >= ParamLists.size()) {
1949     if (TemplateId && !IsFriend) {
1950       // We don't have a template header for the declaration itself, but we
1951       // should.
1952       IsExplicitSpecialization = true;
1953       DiagnoseMissingExplicitSpecialization(SourceRange(TemplateId->LAngleLoc,
1954                                                         TemplateId->RAngleLoc));
1955 
1956       // Fabricate an empty template parameter list for the invented header.
1957       return TemplateParameterList::Create(Context, SourceLocation(),
1958                                            SourceLocation(), None,
1959                                            SourceLocation());
1960     }
1961 
1962     return nullptr;
1963   }
1964 
1965   // If there were too many template parameter lists, complain about that now.
1966   if (ParamIdx < ParamLists.size() - 1) {
1967     bool HasAnyExplicitSpecHeader = false;
1968     bool AllExplicitSpecHeaders = true;
1969     for (unsigned I = ParamIdx, E = ParamLists.size() - 1; I != E; ++I) {
1970       if (ParamLists[I]->size() == 0)
1971         HasAnyExplicitSpecHeader = true;
1972       else
1973         AllExplicitSpecHeaders = false;
1974     }
1975 
1976     Diag(ParamLists[ParamIdx]->getTemplateLoc(),
1977          AllExplicitSpecHeaders ? diag::warn_template_spec_extra_headers
1978                                 : diag::err_template_spec_extra_headers)
1979         << SourceRange(ParamLists[ParamIdx]->getTemplateLoc(),
1980                        ParamLists[ParamLists.size() - 2]->getRAngleLoc());
1981 
1982     // If there was a specialization somewhere, such that 'template<>' is
1983     // not required, and there were any 'template<>' headers, note where the
1984     // specialization occurred.
1985     if (ExplicitSpecLoc.isValid() && HasAnyExplicitSpecHeader)
1986       Diag(ExplicitSpecLoc,
1987            diag::note_explicit_template_spec_does_not_need_header)
1988         << NestedTypes.back();
1989 
1990     // We have a template parameter list with no corresponding scope, which
1991     // means that the resulting template declaration can't be instantiated
1992     // properly (we'll end up with dependent nodes when we shouldn't).
1993     if (!AllExplicitSpecHeaders)
1994       Invalid = true;
1995   }
1996 
1997   // C++ [temp.expl.spec]p16:
1998   //   In an explicit specialization declaration for a member of a class
1999   //   template or a member template that ap- pears in namespace scope, the
2000   //   member template and some of its enclosing class templates may remain
2001   //   unspecialized, except that the declaration shall not explicitly
2002   //   specialize a class member template if its en- closing class templates
2003   //   are not explicitly specialized as well.
2004   if (ParamLists.back()->size() == 0 &&
2005       CheckExplicitSpecialization(ParamLists[ParamIdx]->getSourceRange(),
2006                                   false))
2007     return nullptr;
2008 
2009   // Return the last template parameter list, which corresponds to the
2010   // entity being declared.
2011   return ParamLists.back();
2012 }
2013 
NoteAllFoundTemplates(TemplateName Name)2014 void Sema::NoteAllFoundTemplates(TemplateName Name) {
2015   if (TemplateDecl *Template = Name.getAsTemplateDecl()) {
2016     Diag(Template->getLocation(), diag::note_template_declared_here)
2017         << (isa<FunctionTemplateDecl>(Template)
2018                 ? 0
2019                 : isa<ClassTemplateDecl>(Template)
2020                       ? 1
2021                       : isa<VarTemplateDecl>(Template)
2022                             ? 2
2023                             : isa<TypeAliasTemplateDecl>(Template) ? 3 : 4)
2024         << Template->getDeclName();
2025     return;
2026   }
2027 
2028   if (OverloadedTemplateStorage *OST = Name.getAsOverloadedTemplate()) {
2029     for (OverloadedTemplateStorage::iterator I = OST->begin(),
2030                                           IEnd = OST->end();
2031          I != IEnd; ++I)
2032       Diag((*I)->getLocation(), diag::note_template_declared_here)
2033         << 0 << (*I)->getDeclName();
2034 
2035     return;
2036   }
2037 }
2038 
2039 static QualType
checkBuiltinTemplateIdType(Sema & SemaRef,BuiltinTemplateDecl * BTD,const SmallVectorImpl<TemplateArgument> & Converted,SourceLocation TemplateLoc,TemplateArgumentListInfo & TemplateArgs)2040 checkBuiltinTemplateIdType(Sema &SemaRef, BuiltinTemplateDecl *BTD,
2041                            const SmallVectorImpl<TemplateArgument> &Converted,
2042                            SourceLocation TemplateLoc,
2043                            TemplateArgumentListInfo &TemplateArgs) {
2044   ASTContext &Context = SemaRef.getASTContext();
2045   switch (BTD->getBuiltinTemplateKind()) {
2046   case BTK__make_integer_seq: {
2047     // Specializations of __make_integer_seq<S, T, N> are treated like
2048     // S<T, 0, ..., N-1>.
2049 
2050     // C++14 [inteseq.intseq]p1:
2051     //   T shall be an integer type.
2052     if (!Converted[1].getAsType()->isIntegralType(Context)) {
2053       SemaRef.Diag(TemplateArgs[1].getLocation(),
2054                    diag::err_integer_sequence_integral_element_type);
2055       return QualType();
2056     }
2057 
2058     // C++14 [inteseq.make]p1:
2059     //   If N is negative the program is ill-formed.
2060     TemplateArgument NumArgsArg = Converted[2];
2061     llvm::APSInt NumArgs = NumArgsArg.getAsIntegral();
2062     if (NumArgs < 0) {
2063       SemaRef.Diag(TemplateArgs[2].getLocation(),
2064                    diag::err_integer_sequence_negative_length);
2065       return QualType();
2066     }
2067 
2068     QualType ArgTy = NumArgsArg.getIntegralType();
2069     TemplateArgumentListInfo SyntheticTemplateArgs;
2070     // The type argument gets reused as the first template argument in the
2071     // synthetic template argument list.
2072     SyntheticTemplateArgs.addArgument(TemplateArgs[1]);
2073     // Expand N into 0 ... N-1.
2074     for (llvm::APSInt I(NumArgs.getBitWidth(), NumArgs.isUnsigned());
2075          I < NumArgs; ++I) {
2076       TemplateArgument TA(Context, I, ArgTy);
2077       Expr *E = SemaRef.BuildExpressionFromIntegralTemplateArgument(
2078                            TA, TemplateArgs[2].getLocation())
2079                     .getAs<Expr>();
2080       SyntheticTemplateArgs.addArgument(
2081           TemplateArgumentLoc(TemplateArgument(E), E));
2082     }
2083     // The first template argument will be reused as the template decl that
2084     // our synthetic template arguments will be applied to.
2085     return SemaRef.CheckTemplateIdType(Converted[0].getAsTemplate(),
2086                                        TemplateLoc, SyntheticTemplateArgs);
2087   }
2088 
2089   case BTK__type_pack_element:
2090     // Specializations of
2091     //    __type_pack_element<Index, T_1, ..., T_N>
2092     // are treated like T_Index.
2093     assert(Converted.size() == 2 &&
2094       "__type_pack_element should be given an index and a parameter pack");
2095 
2096     // If the Index is out of bounds, the program is ill-formed.
2097     TemplateArgument IndexArg = Converted[0], Ts = Converted[1];
2098     llvm::APSInt Index = IndexArg.getAsIntegral();
2099     assert(Index >= 0 && "the index used with __type_pack_element should be of "
2100                          "type std::size_t, and hence be non-negative");
2101     if (Index >= Ts.pack_size()) {
2102       SemaRef.Diag(TemplateArgs[0].getLocation(),
2103                    diag::err_type_pack_element_out_of_bounds);
2104       return QualType();
2105     }
2106 
2107     // We simply return the type at index `Index`.
2108     auto Nth = std::next(Ts.pack_begin(), Index.getExtValue());
2109     return Nth->getAsType();
2110   }
2111   llvm_unreachable("unexpected BuiltinTemplateDecl!");
2112 }
2113 
CheckTemplateIdType(TemplateName Name,SourceLocation TemplateLoc,TemplateArgumentListInfo & TemplateArgs)2114 QualType Sema::CheckTemplateIdType(TemplateName Name,
2115                                    SourceLocation TemplateLoc,
2116                                    TemplateArgumentListInfo &TemplateArgs) {
2117   DependentTemplateName *DTN
2118     = Name.getUnderlying().getAsDependentTemplateName();
2119   if (DTN && DTN->isIdentifier())
2120     // When building a template-id where the template-name is dependent,
2121     // assume the template is a type template. Either our assumption is
2122     // correct, or the code is ill-formed and will be diagnosed when the
2123     // dependent name is substituted.
2124     return Context.getDependentTemplateSpecializationType(ETK_None,
2125                                                           DTN->getQualifier(),
2126                                                           DTN->getIdentifier(),
2127                                                           TemplateArgs);
2128 
2129   TemplateDecl *Template = Name.getAsTemplateDecl();
2130   if (!Template || isa<FunctionTemplateDecl>(Template) ||
2131       isa<VarTemplateDecl>(Template)) {
2132     // We might have a substituted template template parameter pack. If so,
2133     // build a template specialization type for it.
2134     if (Name.getAsSubstTemplateTemplateParmPack())
2135       return Context.getTemplateSpecializationType(Name, TemplateArgs);
2136 
2137     Diag(TemplateLoc, diag::err_template_id_not_a_type)
2138       << Name;
2139     NoteAllFoundTemplates(Name);
2140     return QualType();
2141   }
2142 
2143   // Check that the template argument list is well-formed for this
2144   // template.
2145   SmallVector<TemplateArgument, 4> Converted;
2146   if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
2147                                 false, Converted))
2148     return QualType();
2149 
2150   QualType CanonType;
2151 
2152   bool InstantiationDependent = false;
2153   if (TypeAliasTemplateDecl *AliasTemplate =
2154           dyn_cast<TypeAliasTemplateDecl>(Template)) {
2155     // Find the canonical type for this type alias template specialization.
2156     TypeAliasDecl *Pattern = AliasTemplate->getTemplatedDecl();
2157     if (Pattern->isInvalidDecl())
2158       return QualType();
2159 
2160     TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
2161                                       Converted);
2162 
2163     // Only substitute for the innermost template argument list.
2164     MultiLevelTemplateArgumentList TemplateArgLists;
2165     TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
2166     unsigned Depth = AliasTemplate->getTemplateParameters()->getDepth();
2167     for (unsigned I = 0; I < Depth; ++I)
2168       TemplateArgLists.addOuterTemplateArguments(None);
2169 
2170     LocalInstantiationScope Scope(*this);
2171     InstantiatingTemplate Inst(*this, TemplateLoc, Template);
2172     if (Inst.isInvalid())
2173       return QualType();
2174 
2175     CanonType = SubstType(Pattern->getUnderlyingType(),
2176                           TemplateArgLists, AliasTemplate->getLocation(),
2177                           AliasTemplate->getDeclName());
2178     if (CanonType.isNull())
2179       return QualType();
2180   } else if (Name.isDependent() ||
2181              TemplateSpecializationType::anyDependentTemplateArguments(
2182                TemplateArgs, InstantiationDependent)) {
2183     // This class template specialization is a dependent
2184     // type. Therefore, its canonical type is another class template
2185     // specialization type that contains all of the converted
2186     // arguments in canonical form. This ensures that, e.g., A<T> and
2187     // A<T, T> have identical types when A is declared as:
2188     //
2189     //   template<typename T, typename U = T> struct A;
2190     TemplateName CanonName = Context.getCanonicalTemplateName(Name);
2191     CanonType = Context.getTemplateSpecializationType(CanonName,
2192                                                       Converted);
2193 
2194     // FIXME: CanonType is not actually the canonical type, and unfortunately
2195     // it is a TemplateSpecializationType that we will never use again.
2196     // In the future, we need to teach getTemplateSpecializationType to only
2197     // build the canonical type and return that to us.
2198     CanonType = Context.getCanonicalType(CanonType);
2199 
2200     // This might work out to be a current instantiation, in which
2201     // case the canonical type needs to be the InjectedClassNameType.
2202     //
2203     // TODO: in theory this could be a simple hashtable lookup; most
2204     // changes to CurContext don't change the set of current
2205     // instantiations.
2206     if (isa<ClassTemplateDecl>(Template)) {
2207       for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
2208         // If we get out to a namespace, we're done.
2209         if (Ctx->isFileContext()) break;
2210 
2211         // If this isn't a record, keep looking.
2212         CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
2213         if (!Record) continue;
2214 
2215         // Look for one of the two cases with InjectedClassNameTypes
2216         // and check whether it's the same template.
2217         if (!isa<ClassTemplatePartialSpecializationDecl>(Record) &&
2218             !Record->getDescribedClassTemplate())
2219           continue;
2220 
2221         // Fetch the injected class name type and check whether its
2222         // injected type is equal to the type we just built.
2223         QualType ICNT = Context.getTypeDeclType(Record);
2224         QualType Injected = cast<InjectedClassNameType>(ICNT)
2225           ->getInjectedSpecializationType();
2226 
2227         if (CanonType != Injected->getCanonicalTypeInternal())
2228           continue;
2229 
2230         // If so, the canonical type of this TST is the injected
2231         // class name type of the record we just found.
2232         assert(ICNT.isCanonical());
2233         CanonType = ICNT;
2234         break;
2235       }
2236     }
2237   } else if (ClassTemplateDecl *ClassTemplate
2238                = dyn_cast<ClassTemplateDecl>(Template)) {
2239     // Find the class template specialization declaration that
2240     // corresponds to these arguments.
2241     void *InsertPos = nullptr;
2242     ClassTemplateSpecializationDecl *Decl
2243       = ClassTemplate->findSpecialization(Converted, InsertPos);
2244     if (!Decl) {
2245       // This is the first time we have referenced this class template
2246       // specialization. Create the canonical declaration and add it to
2247       // the set of specializations.
2248       Decl = ClassTemplateSpecializationDecl::Create(Context,
2249                             ClassTemplate->getTemplatedDecl()->getTagKind(),
2250                                                 ClassTemplate->getDeclContext(),
2251                             ClassTemplate->getTemplatedDecl()->getLocStart(),
2252                                                 ClassTemplate->getLocation(),
2253                                                      ClassTemplate,
2254                                                      Converted, nullptr);
2255       ClassTemplate->AddSpecialization(Decl, InsertPos);
2256       if (ClassTemplate->isOutOfLine())
2257         Decl->setLexicalDeclContext(ClassTemplate->getLexicalDeclContext());
2258     }
2259 
2260     // Diagnose uses of this specialization.
2261     (void)DiagnoseUseOfDecl(Decl, TemplateLoc);
2262 
2263     CanonType = Context.getTypeDeclType(Decl);
2264     assert(isa<RecordType>(CanonType) &&
2265            "type of non-dependent specialization is not a RecordType");
2266   } else if (auto *BTD = dyn_cast<BuiltinTemplateDecl>(Template)) {
2267     CanonType = checkBuiltinTemplateIdType(*this, BTD, Converted, TemplateLoc,
2268                                            TemplateArgs);
2269   }
2270 
2271   // Build the fully-sugared type for this class template
2272   // specialization, which refers back to the class template
2273   // specialization we created or found.
2274   return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
2275 }
2276 
2277 TypeResult
ActOnTemplateIdType(CXXScopeSpec & SS,SourceLocation TemplateKWLoc,TemplateTy TemplateD,SourceLocation TemplateLoc,SourceLocation LAngleLoc,ASTTemplateArgsPtr TemplateArgsIn,SourceLocation RAngleLoc,bool IsCtorOrDtorName)2278 Sema::ActOnTemplateIdType(CXXScopeSpec &SS, SourceLocation TemplateKWLoc,
2279                           TemplateTy TemplateD, SourceLocation TemplateLoc,
2280                           SourceLocation LAngleLoc,
2281                           ASTTemplateArgsPtr TemplateArgsIn,
2282                           SourceLocation RAngleLoc,
2283                           bool IsCtorOrDtorName) {
2284   if (SS.isInvalid())
2285     return true;
2286 
2287   TemplateName Template = TemplateD.get();
2288 
2289   // Translate the parser's template argument list in our AST format.
2290   TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
2291   translateTemplateArguments(TemplateArgsIn, TemplateArgs);
2292 
2293   if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
2294     QualType T
2295       = Context.getDependentTemplateSpecializationType(ETK_None,
2296                                                        DTN->getQualifier(),
2297                                                        DTN->getIdentifier(),
2298                                                        TemplateArgs);
2299     // Build type-source information.
2300     TypeLocBuilder TLB;
2301     DependentTemplateSpecializationTypeLoc SpecTL
2302       = TLB.push<DependentTemplateSpecializationTypeLoc>(T);
2303     SpecTL.setElaboratedKeywordLoc(SourceLocation());
2304     SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
2305     SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2306     SpecTL.setTemplateNameLoc(TemplateLoc);
2307     SpecTL.setLAngleLoc(LAngleLoc);
2308     SpecTL.setRAngleLoc(RAngleLoc);
2309     for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
2310       SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
2311     return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
2312   }
2313 
2314   QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
2315 
2316   if (Result.isNull())
2317     return true;
2318 
2319   // Build type-source information.
2320   TypeLocBuilder TLB;
2321   TemplateSpecializationTypeLoc SpecTL
2322     = TLB.push<TemplateSpecializationTypeLoc>(Result);
2323   SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2324   SpecTL.setTemplateNameLoc(TemplateLoc);
2325   SpecTL.setLAngleLoc(LAngleLoc);
2326   SpecTL.setRAngleLoc(RAngleLoc);
2327   for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
2328     SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
2329 
2330   // NOTE: avoid constructing an ElaboratedTypeLoc if this is a
2331   // constructor or destructor name (in such a case, the scope specifier
2332   // will be attached to the enclosing Decl or Expr node).
2333   if (SS.isNotEmpty() && !IsCtorOrDtorName) {
2334     // Create an elaborated-type-specifier containing the nested-name-specifier.
2335     Result = Context.getElaboratedType(ETK_None, SS.getScopeRep(), Result);
2336     ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
2337     ElabTL.setElaboratedKeywordLoc(SourceLocation());
2338     ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
2339   }
2340 
2341   return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
2342 }
2343 
ActOnTagTemplateIdType(TagUseKind TUK,TypeSpecifierType TagSpec,SourceLocation TagLoc,CXXScopeSpec & SS,SourceLocation TemplateKWLoc,TemplateTy TemplateD,SourceLocation TemplateLoc,SourceLocation LAngleLoc,ASTTemplateArgsPtr TemplateArgsIn,SourceLocation RAngleLoc)2344 TypeResult Sema::ActOnTagTemplateIdType(TagUseKind TUK,
2345                                         TypeSpecifierType TagSpec,
2346                                         SourceLocation TagLoc,
2347                                         CXXScopeSpec &SS,
2348                                         SourceLocation TemplateKWLoc,
2349                                         TemplateTy TemplateD,
2350                                         SourceLocation TemplateLoc,
2351                                         SourceLocation LAngleLoc,
2352                                         ASTTemplateArgsPtr TemplateArgsIn,
2353                                         SourceLocation RAngleLoc) {
2354   TemplateName Template = TemplateD.get();
2355 
2356   // Translate the parser's template argument list in our AST format.
2357   TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
2358   translateTemplateArguments(TemplateArgsIn, TemplateArgs);
2359 
2360   // Determine the tag kind
2361   TagTypeKind TagKind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
2362   ElaboratedTypeKeyword Keyword
2363     = TypeWithKeyword::getKeywordForTagTypeKind(TagKind);
2364 
2365   if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
2366     QualType T = Context.getDependentTemplateSpecializationType(Keyword,
2367                                                           DTN->getQualifier(),
2368                                                           DTN->getIdentifier(),
2369                                                                 TemplateArgs);
2370 
2371     // Build type-source information.
2372     TypeLocBuilder TLB;
2373     DependentTemplateSpecializationTypeLoc SpecTL
2374       = TLB.push<DependentTemplateSpecializationTypeLoc>(T);
2375     SpecTL.setElaboratedKeywordLoc(TagLoc);
2376     SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
2377     SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2378     SpecTL.setTemplateNameLoc(TemplateLoc);
2379     SpecTL.setLAngleLoc(LAngleLoc);
2380     SpecTL.setRAngleLoc(RAngleLoc);
2381     for (unsigned I = 0, N = SpecTL.getNumArgs(); I != N; ++I)
2382       SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
2383     return CreateParsedType(T, TLB.getTypeSourceInfo(Context, T));
2384   }
2385 
2386   if (TypeAliasTemplateDecl *TAT =
2387         dyn_cast_or_null<TypeAliasTemplateDecl>(Template.getAsTemplateDecl())) {
2388     // C++0x [dcl.type.elab]p2:
2389     //   If the identifier resolves to a typedef-name or the simple-template-id
2390     //   resolves to an alias template specialization, the
2391     //   elaborated-type-specifier is ill-formed.
2392     Diag(TemplateLoc, diag::err_tag_reference_non_tag) << 4;
2393     Diag(TAT->getLocation(), diag::note_declared_at);
2394   }
2395 
2396   QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
2397   if (Result.isNull())
2398     return TypeResult(true);
2399 
2400   // Check the tag kind
2401   if (const RecordType *RT = Result->getAs<RecordType>()) {
2402     RecordDecl *D = RT->getDecl();
2403 
2404     IdentifierInfo *Id = D->getIdentifier();
2405     assert(Id && "templated class must have an identifier");
2406 
2407     if (!isAcceptableTagRedeclaration(D, TagKind, TUK == TUK_Definition,
2408                                       TagLoc, Id)) {
2409       Diag(TagLoc, diag::err_use_with_wrong_tag)
2410         << Result
2411         << FixItHint::CreateReplacement(SourceRange(TagLoc), D->getKindName());
2412       Diag(D->getLocation(), diag::note_previous_use);
2413     }
2414   }
2415 
2416   // Provide source-location information for the template specialization.
2417   TypeLocBuilder TLB;
2418   TemplateSpecializationTypeLoc SpecTL
2419     = TLB.push<TemplateSpecializationTypeLoc>(Result);
2420   SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
2421   SpecTL.setTemplateNameLoc(TemplateLoc);
2422   SpecTL.setLAngleLoc(LAngleLoc);
2423   SpecTL.setRAngleLoc(RAngleLoc);
2424   for (unsigned i = 0, e = SpecTL.getNumArgs(); i != e; ++i)
2425     SpecTL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
2426 
2427   // Construct an elaborated type containing the nested-name-specifier (if any)
2428   // and tag keyword.
2429   Result = Context.getElaboratedType(Keyword, SS.getScopeRep(), Result);
2430   ElaboratedTypeLoc ElabTL = TLB.push<ElaboratedTypeLoc>(Result);
2431   ElabTL.setElaboratedKeywordLoc(TagLoc);
2432   ElabTL.setQualifierLoc(SS.getWithLocInContext(Context));
2433   return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
2434 }
2435 
2436 static bool CheckTemplatePartialSpecializationArgs(
2437     Sema &S, SourceLocation NameLoc, TemplateParameterList *TemplateParams,
2438     unsigned ExplicitArgs, SmallVectorImpl<TemplateArgument> &TemplateArgs);
2439 
2440 static bool CheckTemplateSpecializationScope(Sema &S, NamedDecl *Specialized,
2441                                              NamedDecl *PrevDecl,
2442                                              SourceLocation Loc,
2443                                              bool IsPartialSpecialization);
2444 
2445 static TemplateSpecializationKind getTemplateSpecializationKind(Decl *D);
2446 
isTemplateArgumentTemplateParameter(const TemplateArgument & Arg,unsigned Depth,unsigned Index)2447 static bool isTemplateArgumentTemplateParameter(
2448     const TemplateArgument &Arg, unsigned Depth, unsigned Index) {
2449   switch (Arg.getKind()) {
2450   case TemplateArgument::Null:
2451   case TemplateArgument::NullPtr:
2452   case TemplateArgument::Integral:
2453   case TemplateArgument::Declaration:
2454   case TemplateArgument::Pack:
2455   case TemplateArgument::TemplateExpansion:
2456     return false;
2457 
2458   case TemplateArgument::Type: {
2459     QualType Type = Arg.getAsType();
2460     const TemplateTypeParmType *TPT =
2461         Arg.getAsType()->getAs<TemplateTypeParmType>();
2462     return TPT && !Type.hasQualifiers() &&
2463            TPT->getDepth() == Depth && TPT->getIndex() == Index;
2464   }
2465 
2466   case TemplateArgument::Expression: {
2467     DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg.getAsExpr());
2468     if (!DRE || !DRE->getDecl())
2469       return false;
2470     const NonTypeTemplateParmDecl *NTTP =
2471         dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl());
2472     return NTTP && NTTP->getDepth() == Depth && NTTP->getIndex() == Index;
2473   }
2474 
2475   case TemplateArgument::Template:
2476     const TemplateTemplateParmDecl *TTP =
2477         dyn_cast_or_null<TemplateTemplateParmDecl>(
2478             Arg.getAsTemplateOrTemplatePattern().getAsTemplateDecl());
2479     return TTP && TTP->getDepth() == Depth && TTP->getIndex() == Index;
2480   }
2481   llvm_unreachable("unexpected kind of template argument");
2482 }
2483 
isSameAsPrimaryTemplate(TemplateParameterList * Params,ArrayRef<TemplateArgument> Args)2484 static bool isSameAsPrimaryTemplate(TemplateParameterList *Params,
2485                                     ArrayRef<TemplateArgument> Args) {
2486   if (Params->size() != Args.size())
2487     return false;
2488 
2489   unsigned Depth = Params->getDepth();
2490 
2491   for (unsigned I = 0, N = Args.size(); I != N; ++I) {
2492     TemplateArgument Arg = Args[I];
2493 
2494     // If the parameter is a pack expansion, the argument must be a pack
2495     // whose only element is a pack expansion.
2496     if (Params->getParam(I)->isParameterPack()) {
2497       if (Arg.getKind() != TemplateArgument::Pack || Arg.pack_size() != 1 ||
2498           !Arg.pack_begin()->isPackExpansion())
2499         return false;
2500       Arg = Arg.pack_begin()->getPackExpansionPattern();
2501     }
2502 
2503     if (!isTemplateArgumentTemplateParameter(Arg, Depth, I))
2504       return false;
2505   }
2506 
2507   return true;
2508 }
2509 
2510 /// Convert the parser's template argument list representation into our form.
2511 static TemplateArgumentListInfo
makeTemplateArgumentListInfo(Sema & S,TemplateIdAnnotation & TemplateId)2512 makeTemplateArgumentListInfo(Sema &S, TemplateIdAnnotation &TemplateId) {
2513   TemplateArgumentListInfo TemplateArgs(TemplateId.LAngleLoc,
2514                                         TemplateId.RAngleLoc);
2515   ASTTemplateArgsPtr TemplateArgsPtr(TemplateId.getTemplateArgs(),
2516                                      TemplateId.NumArgs);
2517   S.translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
2518   return TemplateArgs;
2519 }
2520 
ActOnVarTemplateSpecialization(Scope * S,Declarator & D,TypeSourceInfo * DI,SourceLocation TemplateKWLoc,TemplateParameterList * TemplateParams,StorageClass SC,bool IsPartialSpecialization)2521 DeclResult Sema::ActOnVarTemplateSpecialization(
2522     Scope *S, Declarator &D, TypeSourceInfo *DI, SourceLocation TemplateKWLoc,
2523     TemplateParameterList *TemplateParams, StorageClass SC,
2524     bool IsPartialSpecialization) {
2525   // D must be variable template id.
2526   assert(D.getName().getKind() == UnqualifiedId::IK_TemplateId &&
2527          "Variable template specialization is declared with a template it.");
2528 
2529   TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
2530   TemplateArgumentListInfo TemplateArgs =
2531       makeTemplateArgumentListInfo(*this, *TemplateId);
2532   SourceLocation TemplateNameLoc = D.getIdentifierLoc();
2533   SourceLocation LAngleLoc = TemplateId->LAngleLoc;
2534   SourceLocation RAngleLoc = TemplateId->RAngleLoc;
2535 
2536   TemplateName Name = TemplateId->Template.get();
2537 
2538   // The template-id must name a variable template.
2539   VarTemplateDecl *VarTemplate =
2540       dyn_cast_or_null<VarTemplateDecl>(Name.getAsTemplateDecl());
2541   if (!VarTemplate) {
2542     NamedDecl *FnTemplate;
2543     if (auto *OTS = Name.getAsOverloadedTemplate())
2544       FnTemplate = *OTS->begin();
2545     else
2546       FnTemplate = dyn_cast_or_null<FunctionTemplateDecl>(Name.getAsTemplateDecl());
2547     if (FnTemplate)
2548       return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template_but_method)
2549                << FnTemplate->getDeclName();
2550     return Diag(D.getIdentifierLoc(), diag::err_var_spec_no_template)
2551              << IsPartialSpecialization;
2552   }
2553 
2554   // Check for unexpanded parameter packs in any of the template arguments.
2555   for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
2556     if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
2557                                         UPPC_PartialSpecialization))
2558       return true;
2559 
2560   // Check that the template argument list is well-formed for this
2561   // template.
2562   SmallVector<TemplateArgument, 4> Converted;
2563   if (CheckTemplateArgumentList(VarTemplate, TemplateNameLoc, TemplateArgs,
2564                                 false, Converted))
2565     return true;
2566 
2567   // Find the variable template (partial) specialization declaration that
2568   // corresponds to these arguments.
2569   if (IsPartialSpecialization) {
2570     if (CheckTemplatePartialSpecializationArgs(
2571             *this, TemplateNameLoc, VarTemplate->getTemplateParameters(),
2572             TemplateArgs.size(), Converted))
2573       return true;
2574 
2575     bool InstantiationDependent;
2576     if (!Name.isDependent() &&
2577         !TemplateSpecializationType::anyDependentTemplateArguments(
2578             TemplateArgs.arguments(),
2579             InstantiationDependent)) {
2580       Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
2581           << VarTemplate->getDeclName();
2582       IsPartialSpecialization = false;
2583     }
2584 
2585     if (isSameAsPrimaryTemplate(VarTemplate->getTemplateParameters(),
2586                                 Converted)) {
2587       // C++ [temp.class.spec]p9b3:
2588       //
2589       //   -- The argument list of the specialization shall not be identical
2590       //      to the implicit argument list of the primary template.
2591       Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
2592         << /*variable template*/ 1
2593         << /*is definition*/(SC != SC_Extern && !CurContext->isRecord())
2594         << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
2595       // FIXME: Recover from this by treating the declaration as a redeclaration
2596       // of the primary template.
2597       return true;
2598     }
2599   }
2600 
2601   void *InsertPos = nullptr;
2602   VarTemplateSpecializationDecl *PrevDecl = nullptr;
2603 
2604   if (IsPartialSpecialization)
2605     // FIXME: Template parameter list matters too
2606     PrevDecl = VarTemplate->findPartialSpecialization(Converted, InsertPos);
2607   else
2608     PrevDecl = VarTemplate->findSpecialization(Converted, InsertPos);
2609 
2610   VarTemplateSpecializationDecl *Specialization = nullptr;
2611 
2612   // Check whether we can declare a variable template specialization in
2613   // the current scope.
2614   if (CheckTemplateSpecializationScope(*this, VarTemplate, PrevDecl,
2615                                        TemplateNameLoc,
2616                                        IsPartialSpecialization))
2617     return true;
2618 
2619   if (PrevDecl && PrevDecl->getSpecializationKind() == TSK_Undeclared) {
2620     // Since the only prior variable template specialization with these
2621     // arguments was referenced but not declared,  reuse that
2622     // declaration node as our own, updating its source location and
2623     // the list of outer template parameters to reflect our new declaration.
2624     Specialization = PrevDecl;
2625     Specialization->setLocation(TemplateNameLoc);
2626     PrevDecl = nullptr;
2627   } else if (IsPartialSpecialization) {
2628     // Create a new class template partial specialization declaration node.
2629     VarTemplatePartialSpecializationDecl *PrevPartial =
2630         cast_or_null<VarTemplatePartialSpecializationDecl>(PrevDecl);
2631     VarTemplatePartialSpecializationDecl *Partial =
2632         VarTemplatePartialSpecializationDecl::Create(
2633             Context, VarTemplate->getDeclContext(), TemplateKWLoc,
2634             TemplateNameLoc, TemplateParams, VarTemplate, DI->getType(), DI, SC,
2635             Converted, TemplateArgs);
2636 
2637     if (!PrevPartial)
2638       VarTemplate->AddPartialSpecialization(Partial, InsertPos);
2639     Specialization = Partial;
2640 
2641     // If we are providing an explicit specialization of a member variable
2642     // template specialization, make a note of that.
2643     if (PrevPartial && PrevPartial->getInstantiatedFromMember())
2644       PrevPartial->setMemberSpecialization();
2645 
2646     // Check that all of the template parameters of the variable template
2647     // partial specialization are deducible from the template
2648     // arguments. If not, this variable template partial specialization
2649     // will never be used.
2650     llvm::SmallBitVector DeducibleParams(TemplateParams->size());
2651     MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
2652                                TemplateParams->getDepth(), DeducibleParams);
2653 
2654     if (!DeducibleParams.all()) {
2655       unsigned NumNonDeducible =
2656           DeducibleParams.size() - DeducibleParams.count();
2657       Diag(TemplateNameLoc, diag::warn_partial_specs_not_deducible)
2658         << /*variable template*/ 1 << (NumNonDeducible > 1)
2659         << SourceRange(TemplateNameLoc, RAngleLoc);
2660       for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
2661         if (!DeducibleParams[I]) {
2662           NamedDecl *Param = cast<NamedDecl>(TemplateParams->getParam(I));
2663           if (Param->getDeclName())
2664             Diag(Param->getLocation(), diag::note_partial_spec_unused_parameter)
2665                 << Param->getDeclName();
2666           else
2667             Diag(Param->getLocation(), diag::note_partial_spec_unused_parameter)
2668                 << "(anonymous)";
2669         }
2670       }
2671     }
2672   } else {
2673     // Create a new class template specialization declaration node for
2674     // this explicit specialization or friend declaration.
2675     Specialization = VarTemplateSpecializationDecl::Create(
2676         Context, VarTemplate->getDeclContext(), TemplateKWLoc, TemplateNameLoc,
2677         VarTemplate, DI->getType(), DI, SC, Converted);
2678     Specialization->setTemplateArgsInfo(TemplateArgs);
2679 
2680     if (!PrevDecl)
2681       VarTemplate->AddSpecialization(Specialization, InsertPos);
2682   }
2683 
2684   // C++ [temp.expl.spec]p6:
2685   //   If a template, a member template or the member of a class template is
2686   //   explicitly specialized then that specialization shall be declared
2687   //   before the first use of that specialization that would cause an implicit
2688   //   instantiation to take place, in every translation unit in which such a
2689   //   use occurs; no diagnostic is required.
2690   if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
2691     bool Okay = false;
2692     for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
2693       // Is there any previous explicit specialization declaration?
2694       if (getTemplateSpecializationKind(Prev) == TSK_ExplicitSpecialization) {
2695         Okay = true;
2696         break;
2697       }
2698     }
2699 
2700     if (!Okay) {
2701       SourceRange Range(TemplateNameLoc, RAngleLoc);
2702       Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
2703           << Name << Range;
2704 
2705       Diag(PrevDecl->getPointOfInstantiation(),
2706            diag::note_instantiation_required_here)
2707           << (PrevDecl->getTemplateSpecializationKind() !=
2708               TSK_ImplicitInstantiation);
2709       return true;
2710     }
2711   }
2712 
2713   Specialization->setTemplateKeywordLoc(TemplateKWLoc);
2714   Specialization->setLexicalDeclContext(CurContext);
2715 
2716   // Add the specialization into its lexical context, so that it can
2717   // be seen when iterating through the list of declarations in that
2718   // context. However, specializations are not found by name lookup.
2719   CurContext->addDecl(Specialization);
2720 
2721   // Note that this is an explicit specialization.
2722   Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
2723 
2724   if (PrevDecl) {
2725     // Check that this isn't a redefinition of this specialization,
2726     // merging with previous declarations.
2727     LookupResult PrevSpec(*this, GetNameForDeclarator(D), LookupOrdinaryName,
2728                           ForRedeclaration);
2729     PrevSpec.addDecl(PrevDecl);
2730     D.setRedeclaration(CheckVariableDeclaration(Specialization, PrevSpec));
2731   } else if (Specialization->isStaticDataMember() &&
2732              Specialization->isOutOfLine()) {
2733     Specialization->setAccess(VarTemplate->getAccess());
2734   }
2735 
2736   // Link instantiations of static data members back to the template from
2737   // which they were instantiated.
2738   if (Specialization->isStaticDataMember())
2739     Specialization->setInstantiationOfStaticDataMember(
2740         VarTemplate->getTemplatedDecl(),
2741         Specialization->getSpecializationKind());
2742 
2743   return Specialization;
2744 }
2745 
2746 namespace {
2747 /// \brief A partial specialization whose template arguments have matched
2748 /// a given template-id.
2749 struct PartialSpecMatchResult {
2750   VarTemplatePartialSpecializationDecl *Partial;
2751   TemplateArgumentList *Args;
2752 };
2753 } // end anonymous namespace
2754 
2755 DeclResult
CheckVarTemplateId(VarTemplateDecl * Template,SourceLocation TemplateLoc,SourceLocation TemplateNameLoc,const TemplateArgumentListInfo & TemplateArgs)2756 Sema::CheckVarTemplateId(VarTemplateDecl *Template, SourceLocation TemplateLoc,
2757                          SourceLocation TemplateNameLoc,
2758                          const TemplateArgumentListInfo &TemplateArgs) {
2759   assert(Template && "A variable template id without template?");
2760 
2761   // Check that the template argument list is well-formed for this template.
2762   SmallVector<TemplateArgument, 4> Converted;
2763   if (CheckTemplateArgumentList(
2764           Template, TemplateNameLoc,
2765           const_cast<TemplateArgumentListInfo &>(TemplateArgs), false,
2766           Converted))
2767     return true;
2768 
2769   // Find the variable template specialization declaration that
2770   // corresponds to these arguments.
2771   void *InsertPos = nullptr;
2772   if (VarTemplateSpecializationDecl *Spec = Template->findSpecialization(
2773           Converted, InsertPos)) {
2774     checkSpecializationVisibility(TemplateNameLoc, Spec);
2775     // If we already have a variable template specialization, return it.
2776     return Spec;
2777   }
2778 
2779   // This is the first time we have referenced this variable template
2780   // specialization. Create the canonical declaration and add it to
2781   // the set of specializations, based on the closest partial specialization
2782   // that it represents. That is,
2783   VarDecl *InstantiationPattern = Template->getTemplatedDecl();
2784   TemplateArgumentList TemplateArgList(TemplateArgumentList::OnStack,
2785                                        Converted);
2786   TemplateArgumentList *InstantiationArgs = &TemplateArgList;
2787   bool AmbiguousPartialSpec = false;
2788   typedef PartialSpecMatchResult MatchResult;
2789   SmallVector<MatchResult, 4> Matched;
2790   SourceLocation PointOfInstantiation = TemplateNameLoc;
2791   TemplateSpecCandidateSet FailedCandidates(PointOfInstantiation,
2792                                             /*ForTakingAddress=*/false);
2793 
2794   // 1. Attempt to find the closest partial specialization that this
2795   // specializes, if any.
2796   // If any of the template arguments is dependent, then this is probably
2797   // a placeholder for an incomplete declarative context; which must be
2798   // complete by instantiation time. Thus, do not search through the partial
2799   // specializations yet.
2800   // TODO: Unify with InstantiateClassTemplateSpecialization()?
2801   //       Perhaps better after unification of DeduceTemplateArguments() and
2802   //       getMoreSpecializedPartialSpecialization().
2803   bool InstantiationDependent = false;
2804   if (!TemplateSpecializationType::anyDependentTemplateArguments(
2805           TemplateArgs, InstantiationDependent)) {
2806 
2807     SmallVector<VarTemplatePartialSpecializationDecl *, 4> PartialSpecs;
2808     Template->getPartialSpecializations(PartialSpecs);
2809 
2810     for (unsigned I = 0, N = PartialSpecs.size(); I != N; ++I) {
2811       VarTemplatePartialSpecializationDecl *Partial = PartialSpecs[I];
2812       TemplateDeductionInfo Info(FailedCandidates.getLocation());
2813 
2814       if (TemplateDeductionResult Result =
2815               DeduceTemplateArguments(Partial, TemplateArgList, Info)) {
2816         // Store the failed-deduction information for use in diagnostics, later.
2817         // TODO: Actually use the failed-deduction info?
2818         FailedCandidates.addCandidate().set(
2819             DeclAccessPair::make(Template, AS_public), Partial,
2820             MakeDeductionFailureInfo(Context, Result, Info));
2821         (void)Result;
2822       } else {
2823         Matched.push_back(PartialSpecMatchResult());
2824         Matched.back().Partial = Partial;
2825         Matched.back().Args = Info.take();
2826       }
2827     }
2828 
2829     if (Matched.size() >= 1) {
2830       SmallVector<MatchResult, 4>::iterator Best = Matched.begin();
2831       if (Matched.size() == 1) {
2832         //   -- If exactly one matching specialization is found, the
2833         //      instantiation is generated from that specialization.
2834         // We don't need to do anything for this.
2835       } else {
2836         //   -- If more than one matching specialization is found, the
2837         //      partial order rules (14.5.4.2) are used to determine
2838         //      whether one of the specializations is more specialized
2839         //      than the others. If none of the specializations is more
2840         //      specialized than all of the other matching
2841         //      specializations, then the use of the variable template is
2842         //      ambiguous and the program is ill-formed.
2843         for (SmallVector<MatchResult, 4>::iterator P = Best + 1,
2844                                                    PEnd = Matched.end();
2845              P != PEnd; ++P) {
2846           if (getMoreSpecializedPartialSpecialization(P->Partial, Best->Partial,
2847                                                       PointOfInstantiation) ==
2848               P->Partial)
2849             Best = P;
2850         }
2851 
2852         // Determine if the best partial specialization is more specialized than
2853         // the others.
2854         for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
2855                                                    PEnd = Matched.end();
2856              P != PEnd; ++P) {
2857           if (P != Best && getMoreSpecializedPartialSpecialization(
2858                                P->Partial, Best->Partial,
2859                                PointOfInstantiation) != Best->Partial) {
2860             AmbiguousPartialSpec = true;
2861             break;
2862           }
2863         }
2864       }
2865 
2866       // Instantiate using the best variable template partial specialization.
2867       InstantiationPattern = Best->Partial;
2868       InstantiationArgs = Best->Args;
2869     } else {
2870       //   -- If no match is found, the instantiation is generated
2871       //      from the primary template.
2872       // InstantiationPattern = Template->getTemplatedDecl();
2873     }
2874   }
2875 
2876   // 2. Create the canonical declaration.
2877   // Note that we do not instantiate a definition until we see an odr-use
2878   // in DoMarkVarDeclReferenced().
2879   // FIXME: LateAttrs et al.?
2880   VarTemplateSpecializationDecl *Decl = BuildVarTemplateInstantiation(
2881       Template, InstantiationPattern, *InstantiationArgs, TemplateArgs,
2882       Converted, TemplateNameLoc, InsertPos /*, LateAttrs, StartingScope*/);
2883   if (!Decl)
2884     return true;
2885 
2886   if (AmbiguousPartialSpec) {
2887     // Partial ordering did not produce a clear winner. Complain.
2888     Decl->setInvalidDecl();
2889     Diag(PointOfInstantiation, diag::err_partial_spec_ordering_ambiguous)
2890         << Decl;
2891 
2892     // Print the matching partial specializations.
2893     for (SmallVector<MatchResult, 4>::iterator P = Matched.begin(),
2894                                                PEnd = Matched.end();
2895          P != PEnd; ++P)
2896       Diag(P->Partial->getLocation(), diag::note_partial_spec_match)
2897           << getTemplateArgumentBindingsText(
2898                  P->Partial->getTemplateParameters(), *P->Args);
2899     return true;
2900   }
2901 
2902   if (VarTemplatePartialSpecializationDecl *D =
2903           dyn_cast<VarTemplatePartialSpecializationDecl>(InstantiationPattern))
2904     Decl->setInstantiationOf(D, InstantiationArgs);
2905 
2906   checkSpecializationVisibility(TemplateNameLoc, Decl);
2907 
2908   assert(Decl && "No variable template specialization?");
2909   return Decl;
2910 }
2911 
2912 ExprResult
CheckVarTemplateId(const CXXScopeSpec & SS,const DeclarationNameInfo & NameInfo,VarTemplateDecl * Template,SourceLocation TemplateLoc,const TemplateArgumentListInfo * TemplateArgs)2913 Sema::CheckVarTemplateId(const CXXScopeSpec &SS,
2914                          const DeclarationNameInfo &NameInfo,
2915                          VarTemplateDecl *Template, SourceLocation TemplateLoc,
2916                          const TemplateArgumentListInfo *TemplateArgs) {
2917 
2918   DeclResult Decl = CheckVarTemplateId(Template, TemplateLoc, NameInfo.getLoc(),
2919                                        *TemplateArgs);
2920   if (Decl.isInvalid())
2921     return ExprError();
2922 
2923   VarDecl *Var = cast<VarDecl>(Decl.get());
2924   if (!Var->getTemplateSpecializationKind())
2925     Var->setTemplateSpecializationKind(TSK_ImplicitInstantiation,
2926                                        NameInfo.getLoc());
2927 
2928   // Build an ordinary singleton decl ref.
2929   return BuildDeclarationNameExpr(SS, NameInfo, Var,
2930                                   /*FoundD=*/nullptr, TemplateArgs);
2931 }
2932 
BuildTemplateIdExpr(const CXXScopeSpec & SS,SourceLocation TemplateKWLoc,LookupResult & R,bool RequiresADL,const TemplateArgumentListInfo * TemplateArgs)2933 ExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
2934                                      SourceLocation TemplateKWLoc,
2935                                      LookupResult &R,
2936                                      bool RequiresADL,
2937                                  const TemplateArgumentListInfo *TemplateArgs) {
2938   // FIXME: Can we do any checking at this point? I guess we could check the
2939   // template arguments that we have against the template name, if the template
2940   // name refers to a single template. That's not a terribly common case,
2941   // though.
2942   // foo<int> could identify a single function unambiguously
2943   // This approach does NOT work, since f<int>(1);
2944   // gets resolved prior to resorting to overload resolution
2945   // i.e., template<class T> void f(double);
2946   //       vs template<class T, class U> void f(U);
2947 
2948   // These should be filtered out by our callers.
2949   assert(!R.empty() && "empty lookup results when building templateid");
2950   assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
2951 
2952   // In C++1y, check variable template ids.
2953   bool InstantiationDependent;
2954   if (R.getAsSingle<VarTemplateDecl>() &&
2955       !TemplateSpecializationType::anyDependentTemplateArguments(
2956            *TemplateArgs, InstantiationDependent)) {
2957     return CheckVarTemplateId(SS, R.getLookupNameInfo(),
2958                               R.getAsSingle<VarTemplateDecl>(),
2959                               TemplateKWLoc, TemplateArgs);
2960   }
2961 
2962   // We don't want lookup warnings at this point.
2963   R.suppressDiagnostics();
2964 
2965   UnresolvedLookupExpr *ULE
2966     = UnresolvedLookupExpr::Create(Context, R.getNamingClass(),
2967                                    SS.getWithLocInContext(Context),
2968                                    TemplateKWLoc,
2969                                    R.getLookupNameInfo(),
2970                                    RequiresADL, TemplateArgs,
2971                                    R.begin(), R.end());
2972 
2973   return ULE;
2974 }
2975 
2976 // We actually only call this from template instantiation.
2977 ExprResult
BuildQualifiedTemplateIdExpr(CXXScopeSpec & SS,SourceLocation TemplateKWLoc,const DeclarationNameInfo & NameInfo,const TemplateArgumentListInfo * TemplateArgs)2978 Sema::BuildQualifiedTemplateIdExpr(CXXScopeSpec &SS,
2979                                    SourceLocation TemplateKWLoc,
2980                                    const DeclarationNameInfo &NameInfo,
2981                              const TemplateArgumentListInfo *TemplateArgs) {
2982 
2983   assert(TemplateArgs || TemplateKWLoc.isValid());
2984   DeclContext *DC;
2985   if (!(DC = computeDeclContext(SS, false)) ||
2986       DC->isDependentContext() ||
2987       RequireCompleteDeclContext(SS, DC))
2988     return BuildDependentDeclRefExpr(SS, TemplateKWLoc, NameInfo, TemplateArgs);
2989 
2990   bool MemberOfUnknownSpecialization;
2991   LookupResult R(*this, NameInfo, LookupOrdinaryName);
2992   LookupTemplateName(R, (Scope*)nullptr, SS, QualType(), /*Entering*/ false,
2993                      MemberOfUnknownSpecialization);
2994 
2995   if (R.isAmbiguous())
2996     return ExprError();
2997 
2998   if (R.empty()) {
2999     Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_non_template)
3000       << NameInfo.getName() << SS.getRange();
3001     return ExprError();
3002   }
3003 
3004   if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
3005     Diag(NameInfo.getLoc(), diag::err_template_kw_refers_to_class_template)
3006       << SS.getScopeRep()
3007       << NameInfo.getName().getAsString() << SS.getRange();
3008     Diag(Temp->getLocation(), diag::note_referenced_class_template);
3009     return ExprError();
3010   }
3011 
3012   return BuildTemplateIdExpr(SS, TemplateKWLoc, R, /*ADL*/ false, TemplateArgs);
3013 }
3014 
3015 /// \brief Form a dependent template name.
3016 ///
3017 /// This action forms a dependent template name given the template
3018 /// name and its (presumably dependent) scope specifier. For
3019 /// example, given "MetaFun::template apply", the scope specifier \p
3020 /// SS will be "MetaFun::", \p TemplateKWLoc contains the location
3021 /// of the "template" keyword, and "apply" is the \p Name.
ActOnDependentTemplateName(Scope * S,CXXScopeSpec & SS,SourceLocation TemplateKWLoc,UnqualifiedId & Name,ParsedType ObjectType,bool EnteringContext,TemplateTy & Result)3022 TemplateNameKind Sema::ActOnDependentTemplateName(Scope *S,
3023                                                   CXXScopeSpec &SS,
3024                                                   SourceLocation TemplateKWLoc,
3025                                                   UnqualifiedId &Name,
3026                                                   ParsedType ObjectType,
3027                                                   bool EnteringContext,
3028                                                   TemplateTy &Result) {
3029   if (TemplateKWLoc.isValid() && S && !S->getTemplateParamParent())
3030     Diag(TemplateKWLoc,
3031          getLangOpts().CPlusPlus11 ?
3032            diag::warn_cxx98_compat_template_outside_of_template :
3033            diag::ext_template_outside_of_template)
3034       << FixItHint::CreateRemoval(TemplateKWLoc);
3035 
3036   DeclContext *LookupCtx = nullptr;
3037   if (SS.isSet())
3038     LookupCtx = computeDeclContext(SS, EnteringContext);
3039   if (!LookupCtx && ObjectType)
3040     LookupCtx = computeDeclContext(ObjectType.get());
3041   if (LookupCtx) {
3042     // C++0x [temp.names]p5:
3043     //   If a name prefixed by the keyword template is not the name of
3044     //   a template, the program is ill-formed. [Note: the keyword
3045     //   template may not be applied to non-template members of class
3046     //   templates. -end note ] [ Note: as is the case with the
3047     //   typename prefix, the template prefix is allowed in cases
3048     //   where it is not strictly necessary; i.e., when the
3049     //   nested-name-specifier or the expression on the left of the ->
3050     //   or . is not dependent on a template-parameter, or the use
3051     //   does not appear in the scope of a template. -end note]
3052     //
3053     // Note: C++03 was more strict here, because it banned the use of
3054     // the "template" keyword prior to a template-name that was not a
3055     // dependent name. C++ DR468 relaxed this requirement (the
3056     // "template" keyword is now permitted). We follow the C++0x
3057     // rules, even in C++03 mode with a warning, retroactively applying the DR.
3058     bool MemberOfUnknownSpecialization;
3059     TemplateNameKind TNK = isTemplateName(S, SS, TemplateKWLoc.isValid(), Name,
3060                                           ObjectType, EnteringContext, Result,
3061                                           MemberOfUnknownSpecialization);
3062     if (TNK == TNK_Non_template && LookupCtx->isDependentContext() &&
3063         isa<CXXRecordDecl>(LookupCtx) &&
3064         (!cast<CXXRecordDecl>(LookupCtx)->hasDefinition() ||
3065          cast<CXXRecordDecl>(LookupCtx)->hasAnyDependentBases())) {
3066       // This is a dependent template. Handle it below.
3067     } else if (TNK == TNK_Non_template) {
3068       Diag(Name.getLocStart(),
3069            diag::err_template_kw_refers_to_non_template)
3070         << GetNameFromUnqualifiedId(Name).getName()
3071         << Name.getSourceRange()
3072         << TemplateKWLoc;
3073       return TNK_Non_template;
3074     } else {
3075       // We found something; return it.
3076       return TNK;
3077     }
3078   }
3079 
3080   NestedNameSpecifier *Qualifier = SS.getScopeRep();
3081 
3082   switch (Name.getKind()) {
3083   case UnqualifiedId::IK_Identifier:
3084     Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
3085                                                               Name.Identifier));
3086     return TNK_Dependent_template_name;
3087 
3088   case UnqualifiedId::IK_OperatorFunctionId:
3089     Result = TemplateTy::make(Context.getDependentTemplateName(Qualifier,
3090                                              Name.OperatorFunctionId.Operator));
3091     return TNK_Function_template;
3092 
3093   case UnqualifiedId::IK_LiteralOperatorId:
3094     llvm_unreachable("literal operator id cannot have a dependent scope");
3095 
3096   default:
3097     break;
3098   }
3099 
3100   Diag(Name.getLocStart(),
3101        diag::err_template_kw_refers_to_non_template)
3102     << GetNameFromUnqualifiedId(Name).getName()
3103     << Name.getSourceRange()
3104     << TemplateKWLoc;
3105   return TNK_Non_template;
3106 }
3107 
CheckTemplateTypeArgument(TemplateTypeParmDecl * Param,TemplateArgumentLoc & AL,SmallVectorImpl<TemplateArgument> & Converted)3108 bool Sema::CheckTemplateTypeArgument(TemplateTypeParmDecl *Param,
3109                                      TemplateArgumentLoc &AL,
3110                           SmallVectorImpl<TemplateArgument> &Converted) {
3111   const TemplateArgument &Arg = AL.getArgument();
3112   QualType ArgType;
3113   TypeSourceInfo *TSI = nullptr;
3114 
3115   // Check template type parameter.
3116   switch(Arg.getKind()) {
3117   case TemplateArgument::Type:
3118     // C++ [temp.arg.type]p1:
3119     //   A template-argument for a template-parameter which is a
3120     //   type shall be a type-id.
3121     ArgType = Arg.getAsType();
3122     TSI = AL.getTypeSourceInfo();
3123     break;
3124   case TemplateArgument::Template: {
3125     // We have a template type parameter but the template argument
3126     // is a template without any arguments.
3127     SourceRange SR = AL.getSourceRange();
3128     TemplateName Name = Arg.getAsTemplate();
3129     Diag(SR.getBegin(), diag::err_template_missing_args)
3130       << Name << SR;
3131     if (TemplateDecl *Decl = Name.getAsTemplateDecl())
3132       Diag(Decl->getLocation(), diag::note_template_decl_here);
3133 
3134     return true;
3135   }
3136   case TemplateArgument::Expression: {
3137     // We have a template type parameter but the template argument is an
3138     // expression; see if maybe it is missing the "typename" keyword.
3139     CXXScopeSpec SS;
3140     DeclarationNameInfo NameInfo;
3141 
3142     if (DeclRefExpr *ArgExpr = dyn_cast<DeclRefExpr>(Arg.getAsExpr())) {
3143       SS.Adopt(ArgExpr->getQualifierLoc());
3144       NameInfo = ArgExpr->getNameInfo();
3145     } else if (DependentScopeDeclRefExpr *ArgExpr =
3146                dyn_cast<DependentScopeDeclRefExpr>(Arg.getAsExpr())) {
3147       SS.Adopt(ArgExpr->getQualifierLoc());
3148       NameInfo = ArgExpr->getNameInfo();
3149     } else if (CXXDependentScopeMemberExpr *ArgExpr =
3150                dyn_cast<CXXDependentScopeMemberExpr>(Arg.getAsExpr())) {
3151       if (ArgExpr->isImplicitAccess()) {
3152         SS.Adopt(ArgExpr->getQualifierLoc());
3153         NameInfo = ArgExpr->getMemberNameInfo();
3154       }
3155     }
3156 
3157     if (auto *II = NameInfo.getName().getAsIdentifierInfo()) {
3158       LookupResult Result(*this, NameInfo, LookupOrdinaryName);
3159       LookupParsedName(Result, CurScope, &SS);
3160 
3161       if (Result.getAsSingle<TypeDecl>() ||
3162           Result.getResultKind() ==
3163               LookupResult::NotFoundInCurrentInstantiation) {
3164         // Suggest that the user add 'typename' before the NNS.
3165         SourceLocation Loc = AL.getSourceRange().getBegin();
3166         Diag(Loc, getLangOpts().MSVCCompat
3167                       ? diag::ext_ms_template_type_arg_missing_typename
3168                       : diag::err_template_arg_must_be_type_suggest)
3169             << FixItHint::CreateInsertion(Loc, "typename ");
3170         Diag(Param->getLocation(), diag::note_template_param_here);
3171 
3172         // Recover by synthesizing a type using the location information that we
3173         // already have.
3174         ArgType =
3175             Context.getDependentNameType(ETK_Typename, SS.getScopeRep(), II);
3176         TypeLocBuilder TLB;
3177         DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(ArgType);
3178         TL.setElaboratedKeywordLoc(SourceLocation(/*synthesized*/));
3179         TL.setQualifierLoc(SS.getWithLocInContext(Context));
3180         TL.setNameLoc(NameInfo.getLoc());
3181         TSI = TLB.getTypeSourceInfo(Context, ArgType);
3182 
3183         // Overwrite our input TemplateArgumentLoc so that we can recover
3184         // properly.
3185         AL = TemplateArgumentLoc(TemplateArgument(ArgType),
3186                                  TemplateArgumentLocInfo(TSI));
3187 
3188         break;
3189       }
3190     }
3191     // fallthrough
3192   }
3193   default: {
3194     // We have a template type parameter but the template argument
3195     // is not a type.
3196     SourceRange SR = AL.getSourceRange();
3197     Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
3198     Diag(Param->getLocation(), diag::note_template_param_here);
3199 
3200     return true;
3201   }
3202   }
3203 
3204   if (CheckTemplateArgument(Param, TSI))
3205     return true;
3206 
3207   // Add the converted template type argument.
3208   ArgType = Context.getCanonicalType(ArgType);
3209 
3210   // Objective-C ARC:
3211   //   If an explicitly-specified template argument type is a lifetime type
3212   //   with no lifetime qualifier, the __strong lifetime qualifier is inferred.
3213   if (getLangOpts().ObjCAutoRefCount &&
3214       ArgType->isObjCLifetimeType() &&
3215       !ArgType.getObjCLifetime()) {
3216     Qualifiers Qs;
3217     Qs.setObjCLifetime(Qualifiers::OCL_Strong);
3218     ArgType = Context.getQualifiedType(ArgType, Qs);
3219   }
3220 
3221   Converted.push_back(TemplateArgument(ArgType));
3222   return false;
3223 }
3224 
3225 /// \brief Substitute template arguments into the default template argument for
3226 /// the given template type parameter.
3227 ///
3228 /// \param SemaRef the semantic analysis object for which we are performing
3229 /// the substitution.
3230 ///
3231 /// \param Template the template that we are synthesizing template arguments
3232 /// for.
3233 ///
3234 /// \param TemplateLoc the location of the template name that started the
3235 /// template-id we are checking.
3236 ///
3237 /// \param RAngleLoc the location of the right angle bracket ('>') that
3238 /// terminates the template-id.
3239 ///
3240 /// \param Param the template template parameter whose default we are
3241 /// substituting into.
3242 ///
3243 /// \param Converted the list of template arguments provided for template
3244 /// parameters that precede \p Param in the template parameter list.
3245 /// \returns the substituted template argument, or NULL if an error occurred.
3246 static TypeSourceInfo *
SubstDefaultTemplateArgument(Sema & SemaRef,TemplateDecl * Template,SourceLocation TemplateLoc,SourceLocation RAngleLoc,TemplateTypeParmDecl * Param,SmallVectorImpl<TemplateArgument> & Converted)3247 SubstDefaultTemplateArgument(Sema &SemaRef,
3248                              TemplateDecl *Template,
3249                              SourceLocation TemplateLoc,
3250                              SourceLocation RAngleLoc,
3251                              TemplateTypeParmDecl *Param,
3252                          SmallVectorImpl<TemplateArgument> &Converted) {
3253   TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
3254 
3255   // If the argument type is dependent, instantiate it now based
3256   // on the previously-computed template arguments.
3257   if (ArgType->getType()->isDependentType()) {
3258     Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
3259                                      Template, Converted,
3260                                      SourceRange(TemplateLoc, RAngleLoc));
3261     if (Inst.isInvalid())
3262       return nullptr;
3263 
3264     TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
3265 
3266     // Only substitute for the innermost template argument list.
3267     MultiLevelTemplateArgumentList TemplateArgLists;
3268     TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
3269     for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
3270       TemplateArgLists.addOuterTemplateArguments(None);
3271 
3272     Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
3273     ArgType =
3274         SemaRef.SubstType(ArgType, TemplateArgLists,
3275                           Param->getDefaultArgumentLoc(), Param->getDeclName());
3276   }
3277 
3278   return ArgType;
3279 }
3280 
3281 /// \brief Substitute template arguments into the default template argument for
3282 /// the given non-type template parameter.
3283 ///
3284 /// \param SemaRef the semantic analysis object for which we are performing
3285 /// the substitution.
3286 ///
3287 /// \param Template the template that we are synthesizing template arguments
3288 /// for.
3289 ///
3290 /// \param TemplateLoc the location of the template name that started the
3291 /// template-id we are checking.
3292 ///
3293 /// \param RAngleLoc the location of the right angle bracket ('>') that
3294 /// terminates the template-id.
3295 ///
3296 /// \param Param the non-type template parameter whose default we are
3297 /// substituting into.
3298 ///
3299 /// \param Converted the list of template arguments provided for template
3300 /// parameters that precede \p Param in the template parameter list.
3301 ///
3302 /// \returns the substituted template argument, or NULL if an error occurred.
3303 static ExprResult
SubstDefaultTemplateArgument(Sema & SemaRef,TemplateDecl * Template,SourceLocation TemplateLoc,SourceLocation RAngleLoc,NonTypeTemplateParmDecl * Param,SmallVectorImpl<TemplateArgument> & Converted)3304 SubstDefaultTemplateArgument(Sema &SemaRef,
3305                              TemplateDecl *Template,
3306                              SourceLocation TemplateLoc,
3307                              SourceLocation RAngleLoc,
3308                              NonTypeTemplateParmDecl *Param,
3309                         SmallVectorImpl<TemplateArgument> &Converted) {
3310   Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
3311                                    Template, Converted,
3312                                    SourceRange(TemplateLoc, RAngleLoc));
3313   if (Inst.isInvalid())
3314     return ExprError();
3315 
3316   TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
3317 
3318   // Only substitute for the innermost template argument list.
3319   MultiLevelTemplateArgumentList TemplateArgLists;
3320   TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
3321   for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
3322     TemplateArgLists.addOuterTemplateArguments(None);
3323 
3324   EnterExpressionEvaluationContext ConstantEvaluated(SemaRef,
3325                                                      Sema::ConstantEvaluated);
3326   return SemaRef.SubstExpr(Param->getDefaultArgument(), TemplateArgLists);
3327 }
3328 
3329 /// \brief Substitute template arguments into the default template argument for
3330 /// the given template template parameter.
3331 ///
3332 /// \param SemaRef the semantic analysis object for which we are performing
3333 /// the substitution.
3334 ///
3335 /// \param Template the template that we are synthesizing template arguments
3336 /// for.
3337 ///
3338 /// \param TemplateLoc the location of the template name that started the
3339 /// template-id we are checking.
3340 ///
3341 /// \param RAngleLoc the location of the right angle bracket ('>') that
3342 /// terminates the template-id.
3343 ///
3344 /// \param Param the template template parameter whose default we are
3345 /// substituting into.
3346 ///
3347 /// \param Converted the list of template arguments provided for template
3348 /// parameters that precede \p Param in the template parameter list.
3349 ///
3350 /// \param QualifierLoc Will be set to the nested-name-specifier (with
3351 /// source-location information) that precedes the template name.
3352 ///
3353 /// \returns the substituted template argument, or NULL if an error occurred.
3354 static TemplateName
SubstDefaultTemplateArgument(Sema & SemaRef,TemplateDecl * Template,SourceLocation TemplateLoc,SourceLocation RAngleLoc,TemplateTemplateParmDecl * Param,SmallVectorImpl<TemplateArgument> & Converted,NestedNameSpecifierLoc & QualifierLoc)3355 SubstDefaultTemplateArgument(Sema &SemaRef,
3356                              TemplateDecl *Template,
3357                              SourceLocation TemplateLoc,
3358                              SourceLocation RAngleLoc,
3359                              TemplateTemplateParmDecl *Param,
3360                        SmallVectorImpl<TemplateArgument> &Converted,
3361                              NestedNameSpecifierLoc &QualifierLoc) {
3362   Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc, Template, Converted,
3363                                    SourceRange(TemplateLoc, RAngleLoc));
3364   if (Inst.isInvalid())
3365     return TemplateName();
3366 
3367   TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
3368 
3369   // Only substitute for the innermost template argument list.
3370   MultiLevelTemplateArgumentList TemplateArgLists;
3371   TemplateArgLists.addOuterTemplateArguments(&TemplateArgs);
3372   for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
3373     TemplateArgLists.addOuterTemplateArguments(None);
3374 
3375   Sema::ContextRAII SavedContext(SemaRef, Template->getDeclContext());
3376   // Substitute into the nested-name-specifier first,
3377   QualifierLoc = Param->getDefaultArgument().getTemplateQualifierLoc();
3378   if (QualifierLoc) {
3379     QualifierLoc =
3380         SemaRef.SubstNestedNameSpecifierLoc(QualifierLoc, TemplateArgLists);
3381     if (!QualifierLoc)
3382       return TemplateName();
3383   }
3384 
3385   return SemaRef.SubstTemplateName(
3386              QualifierLoc,
3387              Param->getDefaultArgument().getArgument().getAsTemplate(),
3388              Param->getDefaultArgument().getTemplateNameLoc(),
3389              TemplateArgLists);
3390 }
3391 
3392 /// \brief If the given template parameter has a default template
3393 /// argument, substitute into that default template argument and
3394 /// return the corresponding template argument.
3395 TemplateArgumentLoc
SubstDefaultTemplateArgumentIfAvailable(TemplateDecl * Template,SourceLocation TemplateLoc,SourceLocation RAngleLoc,Decl * Param,SmallVectorImpl<TemplateArgument> & Converted,bool & HasDefaultArg)3396 Sema::SubstDefaultTemplateArgumentIfAvailable(TemplateDecl *Template,
3397                                               SourceLocation TemplateLoc,
3398                                               SourceLocation RAngleLoc,
3399                                               Decl *Param,
3400                                               SmallVectorImpl<TemplateArgument>
3401                                                 &Converted,
3402                                               bool &HasDefaultArg) {
3403   HasDefaultArg = false;
3404 
3405   if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
3406     if (!hasVisibleDefaultArgument(TypeParm))
3407       return TemplateArgumentLoc();
3408 
3409     HasDefaultArg = true;
3410     TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
3411                                                       TemplateLoc,
3412                                                       RAngleLoc,
3413                                                       TypeParm,
3414                                                       Converted);
3415     if (DI)
3416       return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
3417 
3418     return TemplateArgumentLoc();
3419   }
3420 
3421   if (NonTypeTemplateParmDecl *NonTypeParm
3422         = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
3423     if (!hasVisibleDefaultArgument(NonTypeParm))
3424       return TemplateArgumentLoc();
3425 
3426     HasDefaultArg = true;
3427     ExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
3428                                                   TemplateLoc,
3429                                                   RAngleLoc,
3430                                                   NonTypeParm,
3431                                                   Converted);
3432     if (Arg.isInvalid())
3433       return TemplateArgumentLoc();
3434 
3435     Expr *ArgE = Arg.getAs<Expr>();
3436     return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
3437   }
3438 
3439   TemplateTemplateParmDecl *TempTempParm
3440     = cast<TemplateTemplateParmDecl>(Param);
3441   if (!hasVisibleDefaultArgument(TempTempParm))
3442     return TemplateArgumentLoc();
3443 
3444   HasDefaultArg = true;
3445   NestedNameSpecifierLoc QualifierLoc;
3446   TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
3447                                                     TemplateLoc,
3448                                                     RAngleLoc,
3449                                                     TempTempParm,
3450                                                     Converted,
3451                                                     QualifierLoc);
3452   if (TName.isNull())
3453     return TemplateArgumentLoc();
3454 
3455   return TemplateArgumentLoc(TemplateArgument(TName),
3456                 TempTempParm->getDefaultArgument().getTemplateQualifierLoc(),
3457                 TempTempParm->getDefaultArgument().getTemplateNameLoc());
3458 }
3459 
3460 /// \brief Check that the given template argument corresponds to the given
3461 /// template parameter.
3462 ///
3463 /// \param Param The template parameter against which the argument will be
3464 /// checked.
3465 ///
3466 /// \param Arg The template argument, which may be updated due to conversions.
3467 ///
3468 /// \param Template The template in which the template argument resides.
3469 ///
3470 /// \param TemplateLoc The location of the template name for the template
3471 /// whose argument list we're matching.
3472 ///
3473 /// \param RAngleLoc The location of the right angle bracket ('>') that closes
3474 /// the template argument list.
3475 ///
3476 /// \param ArgumentPackIndex The index into the argument pack where this
3477 /// argument will be placed. Only valid if the parameter is a parameter pack.
3478 ///
3479 /// \param Converted The checked, converted argument will be added to the
3480 /// end of this small vector.
3481 ///
3482 /// \param CTAK Describes how we arrived at this particular template argument:
3483 /// explicitly written, deduced, etc.
3484 ///
3485 /// \returns true on error, false otherwise.
CheckTemplateArgument(NamedDecl * Param,TemplateArgumentLoc & Arg,NamedDecl * Template,SourceLocation TemplateLoc,SourceLocation RAngleLoc,unsigned ArgumentPackIndex,SmallVectorImpl<TemplateArgument> & Converted,CheckTemplateArgumentKind CTAK)3486 bool Sema::CheckTemplateArgument(NamedDecl *Param,
3487                                  TemplateArgumentLoc &Arg,
3488                                  NamedDecl *Template,
3489                                  SourceLocation TemplateLoc,
3490                                  SourceLocation RAngleLoc,
3491                                  unsigned ArgumentPackIndex,
3492                             SmallVectorImpl<TemplateArgument> &Converted,
3493                                  CheckTemplateArgumentKind CTAK) {
3494   // Check template type parameters.
3495   if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
3496     return CheckTemplateTypeArgument(TTP, Arg, Converted);
3497 
3498   // Check non-type template parameters.
3499   if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {
3500     // Do substitution on the type of the non-type template parameter
3501     // with the template arguments we've seen thus far.  But if the
3502     // template has a dependent context then we cannot substitute yet.
3503     QualType NTTPType = NTTP->getType();
3504     if (NTTP->isParameterPack() && NTTP->isExpandedParameterPack())
3505       NTTPType = NTTP->getExpansionType(ArgumentPackIndex);
3506 
3507     if (NTTPType->isDependentType() &&
3508         !isa<TemplateTemplateParmDecl>(Template) &&
3509         !Template->getDeclContext()->isDependentContext()) {
3510       // Do substitution on the type of the non-type template parameter.
3511       InstantiatingTemplate Inst(*this, TemplateLoc, Template,
3512                                  NTTP, Converted,
3513                                  SourceRange(TemplateLoc, RAngleLoc));
3514       if (Inst.isInvalid())
3515         return true;
3516 
3517       TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
3518                                         Converted);
3519       NTTPType = SubstType(NTTPType,
3520                            MultiLevelTemplateArgumentList(TemplateArgs),
3521                            NTTP->getLocation(),
3522                            NTTP->getDeclName());
3523       // If that worked, check the non-type template parameter type
3524       // for validity.
3525       if (!NTTPType.isNull())
3526         NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
3527                                                      NTTP->getLocation());
3528       if (NTTPType.isNull())
3529         return true;
3530     }
3531 
3532     switch (Arg.getArgument().getKind()) {
3533     case TemplateArgument::Null:
3534       llvm_unreachable("Should never see a NULL template argument here");
3535 
3536     case TemplateArgument::Expression: {
3537       TemplateArgument Result;
3538       ExprResult Res =
3539         CheckTemplateArgument(NTTP, NTTPType, Arg.getArgument().getAsExpr(),
3540                               Result, CTAK);
3541       if (Res.isInvalid())
3542         return true;
3543 
3544       // If the resulting expression is new, then use it in place of the
3545       // old expression in the template argument.
3546       if (Res.get() != Arg.getArgument().getAsExpr()) {
3547         TemplateArgument TA(Res.get());
3548         Arg = TemplateArgumentLoc(TA, Res.get());
3549       }
3550 
3551       Converted.push_back(Result);
3552       break;
3553     }
3554 
3555     case TemplateArgument::Declaration:
3556     case TemplateArgument::Integral:
3557     case TemplateArgument::NullPtr:
3558       // We've already checked this template argument, so just copy
3559       // it to the list of converted arguments.
3560       Converted.push_back(Arg.getArgument());
3561       break;
3562 
3563     case TemplateArgument::Template:
3564     case TemplateArgument::TemplateExpansion:
3565       // We were given a template template argument. It may not be ill-formed;
3566       // see below.
3567       if (DependentTemplateName *DTN
3568             = Arg.getArgument().getAsTemplateOrTemplatePattern()
3569                                               .getAsDependentTemplateName()) {
3570         // We have a template argument such as \c T::template X, which we
3571         // parsed as a template template argument. However, since we now
3572         // know that we need a non-type template argument, convert this
3573         // template name into an expression.
3574 
3575         DeclarationNameInfo NameInfo(DTN->getIdentifier(),
3576                                      Arg.getTemplateNameLoc());
3577 
3578         CXXScopeSpec SS;
3579         SS.Adopt(Arg.getTemplateQualifierLoc());
3580         // FIXME: the template-template arg was a DependentTemplateName,
3581         // so it was provided with a template keyword. However, its source
3582         // location is not stored in the template argument structure.
3583         SourceLocation TemplateKWLoc;
3584         ExprResult E = DependentScopeDeclRefExpr::Create(
3585             Context, SS.getWithLocInContext(Context), TemplateKWLoc, NameInfo,
3586             nullptr);
3587 
3588         // If we parsed the template argument as a pack expansion, create a
3589         // pack expansion expression.
3590         if (Arg.getArgument().getKind() == TemplateArgument::TemplateExpansion){
3591           E = ActOnPackExpansion(E.get(), Arg.getTemplateEllipsisLoc());
3592           if (E.isInvalid())
3593             return true;
3594         }
3595 
3596         TemplateArgument Result;
3597         E = CheckTemplateArgument(NTTP, NTTPType, E.get(), Result);
3598         if (E.isInvalid())
3599           return true;
3600 
3601         Converted.push_back(Result);
3602         break;
3603       }
3604 
3605       // We have a template argument that actually does refer to a class
3606       // template, alias template, or template template parameter, and
3607       // therefore cannot be a non-type template argument.
3608       Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
3609         << Arg.getSourceRange();
3610 
3611       Diag(Param->getLocation(), diag::note_template_param_here);
3612       return true;
3613 
3614     case TemplateArgument::Type: {
3615       // We have a non-type template parameter but the template
3616       // argument is a type.
3617 
3618       // C++ [temp.arg]p2:
3619       //   In a template-argument, an ambiguity between a type-id and
3620       //   an expression is resolved to a type-id, regardless of the
3621       //   form of the corresponding template-parameter.
3622       //
3623       // We warn specifically about this case, since it can be rather
3624       // confusing for users.
3625       QualType T = Arg.getArgument().getAsType();
3626       SourceRange SR = Arg.getSourceRange();
3627       if (T->isFunctionType())
3628         Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
3629       else
3630         Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
3631       Diag(Param->getLocation(), diag::note_template_param_here);
3632       return true;
3633     }
3634 
3635     case TemplateArgument::Pack:
3636       llvm_unreachable("Caller must expand template argument packs");
3637     }
3638 
3639     return false;
3640   }
3641 
3642 
3643   // Check template template parameters.
3644   TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
3645 
3646   // Substitute into the template parameter list of the template
3647   // template parameter, since previously-supplied template arguments
3648   // may appear within the template template parameter.
3649   {
3650     // Set up a template instantiation context.
3651     LocalInstantiationScope Scope(*this);
3652     InstantiatingTemplate Inst(*this, TemplateLoc, Template,
3653                                TempParm, Converted,
3654                                SourceRange(TemplateLoc, RAngleLoc));
3655     if (Inst.isInvalid())
3656       return true;
3657 
3658     TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
3659     TempParm = cast_or_null<TemplateTemplateParmDecl>(
3660                       SubstDecl(TempParm, CurContext,
3661                                 MultiLevelTemplateArgumentList(TemplateArgs)));
3662     if (!TempParm)
3663       return true;
3664   }
3665 
3666   switch (Arg.getArgument().getKind()) {
3667   case TemplateArgument::Null:
3668     llvm_unreachable("Should never see a NULL template argument here");
3669 
3670   case TemplateArgument::Template:
3671   case TemplateArgument::TemplateExpansion:
3672     if (CheckTemplateArgument(TempParm, Arg, ArgumentPackIndex))
3673       return true;
3674 
3675     Converted.push_back(Arg.getArgument());
3676     break;
3677 
3678   case TemplateArgument::Expression:
3679   case TemplateArgument::Type:
3680     // We have a template template parameter but the template
3681     // argument does not refer to a template.
3682     Diag(Arg.getLocation(), diag::err_template_arg_must_be_template)
3683       << getLangOpts().CPlusPlus11;
3684     return true;
3685 
3686   case TemplateArgument::Declaration:
3687     llvm_unreachable("Declaration argument with template template parameter");
3688   case TemplateArgument::Integral:
3689     llvm_unreachable("Integral argument with template template parameter");
3690   case TemplateArgument::NullPtr:
3691     llvm_unreachable("Null pointer argument with template template parameter");
3692 
3693   case TemplateArgument::Pack:
3694     llvm_unreachable("Caller must expand template argument packs");
3695   }
3696 
3697   return false;
3698 }
3699 
3700 /// \brief Diagnose an arity mismatch in the
diagnoseArityMismatch(Sema & S,TemplateDecl * Template,SourceLocation TemplateLoc,TemplateArgumentListInfo & TemplateArgs)3701 static bool diagnoseArityMismatch(Sema &S, TemplateDecl *Template,
3702                                   SourceLocation TemplateLoc,
3703                                   TemplateArgumentListInfo &TemplateArgs) {
3704   TemplateParameterList *Params = Template->getTemplateParameters();
3705   unsigned NumParams = Params->size();
3706   unsigned NumArgs = TemplateArgs.size();
3707 
3708   SourceRange Range;
3709   if (NumArgs > NumParams)
3710     Range = SourceRange(TemplateArgs[NumParams].getLocation(),
3711                         TemplateArgs.getRAngleLoc());
3712   S.Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
3713     << (NumArgs > NumParams)
3714     << (isa<ClassTemplateDecl>(Template)? 0 :
3715         isa<FunctionTemplateDecl>(Template)? 1 :
3716         isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
3717     << Template << Range;
3718   S.Diag(Template->getLocation(), diag::note_template_decl_here)
3719     << Params->getSourceRange();
3720   return true;
3721 }
3722 
3723 /// \brief Check whether the template parameter is a pack expansion, and if so,
3724 /// determine the number of parameters produced by that expansion. For instance:
3725 ///
3726 /// \code
3727 /// template<typename ...Ts> struct A {
3728 ///   template<Ts ...NTs, template<Ts> class ...TTs, typename ...Us> struct B;
3729 /// };
3730 /// \endcode
3731 ///
3732 /// In \c A<int,int>::B, \c NTs and \c TTs have expanded pack size 2, and \c Us
3733 /// is not a pack expansion, so returns an empty Optional.
getExpandedPackSize(NamedDecl * Param)3734 static Optional<unsigned> getExpandedPackSize(NamedDecl *Param) {
3735   if (NonTypeTemplateParmDecl *NTTP
3736         = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
3737     if (NTTP->isExpandedParameterPack())
3738       return NTTP->getNumExpansionTypes();
3739   }
3740 
3741   if (TemplateTemplateParmDecl *TTP
3742         = dyn_cast<TemplateTemplateParmDecl>(Param)) {
3743     if (TTP->isExpandedParameterPack())
3744       return TTP->getNumExpansionTemplateParameters();
3745   }
3746 
3747   return None;
3748 }
3749 
3750 /// Diagnose a missing template argument.
3751 template<typename TemplateParmDecl>
diagnoseMissingArgument(Sema & S,SourceLocation Loc,TemplateDecl * TD,const TemplateParmDecl * D,TemplateArgumentListInfo & Args)3752 static bool diagnoseMissingArgument(Sema &S, SourceLocation Loc,
3753                                     TemplateDecl *TD,
3754                                     const TemplateParmDecl *D,
3755                                     TemplateArgumentListInfo &Args) {
3756   // Dig out the most recent declaration of the template parameter; there may be
3757   // declarations of the template that are more recent than TD.
3758   D = cast<TemplateParmDecl>(cast<TemplateDecl>(TD->getMostRecentDecl())
3759                                  ->getTemplateParameters()
3760                                  ->getParam(D->getIndex()));
3761 
3762   // If there's a default argument that's not visible, diagnose that we're
3763   // missing a module import.
3764   llvm::SmallVector<Module*, 8> Modules;
3765   if (D->hasDefaultArgument() && !S.hasVisibleDefaultArgument(D, &Modules)) {
3766     S.diagnoseMissingImport(Loc, cast<NamedDecl>(TD),
3767                             D->getDefaultArgumentLoc(), Modules,
3768                             Sema::MissingImportKind::DefaultArgument,
3769                             /*Recover*/true);
3770     return true;
3771   }
3772 
3773   // FIXME: If there's a more recent default argument that *is* visible,
3774   // diagnose that it was declared too late.
3775 
3776   return diagnoseArityMismatch(S, TD, Loc, Args);
3777 }
3778 
3779 /// \brief Check that the given template argument list is well-formed
3780 /// for specializing the given template.
CheckTemplateArgumentList(TemplateDecl * Template,SourceLocation TemplateLoc,TemplateArgumentListInfo & TemplateArgs,bool PartialTemplateArgs,SmallVectorImpl<TemplateArgument> & Converted)3781 bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
3782                                      SourceLocation TemplateLoc,
3783                                      TemplateArgumentListInfo &TemplateArgs,
3784                                      bool PartialTemplateArgs,
3785                           SmallVectorImpl<TemplateArgument> &Converted) {
3786   // Make a copy of the template arguments for processing.  Only make the
3787   // changes at the end when successful in matching the arguments to the
3788   // template.
3789   TemplateArgumentListInfo NewArgs = TemplateArgs;
3790 
3791   TemplateParameterList *Params = Template->getTemplateParameters();
3792 
3793   SourceLocation RAngleLoc = NewArgs.getRAngleLoc();
3794 
3795   // C++ [temp.arg]p1:
3796   //   [...] The type and form of each template-argument specified in
3797   //   a template-id shall match the type and form specified for the
3798   //   corresponding parameter declared by the template in its
3799   //   template-parameter-list.
3800   bool isTemplateTemplateParameter = isa<TemplateTemplateParmDecl>(Template);
3801   SmallVector<TemplateArgument, 2> ArgumentPack;
3802   unsigned ArgIdx = 0, NumArgs = NewArgs.size();
3803   LocalInstantiationScope InstScope(*this, true);
3804   for (TemplateParameterList::iterator Param = Params->begin(),
3805                                        ParamEnd = Params->end();
3806        Param != ParamEnd; /* increment in loop */) {
3807     // If we have an expanded parameter pack, make sure we don't have too
3808     // many arguments.
3809     if (Optional<unsigned> Expansions = getExpandedPackSize(*Param)) {
3810       if (*Expansions == ArgumentPack.size()) {
3811         // We're done with this parameter pack. Pack up its arguments and add
3812         // them to the list.
3813         Converted.push_back(
3814             TemplateArgument::CreatePackCopy(Context, ArgumentPack));
3815         ArgumentPack.clear();
3816 
3817         // This argument is assigned to the next parameter.
3818         ++Param;
3819         continue;
3820       } else if (ArgIdx == NumArgs && !PartialTemplateArgs) {
3821         // Not enough arguments for this parameter pack.
3822         Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
3823           << false
3824           << (isa<ClassTemplateDecl>(Template)? 0 :
3825               isa<FunctionTemplateDecl>(Template)? 1 :
3826               isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
3827           << Template;
3828         Diag(Template->getLocation(), diag::note_template_decl_here)
3829           << Params->getSourceRange();
3830         return true;
3831       }
3832     }
3833 
3834     if (ArgIdx < NumArgs) {
3835       // Check the template argument we were given.
3836       if (CheckTemplateArgument(*Param, NewArgs[ArgIdx], Template,
3837                                 TemplateLoc, RAngleLoc,
3838                                 ArgumentPack.size(), Converted))
3839         return true;
3840 
3841       bool PackExpansionIntoNonPack =
3842           NewArgs[ArgIdx].getArgument().isPackExpansion() &&
3843           (!(*Param)->isTemplateParameterPack() || getExpandedPackSize(*Param));
3844       if (PackExpansionIntoNonPack && isa<TypeAliasTemplateDecl>(Template)) {
3845         // Core issue 1430: we have a pack expansion as an argument to an
3846         // alias template, and it's not part of a parameter pack. This
3847         // can't be canonicalized, so reject it now.
3848         Diag(NewArgs[ArgIdx].getLocation(),
3849              diag::err_alias_template_expansion_into_fixed_list)
3850           << NewArgs[ArgIdx].getSourceRange();
3851         Diag((*Param)->getLocation(), diag::note_template_param_here);
3852         return true;
3853       }
3854 
3855       // We're now done with this argument.
3856       ++ArgIdx;
3857 
3858       if ((*Param)->isTemplateParameterPack()) {
3859         // The template parameter was a template parameter pack, so take the
3860         // deduced argument and place it on the argument pack. Note that we
3861         // stay on the same template parameter so that we can deduce more
3862         // arguments.
3863         ArgumentPack.push_back(Converted.pop_back_val());
3864       } else {
3865         // Move to the next template parameter.
3866         ++Param;
3867       }
3868 
3869       // If we just saw a pack expansion into a non-pack, then directly convert
3870       // the remaining arguments, because we don't know what parameters they'll
3871       // match up with.
3872       if (PackExpansionIntoNonPack) {
3873         if (!ArgumentPack.empty()) {
3874           // If we were part way through filling in an expanded parameter pack,
3875           // fall back to just producing individual arguments.
3876           Converted.insert(Converted.end(),
3877                            ArgumentPack.begin(), ArgumentPack.end());
3878           ArgumentPack.clear();
3879         }
3880 
3881         while (ArgIdx < NumArgs) {
3882           Converted.push_back(NewArgs[ArgIdx].getArgument());
3883           ++ArgIdx;
3884         }
3885 
3886         return false;
3887       }
3888 
3889       continue;
3890     }
3891 
3892     // If we're checking a partial template argument list, we're done.
3893     if (PartialTemplateArgs) {
3894       if ((*Param)->isTemplateParameterPack() && !ArgumentPack.empty())
3895         Converted.push_back(
3896             TemplateArgument::CreatePackCopy(Context, ArgumentPack));
3897 
3898       return false;
3899     }
3900 
3901     // If we have a template parameter pack with no more corresponding
3902     // arguments, just break out now and we'll fill in the argument pack below.
3903     if ((*Param)->isTemplateParameterPack()) {
3904       assert(!getExpandedPackSize(*Param) &&
3905              "Should have dealt with this already");
3906 
3907       // A non-expanded parameter pack before the end of the parameter list
3908       // only occurs for an ill-formed template parameter list, unless we've
3909       // got a partial argument list for a function template, so just bail out.
3910       if (Param + 1 != ParamEnd)
3911         return true;
3912 
3913       Converted.push_back(
3914           TemplateArgument::CreatePackCopy(Context, ArgumentPack));
3915       ArgumentPack.clear();
3916 
3917       ++Param;
3918       continue;
3919     }
3920 
3921     // Check whether we have a default argument.
3922     TemplateArgumentLoc Arg;
3923 
3924     // Retrieve the default template argument from the template
3925     // parameter. For each kind of template parameter, we substitute the
3926     // template arguments provided thus far and any "outer" template arguments
3927     // (when the template parameter was part of a nested template) into
3928     // the default argument.
3929     if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
3930       if (!hasVisibleDefaultArgument(TTP))
3931         return diagnoseMissingArgument(*this, TemplateLoc, Template, TTP,
3932                                        NewArgs);
3933 
3934       TypeSourceInfo *ArgType = SubstDefaultTemplateArgument(*this,
3935                                                              Template,
3936                                                              TemplateLoc,
3937                                                              RAngleLoc,
3938                                                              TTP,
3939                                                              Converted);
3940       if (!ArgType)
3941         return true;
3942 
3943       Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
3944                                 ArgType);
3945     } else if (NonTypeTemplateParmDecl *NTTP
3946                  = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
3947       if (!hasVisibleDefaultArgument(NTTP))
3948         return diagnoseMissingArgument(*this, TemplateLoc, Template, NTTP,
3949                                        NewArgs);
3950 
3951       ExprResult E = SubstDefaultTemplateArgument(*this, Template,
3952                                                               TemplateLoc,
3953                                                               RAngleLoc,
3954                                                               NTTP,
3955                                                               Converted);
3956       if (E.isInvalid())
3957         return true;
3958 
3959       Expr *Ex = E.getAs<Expr>();
3960       Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
3961     } else {
3962       TemplateTemplateParmDecl *TempParm
3963         = cast<TemplateTemplateParmDecl>(*Param);
3964 
3965       if (!hasVisibleDefaultArgument(TempParm))
3966         return diagnoseMissingArgument(*this, TemplateLoc, Template, TempParm,
3967                                        NewArgs);
3968 
3969       NestedNameSpecifierLoc QualifierLoc;
3970       TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
3971                                                        TemplateLoc,
3972                                                        RAngleLoc,
3973                                                        TempParm,
3974                                                        Converted,
3975                                                        QualifierLoc);
3976       if (Name.isNull())
3977         return true;
3978 
3979       Arg = TemplateArgumentLoc(TemplateArgument(Name), QualifierLoc,
3980                            TempParm->getDefaultArgument().getTemplateNameLoc());
3981     }
3982 
3983     // Introduce an instantiation record that describes where we are using
3984     // the default template argument.
3985     InstantiatingTemplate Inst(*this, RAngleLoc, Template, *Param, Converted,
3986                                SourceRange(TemplateLoc, RAngleLoc));
3987     if (Inst.isInvalid())
3988       return true;
3989 
3990     // Check the default template argument.
3991     if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
3992                               RAngleLoc, 0, Converted))
3993       return true;
3994 
3995     // Core issue 150 (assumed resolution): if this is a template template
3996     // parameter, keep track of the default template arguments from the
3997     // template definition.
3998     if (isTemplateTemplateParameter)
3999       NewArgs.addArgument(Arg);
4000 
4001     // Move to the next template parameter and argument.
4002     ++Param;
4003     ++ArgIdx;
4004   }
4005 
4006   // If we're performing a partial argument substitution, allow any trailing
4007   // pack expansions; they might be empty. This can happen even if
4008   // PartialTemplateArgs is false (the list of arguments is complete but
4009   // still dependent).
4010   if (ArgIdx < NumArgs && CurrentInstantiationScope &&
4011       CurrentInstantiationScope->getPartiallySubstitutedPack()) {
4012     while (ArgIdx < NumArgs && NewArgs[ArgIdx].getArgument().isPackExpansion())
4013       Converted.push_back(NewArgs[ArgIdx++].getArgument());
4014   }
4015 
4016   // If we have any leftover arguments, then there were too many arguments.
4017   // Complain and fail.
4018   if (ArgIdx < NumArgs)
4019     return diagnoseArityMismatch(*this, Template, TemplateLoc, NewArgs);
4020 
4021   // No problems found with the new argument list, propagate changes back
4022   // to caller.
4023   TemplateArgs = std::move(NewArgs);
4024 
4025   return false;
4026 }
4027 
4028 namespace {
4029   class UnnamedLocalNoLinkageFinder
4030     : public TypeVisitor<UnnamedLocalNoLinkageFinder, bool>
4031   {
4032     Sema &S;
4033     SourceRange SR;
4034 
4035     typedef TypeVisitor<UnnamedLocalNoLinkageFinder, bool> inherited;
4036 
4037   public:
UnnamedLocalNoLinkageFinder(Sema & S,SourceRange SR)4038     UnnamedLocalNoLinkageFinder(Sema &S, SourceRange SR) : S(S), SR(SR) { }
4039 
Visit(QualType T)4040     bool Visit(QualType T) {
4041       return inherited::Visit(T.getTypePtr());
4042     }
4043 
4044 #define TYPE(Class, Parent) \
4045     bool Visit##Class##Type(const Class##Type *);
4046 #define ABSTRACT_TYPE(Class, Parent) \
4047     bool Visit##Class##Type(const Class##Type *) { return false; }
4048 #define NON_CANONICAL_TYPE(Class, Parent) \
4049     bool Visit##Class##Type(const Class##Type *) { return false; }
4050 #include "clang/AST/TypeNodes.def"
4051 
4052     bool VisitTagDecl(const TagDecl *Tag);
4053     bool VisitNestedNameSpecifier(NestedNameSpecifier *NNS);
4054   };
4055 } // end anonymous namespace
4056 
VisitBuiltinType(const BuiltinType *)4057 bool UnnamedLocalNoLinkageFinder::VisitBuiltinType(const BuiltinType*) {
4058   return false;
4059 }
4060 
VisitComplexType(const ComplexType * T)4061 bool UnnamedLocalNoLinkageFinder::VisitComplexType(const ComplexType* T) {
4062   return Visit(T->getElementType());
4063 }
4064 
VisitPointerType(const PointerType * T)4065 bool UnnamedLocalNoLinkageFinder::VisitPointerType(const PointerType* T) {
4066   return Visit(T->getPointeeType());
4067 }
4068 
VisitBlockPointerType(const BlockPointerType * T)4069 bool UnnamedLocalNoLinkageFinder::VisitBlockPointerType(
4070                                                     const BlockPointerType* T) {
4071   return Visit(T->getPointeeType());
4072 }
4073 
VisitLValueReferenceType(const LValueReferenceType * T)4074 bool UnnamedLocalNoLinkageFinder::VisitLValueReferenceType(
4075                                                 const LValueReferenceType* T) {
4076   return Visit(T->getPointeeType());
4077 }
4078 
VisitRValueReferenceType(const RValueReferenceType * T)4079 bool UnnamedLocalNoLinkageFinder::VisitRValueReferenceType(
4080                                                 const RValueReferenceType* T) {
4081   return Visit(T->getPointeeType());
4082 }
4083 
VisitMemberPointerType(const MemberPointerType * T)4084 bool UnnamedLocalNoLinkageFinder::VisitMemberPointerType(
4085                                                   const MemberPointerType* T) {
4086   return Visit(T->getPointeeType()) || Visit(QualType(T->getClass(), 0));
4087 }
4088 
VisitConstantArrayType(const ConstantArrayType * T)4089 bool UnnamedLocalNoLinkageFinder::VisitConstantArrayType(
4090                                                   const ConstantArrayType* T) {
4091   return Visit(T->getElementType());
4092 }
4093 
VisitIncompleteArrayType(const IncompleteArrayType * T)4094 bool UnnamedLocalNoLinkageFinder::VisitIncompleteArrayType(
4095                                                  const IncompleteArrayType* T) {
4096   return Visit(T->getElementType());
4097 }
4098 
VisitVariableArrayType(const VariableArrayType * T)4099 bool UnnamedLocalNoLinkageFinder::VisitVariableArrayType(
4100                                                    const VariableArrayType* T) {
4101   return Visit(T->getElementType());
4102 }
4103 
VisitDependentSizedArrayType(const DependentSizedArrayType * T)4104 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedArrayType(
4105                                             const DependentSizedArrayType* T) {
4106   return Visit(T->getElementType());
4107 }
4108 
VisitDependentSizedExtVectorType(const DependentSizedExtVectorType * T)4109 bool UnnamedLocalNoLinkageFinder::VisitDependentSizedExtVectorType(
4110                                          const DependentSizedExtVectorType* T) {
4111   return Visit(T->getElementType());
4112 }
4113 
VisitVectorType(const VectorType * T)4114 bool UnnamedLocalNoLinkageFinder::VisitVectorType(const VectorType* T) {
4115   return Visit(T->getElementType());
4116 }
4117 
VisitExtVectorType(const ExtVectorType * T)4118 bool UnnamedLocalNoLinkageFinder::VisitExtVectorType(const ExtVectorType* T) {
4119   return Visit(T->getElementType());
4120 }
4121 
VisitFunctionProtoType(const FunctionProtoType * T)4122 bool UnnamedLocalNoLinkageFinder::VisitFunctionProtoType(
4123                                                   const FunctionProtoType* T) {
4124   for (const auto &A : T->param_types()) {
4125     if (Visit(A))
4126       return true;
4127   }
4128 
4129   return Visit(T->getReturnType());
4130 }
4131 
VisitFunctionNoProtoType(const FunctionNoProtoType * T)4132 bool UnnamedLocalNoLinkageFinder::VisitFunctionNoProtoType(
4133                                                const FunctionNoProtoType* T) {
4134   return Visit(T->getReturnType());
4135 }
4136 
VisitUnresolvedUsingType(const UnresolvedUsingType *)4137 bool UnnamedLocalNoLinkageFinder::VisitUnresolvedUsingType(
4138                                                   const UnresolvedUsingType*) {
4139   return false;
4140 }
4141 
VisitTypeOfExprType(const TypeOfExprType *)4142 bool UnnamedLocalNoLinkageFinder::VisitTypeOfExprType(const TypeOfExprType*) {
4143   return false;
4144 }
4145 
VisitTypeOfType(const TypeOfType * T)4146 bool UnnamedLocalNoLinkageFinder::VisitTypeOfType(const TypeOfType* T) {
4147   return Visit(T->getUnderlyingType());
4148 }
4149 
VisitDecltypeType(const DecltypeType *)4150 bool UnnamedLocalNoLinkageFinder::VisitDecltypeType(const DecltypeType*) {
4151   return false;
4152 }
4153 
VisitUnaryTransformType(const UnaryTransformType *)4154 bool UnnamedLocalNoLinkageFinder::VisitUnaryTransformType(
4155                                                     const UnaryTransformType*) {
4156   return false;
4157 }
4158 
VisitAutoType(const AutoType * T)4159 bool UnnamedLocalNoLinkageFinder::VisitAutoType(const AutoType *T) {
4160   return Visit(T->getDeducedType());
4161 }
4162 
VisitRecordType(const RecordType * T)4163 bool UnnamedLocalNoLinkageFinder::VisitRecordType(const RecordType* T) {
4164   return VisitTagDecl(T->getDecl());
4165 }
4166 
VisitEnumType(const EnumType * T)4167 bool UnnamedLocalNoLinkageFinder::VisitEnumType(const EnumType* T) {
4168   return VisitTagDecl(T->getDecl());
4169 }
4170 
VisitTemplateTypeParmType(const TemplateTypeParmType *)4171 bool UnnamedLocalNoLinkageFinder::VisitTemplateTypeParmType(
4172                                                  const TemplateTypeParmType*) {
4173   return false;
4174 }
4175 
VisitSubstTemplateTypeParmPackType(const SubstTemplateTypeParmPackType *)4176 bool UnnamedLocalNoLinkageFinder::VisitSubstTemplateTypeParmPackType(
4177                                         const SubstTemplateTypeParmPackType *) {
4178   return false;
4179 }
4180 
VisitTemplateSpecializationType(const TemplateSpecializationType *)4181 bool UnnamedLocalNoLinkageFinder::VisitTemplateSpecializationType(
4182                                             const TemplateSpecializationType*) {
4183   return false;
4184 }
4185 
VisitInjectedClassNameType(const InjectedClassNameType * T)4186 bool UnnamedLocalNoLinkageFinder::VisitInjectedClassNameType(
4187                                               const InjectedClassNameType* T) {
4188   return VisitTagDecl(T->getDecl());
4189 }
4190 
VisitDependentNameType(const DependentNameType * T)4191 bool UnnamedLocalNoLinkageFinder::VisitDependentNameType(
4192                                                    const DependentNameType* T) {
4193   return VisitNestedNameSpecifier(T->getQualifier());
4194 }
4195 
VisitDependentTemplateSpecializationType(const DependentTemplateSpecializationType * T)4196 bool UnnamedLocalNoLinkageFinder::VisitDependentTemplateSpecializationType(
4197                                  const DependentTemplateSpecializationType* T) {
4198   return VisitNestedNameSpecifier(T->getQualifier());
4199 }
4200 
VisitPackExpansionType(const PackExpansionType * T)4201 bool UnnamedLocalNoLinkageFinder::VisitPackExpansionType(
4202                                                    const PackExpansionType* T) {
4203   return Visit(T->getPattern());
4204 }
4205 
VisitObjCObjectType(const ObjCObjectType *)4206 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectType(const ObjCObjectType *) {
4207   return false;
4208 }
4209 
VisitObjCInterfaceType(const ObjCInterfaceType *)4210 bool UnnamedLocalNoLinkageFinder::VisitObjCInterfaceType(
4211                                                    const ObjCInterfaceType *) {
4212   return false;
4213 }
4214 
VisitObjCObjectPointerType(const ObjCObjectPointerType *)4215 bool UnnamedLocalNoLinkageFinder::VisitObjCObjectPointerType(
4216                                                 const ObjCObjectPointerType *) {
4217   return false;
4218 }
4219 
VisitAtomicType(const AtomicType * T)4220 bool UnnamedLocalNoLinkageFinder::VisitAtomicType(const AtomicType* T) {
4221   return Visit(T->getValueType());
4222 }
4223 
VisitPipeType(const PipeType * T)4224 bool UnnamedLocalNoLinkageFinder::VisitPipeType(const PipeType* T) {
4225   return false;
4226 }
4227 
VisitTagDecl(const TagDecl * Tag)4228 bool UnnamedLocalNoLinkageFinder::VisitTagDecl(const TagDecl *Tag) {
4229   if (Tag->getDeclContext()->isFunctionOrMethod()) {
4230     S.Diag(SR.getBegin(),
4231            S.getLangOpts().CPlusPlus11 ?
4232              diag::warn_cxx98_compat_template_arg_local_type :
4233              diag::ext_template_arg_local_type)
4234       << S.Context.getTypeDeclType(Tag) << SR;
4235     return true;
4236   }
4237 
4238   if (!Tag->hasNameForLinkage()) {
4239     S.Diag(SR.getBegin(),
4240            S.getLangOpts().CPlusPlus11 ?
4241              diag::warn_cxx98_compat_template_arg_unnamed_type :
4242              diag::ext_template_arg_unnamed_type) << SR;
4243     S.Diag(Tag->getLocation(), diag::note_template_unnamed_type_here);
4244     return true;
4245   }
4246 
4247   return false;
4248 }
4249 
VisitNestedNameSpecifier(NestedNameSpecifier * NNS)4250 bool UnnamedLocalNoLinkageFinder::VisitNestedNameSpecifier(
4251                                                     NestedNameSpecifier *NNS) {
4252   if (NNS->getPrefix() && VisitNestedNameSpecifier(NNS->getPrefix()))
4253     return true;
4254 
4255   switch (NNS->getKind()) {
4256   case NestedNameSpecifier::Identifier:
4257   case NestedNameSpecifier::Namespace:
4258   case NestedNameSpecifier::NamespaceAlias:
4259   case NestedNameSpecifier::Global:
4260   case NestedNameSpecifier::Super:
4261     return false;
4262 
4263   case NestedNameSpecifier::TypeSpec:
4264   case NestedNameSpecifier::TypeSpecWithTemplate:
4265     return Visit(QualType(NNS->getAsType(), 0));
4266   }
4267   llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
4268 }
4269 
4270 /// \brief Check a template argument against its corresponding
4271 /// template type parameter.
4272 ///
4273 /// This routine implements the semantics of C++ [temp.arg.type]. It
4274 /// returns true if an error occurred, and false otherwise.
CheckTemplateArgument(TemplateTypeParmDecl * Param,TypeSourceInfo * ArgInfo)4275 bool Sema::CheckTemplateArgument(TemplateTypeParmDecl *Param,
4276                                  TypeSourceInfo *ArgInfo) {
4277   assert(ArgInfo && "invalid TypeSourceInfo");
4278   QualType Arg = ArgInfo->getType();
4279   SourceRange SR = ArgInfo->getTypeLoc().getSourceRange();
4280 
4281   if (Arg->isVariablyModifiedType()) {
4282     return Diag(SR.getBegin(), diag::err_variably_modified_template_arg) << Arg;
4283   } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
4284     return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
4285   }
4286 
4287   // C++03 [temp.arg.type]p2:
4288   //   A local type, a type with no linkage, an unnamed type or a type
4289   //   compounded from any of these types shall not be used as a
4290   //   template-argument for a template type-parameter.
4291   //
4292   // C++11 allows these, and even in C++03 we allow them as an extension with
4293   // a warning.
4294   bool NeedsCheck;
4295   if (LangOpts.CPlusPlus11)
4296     NeedsCheck =
4297         !Diags.isIgnored(diag::warn_cxx98_compat_template_arg_unnamed_type,
4298                          SR.getBegin()) ||
4299         !Diags.isIgnored(diag::warn_cxx98_compat_template_arg_local_type,
4300                          SR.getBegin());
4301   else
4302     NeedsCheck = Arg->hasUnnamedOrLocalType();
4303 
4304   if (NeedsCheck) {
4305     UnnamedLocalNoLinkageFinder Finder(*this, SR);
4306     (void)Finder.Visit(Context.getCanonicalType(Arg));
4307   }
4308 
4309   return false;
4310 }
4311 
4312 enum NullPointerValueKind {
4313   NPV_NotNullPointer,
4314   NPV_NullPointer,
4315   NPV_Error
4316 };
4317 
4318 /// \brief Determine whether the given template argument is a null pointer
4319 /// value of the appropriate type.
4320 static NullPointerValueKind
isNullPointerValueTemplateArgument(Sema & S,NonTypeTemplateParmDecl * Param,QualType ParamType,Expr * Arg)4321 isNullPointerValueTemplateArgument(Sema &S, NonTypeTemplateParmDecl *Param,
4322                                    QualType ParamType, Expr *Arg) {
4323   if (Arg->isValueDependent() || Arg->isTypeDependent())
4324     return NPV_NotNullPointer;
4325 
4326   if (!S.isCompleteType(Arg->getExprLoc(), ParamType))
4327     llvm_unreachable(
4328         "Incomplete parameter type in isNullPointerValueTemplateArgument!");
4329 
4330   if (!S.getLangOpts().CPlusPlus11)
4331     return NPV_NotNullPointer;
4332 
4333   // Determine whether we have a constant expression.
4334   ExprResult ArgRV = S.DefaultFunctionArrayConversion(Arg);
4335   if (ArgRV.isInvalid())
4336     return NPV_Error;
4337   Arg = ArgRV.get();
4338 
4339   Expr::EvalResult EvalResult;
4340   SmallVector<PartialDiagnosticAt, 8> Notes;
4341   EvalResult.Diag = &Notes;
4342   if (!Arg->EvaluateAsRValue(EvalResult, S.Context) ||
4343       EvalResult.HasSideEffects) {
4344     SourceLocation DiagLoc = Arg->getExprLoc();
4345 
4346     // If our only note is the usual "invalid subexpression" note, just point
4347     // the caret at its location rather than producing an essentially
4348     // redundant note.
4349     if (Notes.size() == 1 && Notes[0].second.getDiagID() ==
4350         diag::note_invalid_subexpr_in_const_expr) {
4351       DiagLoc = Notes[0].first;
4352       Notes.clear();
4353     }
4354 
4355     S.Diag(DiagLoc, diag::err_template_arg_not_address_constant)
4356       << Arg->getType() << Arg->getSourceRange();
4357     for (unsigned I = 0, N = Notes.size(); I != N; ++I)
4358       S.Diag(Notes[I].first, Notes[I].second);
4359 
4360     S.Diag(Param->getLocation(), diag::note_template_param_here);
4361     return NPV_Error;
4362   }
4363 
4364   // C++11 [temp.arg.nontype]p1:
4365   //   - an address constant expression of type std::nullptr_t
4366   if (Arg->getType()->isNullPtrType())
4367     return NPV_NullPointer;
4368 
4369   //   - a constant expression that evaluates to a null pointer value (4.10); or
4370   //   - a constant expression that evaluates to a null member pointer value
4371   //     (4.11); or
4372   if ((EvalResult.Val.isLValue() && !EvalResult.Val.getLValueBase()) ||
4373       (EvalResult.Val.isMemberPointer() &&
4374        !EvalResult.Val.getMemberPointerDecl())) {
4375     // If our expression has an appropriate type, we've succeeded.
4376     bool ObjCLifetimeConversion;
4377     if (S.Context.hasSameUnqualifiedType(Arg->getType(), ParamType) ||
4378         S.IsQualificationConversion(Arg->getType(), ParamType, false,
4379                                      ObjCLifetimeConversion))
4380       return NPV_NullPointer;
4381 
4382     // The types didn't match, but we know we got a null pointer; complain,
4383     // then recover as if the types were correct.
4384     S.Diag(Arg->getExprLoc(), diag::err_template_arg_wrongtype_null_constant)
4385       << Arg->getType() << ParamType << Arg->getSourceRange();
4386     S.Diag(Param->getLocation(), diag::note_template_param_here);
4387     return NPV_NullPointer;
4388   }
4389 
4390   // If we don't have a null pointer value, but we do have a NULL pointer
4391   // constant, suggest a cast to the appropriate type.
4392   if (Arg->isNullPointerConstant(S.Context, Expr::NPC_NeverValueDependent)) {
4393     std::string Code = "static_cast<" + ParamType.getAsString() + ">(";
4394     S.Diag(Arg->getExprLoc(), diag::err_template_arg_untyped_null_constant)
4395         << ParamType << FixItHint::CreateInsertion(Arg->getLocStart(), Code)
4396         << FixItHint::CreateInsertion(S.getLocForEndOfToken(Arg->getLocEnd()),
4397                                       ")");
4398     S.Diag(Param->getLocation(), diag::note_template_param_here);
4399     return NPV_NullPointer;
4400   }
4401 
4402   // FIXME: If we ever want to support general, address-constant expressions
4403   // as non-type template arguments, we should return the ExprResult here to
4404   // be interpreted by the caller.
4405   return NPV_NotNullPointer;
4406 }
4407 
4408 /// \brief Checks whether the given template argument is compatible with its
4409 /// template parameter.
CheckTemplateArgumentIsCompatibleWithParameter(Sema & S,NonTypeTemplateParmDecl * Param,QualType ParamType,Expr * ArgIn,Expr * Arg,QualType ArgType)4410 static bool CheckTemplateArgumentIsCompatibleWithParameter(
4411     Sema &S, NonTypeTemplateParmDecl *Param, QualType ParamType, Expr *ArgIn,
4412     Expr *Arg, QualType ArgType) {
4413   bool ObjCLifetimeConversion;
4414   if (ParamType->isPointerType() &&
4415       !ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType() &&
4416       S.IsQualificationConversion(ArgType, ParamType, false,
4417                                   ObjCLifetimeConversion)) {
4418     // For pointer-to-object types, qualification conversions are
4419     // permitted.
4420   } else {
4421     if (const ReferenceType *ParamRef = ParamType->getAs<ReferenceType>()) {
4422       if (!ParamRef->getPointeeType()->isFunctionType()) {
4423         // C++ [temp.arg.nontype]p5b3:
4424         //   For a non-type template-parameter of type reference to
4425         //   object, no conversions apply. The type referred to by the
4426         //   reference may be more cv-qualified than the (otherwise
4427         //   identical) type of the template- argument. The
4428         //   template-parameter is bound directly to the
4429         //   template-argument, which shall be an lvalue.
4430 
4431         // FIXME: Other qualifiers?
4432         unsigned ParamQuals = ParamRef->getPointeeType().getCVRQualifiers();
4433         unsigned ArgQuals = ArgType.getCVRQualifiers();
4434 
4435         if ((ParamQuals | ArgQuals) != ParamQuals) {
4436           S.Diag(Arg->getLocStart(),
4437                  diag::err_template_arg_ref_bind_ignores_quals)
4438             << ParamType << Arg->getType() << Arg->getSourceRange();
4439           S.Diag(Param->getLocation(), diag::note_template_param_here);
4440           return true;
4441         }
4442       }
4443     }
4444 
4445     // At this point, the template argument refers to an object or
4446     // function with external linkage. We now need to check whether the
4447     // argument and parameter types are compatible.
4448     if (!S.Context.hasSameUnqualifiedType(ArgType,
4449                                           ParamType.getNonReferenceType())) {
4450       // We can't perform this conversion or binding.
4451       if (ParamType->isReferenceType())
4452         S.Diag(Arg->getLocStart(), diag::err_template_arg_no_ref_bind)
4453           << ParamType << ArgIn->getType() << Arg->getSourceRange();
4454       else
4455         S.Diag(Arg->getLocStart(),  diag::err_template_arg_not_convertible)
4456           << ArgIn->getType() << ParamType << Arg->getSourceRange();
4457       S.Diag(Param->getLocation(), diag::note_template_param_here);
4458       return true;
4459     }
4460   }
4461 
4462   return false;
4463 }
4464 
4465 /// \brief Checks whether the given template argument is the address
4466 /// of an object or function according to C++ [temp.arg.nontype]p1.
4467 static bool
CheckTemplateArgumentAddressOfObjectOrFunction(Sema & S,NonTypeTemplateParmDecl * Param,QualType ParamType,Expr * ArgIn,TemplateArgument & Converted)4468 CheckTemplateArgumentAddressOfObjectOrFunction(Sema &S,
4469                                                NonTypeTemplateParmDecl *Param,
4470                                                QualType ParamType,
4471                                                Expr *ArgIn,
4472                                                TemplateArgument &Converted) {
4473   bool Invalid = false;
4474   Expr *Arg = ArgIn;
4475   QualType ArgType = Arg->getType();
4476 
4477   bool AddressTaken = false;
4478   SourceLocation AddrOpLoc;
4479   if (S.getLangOpts().MicrosoftExt) {
4480     // Microsoft Visual C++ strips all casts, allows an arbitrary number of
4481     // dereference and address-of operators.
4482     Arg = Arg->IgnoreParenCasts();
4483 
4484     bool ExtWarnMSTemplateArg = false;
4485     UnaryOperatorKind FirstOpKind;
4486     SourceLocation FirstOpLoc;
4487     while (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
4488       UnaryOperatorKind UnOpKind = UnOp->getOpcode();
4489       if (UnOpKind == UO_Deref)
4490         ExtWarnMSTemplateArg = true;
4491       if (UnOpKind == UO_AddrOf || UnOpKind == UO_Deref) {
4492         Arg = UnOp->getSubExpr()->IgnoreParenCasts();
4493         if (!AddrOpLoc.isValid()) {
4494           FirstOpKind = UnOpKind;
4495           FirstOpLoc = UnOp->getOperatorLoc();
4496         }
4497       } else
4498         break;
4499     }
4500     if (FirstOpLoc.isValid()) {
4501       if (ExtWarnMSTemplateArg)
4502         S.Diag(ArgIn->getLocStart(), diag::ext_ms_deref_template_argument)
4503           << ArgIn->getSourceRange();
4504 
4505       if (FirstOpKind == UO_AddrOf)
4506         AddressTaken = true;
4507       else if (Arg->getType()->isPointerType()) {
4508         // We cannot let pointers get dereferenced here, that is obviously not a
4509         // constant expression.
4510         assert(FirstOpKind == UO_Deref);
4511         S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
4512           << Arg->getSourceRange();
4513       }
4514     }
4515   } else {
4516     // See through any implicit casts we added to fix the type.
4517     Arg = Arg->IgnoreImpCasts();
4518 
4519     // C++ [temp.arg.nontype]p1:
4520     //
4521     //   A template-argument for a non-type, non-template
4522     //   template-parameter shall be one of: [...]
4523     //
4524     //     -- the address of an object or function with external
4525     //        linkage, including function templates and function
4526     //        template-ids but excluding non-static class members,
4527     //        expressed as & id-expression where the & is optional if
4528     //        the name refers to a function or array, or if the
4529     //        corresponding template-parameter is a reference; or
4530 
4531     // In C++98/03 mode, give an extension warning on any extra parentheses.
4532     // See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#773
4533     bool ExtraParens = false;
4534     while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
4535       if (!Invalid && !ExtraParens) {
4536         S.Diag(Arg->getLocStart(),
4537                S.getLangOpts().CPlusPlus11
4538                    ? diag::warn_cxx98_compat_template_arg_extra_parens
4539                    : diag::ext_template_arg_extra_parens)
4540             << Arg->getSourceRange();
4541         ExtraParens = true;
4542       }
4543 
4544       Arg = Parens->getSubExpr();
4545     }
4546 
4547     while (SubstNonTypeTemplateParmExpr *subst =
4548                dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
4549       Arg = subst->getReplacement()->IgnoreImpCasts();
4550 
4551     if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
4552       if (UnOp->getOpcode() == UO_AddrOf) {
4553         Arg = UnOp->getSubExpr();
4554         AddressTaken = true;
4555         AddrOpLoc = UnOp->getOperatorLoc();
4556       }
4557     }
4558 
4559     while (SubstNonTypeTemplateParmExpr *subst =
4560                dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
4561       Arg = subst->getReplacement()->IgnoreImpCasts();
4562   }
4563 
4564   DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(Arg);
4565   ValueDecl *Entity = DRE ? DRE->getDecl() : nullptr;
4566 
4567   // If our parameter has pointer type, check for a null template value.
4568   if (ParamType->isPointerType() || ParamType->isNullPtrType()) {
4569     NullPointerValueKind NPV;
4570     // dllimport'd entities aren't constant but are available inside of template
4571     // arguments.
4572     if (Entity && Entity->hasAttr<DLLImportAttr>())
4573       NPV = NPV_NotNullPointer;
4574     else
4575       NPV = isNullPointerValueTemplateArgument(S, Param, ParamType, ArgIn);
4576     switch (NPV) {
4577     case NPV_NullPointer:
4578       S.Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
4579       Converted = TemplateArgument(S.Context.getCanonicalType(ParamType),
4580                                    /*isNullPtr=*/true);
4581       return false;
4582 
4583     case NPV_Error:
4584       return true;
4585 
4586     case NPV_NotNullPointer:
4587       break;
4588     }
4589   }
4590 
4591   // Stop checking the precise nature of the argument if it is value dependent,
4592   // it should be checked when instantiated.
4593   if (Arg->isValueDependent()) {
4594     Converted = TemplateArgument(ArgIn);
4595     return false;
4596   }
4597 
4598   if (isa<CXXUuidofExpr>(Arg)) {
4599     if (CheckTemplateArgumentIsCompatibleWithParameter(S, Param, ParamType,
4600                                                        ArgIn, Arg, ArgType))
4601       return true;
4602 
4603     Converted = TemplateArgument(ArgIn);
4604     return false;
4605   }
4606 
4607   if (!DRE) {
4608     S.Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
4609     << Arg->getSourceRange();
4610     S.Diag(Param->getLocation(), diag::note_template_param_here);
4611     return true;
4612   }
4613 
4614   // Cannot refer to non-static data members
4615   if (isa<FieldDecl>(Entity) || isa<IndirectFieldDecl>(Entity)) {
4616     S.Diag(Arg->getLocStart(), diag::err_template_arg_field)
4617       << Entity << Arg->getSourceRange();
4618     S.Diag(Param->getLocation(), diag::note_template_param_here);
4619     return true;
4620   }
4621 
4622   // Cannot refer to non-static member functions
4623   if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Entity)) {
4624     if (!Method->isStatic()) {
4625       S.Diag(Arg->getLocStart(), diag::err_template_arg_method)
4626         << Method << Arg->getSourceRange();
4627       S.Diag(Param->getLocation(), diag::note_template_param_here);
4628       return true;
4629     }
4630   }
4631 
4632   FunctionDecl *Func = dyn_cast<FunctionDecl>(Entity);
4633   VarDecl *Var = dyn_cast<VarDecl>(Entity);
4634 
4635   // A non-type template argument must refer to an object or function.
4636   if (!Func && !Var) {
4637     // We found something, but we don't know specifically what it is.
4638     S.Diag(Arg->getLocStart(), diag::err_template_arg_not_object_or_func)
4639       << Arg->getSourceRange();
4640     S.Diag(DRE->getDecl()->getLocation(), diag::note_template_arg_refers_here);
4641     return true;
4642   }
4643 
4644   // Address / reference template args must have external linkage in C++98.
4645   if (Entity->getFormalLinkage() == InternalLinkage) {
4646     S.Diag(Arg->getLocStart(), S.getLangOpts().CPlusPlus11 ?
4647              diag::warn_cxx98_compat_template_arg_object_internal :
4648              diag::ext_template_arg_object_internal)
4649       << !Func << Entity << Arg->getSourceRange();
4650     S.Diag(Entity->getLocation(), diag::note_template_arg_internal_object)
4651       << !Func;
4652   } else if (!Entity->hasLinkage()) {
4653     S.Diag(Arg->getLocStart(), diag::err_template_arg_object_no_linkage)
4654       << !Func << Entity << Arg->getSourceRange();
4655     S.Diag(Entity->getLocation(), diag::note_template_arg_internal_object)
4656       << !Func;
4657     return true;
4658   }
4659 
4660   if (Func) {
4661     // If the template parameter has pointer type, the function decays.
4662     if (ParamType->isPointerType() && !AddressTaken)
4663       ArgType = S.Context.getPointerType(Func->getType());
4664     else if (AddressTaken && ParamType->isReferenceType()) {
4665       // If we originally had an address-of operator, but the
4666       // parameter has reference type, complain and (if things look
4667       // like they will work) drop the address-of operator.
4668       if (!S.Context.hasSameUnqualifiedType(Func->getType(),
4669                                             ParamType.getNonReferenceType())) {
4670         S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4671           << ParamType;
4672         S.Diag(Param->getLocation(), diag::note_template_param_here);
4673         return true;
4674       }
4675 
4676       S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4677         << ParamType
4678         << FixItHint::CreateRemoval(AddrOpLoc);
4679       S.Diag(Param->getLocation(), diag::note_template_param_here);
4680 
4681       ArgType = Func->getType();
4682     }
4683   } else {
4684     // A value of reference type is not an object.
4685     if (Var->getType()->isReferenceType()) {
4686       S.Diag(Arg->getLocStart(),
4687              diag::err_template_arg_reference_var)
4688         << Var->getType() << Arg->getSourceRange();
4689       S.Diag(Param->getLocation(), diag::note_template_param_here);
4690       return true;
4691     }
4692 
4693     // A template argument must have static storage duration.
4694     if (Var->getTLSKind()) {
4695       S.Diag(Arg->getLocStart(), diag::err_template_arg_thread_local)
4696         << Arg->getSourceRange();
4697       S.Diag(Var->getLocation(), diag::note_template_arg_refers_here);
4698       return true;
4699     }
4700 
4701     // If the template parameter has pointer type, we must have taken
4702     // the address of this object.
4703     if (ParamType->isReferenceType()) {
4704       if (AddressTaken) {
4705         // If we originally had an address-of operator, but the
4706         // parameter has reference type, complain and (if things look
4707         // like they will work) drop the address-of operator.
4708         if (!S.Context.hasSameUnqualifiedType(Var->getType(),
4709                                             ParamType.getNonReferenceType())) {
4710           S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4711             << ParamType;
4712           S.Diag(Param->getLocation(), diag::note_template_param_here);
4713           return true;
4714         }
4715 
4716         S.Diag(AddrOpLoc, diag::err_template_arg_address_of_non_pointer)
4717           << ParamType
4718           << FixItHint::CreateRemoval(AddrOpLoc);
4719         S.Diag(Param->getLocation(), diag::note_template_param_here);
4720 
4721         ArgType = Var->getType();
4722       }
4723     } else if (!AddressTaken && ParamType->isPointerType()) {
4724       if (Var->getType()->isArrayType()) {
4725         // Array-to-pointer decay.
4726         ArgType = S.Context.getArrayDecayedType(Var->getType());
4727       } else {
4728         // If the template parameter has pointer type but the address of
4729         // this object was not taken, complain and (possibly) recover by
4730         // taking the address of the entity.
4731         ArgType = S.Context.getPointerType(Var->getType());
4732         if (!S.Context.hasSameUnqualifiedType(ArgType, ParamType)) {
4733           S.Diag(Arg->getLocStart(), diag::err_template_arg_not_address_of)
4734             << ParamType;
4735           S.Diag(Param->getLocation(), diag::note_template_param_here);
4736           return true;
4737         }
4738 
4739         S.Diag(Arg->getLocStart(), diag::err_template_arg_not_address_of)
4740           << ParamType
4741           << FixItHint::CreateInsertion(Arg->getLocStart(), "&");
4742 
4743         S.Diag(Param->getLocation(), diag::note_template_param_here);
4744       }
4745     }
4746   }
4747 
4748   if (CheckTemplateArgumentIsCompatibleWithParameter(S, Param, ParamType, ArgIn,
4749                                                      Arg, ArgType))
4750     return true;
4751 
4752   // Create the template argument.
4753   Converted =
4754       TemplateArgument(cast<ValueDecl>(Entity->getCanonicalDecl()), ParamType);
4755   S.MarkAnyDeclReferenced(Arg->getLocStart(), Entity, false);
4756   return false;
4757 }
4758 
4759 /// \brief Checks whether the given template argument is a pointer to
4760 /// member constant according to C++ [temp.arg.nontype]p1.
CheckTemplateArgumentPointerToMember(Sema & S,NonTypeTemplateParmDecl * Param,QualType ParamType,Expr * & ResultArg,TemplateArgument & Converted)4761 static bool CheckTemplateArgumentPointerToMember(Sema &S,
4762                                                  NonTypeTemplateParmDecl *Param,
4763                                                  QualType ParamType,
4764                                                  Expr *&ResultArg,
4765                                                  TemplateArgument &Converted) {
4766   bool Invalid = false;
4767 
4768   // Check for a null pointer value.
4769   Expr *Arg = ResultArg;
4770   switch (isNullPointerValueTemplateArgument(S, Param, ParamType, Arg)) {
4771   case NPV_Error:
4772     return true;
4773   case NPV_NullPointer:
4774     S.Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
4775     Converted = TemplateArgument(S.Context.getCanonicalType(ParamType),
4776                                  /*isNullPtr*/true);
4777     return false;
4778   case NPV_NotNullPointer:
4779     break;
4780   }
4781 
4782   bool ObjCLifetimeConversion;
4783   if (S.IsQualificationConversion(Arg->getType(),
4784                                   ParamType.getNonReferenceType(),
4785                                   false, ObjCLifetimeConversion)) {
4786     Arg = S.ImpCastExprToType(Arg, ParamType, CK_NoOp,
4787                               Arg->getValueKind()).get();
4788     ResultArg = Arg;
4789   } else if (!S.Context.hasSameUnqualifiedType(Arg->getType(),
4790                 ParamType.getNonReferenceType())) {
4791     // We can't perform this conversion.
4792     S.Diag(Arg->getLocStart(), diag::err_template_arg_not_convertible)
4793       << Arg->getType() << ParamType << Arg->getSourceRange();
4794     S.Diag(Param->getLocation(), diag::note_template_param_here);
4795     return true;
4796   }
4797 
4798   // See through any implicit casts we added to fix the type.
4799   while (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(Arg))
4800     Arg = Cast->getSubExpr();
4801 
4802   // C++ [temp.arg.nontype]p1:
4803   //
4804   //   A template-argument for a non-type, non-template
4805   //   template-parameter shall be one of: [...]
4806   //
4807   //     -- a pointer to member expressed as described in 5.3.1.
4808   DeclRefExpr *DRE = nullptr;
4809 
4810   // In C++98/03 mode, give an extension warning on any extra parentheses.
4811   // See http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#773
4812   bool ExtraParens = false;
4813   while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
4814     if (!Invalid && !ExtraParens) {
4815       S.Diag(Arg->getLocStart(),
4816              S.getLangOpts().CPlusPlus11 ?
4817                diag::warn_cxx98_compat_template_arg_extra_parens :
4818                diag::ext_template_arg_extra_parens)
4819         << Arg->getSourceRange();
4820       ExtraParens = true;
4821     }
4822 
4823     Arg = Parens->getSubExpr();
4824   }
4825 
4826   while (SubstNonTypeTemplateParmExpr *subst =
4827            dyn_cast<SubstNonTypeTemplateParmExpr>(Arg))
4828     Arg = subst->getReplacement()->IgnoreImpCasts();
4829 
4830   // A pointer-to-member constant written &Class::member.
4831   if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
4832     if (UnOp->getOpcode() == UO_AddrOf) {
4833       DRE = dyn_cast<DeclRefExpr>(UnOp->getSubExpr());
4834       if (DRE && !DRE->getQualifier())
4835         DRE = nullptr;
4836     }
4837   }
4838   // A constant of pointer-to-member type.
4839   else if ((DRE = dyn_cast<DeclRefExpr>(Arg))) {
4840     if (ValueDecl *VD = dyn_cast<ValueDecl>(DRE->getDecl())) {
4841       if (VD->getType()->isMemberPointerType()) {
4842         if (isa<NonTypeTemplateParmDecl>(VD)) {
4843           if (Arg->isTypeDependent() || Arg->isValueDependent()) {
4844             Converted = TemplateArgument(Arg);
4845           } else {
4846             VD = cast<ValueDecl>(VD->getCanonicalDecl());
4847             Converted = TemplateArgument(VD, ParamType);
4848           }
4849           return Invalid;
4850         }
4851       }
4852     }
4853 
4854     DRE = nullptr;
4855   }
4856 
4857   if (!DRE)
4858     return S.Diag(Arg->getLocStart(),
4859                   diag::err_template_arg_not_pointer_to_member_form)
4860       << Arg->getSourceRange();
4861 
4862   if (isa<FieldDecl>(DRE->getDecl()) ||
4863       isa<IndirectFieldDecl>(DRE->getDecl()) ||
4864       isa<CXXMethodDecl>(DRE->getDecl())) {
4865     assert((isa<FieldDecl>(DRE->getDecl()) ||
4866             isa<IndirectFieldDecl>(DRE->getDecl()) ||
4867             !cast<CXXMethodDecl>(DRE->getDecl())->isStatic()) &&
4868            "Only non-static member pointers can make it here");
4869 
4870     // Okay: this is the address of a non-static member, and therefore
4871     // a member pointer constant.
4872     if (Arg->isTypeDependent() || Arg->isValueDependent()) {
4873       Converted = TemplateArgument(Arg);
4874     } else {
4875       ValueDecl *D = cast<ValueDecl>(DRE->getDecl()->getCanonicalDecl());
4876       Converted = TemplateArgument(D, ParamType);
4877     }
4878     return Invalid;
4879   }
4880 
4881   // We found something else, but we don't know specifically what it is.
4882   S.Diag(Arg->getLocStart(),
4883          diag::err_template_arg_not_pointer_to_member_form)
4884     << Arg->getSourceRange();
4885   S.Diag(DRE->getDecl()->getLocation(), diag::note_template_arg_refers_here);
4886   return true;
4887 }
4888 
4889 /// \brief Check a template argument against its corresponding
4890 /// non-type template parameter.
4891 ///
4892 /// This routine implements the semantics of C++ [temp.arg.nontype].
4893 /// If an error occurred, it returns ExprError(); otherwise, it
4894 /// returns the converted template argument. \p ParamType is the
4895 /// type of the non-type template parameter after it has been instantiated.
CheckTemplateArgument(NonTypeTemplateParmDecl * Param,QualType ParamType,Expr * Arg,TemplateArgument & Converted,CheckTemplateArgumentKind CTAK)4896 ExprResult Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
4897                                        QualType ParamType, Expr *Arg,
4898                                        TemplateArgument &Converted,
4899                                        CheckTemplateArgumentKind CTAK) {
4900   SourceLocation StartLoc = Arg->getLocStart();
4901 
4902   // If either the parameter has a dependent type or the argument is
4903   // type-dependent, there's nothing we can check now.
4904   if (ParamType->isDependentType() || Arg->isTypeDependent()) {
4905     // FIXME: Produce a cloned, canonical expression?
4906     Converted = TemplateArgument(Arg);
4907     return Arg;
4908   }
4909 
4910   // We should have already dropped all cv-qualifiers by now.
4911   assert(!ParamType.hasQualifiers() &&
4912          "non-type template parameter type cannot be qualified");
4913 
4914   if (CTAK == CTAK_Deduced &&
4915       !Context.hasSameUnqualifiedType(ParamType, Arg->getType())) {
4916     // C++ [temp.deduct.type]p17:
4917     //   If, in the declaration of a function template with a non-type
4918     //   template-parameter, the non-type template-parameter is used
4919     //   in an expression in the function parameter-list and, if the
4920     //   corresponding template-argument is deduced, the
4921     //   template-argument type shall match the type of the
4922     //   template-parameter exactly, except that a template-argument
4923     //   deduced from an array bound may be of any integral type.
4924     Diag(StartLoc, diag::err_deduced_non_type_template_arg_type_mismatch)
4925       << Arg->getType().getUnqualifiedType()
4926       << ParamType.getUnqualifiedType();
4927     Diag(Param->getLocation(), diag::note_template_param_here);
4928     return ExprError();
4929   }
4930 
4931   if (getLangOpts().CPlusPlus1z) {
4932     // FIXME: We can do some limited checking for a value-dependent but not
4933     // type-dependent argument.
4934     if (Arg->isValueDependent()) {
4935       Converted = TemplateArgument(Arg);
4936       return Arg;
4937     }
4938 
4939     // C++1z [temp.arg.nontype]p1:
4940     //   A template-argument for a non-type template parameter shall be
4941     //   a converted constant expression of the type of the template-parameter.
4942     APValue Value;
4943     ExprResult ArgResult = CheckConvertedConstantExpression(
4944         Arg, ParamType, Value, CCEK_TemplateArg);
4945     if (ArgResult.isInvalid())
4946       return ExprError();
4947 
4948     QualType CanonParamType = Context.getCanonicalType(ParamType);
4949 
4950     // Convert the APValue to a TemplateArgument.
4951     switch (Value.getKind()) {
4952     case APValue::Uninitialized:
4953       assert(ParamType->isNullPtrType());
4954       Converted = TemplateArgument(CanonParamType, /*isNullPtr*/true);
4955       break;
4956     case APValue::Int:
4957       assert(ParamType->isIntegralOrEnumerationType());
4958       Converted = TemplateArgument(Context, Value.getInt(), CanonParamType);
4959       break;
4960     case APValue::MemberPointer: {
4961       assert(ParamType->isMemberPointerType());
4962 
4963       // FIXME: We need TemplateArgument representation and mangling for these.
4964       if (!Value.getMemberPointerPath().empty()) {
4965         Diag(Arg->getLocStart(),
4966              diag::err_template_arg_member_ptr_base_derived_not_supported)
4967             << Value.getMemberPointerDecl() << ParamType
4968             << Arg->getSourceRange();
4969         return ExprError();
4970       }
4971 
4972       auto *VD = const_cast<ValueDecl*>(Value.getMemberPointerDecl());
4973       Converted = VD ? TemplateArgument(VD, CanonParamType)
4974                      : TemplateArgument(CanonParamType, /*isNullPtr*/true);
4975       break;
4976     }
4977     case APValue::LValue: {
4978       //   For a non-type template-parameter of pointer or reference type,
4979       //   the value of the constant expression shall not refer to
4980       assert(ParamType->isPointerType() || ParamType->isReferenceType() ||
4981              ParamType->isNullPtrType());
4982       // -- a temporary object
4983       // -- a string literal
4984       // -- the result of a typeid expression, or
4985       // -- a predefind __func__ variable
4986       if (auto *E = Value.getLValueBase().dyn_cast<const Expr*>()) {
4987         if (isa<CXXUuidofExpr>(E)) {
4988           Converted = TemplateArgument(const_cast<Expr*>(E));
4989           break;
4990         }
4991         Diag(Arg->getLocStart(), diag::err_template_arg_not_decl_ref)
4992           << Arg->getSourceRange();
4993         return ExprError();
4994       }
4995       auto *VD = const_cast<ValueDecl *>(
4996           Value.getLValueBase().dyn_cast<const ValueDecl *>());
4997       // -- a subobject
4998       if (Value.hasLValuePath() && Value.getLValuePath().size() == 1 &&
4999           VD && VD->getType()->isArrayType() &&
5000           Value.getLValuePath()[0].ArrayIndex == 0 &&
5001           !Value.isLValueOnePastTheEnd() && ParamType->isPointerType()) {
5002         // Per defect report (no number yet):
5003         //   ... other than a pointer to the first element of a complete array
5004         //       object.
5005       } else if (!Value.hasLValuePath() || Value.getLValuePath().size() ||
5006                  Value.isLValueOnePastTheEnd()) {
5007         Diag(StartLoc, diag::err_non_type_template_arg_subobject)
5008           << Value.getAsString(Context, ParamType);
5009         return ExprError();
5010       }
5011       assert((VD || !ParamType->isReferenceType()) &&
5012              "null reference should not be a constant expression");
5013       assert((!VD || !ParamType->isNullPtrType()) &&
5014              "non-null value of type nullptr_t?");
5015       Converted = VD ? TemplateArgument(VD, CanonParamType)
5016                      : TemplateArgument(CanonParamType, /*isNullPtr*/true);
5017       break;
5018     }
5019     case APValue::AddrLabelDiff:
5020       return Diag(StartLoc, diag::err_non_type_template_arg_addr_label_diff);
5021     case APValue::Float:
5022     case APValue::ComplexInt:
5023     case APValue::ComplexFloat:
5024     case APValue::Vector:
5025     case APValue::Array:
5026     case APValue::Struct:
5027     case APValue::Union:
5028       llvm_unreachable("invalid kind for template argument");
5029     }
5030 
5031     return ArgResult.get();
5032   }
5033 
5034   // C++ [temp.arg.nontype]p5:
5035   //   The following conversions are performed on each expression used
5036   //   as a non-type template-argument. If a non-type
5037   //   template-argument cannot be converted to the type of the
5038   //   corresponding template-parameter then the program is
5039   //   ill-formed.
5040   if (ParamType->isIntegralOrEnumerationType()) {
5041     // C++11:
5042     //   -- for a non-type template-parameter of integral or
5043     //      enumeration type, conversions permitted in a converted
5044     //      constant expression are applied.
5045     //
5046     // C++98:
5047     //   -- for a non-type template-parameter of integral or
5048     //      enumeration type, integral promotions (4.5) and integral
5049     //      conversions (4.7) are applied.
5050 
5051     if (getLangOpts().CPlusPlus11) {
5052       // We can't check arbitrary value-dependent arguments.
5053       // FIXME: If there's no viable conversion to the template parameter type,
5054       // we should be able to diagnose that prior to instantiation.
5055       if (Arg->isValueDependent()) {
5056         Converted = TemplateArgument(Arg);
5057         return Arg;
5058       }
5059 
5060       // C++ [temp.arg.nontype]p1:
5061       //   A template-argument for a non-type, non-template template-parameter
5062       //   shall be one of:
5063       //
5064       //     -- for a non-type template-parameter of integral or enumeration
5065       //        type, a converted constant expression of the type of the
5066       //        template-parameter; or
5067       llvm::APSInt Value;
5068       ExprResult ArgResult =
5069         CheckConvertedConstantExpression(Arg, ParamType, Value,
5070                                          CCEK_TemplateArg);
5071       if (ArgResult.isInvalid())
5072         return ExprError();
5073 
5074       // Widen the argument value to sizeof(parameter type). This is almost
5075       // always a no-op, except when the parameter type is bool. In
5076       // that case, this may extend the argument from 1 bit to 8 bits.
5077       QualType IntegerType = ParamType;
5078       if (const EnumType *Enum = IntegerType->getAs<EnumType>())
5079         IntegerType = Enum->getDecl()->getIntegerType();
5080       Value = Value.extOrTrunc(Context.getTypeSize(IntegerType));
5081 
5082       Converted = TemplateArgument(Context, Value,
5083                                    Context.getCanonicalType(ParamType));
5084       return ArgResult;
5085     }
5086 
5087     ExprResult ArgResult = DefaultLvalueConversion(Arg);
5088     if (ArgResult.isInvalid())
5089       return ExprError();
5090     Arg = ArgResult.get();
5091 
5092     QualType ArgType = Arg->getType();
5093 
5094     // C++ [temp.arg.nontype]p1:
5095     //   A template-argument for a non-type, non-template
5096     //   template-parameter shall be one of:
5097     //
5098     //     -- an integral constant-expression of integral or enumeration
5099     //        type; or
5100     //     -- the name of a non-type template-parameter; or
5101     SourceLocation NonConstantLoc;
5102     llvm::APSInt Value;
5103     if (!ArgType->isIntegralOrEnumerationType()) {
5104       Diag(Arg->getLocStart(),
5105            diag::err_template_arg_not_integral_or_enumeral)
5106         << ArgType << Arg->getSourceRange();
5107       Diag(Param->getLocation(), diag::note_template_param_here);
5108       return ExprError();
5109     } else if (!Arg->isValueDependent()) {
5110       class TmplArgICEDiagnoser : public VerifyICEDiagnoser {
5111         QualType T;
5112 
5113       public:
5114         TmplArgICEDiagnoser(QualType T) : T(T) { }
5115 
5116         void diagnoseNotICE(Sema &S, SourceLocation Loc,
5117                             SourceRange SR) override {
5118           S.Diag(Loc, diag::err_template_arg_not_ice) << T << SR;
5119         }
5120       } Diagnoser(ArgType);
5121 
5122       Arg = VerifyIntegerConstantExpression(Arg, &Value, Diagnoser,
5123                                             false).get();
5124       if (!Arg)
5125         return ExprError();
5126     }
5127 
5128     // From here on out, all we care about is the unqualified form
5129     // of the argument type.
5130     ArgType = ArgType.getUnqualifiedType();
5131 
5132     // Try to convert the argument to the parameter's type.
5133     if (Context.hasSameType(ParamType, ArgType)) {
5134       // Okay: no conversion necessary
5135     } else if (ParamType->isBooleanType()) {
5136       // This is an integral-to-boolean conversion.
5137       Arg = ImpCastExprToType(Arg, ParamType, CK_IntegralToBoolean).get();
5138     } else if (IsIntegralPromotion(Arg, ArgType, ParamType) ||
5139                !ParamType->isEnumeralType()) {
5140       // This is an integral promotion or conversion.
5141       Arg = ImpCastExprToType(Arg, ParamType, CK_IntegralCast).get();
5142     } else {
5143       // We can't perform this conversion.
5144       Diag(Arg->getLocStart(),
5145            diag::err_template_arg_not_convertible)
5146         << Arg->getType() << ParamType << Arg->getSourceRange();
5147       Diag(Param->getLocation(), diag::note_template_param_here);
5148       return ExprError();
5149     }
5150 
5151     // Add the value of this argument to the list of converted
5152     // arguments. We use the bitwidth and signedness of the template
5153     // parameter.
5154     if (Arg->isValueDependent()) {
5155       // The argument is value-dependent. Create a new
5156       // TemplateArgument with the converted expression.
5157       Converted = TemplateArgument(Arg);
5158       return Arg;
5159     }
5160 
5161     QualType IntegerType = Context.getCanonicalType(ParamType);
5162     if (const EnumType *Enum = IntegerType->getAs<EnumType>())
5163       IntegerType = Context.getCanonicalType(Enum->getDecl()->getIntegerType());
5164 
5165     if (ParamType->isBooleanType()) {
5166       // Value must be zero or one.
5167       Value = Value != 0;
5168       unsigned AllowedBits = Context.getTypeSize(IntegerType);
5169       if (Value.getBitWidth() != AllowedBits)
5170         Value = Value.extOrTrunc(AllowedBits);
5171       Value.setIsSigned(IntegerType->isSignedIntegerOrEnumerationType());
5172     } else {
5173       llvm::APSInt OldValue = Value;
5174 
5175       // Coerce the template argument's value to the value it will have
5176       // based on the template parameter's type.
5177       unsigned AllowedBits = Context.getTypeSize(IntegerType);
5178       if (Value.getBitWidth() != AllowedBits)
5179         Value = Value.extOrTrunc(AllowedBits);
5180       Value.setIsSigned(IntegerType->isSignedIntegerOrEnumerationType());
5181 
5182       // Complain if an unsigned parameter received a negative value.
5183       if (IntegerType->isUnsignedIntegerOrEnumerationType()
5184                && (OldValue.isSigned() && OldValue.isNegative())) {
5185         Diag(Arg->getLocStart(), diag::warn_template_arg_negative)
5186           << OldValue.toString(10) << Value.toString(10) << Param->getType()
5187           << Arg->getSourceRange();
5188         Diag(Param->getLocation(), diag::note_template_param_here);
5189       }
5190 
5191       // Complain if we overflowed the template parameter's type.
5192       unsigned RequiredBits;
5193       if (IntegerType->isUnsignedIntegerOrEnumerationType())
5194         RequiredBits = OldValue.getActiveBits();
5195       else if (OldValue.isUnsigned())
5196         RequiredBits = OldValue.getActiveBits() + 1;
5197       else
5198         RequiredBits = OldValue.getMinSignedBits();
5199       if (RequiredBits > AllowedBits) {
5200         Diag(Arg->getLocStart(),
5201              diag::warn_template_arg_too_large)
5202           << OldValue.toString(10) << Value.toString(10) << Param->getType()
5203           << Arg->getSourceRange();
5204         Diag(Param->getLocation(), diag::note_template_param_here);
5205       }
5206     }
5207 
5208     Converted = TemplateArgument(Context, Value,
5209                                  ParamType->isEnumeralType()
5210                                    ? Context.getCanonicalType(ParamType)
5211                                    : IntegerType);
5212     return Arg;
5213   }
5214 
5215   QualType ArgType = Arg->getType();
5216   DeclAccessPair FoundResult; // temporary for ResolveOverloadedFunction
5217 
5218   // Handle pointer-to-function, reference-to-function, and
5219   // pointer-to-member-function all in (roughly) the same way.
5220   if (// -- For a non-type template-parameter of type pointer to
5221       //    function, only the function-to-pointer conversion (4.3) is
5222       //    applied. If the template-argument represents a set of
5223       //    overloaded functions (or a pointer to such), the matching
5224       //    function is selected from the set (13.4).
5225       (ParamType->isPointerType() &&
5226        ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType()) ||
5227       // -- For a non-type template-parameter of type reference to
5228       //    function, no conversions apply. If the template-argument
5229       //    represents a set of overloaded functions, the matching
5230       //    function is selected from the set (13.4).
5231       (ParamType->isReferenceType() &&
5232        ParamType->getAs<ReferenceType>()->getPointeeType()->isFunctionType()) ||
5233       // -- For a non-type template-parameter of type pointer to
5234       //    member function, no conversions apply. If the
5235       //    template-argument represents a set of overloaded member
5236       //    functions, the matching member function is selected from
5237       //    the set (13.4).
5238       (ParamType->isMemberPointerType() &&
5239        ParamType->getAs<MemberPointerType>()->getPointeeType()
5240          ->isFunctionType())) {
5241 
5242     if (Arg->getType() == Context.OverloadTy) {
5243       if (FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(Arg, ParamType,
5244                                                                 true,
5245                                                                 FoundResult)) {
5246         if (DiagnoseUseOfDecl(Fn, Arg->getLocStart()))
5247           return ExprError();
5248 
5249         Arg = FixOverloadedFunctionReference(Arg, FoundResult, Fn);
5250         ArgType = Arg->getType();
5251       } else
5252         return ExprError();
5253     }
5254 
5255     if (!ParamType->isMemberPointerType()) {
5256       if (CheckTemplateArgumentAddressOfObjectOrFunction(*this, Param,
5257                                                          ParamType,
5258                                                          Arg, Converted))
5259         return ExprError();
5260       return Arg;
5261     }
5262 
5263     if (CheckTemplateArgumentPointerToMember(*this, Param, ParamType, Arg,
5264                                              Converted))
5265       return ExprError();
5266     return Arg;
5267   }
5268 
5269   if (ParamType->isPointerType()) {
5270     //   -- for a non-type template-parameter of type pointer to
5271     //      object, qualification conversions (4.4) and the
5272     //      array-to-pointer conversion (4.2) are applied.
5273     // C++0x also allows a value of std::nullptr_t.
5274     assert(ParamType->getPointeeType()->isIncompleteOrObjectType() &&
5275            "Only object pointers allowed here");
5276 
5277     if (CheckTemplateArgumentAddressOfObjectOrFunction(*this, Param,
5278                                                        ParamType,
5279                                                        Arg, Converted))
5280       return ExprError();
5281     return Arg;
5282   }
5283 
5284   if (const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>()) {
5285     //   -- For a non-type template-parameter of type reference to
5286     //      object, no conversions apply. The type referred to by the
5287     //      reference may be more cv-qualified than the (otherwise
5288     //      identical) type of the template-argument. The
5289     //      template-parameter is bound directly to the
5290     //      template-argument, which must be an lvalue.
5291     assert(ParamRefType->getPointeeType()->isIncompleteOrObjectType() &&
5292            "Only object references allowed here");
5293 
5294     if (Arg->getType() == Context.OverloadTy) {
5295       if (FunctionDecl *Fn = ResolveAddressOfOverloadedFunction(Arg,
5296                                                  ParamRefType->getPointeeType(),
5297                                                                 true,
5298                                                                 FoundResult)) {
5299         if (DiagnoseUseOfDecl(Fn, Arg->getLocStart()))
5300           return ExprError();
5301 
5302         Arg = FixOverloadedFunctionReference(Arg, FoundResult, Fn);
5303         ArgType = Arg->getType();
5304       } else
5305         return ExprError();
5306     }
5307 
5308     if (CheckTemplateArgumentAddressOfObjectOrFunction(*this, Param,
5309                                                        ParamType,
5310                                                        Arg, Converted))
5311       return ExprError();
5312     return Arg;
5313   }
5314 
5315   // Deal with parameters of type std::nullptr_t.
5316   if (ParamType->isNullPtrType()) {
5317     if (Arg->isTypeDependent() || Arg->isValueDependent()) {
5318       Converted = TemplateArgument(Arg);
5319       return Arg;
5320     }
5321 
5322     switch (isNullPointerValueTemplateArgument(*this, Param, ParamType, Arg)) {
5323     case NPV_NotNullPointer:
5324       Diag(Arg->getExprLoc(), diag::err_template_arg_not_convertible)
5325         << Arg->getType() << ParamType;
5326       Diag(Param->getLocation(), diag::note_template_param_here);
5327       return ExprError();
5328 
5329     case NPV_Error:
5330       return ExprError();
5331 
5332     case NPV_NullPointer:
5333       Diag(Arg->getExprLoc(), diag::warn_cxx98_compat_template_arg_null);
5334       Converted = TemplateArgument(Context.getCanonicalType(ParamType),
5335                                    /*isNullPtr*/true);
5336       return Arg;
5337     }
5338   }
5339 
5340   //     -- For a non-type template-parameter of type pointer to data
5341   //        member, qualification conversions (4.4) are applied.
5342   assert(ParamType->isMemberPointerType() && "Only pointers to members remain");
5343 
5344   if (CheckTemplateArgumentPointerToMember(*this, Param, ParamType, Arg,
5345                                            Converted))
5346     return ExprError();
5347   return Arg;
5348 }
5349 
5350 /// \brief Check a template argument against its corresponding
5351 /// template template parameter.
5352 ///
5353 /// This routine implements the semantics of C++ [temp.arg.template].
5354 /// It returns true if an error occurred, and false otherwise.
CheckTemplateArgument(TemplateTemplateParmDecl * Param,TemplateArgumentLoc & Arg,unsigned ArgumentPackIndex)5355 bool Sema::CheckTemplateArgument(TemplateTemplateParmDecl *Param,
5356                                  TemplateArgumentLoc &Arg,
5357                                  unsigned ArgumentPackIndex) {
5358   TemplateName Name = Arg.getArgument().getAsTemplateOrTemplatePattern();
5359   TemplateDecl *Template = Name.getAsTemplateDecl();
5360   if (!Template) {
5361     // Any dependent template name is fine.
5362     assert(Name.isDependent() && "Non-dependent template isn't a declaration?");
5363     return false;
5364   }
5365 
5366   // C++0x [temp.arg.template]p1:
5367   //   A template-argument for a template template-parameter shall be
5368   //   the name of a class template or an alias template, expressed as an
5369   //   id-expression. When the template-argument names a class template, only
5370   //   primary class templates are considered when matching the
5371   //   template template argument with the corresponding parameter;
5372   //   partial specializations are not considered even if their
5373   //   parameter lists match that of the template template parameter.
5374   //
5375   // Note that we also allow template template parameters here, which
5376   // will happen when we are dealing with, e.g., class template
5377   // partial specializations.
5378   if (!isa<ClassTemplateDecl>(Template) &&
5379       !isa<TemplateTemplateParmDecl>(Template) &&
5380       !isa<TypeAliasTemplateDecl>(Template) &&
5381       !isa<BuiltinTemplateDecl>(Template)) {
5382     assert(isa<FunctionTemplateDecl>(Template) &&
5383            "Only function templates are possible here");
5384     Diag(Arg.getLocation(), diag::err_template_arg_not_valid_template);
5385     Diag(Template->getLocation(), diag::note_template_arg_refers_here_func)
5386       << Template;
5387   }
5388 
5389   TemplateParameterList *Params = Param->getTemplateParameters();
5390   if (Param->isExpandedParameterPack())
5391     Params = Param->getExpansionTemplateParameters(ArgumentPackIndex);
5392 
5393   return !TemplateParameterListsAreEqual(Template->getTemplateParameters(),
5394                                          Params,
5395                                          true,
5396                                          TPL_TemplateTemplateArgumentMatch,
5397                                          Arg.getLocation());
5398 }
5399 
5400 /// \brief Given a non-type template argument that refers to a
5401 /// declaration and the type of its corresponding non-type template
5402 /// parameter, produce an expression that properly refers to that
5403 /// declaration.
5404 ExprResult
BuildExpressionFromDeclTemplateArgument(const TemplateArgument & Arg,QualType ParamType,SourceLocation Loc)5405 Sema::BuildExpressionFromDeclTemplateArgument(const TemplateArgument &Arg,
5406                                               QualType ParamType,
5407                                               SourceLocation Loc) {
5408   // C++ [temp.param]p8:
5409   //
5410   //   A non-type template-parameter of type "array of T" or
5411   //   "function returning T" is adjusted to be of type "pointer to
5412   //   T" or "pointer to function returning T", respectively.
5413   if (ParamType->isArrayType())
5414     ParamType = Context.getArrayDecayedType(ParamType);
5415   else if (ParamType->isFunctionType())
5416     ParamType = Context.getPointerType(ParamType);
5417 
5418   // For a NULL non-type template argument, return nullptr casted to the
5419   // parameter's type.
5420   if (Arg.getKind() == TemplateArgument::NullPtr) {
5421     return ImpCastExprToType(
5422              new (Context) CXXNullPtrLiteralExpr(Context.NullPtrTy, Loc),
5423                              ParamType,
5424                              ParamType->getAs<MemberPointerType>()
5425                                ? CK_NullToMemberPointer
5426                                : CK_NullToPointer);
5427   }
5428   assert(Arg.getKind() == TemplateArgument::Declaration &&
5429          "Only declaration template arguments permitted here");
5430 
5431   ValueDecl *VD = cast<ValueDecl>(Arg.getAsDecl());
5432 
5433   if (VD->getDeclContext()->isRecord() &&
5434       (isa<CXXMethodDecl>(VD) || isa<FieldDecl>(VD) ||
5435        isa<IndirectFieldDecl>(VD))) {
5436     // If the value is a class member, we might have a pointer-to-member.
5437     // Determine whether the non-type template template parameter is of
5438     // pointer-to-member type. If so, we need to build an appropriate
5439     // expression for a pointer-to-member, since a "normal" DeclRefExpr
5440     // would refer to the member itself.
5441     if (ParamType->isMemberPointerType()) {
5442       QualType ClassType
5443         = Context.getTypeDeclType(cast<RecordDecl>(VD->getDeclContext()));
5444       NestedNameSpecifier *Qualifier
5445         = NestedNameSpecifier::Create(Context, nullptr, false,
5446                                       ClassType.getTypePtr());
5447       CXXScopeSpec SS;
5448       SS.MakeTrivial(Context, Qualifier, Loc);
5449 
5450       // The actual value-ness of this is unimportant, but for
5451       // internal consistency's sake, references to instance methods
5452       // are r-values.
5453       ExprValueKind VK = VK_LValue;
5454       if (isa<CXXMethodDecl>(VD) && cast<CXXMethodDecl>(VD)->isInstance())
5455         VK = VK_RValue;
5456 
5457       ExprResult RefExpr = BuildDeclRefExpr(VD,
5458                                             VD->getType().getNonReferenceType(),
5459                                             VK,
5460                                             Loc,
5461                                             &SS);
5462       if (RefExpr.isInvalid())
5463         return ExprError();
5464 
5465       RefExpr = CreateBuiltinUnaryOp(Loc, UO_AddrOf, RefExpr.get());
5466 
5467       // We might need to perform a trailing qualification conversion, since
5468       // the element type on the parameter could be more qualified than the
5469       // element type in the expression we constructed.
5470       bool ObjCLifetimeConversion;
5471       if (IsQualificationConversion(((Expr*) RefExpr.get())->getType(),
5472                                     ParamType.getUnqualifiedType(), false,
5473                                     ObjCLifetimeConversion))
5474         RefExpr = ImpCastExprToType(RefExpr.get(), ParamType.getUnqualifiedType(), CK_NoOp);
5475 
5476       assert(!RefExpr.isInvalid() &&
5477              Context.hasSameType(((Expr*) RefExpr.get())->getType(),
5478                                  ParamType.getUnqualifiedType()));
5479       return RefExpr;
5480     }
5481   }
5482 
5483   QualType T = VD->getType().getNonReferenceType();
5484 
5485   if (ParamType->isPointerType()) {
5486     // When the non-type template parameter is a pointer, take the
5487     // address of the declaration.
5488     ExprResult RefExpr = BuildDeclRefExpr(VD, T, VK_LValue, Loc);
5489     if (RefExpr.isInvalid())
5490       return ExprError();
5491 
5492     if (T->isFunctionType() || T->isArrayType()) {
5493       // Decay functions and arrays.
5494       RefExpr = DefaultFunctionArrayConversion(RefExpr.get());
5495       if (RefExpr.isInvalid())
5496         return ExprError();
5497 
5498       return RefExpr;
5499     }
5500 
5501     // Take the address of everything else
5502     return CreateBuiltinUnaryOp(Loc, UO_AddrOf, RefExpr.get());
5503   }
5504 
5505   ExprValueKind VK = VK_RValue;
5506 
5507   // If the non-type template parameter has reference type, qualify the
5508   // resulting declaration reference with the extra qualifiers on the
5509   // type that the reference refers to.
5510   if (const ReferenceType *TargetRef = ParamType->getAs<ReferenceType>()) {
5511     VK = VK_LValue;
5512     T = Context.getQualifiedType(T,
5513                               TargetRef->getPointeeType().getQualifiers());
5514   } else if (isa<FunctionDecl>(VD)) {
5515     // References to functions are always lvalues.
5516     VK = VK_LValue;
5517   }
5518 
5519   return BuildDeclRefExpr(VD, T, VK, Loc);
5520 }
5521 
5522 /// \brief Construct a new expression that refers to the given
5523 /// integral template argument with the given source-location
5524 /// information.
5525 ///
5526 /// This routine takes care of the mapping from an integral template
5527 /// argument (which may have any integral type) to the appropriate
5528 /// literal value.
5529 ExprResult
BuildExpressionFromIntegralTemplateArgument(const TemplateArgument & Arg,SourceLocation Loc)5530 Sema::BuildExpressionFromIntegralTemplateArgument(const TemplateArgument &Arg,
5531                                                   SourceLocation Loc) {
5532   assert(Arg.getKind() == TemplateArgument::Integral &&
5533          "Operation is only valid for integral template arguments");
5534   QualType OrigT = Arg.getIntegralType();
5535 
5536   // If this is an enum type that we're instantiating, we need to use an integer
5537   // type the same size as the enumerator.  We don't want to build an
5538   // IntegerLiteral with enum type.  The integer type of an enum type can be of
5539   // any integral type with C++11 enum classes, make sure we create the right
5540   // type of literal for it.
5541   QualType T = OrigT;
5542   if (const EnumType *ET = OrigT->getAs<EnumType>())
5543     T = ET->getDecl()->getIntegerType();
5544 
5545   Expr *E;
5546   if (T->isAnyCharacterType()) {
5547     // This does not need to handle u8 character literals because those are
5548     // of type char, and so can also be covered by an ASCII character literal.
5549     CharacterLiteral::CharacterKind Kind;
5550     if (T->isWideCharType())
5551       Kind = CharacterLiteral::Wide;
5552     else if (T->isChar16Type())
5553       Kind = CharacterLiteral::UTF16;
5554     else if (T->isChar32Type())
5555       Kind = CharacterLiteral::UTF32;
5556     else
5557       Kind = CharacterLiteral::Ascii;
5558 
5559     E = new (Context) CharacterLiteral(Arg.getAsIntegral().getZExtValue(),
5560                                        Kind, T, Loc);
5561   } else if (T->isBooleanType()) {
5562     E = new (Context) CXXBoolLiteralExpr(Arg.getAsIntegral().getBoolValue(),
5563                                          T, Loc);
5564   } else if (T->isNullPtrType()) {
5565     E = new (Context) CXXNullPtrLiteralExpr(Context.NullPtrTy, Loc);
5566   } else {
5567     E = IntegerLiteral::Create(Context, Arg.getAsIntegral(), T, Loc);
5568   }
5569 
5570   if (OrigT->isEnumeralType()) {
5571     // FIXME: This is a hack. We need a better way to handle substituted
5572     // non-type template parameters.
5573     E = CStyleCastExpr::Create(Context, OrigT, VK_RValue, CK_IntegralCast, E,
5574                                nullptr,
5575                                Context.getTrivialTypeSourceInfo(OrigT, Loc),
5576                                Loc, Loc);
5577   }
5578 
5579   return E;
5580 }
5581 
5582 /// \brief Match two template parameters within template parameter lists.
MatchTemplateParameterKind(Sema & S,NamedDecl * New,NamedDecl * Old,bool Complain,Sema::TemplateParameterListEqualKind Kind,SourceLocation TemplateArgLoc)5583 static bool MatchTemplateParameterKind(Sema &S, NamedDecl *New, NamedDecl *Old,
5584                                        bool Complain,
5585                                      Sema::TemplateParameterListEqualKind Kind,
5586                                        SourceLocation TemplateArgLoc) {
5587   // Check the actual kind (type, non-type, template).
5588   if (Old->getKind() != New->getKind()) {
5589     if (Complain) {
5590       unsigned NextDiag = diag::err_template_param_different_kind;
5591       if (TemplateArgLoc.isValid()) {
5592         S.Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
5593         NextDiag = diag::note_template_param_different_kind;
5594       }
5595       S.Diag(New->getLocation(), NextDiag)
5596         << (Kind != Sema::TPL_TemplateMatch);
5597       S.Diag(Old->getLocation(), diag::note_template_prev_declaration)
5598         << (Kind != Sema::TPL_TemplateMatch);
5599     }
5600 
5601     return false;
5602   }
5603 
5604   // Check that both are parameter packs are neither are parameter packs.
5605   // However, if we are matching a template template argument to a
5606   // template template parameter, the template template parameter can have
5607   // a parameter pack where the template template argument does not.
5608   if (Old->isTemplateParameterPack() != New->isTemplateParameterPack() &&
5609       !(Kind == Sema::TPL_TemplateTemplateArgumentMatch &&
5610         Old->isTemplateParameterPack())) {
5611     if (Complain) {
5612       unsigned NextDiag = diag::err_template_parameter_pack_non_pack;
5613       if (TemplateArgLoc.isValid()) {
5614         S.Diag(TemplateArgLoc,
5615              diag::err_template_arg_template_params_mismatch);
5616         NextDiag = diag::note_template_parameter_pack_non_pack;
5617       }
5618 
5619       unsigned ParamKind = isa<TemplateTypeParmDecl>(New)? 0
5620                       : isa<NonTypeTemplateParmDecl>(New)? 1
5621                       : 2;
5622       S.Diag(New->getLocation(), NextDiag)
5623         << ParamKind << New->isParameterPack();
5624       S.Diag(Old->getLocation(), diag::note_template_parameter_pack_here)
5625         << ParamKind << Old->isParameterPack();
5626     }
5627 
5628     return false;
5629   }
5630 
5631   // For non-type template parameters, check the type of the parameter.
5632   if (NonTypeTemplateParmDecl *OldNTTP
5633                                     = dyn_cast<NonTypeTemplateParmDecl>(Old)) {
5634     NonTypeTemplateParmDecl *NewNTTP = cast<NonTypeTemplateParmDecl>(New);
5635 
5636     // If we are matching a template template argument to a template
5637     // template parameter and one of the non-type template parameter types
5638     // is dependent, then we must wait until template instantiation time
5639     // to actually compare the arguments.
5640     if (Kind == Sema::TPL_TemplateTemplateArgumentMatch &&
5641         (OldNTTP->getType()->isDependentType() ||
5642          NewNTTP->getType()->isDependentType()))
5643       return true;
5644 
5645     if (!S.Context.hasSameType(OldNTTP->getType(), NewNTTP->getType())) {
5646       if (Complain) {
5647         unsigned NextDiag = diag::err_template_nontype_parm_different_type;
5648         if (TemplateArgLoc.isValid()) {
5649           S.Diag(TemplateArgLoc,
5650                  diag::err_template_arg_template_params_mismatch);
5651           NextDiag = diag::note_template_nontype_parm_different_type;
5652         }
5653         S.Diag(NewNTTP->getLocation(), NextDiag)
5654           << NewNTTP->getType()
5655           << (Kind != Sema::TPL_TemplateMatch);
5656         S.Diag(OldNTTP->getLocation(),
5657                diag::note_template_nontype_parm_prev_declaration)
5658           << OldNTTP->getType();
5659       }
5660 
5661       return false;
5662     }
5663 
5664     return true;
5665   }
5666 
5667   // For template template parameters, check the template parameter types.
5668   // The template parameter lists of template template
5669   // parameters must agree.
5670   if (TemplateTemplateParmDecl *OldTTP
5671                                     = dyn_cast<TemplateTemplateParmDecl>(Old)) {
5672     TemplateTemplateParmDecl *NewTTP = cast<TemplateTemplateParmDecl>(New);
5673     return S.TemplateParameterListsAreEqual(NewTTP->getTemplateParameters(),
5674                                             OldTTP->getTemplateParameters(),
5675                                             Complain,
5676                                         (Kind == Sema::TPL_TemplateMatch
5677                                            ? Sema::TPL_TemplateTemplateParmMatch
5678                                            : Kind),
5679                                             TemplateArgLoc);
5680   }
5681 
5682   return true;
5683 }
5684 
5685 /// \brief Diagnose a known arity mismatch when comparing template argument
5686 /// lists.
5687 static
DiagnoseTemplateParameterListArityMismatch(Sema & S,TemplateParameterList * New,TemplateParameterList * Old,Sema::TemplateParameterListEqualKind Kind,SourceLocation TemplateArgLoc)5688 void DiagnoseTemplateParameterListArityMismatch(Sema &S,
5689                                                 TemplateParameterList *New,
5690                                                 TemplateParameterList *Old,
5691                                       Sema::TemplateParameterListEqualKind Kind,
5692                                                 SourceLocation TemplateArgLoc) {
5693   unsigned NextDiag = diag::err_template_param_list_different_arity;
5694   if (TemplateArgLoc.isValid()) {
5695     S.Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
5696     NextDiag = diag::note_template_param_list_different_arity;
5697   }
5698   S.Diag(New->getTemplateLoc(), NextDiag)
5699     << (New->size() > Old->size())
5700     << (Kind != Sema::TPL_TemplateMatch)
5701     << SourceRange(New->getTemplateLoc(), New->getRAngleLoc());
5702   S.Diag(Old->getTemplateLoc(), diag::note_template_prev_declaration)
5703     << (Kind != Sema::TPL_TemplateMatch)
5704     << SourceRange(Old->getTemplateLoc(), Old->getRAngleLoc());
5705 }
5706 
5707 /// \brief Determine whether the given template parameter lists are
5708 /// equivalent.
5709 ///
5710 /// \param New  The new template parameter list, typically written in the
5711 /// source code as part of a new template declaration.
5712 ///
5713 /// \param Old  The old template parameter list, typically found via
5714 /// name lookup of the template declared with this template parameter
5715 /// list.
5716 ///
5717 /// \param Complain  If true, this routine will produce a diagnostic if
5718 /// the template parameter lists are not equivalent.
5719 ///
5720 /// \param Kind describes how we are to match the template parameter lists.
5721 ///
5722 /// \param TemplateArgLoc If this source location is valid, then we
5723 /// are actually checking the template parameter list of a template
5724 /// argument (New) against the template parameter list of its
5725 /// corresponding template template parameter (Old). We produce
5726 /// slightly different diagnostics in this scenario.
5727 ///
5728 /// \returns True if the template parameter lists are equal, false
5729 /// otherwise.
5730 bool
TemplateParameterListsAreEqual(TemplateParameterList * New,TemplateParameterList * Old,bool Complain,TemplateParameterListEqualKind Kind,SourceLocation TemplateArgLoc)5731 Sema::TemplateParameterListsAreEqual(TemplateParameterList *New,
5732                                      TemplateParameterList *Old,
5733                                      bool Complain,
5734                                      TemplateParameterListEqualKind Kind,
5735                                      SourceLocation TemplateArgLoc) {
5736   if (Old->size() != New->size() && Kind != TPL_TemplateTemplateArgumentMatch) {
5737     if (Complain)
5738       DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
5739                                                  TemplateArgLoc);
5740 
5741     return false;
5742   }
5743 
5744   // C++0x [temp.arg.template]p3:
5745   //   A template-argument matches a template template-parameter (call it P)
5746   //   when each of the template parameters in the template-parameter-list of
5747   //   the template-argument's corresponding class template or alias template
5748   //   (call it A) matches the corresponding template parameter in the
5749   //   template-parameter-list of P. [...]
5750   TemplateParameterList::iterator NewParm = New->begin();
5751   TemplateParameterList::iterator NewParmEnd = New->end();
5752   for (TemplateParameterList::iterator OldParm = Old->begin(),
5753                                     OldParmEnd = Old->end();
5754        OldParm != OldParmEnd; ++OldParm) {
5755     if (Kind != TPL_TemplateTemplateArgumentMatch ||
5756         !(*OldParm)->isTemplateParameterPack()) {
5757       if (NewParm == NewParmEnd) {
5758         if (Complain)
5759           DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
5760                                                      TemplateArgLoc);
5761 
5762         return false;
5763       }
5764 
5765       if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
5766                                       Kind, TemplateArgLoc))
5767         return false;
5768 
5769       ++NewParm;
5770       continue;
5771     }
5772 
5773     // C++0x [temp.arg.template]p3:
5774     //   [...] When P's template- parameter-list contains a template parameter
5775     //   pack (14.5.3), the template parameter pack will match zero or more
5776     //   template parameters or template parameter packs in the
5777     //   template-parameter-list of A with the same type and form as the
5778     //   template parameter pack in P (ignoring whether those template
5779     //   parameters are template parameter packs).
5780     for (; NewParm != NewParmEnd; ++NewParm) {
5781       if (!MatchTemplateParameterKind(*this, *NewParm, *OldParm, Complain,
5782                                       Kind, TemplateArgLoc))
5783         return false;
5784     }
5785   }
5786 
5787   // Make sure we exhausted all of the arguments.
5788   if (NewParm != NewParmEnd) {
5789     if (Complain)
5790       DiagnoseTemplateParameterListArityMismatch(*this, New, Old, Kind,
5791                                                  TemplateArgLoc);
5792 
5793     return false;
5794   }
5795 
5796   return true;
5797 }
5798 
5799 /// \brief Check whether a template can be declared within this scope.
5800 ///
5801 /// If the template declaration is valid in this scope, returns
5802 /// false. Otherwise, issues a diagnostic and returns true.
5803 bool
CheckTemplateDeclScope(Scope * S,TemplateParameterList * TemplateParams)5804 Sema::CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams) {
5805   if (!S)
5806     return false;
5807 
5808   // Find the nearest enclosing declaration scope.
5809   while ((S->getFlags() & Scope::DeclScope) == 0 ||
5810          (S->getFlags() & Scope::TemplateParamScope) != 0)
5811     S = S->getParent();
5812 
5813   // C++ [temp]p4:
5814   //   A template [...] shall not have C linkage.
5815   DeclContext *Ctx = S->getEntity();
5816   if (Ctx && Ctx->isExternCContext())
5817     return Diag(TemplateParams->getTemplateLoc(), diag::err_template_linkage)
5818              << TemplateParams->getSourceRange();
5819 
5820   while (Ctx && isa<LinkageSpecDecl>(Ctx))
5821     Ctx = Ctx->getParent();
5822 
5823   // C++ [temp]p2:
5824   //   A template-declaration can appear only as a namespace scope or
5825   //   class scope declaration.
5826   if (Ctx) {
5827     if (Ctx->isFileContext())
5828       return false;
5829     if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(Ctx)) {
5830       // C++ [temp.mem]p2:
5831       //   A local class shall not have member templates.
5832       if (RD->isLocalClass())
5833         return Diag(TemplateParams->getTemplateLoc(),
5834                     diag::err_template_inside_local_class)
5835           << TemplateParams->getSourceRange();
5836       else
5837         return false;
5838     }
5839   }
5840 
5841   return Diag(TemplateParams->getTemplateLoc(),
5842               diag::err_template_outside_namespace_or_class_scope)
5843     << TemplateParams->getSourceRange();
5844 }
5845 
5846 /// \brief Determine what kind of template specialization the given declaration
5847 /// is.
getTemplateSpecializationKind(Decl * D)5848 static TemplateSpecializationKind getTemplateSpecializationKind(Decl *D) {
5849   if (!D)
5850     return TSK_Undeclared;
5851 
5852   if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D))
5853     return Record->getTemplateSpecializationKind();
5854   if (FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
5855     return Function->getTemplateSpecializationKind();
5856   if (VarDecl *Var = dyn_cast<VarDecl>(D))
5857     return Var->getTemplateSpecializationKind();
5858 
5859   return TSK_Undeclared;
5860 }
5861 
5862 /// \brief Check whether a specialization is well-formed in the current
5863 /// context.
5864 ///
5865 /// This routine determines whether a template specialization can be declared
5866 /// in the current context (C++ [temp.expl.spec]p2).
5867 ///
5868 /// \param S the semantic analysis object for which this check is being
5869 /// performed.
5870 ///
5871 /// \param Specialized the entity being specialized or instantiated, which
5872 /// may be a kind of template (class template, function template, etc.) or
5873 /// a member of a class template (member function, static data member,
5874 /// member class).
5875 ///
5876 /// \param PrevDecl the previous declaration of this entity, if any.
5877 ///
5878 /// \param Loc the location of the explicit specialization or instantiation of
5879 /// this entity.
5880 ///
5881 /// \param IsPartialSpecialization whether this is a partial specialization of
5882 /// a class template.
5883 ///
5884 /// \returns true if there was an error that we cannot recover from, false
5885 /// otherwise.
CheckTemplateSpecializationScope(Sema & S,NamedDecl * Specialized,NamedDecl * PrevDecl,SourceLocation Loc,bool IsPartialSpecialization)5886 static bool CheckTemplateSpecializationScope(Sema &S,
5887                                              NamedDecl *Specialized,
5888                                              NamedDecl *PrevDecl,
5889                                              SourceLocation Loc,
5890                                              bool IsPartialSpecialization) {
5891   // Keep these "kind" numbers in sync with the %select statements in the
5892   // various diagnostics emitted by this routine.
5893   int EntityKind = 0;
5894   if (isa<ClassTemplateDecl>(Specialized))
5895     EntityKind = IsPartialSpecialization? 1 : 0;
5896   else if (isa<VarTemplateDecl>(Specialized))
5897     EntityKind = IsPartialSpecialization ? 3 : 2;
5898   else if (isa<FunctionTemplateDecl>(Specialized))
5899     EntityKind = 4;
5900   else if (isa<CXXMethodDecl>(Specialized))
5901     EntityKind = 5;
5902   else if (isa<VarDecl>(Specialized))
5903     EntityKind = 6;
5904   else if (isa<RecordDecl>(Specialized))
5905     EntityKind = 7;
5906   else if (isa<EnumDecl>(Specialized) && S.getLangOpts().CPlusPlus11)
5907     EntityKind = 8;
5908   else {
5909     S.Diag(Loc, diag::err_template_spec_unknown_kind)
5910       << S.getLangOpts().CPlusPlus11;
5911     S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
5912     return true;
5913   }
5914 
5915   // C++ [temp.expl.spec]p2:
5916   //   An explicit specialization shall be declared in the namespace
5917   //   of which the template is a member, or, for member templates, in
5918   //   the namespace of which the enclosing class or enclosing class
5919   //   template is a member. An explicit specialization of a member
5920   //   function, member class or static data member of a class
5921   //   template shall be declared in the namespace of which the class
5922   //   template is a member. Such a declaration may also be a
5923   //   definition. If the declaration is not a definition, the
5924   //   specialization may be defined later in the name- space in which
5925   //   the explicit specialization was declared, or in a namespace
5926   //   that encloses the one in which the explicit specialization was
5927   //   declared.
5928   if (S.CurContext->getRedeclContext()->isFunctionOrMethod()) {
5929     S.Diag(Loc, diag::err_template_spec_decl_function_scope)
5930       << Specialized;
5931     return true;
5932   }
5933 
5934   if (S.CurContext->isRecord() && !IsPartialSpecialization) {
5935     if (S.getLangOpts().MicrosoftExt) {
5936       // Do not warn for class scope explicit specialization during
5937       // instantiation, warning was already emitted during pattern
5938       // semantic analysis.
5939       if (!S.ActiveTemplateInstantiations.size())
5940         S.Diag(Loc, diag::ext_function_specialization_in_class)
5941           << Specialized;
5942     } else {
5943       S.Diag(Loc, diag::err_template_spec_decl_class_scope)
5944         << Specialized;
5945       return true;
5946     }
5947   }
5948 
5949   if (S.CurContext->isRecord() &&
5950       !S.CurContext->Equals(Specialized->getDeclContext())) {
5951     // Make sure that we're specializing in the right record context.
5952     // Otherwise, things can go horribly wrong.
5953     S.Diag(Loc, diag::err_template_spec_decl_class_scope)
5954       << Specialized;
5955     return true;
5956   }
5957 
5958   // C++ [temp.class.spec]p6:
5959   //   A class template partial specialization may be declared or redeclared
5960   //   in any namespace scope in which its definition may be defined (14.5.1
5961   //   and 14.5.2).
5962   DeclContext *SpecializedContext
5963     = Specialized->getDeclContext()->getEnclosingNamespaceContext();
5964   DeclContext *DC = S.CurContext->getEnclosingNamespaceContext();
5965 
5966   // Make sure that this redeclaration (or definition) occurs in an enclosing
5967   // namespace.
5968   // Note that HandleDeclarator() performs this check for explicit
5969   // specializations of function templates, static data members, and member
5970   // functions, so we skip the check here for those kinds of entities.
5971   // FIXME: HandleDeclarator's diagnostics aren't quite as good, though.
5972   // Should we refactor that check, so that it occurs later?
5973   if (!DC->Encloses(SpecializedContext) &&
5974       !(isa<FunctionTemplateDecl>(Specialized) ||
5975         isa<FunctionDecl>(Specialized) ||
5976         isa<VarTemplateDecl>(Specialized) ||
5977         isa<VarDecl>(Specialized))) {
5978     if (isa<TranslationUnitDecl>(SpecializedContext))
5979       S.Diag(Loc, diag::err_template_spec_redecl_global_scope)
5980         << EntityKind << Specialized;
5981     else if (isa<NamespaceDecl>(SpecializedContext)) {
5982       int Diag = diag::err_template_spec_redecl_out_of_scope;
5983       if (S.getLangOpts().MicrosoftExt)
5984         Diag = diag::ext_ms_template_spec_redecl_out_of_scope;
5985       S.Diag(Loc, Diag) << EntityKind << Specialized
5986                         << cast<NamedDecl>(SpecializedContext);
5987     } else
5988       llvm_unreachable("unexpected namespace context for specialization");
5989 
5990     S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
5991   } else if ((!PrevDecl ||
5992               getTemplateSpecializationKind(PrevDecl) == TSK_Undeclared ||
5993               getTemplateSpecializationKind(PrevDecl) ==
5994                   TSK_ImplicitInstantiation)) {
5995     // C++ [temp.exp.spec]p2:
5996     //   An explicit specialization shall be declared in the namespace of which
5997     //   the template is a member, or, for member templates, in the namespace
5998     //   of which the enclosing class or enclosing class template is a member.
5999     //   An explicit specialization of a member function, member class or
6000     //   static data member of a class template shall be declared in the
6001     //   namespace of which the class template is a member.
6002     //
6003     // C++11 [temp.expl.spec]p2:
6004     //   An explicit specialization shall be declared in a namespace enclosing
6005     //   the specialized template.
6006     // C++11 [temp.explicit]p3:
6007     //   An explicit instantiation shall appear in an enclosing namespace of its
6008     //   template.
6009     if (!DC->InEnclosingNamespaceSetOf(SpecializedContext)) {
6010       bool IsCPlusPlus11Extension = DC->Encloses(SpecializedContext);
6011       if (isa<TranslationUnitDecl>(SpecializedContext)) {
6012         assert(!IsCPlusPlus11Extension &&
6013                "DC encloses TU but isn't in enclosing namespace set");
6014         S.Diag(Loc, diag::err_template_spec_decl_out_of_scope_global)
6015           << EntityKind << Specialized;
6016       } else if (isa<NamespaceDecl>(SpecializedContext)) {
6017         int Diag;
6018         if (!IsCPlusPlus11Extension)
6019           Diag = diag::err_template_spec_decl_out_of_scope;
6020         else if (!S.getLangOpts().CPlusPlus11)
6021           Diag = diag::ext_template_spec_decl_out_of_scope;
6022         else
6023           Diag = diag::warn_cxx98_compat_template_spec_decl_out_of_scope;
6024         S.Diag(Loc, Diag)
6025           << EntityKind << Specialized << cast<NamedDecl>(SpecializedContext);
6026       }
6027 
6028       S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
6029     }
6030   }
6031 
6032   return false;
6033 }
6034 
findTemplateParameter(unsigned Depth,Expr * E)6035 static SourceRange findTemplateParameter(unsigned Depth, Expr *E) {
6036   if (!E->isInstantiationDependent())
6037     return SourceLocation();
6038   DependencyChecker Checker(Depth);
6039   Checker.TraverseStmt(E);
6040   if (Checker.Match && Checker.MatchLoc.isInvalid())
6041     return E->getSourceRange();
6042   return Checker.MatchLoc;
6043 }
6044 
findTemplateParameter(unsigned Depth,TypeLoc TL)6045 static SourceRange findTemplateParameter(unsigned Depth, TypeLoc TL) {
6046   if (!TL.getType()->isDependentType())
6047     return SourceLocation();
6048   DependencyChecker Checker(Depth);
6049   Checker.TraverseTypeLoc(TL);
6050   if (Checker.Match && Checker.MatchLoc.isInvalid())
6051     return TL.getSourceRange();
6052   return Checker.MatchLoc;
6053 }
6054 
6055 /// \brief Subroutine of Sema::CheckTemplatePartialSpecializationArgs
6056 /// that checks non-type template partial specialization arguments.
CheckNonTypeTemplatePartialSpecializationArgs(Sema & S,SourceLocation TemplateNameLoc,NonTypeTemplateParmDecl * Param,const TemplateArgument * Args,unsigned NumArgs,bool IsDefaultArgument)6057 static bool CheckNonTypeTemplatePartialSpecializationArgs(
6058     Sema &S, SourceLocation TemplateNameLoc, NonTypeTemplateParmDecl *Param,
6059     const TemplateArgument *Args, unsigned NumArgs, bool IsDefaultArgument) {
6060   for (unsigned I = 0; I != NumArgs; ++I) {
6061     if (Args[I].getKind() == TemplateArgument::Pack) {
6062       if (CheckNonTypeTemplatePartialSpecializationArgs(
6063               S, TemplateNameLoc, Param, Args[I].pack_begin(),
6064               Args[I].pack_size(), IsDefaultArgument))
6065         return true;
6066 
6067       continue;
6068     }
6069 
6070     if (Args[I].getKind() != TemplateArgument::Expression)
6071       continue;
6072 
6073     Expr *ArgExpr = Args[I].getAsExpr();
6074 
6075     // We can have a pack expansion of any of the bullets below.
6076     if (PackExpansionExpr *Expansion = dyn_cast<PackExpansionExpr>(ArgExpr))
6077       ArgExpr = Expansion->getPattern();
6078 
6079     // Strip off any implicit casts we added as part of type checking.
6080     while (ImplicitCastExpr *ICE = dyn_cast<ImplicitCastExpr>(ArgExpr))
6081       ArgExpr = ICE->getSubExpr();
6082 
6083     // C++ [temp.class.spec]p8:
6084     //   A non-type argument is non-specialized if it is the name of a
6085     //   non-type parameter. All other non-type arguments are
6086     //   specialized.
6087     //
6088     // Below, we check the two conditions that only apply to
6089     // specialized non-type arguments, so skip any non-specialized
6090     // arguments.
6091     if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ArgExpr))
6092       if (isa<NonTypeTemplateParmDecl>(DRE->getDecl()))
6093         continue;
6094 
6095     // C++ [temp.class.spec]p9:
6096     //   Within the argument list of a class template partial
6097     //   specialization, the following restrictions apply:
6098     //     -- A partially specialized non-type argument expression
6099     //        shall not involve a template parameter of the partial
6100     //        specialization except when the argument expression is a
6101     //        simple identifier.
6102     SourceRange ParamUseRange =
6103         findTemplateParameter(Param->getDepth(), ArgExpr);
6104     if (ParamUseRange.isValid()) {
6105       if (IsDefaultArgument) {
6106         S.Diag(TemplateNameLoc,
6107                diag::err_dependent_non_type_arg_in_partial_spec);
6108         S.Diag(ParamUseRange.getBegin(),
6109                diag::note_dependent_non_type_default_arg_in_partial_spec)
6110           << ParamUseRange;
6111       } else {
6112         S.Diag(ParamUseRange.getBegin(),
6113                diag::err_dependent_non_type_arg_in_partial_spec)
6114           << ParamUseRange;
6115       }
6116       return true;
6117     }
6118 
6119     //     -- The type of a template parameter corresponding to a
6120     //        specialized non-type argument shall not be dependent on a
6121     //        parameter of the specialization.
6122     //
6123     // FIXME: We need to delay this check until instantiation in some cases:
6124     //
6125     //   template<template<typename> class X> struct A {
6126     //     template<typename T, X<T> N> struct B;
6127     //     template<typename T> struct B<T, 0>;
6128     //   };
6129     //   template<typename> using X = int;
6130     //   A<X>::B<int, 0> b;
6131     ParamUseRange = findTemplateParameter(
6132             Param->getDepth(), Param->getTypeSourceInfo()->getTypeLoc());
6133     if (ParamUseRange.isValid()) {
6134       S.Diag(IsDefaultArgument ? TemplateNameLoc : ArgExpr->getLocStart(),
6135              diag::err_dependent_typed_non_type_arg_in_partial_spec)
6136         << Param->getType() << ParamUseRange;
6137       S.Diag(Param->getLocation(), diag::note_template_param_here)
6138         << (IsDefaultArgument ? ParamUseRange : SourceRange());
6139       return true;
6140     }
6141   }
6142 
6143   return false;
6144 }
6145 
6146 /// \brief Check the non-type template arguments of a class template
6147 /// partial specialization according to C++ [temp.class.spec]p9.
6148 ///
6149 /// \param TemplateNameLoc the location of the template name.
6150 /// \param TemplateParams the template parameters of the primary class
6151 ///        template.
6152 /// \param NumExplicit the number of explicitly-specified template arguments.
6153 /// \param TemplateArgs the template arguments of the class template
6154 ///        partial specialization.
6155 ///
6156 /// \returns \c true if there was an error, \c false otherwise.
CheckTemplatePartialSpecializationArgs(Sema & S,SourceLocation TemplateNameLoc,TemplateParameterList * TemplateParams,unsigned NumExplicit,SmallVectorImpl<TemplateArgument> & TemplateArgs)6157 static bool CheckTemplatePartialSpecializationArgs(
6158     Sema &S, SourceLocation TemplateNameLoc,
6159     TemplateParameterList *TemplateParams, unsigned NumExplicit,
6160     SmallVectorImpl<TemplateArgument> &TemplateArgs) {
6161   const TemplateArgument *ArgList = TemplateArgs.data();
6162 
6163   for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
6164     NonTypeTemplateParmDecl *Param
6165       = dyn_cast<NonTypeTemplateParmDecl>(TemplateParams->getParam(I));
6166     if (!Param)
6167       continue;
6168 
6169     if (CheckNonTypeTemplatePartialSpecializationArgs(
6170             S, TemplateNameLoc, Param, &ArgList[I], 1, I >= NumExplicit))
6171       return true;
6172   }
6173 
6174   return false;
6175 }
6176 
6177 DeclResult
ActOnClassTemplateSpecialization(Scope * S,unsigned TagSpec,TagUseKind TUK,SourceLocation KWLoc,SourceLocation ModulePrivateLoc,TemplateIdAnnotation & TemplateId,AttributeList * Attr,MultiTemplateParamsArg TemplateParameterLists,SkipBodyInfo * SkipBody)6178 Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
6179                                        TagUseKind TUK,
6180                                        SourceLocation KWLoc,
6181                                        SourceLocation ModulePrivateLoc,
6182                                        TemplateIdAnnotation &TemplateId,
6183                                        AttributeList *Attr,
6184                                        MultiTemplateParamsArg
6185                                            TemplateParameterLists,
6186                                        SkipBodyInfo *SkipBody) {
6187   assert(TUK != TUK_Reference && "References are not specializations");
6188 
6189   CXXScopeSpec &SS = TemplateId.SS;
6190 
6191   // NOTE: KWLoc is the location of the tag keyword. This will instead
6192   // store the location of the outermost template keyword in the declaration.
6193   SourceLocation TemplateKWLoc = TemplateParameterLists.size() > 0
6194     ? TemplateParameterLists[0]->getTemplateLoc() : KWLoc;
6195   SourceLocation TemplateNameLoc = TemplateId.TemplateNameLoc;
6196   SourceLocation LAngleLoc = TemplateId.LAngleLoc;
6197   SourceLocation RAngleLoc = TemplateId.RAngleLoc;
6198 
6199   // Find the class template we're specializing
6200   TemplateName Name = TemplateId.Template.get();
6201   ClassTemplateDecl *ClassTemplate
6202     = dyn_cast_or_null<ClassTemplateDecl>(Name.getAsTemplateDecl());
6203 
6204   if (!ClassTemplate) {
6205     Diag(TemplateNameLoc, diag::err_not_class_template_specialization)
6206       << (Name.getAsTemplateDecl() &&
6207           isa<TemplateTemplateParmDecl>(Name.getAsTemplateDecl()));
6208     return true;
6209   }
6210 
6211   bool isExplicitSpecialization = false;
6212   bool isPartialSpecialization = false;
6213 
6214   // Check the validity of the template headers that introduce this
6215   // template.
6216   // FIXME: We probably shouldn't complain about these headers for
6217   // friend declarations.
6218   bool Invalid = false;
6219   TemplateParameterList *TemplateParams =
6220       MatchTemplateParametersToScopeSpecifier(
6221           KWLoc, TemplateNameLoc, SS, &TemplateId,
6222           TemplateParameterLists, TUK == TUK_Friend, isExplicitSpecialization,
6223           Invalid);
6224   if (Invalid)
6225     return true;
6226 
6227   if (TemplateParams && TemplateParams->size() > 0) {
6228     isPartialSpecialization = true;
6229 
6230     if (TUK == TUK_Friend) {
6231       Diag(KWLoc, diag::err_partial_specialization_friend)
6232         << SourceRange(LAngleLoc, RAngleLoc);
6233       return true;
6234     }
6235 
6236     // C++ [temp.class.spec]p10:
6237     //   The template parameter list of a specialization shall not
6238     //   contain default template argument values.
6239     for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
6240       Decl *Param = TemplateParams->getParam(I);
6241       if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param)) {
6242         if (TTP->hasDefaultArgument()) {
6243           Diag(TTP->getDefaultArgumentLoc(),
6244                diag::err_default_arg_in_partial_spec);
6245           TTP->removeDefaultArgument();
6246         }
6247       } else if (NonTypeTemplateParmDecl *NTTP
6248                    = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
6249         if (Expr *DefArg = NTTP->getDefaultArgument()) {
6250           Diag(NTTP->getDefaultArgumentLoc(),
6251                diag::err_default_arg_in_partial_spec)
6252             << DefArg->getSourceRange();
6253           NTTP->removeDefaultArgument();
6254         }
6255       } else {
6256         TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(Param);
6257         if (TTP->hasDefaultArgument()) {
6258           Diag(TTP->getDefaultArgument().getLocation(),
6259                diag::err_default_arg_in_partial_spec)
6260             << TTP->getDefaultArgument().getSourceRange();
6261           TTP->removeDefaultArgument();
6262         }
6263       }
6264     }
6265   } else if (TemplateParams) {
6266     if (TUK == TUK_Friend)
6267       Diag(KWLoc, diag::err_template_spec_friend)
6268         << FixItHint::CreateRemoval(
6269                                 SourceRange(TemplateParams->getTemplateLoc(),
6270                                             TemplateParams->getRAngleLoc()))
6271         << SourceRange(LAngleLoc, RAngleLoc);
6272     else
6273       isExplicitSpecialization = true;
6274   } else {
6275     assert(TUK == TUK_Friend && "should have a 'template<>' for this decl");
6276   }
6277 
6278   // Check that the specialization uses the same tag kind as the
6279   // original template.
6280   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
6281   assert(Kind != TTK_Enum && "Invalid enum tag in class template spec!");
6282   if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(),
6283                                     Kind, TUK == TUK_Definition, KWLoc,
6284                                     ClassTemplate->getIdentifier())) {
6285     Diag(KWLoc, diag::err_use_with_wrong_tag)
6286       << ClassTemplate
6287       << FixItHint::CreateReplacement(KWLoc,
6288                             ClassTemplate->getTemplatedDecl()->getKindName());
6289     Diag(ClassTemplate->getTemplatedDecl()->getLocation(),
6290          diag::note_previous_use);
6291     Kind = ClassTemplate->getTemplatedDecl()->getTagKind();
6292   }
6293 
6294   // Translate the parser's template argument list in our AST format.
6295   TemplateArgumentListInfo TemplateArgs =
6296       makeTemplateArgumentListInfo(*this, TemplateId);
6297 
6298   // Check for unexpanded parameter packs in any of the template arguments.
6299   for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
6300     if (DiagnoseUnexpandedParameterPack(TemplateArgs[I],
6301                                         UPPC_PartialSpecialization))
6302       return true;
6303 
6304   // Check that the template argument list is well-formed for this
6305   // template.
6306   SmallVector<TemplateArgument, 4> Converted;
6307   if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc,
6308                                 TemplateArgs, false, Converted))
6309     return true;
6310 
6311   // Find the class template (partial) specialization declaration that
6312   // corresponds to these arguments.
6313   if (isPartialSpecialization) {
6314     if (CheckTemplatePartialSpecializationArgs(
6315             *this, TemplateNameLoc, ClassTemplate->getTemplateParameters(),
6316             TemplateArgs.size(), Converted))
6317       return true;
6318 
6319     bool InstantiationDependent;
6320     if (!Name.isDependent() &&
6321         !TemplateSpecializationType::anyDependentTemplateArguments(
6322             TemplateArgs.arguments(), InstantiationDependent)) {
6323       Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
6324         << ClassTemplate->getDeclName();
6325       isPartialSpecialization = false;
6326     }
6327   }
6328 
6329   void *InsertPos = nullptr;
6330   ClassTemplateSpecializationDecl *PrevDecl = nullptr;
6331 
6332   if (isPartialSpecialization)
6333     // FIXME: Template parameter list matters, too
6334     PrevDecl = ClassTemplate->findPartialSpecialization(Converted, InsertPos);
6335   else
6336     PrevDecl = ClassTemplate->findSpecialization(Converted, InsertPos);
6337 
6338   ClassTemplateSpecializationDecl *Specialization = nullptr;
6339 
6340   // Check whether we can declare a class template specialization in
6341   // the current scope.
6342   if (TUK != TUK_Friend &&
6343       CheckTemplateSpecializationScope(*this, ClassTemplate, PrevDecl,
6344                                        TemplateNameLoc,
6345                                        isPartialSpecialization))
6346     return true;
6347 
6348   // The canonical type
6349   QualType CanonType;
6350   if (isPartialSpecialization) {
6351     // Build the canonical type that describes the converted template
6352     // arguments of the class template partial specialization.
6353     TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
6354     CanonType = Context.getTemplateSpecializationType(CanonTemplate,
6355                                                       Converted);
6356 
6357     if (Context.hasSameType(CanonType,
6358                         ClassTemplate->getInjectedClassNameSpecialization())) {
6359       // C++ [temp.class.spec]p9b3:
6360       //
6361       //   -- The argument list of the specialization shall not be identical
6362       //      to the implicit argument list of the primary template.
6363       Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
6364         << /*class template*/0 << (TUK == TUK_Definition)
6365         << FixItHint::CreateRemoval(SourceRange(LAngleLoc, RAngleLoc));
6366       return CheckClassTemplate(S, TagSpec, TUK, KWLoc, SS,
6367                                 ClassTemplate->getIdentifier(),
6368                                 TemplateNameLoc,
6369                                 Attr,
6370                                 TemplateParams,
6371                                 AS_none, /*ModulePrivateLoc=*/SourceLocation(),
6372                                 /*FriendLoc*/SourceLocation(),
6373                                 TemplateParameterLists.size() - 1,
6374                                 TemplateParameterLists.data());
6375     }
6376 
6377     // Create a new class template partial specialization declaration node.
6378     ClassTemplatePartialSpecializationDecl *PrevPartial
6379       = cast_or_null<ClassTemplatePartialSpecializationDecl>(PrevDecl);
6380     ClassTemplatePartialSpecializationDecl *Partial
6381       = ClassTemplatePartialSpecializationDecl::Create(Context, Kind,
6382                                              ClassTemplate->getDeclContext(),
6383                                                        KWLoc, TemplateNameLoc,
6384                                                        TemplateParams,
6385                                                        ClassTemplate,
6386                                                        Converted,
6387                                                        TemplateArgs,
6388                                                        CanonType,
6389                                                        PrevPartial);
6390     SetNestedNameSpecifier(Partial, SS);
6391     if (TemplateParameterLists.size() > 1 && SS.isSet()) {
6392       Partial->setTemplateParameterListsInfo(
6393           Context, TemplateParameterLists.drop_back(1));
6394     }
6395 
6396     if (!PrevPartial)
6397       ClassTemplate->AddPartialSpecialization(Partial, InsertPos);
6398     Specialization = Partial;
6399 
6400     // If we are providing an explicit specialization of a member class
6401     // template specialization, make a note of that.
6402     if (PrevPartial && PrevPartial->getInstantiatedFromMember())
6403       PrevPartial->setMemberSpecialization();
6404 
6405     // Check that all of the template parameters of the class template
6406     // partial specialization are deducible from the template
6407     // arguments. If not, this class template partial specialization
6408     // will never be used.
6409     llvm::SmallBitVector DeducibleParams(TemplateParams->size());
6410     MarkUsedTemplateParameters(Partial->getTemplateArgs(), true,
6411                                TemplateParams->getDepth(),
6412                                DeducibleParams);
6413 
6414     if (!DeducibleParams.all()) {
6415       unsigned NumNonDeducible = DeducibleParams.size()-DeducibleParams.count();
6416       Diag(TemplateNameLoc, diag::warn_partial_specs_not_deducible)
6417         << /*class template*/0 << (NumNonDeducible > 1)
6418         << SourceRange(TemplateNameLoc, RAngleLoc);
6419       for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
6420         if (!DeducibleParams[I]) {
6421           NamedDecl *Param = cast<NamedDecl>(TemplateParams->getParam(I));
6422           if (Param->getDeclName())
6423             Diag(Param->getLocation(),
6424                  diag::note_partial_spec_unused_parameter)
6425               << Param->getDeclName();
6426           else
6427             Diag(Param->getLocation(),
6428                  diag::note_partial_spec_unused_parameter)
6429               << "(anonymous)";
6430         }
6431       }
6432     }
6433   } else {
6434     // Create a new class template specialization declaration node for
6435     // this explicit specialization or friend declaration.
6436     Specialization
6437       = ClassTemplateSpecializationDecl::Create(Context, Kind,
6438                                              ClassTemplate->getDeclContext(),
6439                                                 KWLoc, TemplateNameLoc,
6440                                                 ClassTemplate,
6441                                                 Converted,
6442                                                 PrevDecl);
6443     SetNestedNameSpecifier(Specialization, SS);
6444     if (TemplateParameterLists.size() > 0) {
6445       Specialization->setTemplateParameterListsInfo(Context,
6446                                                     TemplateParameterLists);
6447     }
6448 
6449     if (!PrevDecl)
6450       ClassTemplate->AddSpecialization(Specialization, InsertPos);
6451 
6452     if (CurContext->isDependentContext()) {
6453       // -fms-extensions permits specialization of nested classes without
6454       // fully specializing the outer class(es).
6455       assert(getLangOpts().MicrosoftExt &&
6456              "Only possible with -fms-extensions!");
6457       TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
6458       CanonType = Context.getTemplateSpecializationType(
6459           CanonTemplate, Converted);
6460     } else {
6461       CanonType = Context.getTypeDeclType(Specialization);
6462     }
6463   }
6464 
6465   // C++ [temp.expl.spec]p6:
6466   //   If a template, a member template or the member of a class template is
6467   //   explicitly specialized then that specialization shall be declared
6468   //   before the first use of that specialization that would cause an implicit
6469   //   instantiation to take place, in every translation unit in which such a
6470   //   use occurs; no diagnostic is required.
6471   if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
6472     bool Okay = false;
6473     for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
6474       // Is there any previous explicit specialization declaration?
6475       if (getTemplateSpecializationKind(Prev) == TSK_ExplicitSpecialization) {
6476         Okay = true;
6477         break;
6478       }
6479     }
6480 
6481     if (!Okay) {
6482       SourceRange Range(TemplateNameLoc, RAngleLoc);
6483       Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
6484         << Context.getTypeDeclType(Specialization) << Range;
6485 
6486       Diag(PrevDecl->getPointOfInstantiation(),
6487            diag::note_instantiation_required_here)
6488         << (PrevDecl->getTemplateSpecializationKind()
6489                                                 != TSK_ImplicitInstantiation);
6490       return true;
6491     }
6492   }
6493 
6494   // If this is not a friend, note that this is an explicit specialization.
6495   if (TUK != TUK_Friend)
6496     Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
6497 
6498   // Check that this isn't a redefinition of this specialization.
6499   if (TUK == TUK_Definition) {
6500     RecordDecl *Def = Specialization->getDefinition();
6501     NamedDecl *Hidden = nullptr;
6502     if (Def && SkipBody && !hasVisibleDefinition(Def, &Hidden)) {
6503       SkipBody->ShouldSkip = true;
6504       makeMergedDefinitionVisible(Hidden, KWLoc);
6505       // From here on out, treat this as just a redeclaration.
6506       TUK = TUK_Declaration;
6507     } else if (Def) {
6508       SourceRange Range(TemplateNameLoc, RAngleLoc);
6509       Diag(TemplateNameLoc, diag::err_redefinition)
6510         << Context.getTypeDeclType(Specialization) << Range;
6511       Diag(Def->getLocation(), diag::note_previous_definition);
6512       Specialization->setInvalidDecl();
6513       return true;
6514     }
6515   }
6516 
6517   if (Attr)
6518     ProcessDeclAttributeList(S, Specialization, Attr);
6519 
6520   // Add alignment attributes if necessary; these attributes are checked when
6521   // the ASTContext lays out the structure.
6522   if (TUK == TUK_Definition) {
6523     AddAlignmentAttributesForRecord(Specialization);
6524     AddMsStructLayoutForRecord(Specialization);
6525   }
6526 
6527   if (ModulePrivateLoc.isValid())
6528     Diag(Specialization->getLocation(), diag::err_module_private_specialization)
6529       << (isPartialSpecialization? 1 : 0)
6530       << FixItHint::CreateRemoval(ModulePrivateLoc);
6531 
6532   // Build the fully-sugared type for this class template
6533   // specialization as the user wrote in the specialization
6534   // itself. This means that we'll pretty-print the type retrieved
6535   // from the specialization's declaration the way that the user
6536   // actually wrote the specialization, rather than formatting the
6537   // name based on the "canonical" representation used to store the
6538   // template arguments in the specialization.
6539   TypeSourceInfo *WrittenTy
6540     = Context.getTemplateSpecializationTypeInfo(Name, TemplateNameLoc,
6541                                                 TemplateArgs, CanonType);
6542   if (TUK != TUK_Friend) {
6543     Specialization->setTypeAsWritten(WrittenTy);
6544     Specialization->setTemplateKeywordLoc(TemplateKWLoc);
6545   }
6546 
6547   // C++ [temp.expl.spec]p9:
6548   //   A template explicit specialization is in the scope of the
6549   //   namespace in which the template was defined.
6550   //
6551   // We actually implement this paragraph where we set the semantic
6552   // context (in the creation of the ClassTemplateSpecializationDecl),
6553   // but we also maintain the lexical context where the actual
6554   // definition occurs.
6555   Specialization->setLexicalDeclContext(CurContext);
6556 
6557   // We may be starting the definition of this specialization.
6558   if (TUK == TUK_Definition)
6559     Specialization->startDefinition();
6560 
6561   if (TUK == TUK_Friend) {
6562     FriendDecl *Friend = FriendDecl::Create(Context, CurContext,
6563                                             TemplateNameLoc,
6564                                             WrittenTy,
6565                                             /*FIXME:*/KWLoc);
6566     Friend->setAccess(AS_public);
6567     CurContext->addDecl(Friend);
6568   } else {
6569     // Add the specialization into its lexical context, so that it can
6570     // be seen when iterating through the list of declarations in that
6571     // context. However, specializations are not found by name lookup.
6572     CurContext->addDecl(Specialization);
6573   }
6574   return Specialization;
6575 }
6576 
ActOnTemplateDeclarator(Scope * S,MultiTemplateParamsArg TemplateParameterLists,Declarator & D)6577 Decl *Sema::ActOnTemplateDeclarator(Scope *S,
6578                               MultiTemplateParamsArg TemplateParameterLists,
6579                                     Declarator &D) {
6580   Decl *NewDecl = HandleDeclarator(S, D, TemplateParameterLists);
6581   ActOnDocumentableDecl(NewDecl);
6582   return NewDecl;
6583 }
6584 
6585 /// \brief Strips various properties off an implicit instantiation
6586 /// that has just been explicitly specialized.
StripImplicitInstantiation(NamedDecl * D)6587 static void StripImplicitInstantiation(NamedDecl *D) {
6588   D->dropAttr<DLLImportAttr>();
6589   D->dropAttr<DLLExportAttr>();
6590 
6591   if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
6592     FD->setInlineSpecified(false);
6593 }
6594 
6595 /// \brief Compute the diagnostic location for an explicit instantiation
6596 //  declaration or definition.
DiagLocForExplicitInstantiation(NamedDecl * D,SourceLocation PointOfInstantiation)6597 static SourceLocation DiagLocForExplicitInstantiation(
6598     NamedDecl* D, SourceLocation PointOfInstantiation) {
6599   // Explicit instantiations following a specialization have no effect and
6600   // hence no PointOfInstantiation. In that case, walk decl backwards
6601   // until a valid name loc is found.
6602   SourceLocation PrevDiagLoc = PointOfInstantiation;
6603   for (Decl *Prev = D; Prev && !PrevDiagLoc.isValid();
6604        Prev = Prev->getPreviousDecl()) {
6605     PrevDiagLoc = Prev->getLocation();
6606   }
6607   assert(PrevDiagLoc.isValid() &&
6608          "Explicit instantiation without point of instantiation?");
6609   return PrevDiagLoc;
6610 }
6611 
6612 /// \brief Diagnose cases where we have an explicit template specialization
6613 /// before/after an explicit template instantiation, producing diagnostics
6614 /// for those cases where they are required and determining whether the
6615 /// new specialization/instantiation will have any effect.
6616 ///
6617 /// \param NewLoc the location of the new explicit specialization or
6618 /// instantiation.
6619 ///
6620 /// \param NewTSK the kind of the new explicit specialization or instantiation.
6621 ///
6622 /// \param PrevDecl the previous declaration of the entity.
6623 ///
6624 /// \param PrevTSK the kind of the old explicit specialization or instantiatin.
6625 ///
6626 /// \param PrevPointOfInstantiation if valid, indicates where the previus
6627 /// declaration was instantiated (either implicitly or explicitly).
6628 ///
6629 /// \param HasNoEffect will be set to true to indicate that the new
6630 /// specialization or instantiation has no effect and should be ignored.
6631 ///
6632 /// \returns true if there was an error that should prevent the introduction of
6633 /// the new declaration into the AST, false otherwise.
6634 bool
CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,TemplateSpecializationKind NewTSK,NamedDecl * PrevDecl,TemplateSpecializationKind PrevTSK,SourceLocation PrevPointOfInstantiation,bool & HasNoEffect)6635 Sema::CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,
6636                                              TemplateSpecializationKind NewTSK,
6637                                              NamedDecl *PrevDecl,
6638                                              TemplateSpecializationKind PrevTSK,
6639                                         SourceLocation PrevPointOfInstantiation,
6640                                              bool &HasNoEffect) {
6641   HasNoEffect = false;
6642 
6643   switch (NewTSK) {
6644   case TSK_Undeclared:
6645   case TSK_ImplicitInstantiation:
6646     assert(
6647         (PrevTSK == TSK_Undeclared || PrevTSK == TSK_ImplicitInstantiation) &&
6648         "previous declaration must be implicit!");
6649     return false;
6650 
6651   case TSK_ExplicitSpecialization:
6652     switch (PrevTSK) {
6653     case TSK_Undeclared:
6654     case TSK_ExplicitSpecialization:
6655       // Okay, we're just specializing something that is either already
6656       // explicitly specialized or has merely been mentioned without any
6657       // instantiation.
6658       return false;
6659 
6660     case TSK_ImplicitInstantiation:
6661       if (PrevPointOfInstantiation.isInvalid()) {
6662         // The declaration itself has not actually been instantiated, so it is
6663         // still okay to specialize it.
6664         StripImplicitInstantiation(PrevDecl);
6665         return false;
6666       }
6667       // Fall through
6668 
6669     case TSK_ExplicitInstantiationDeclaration:
6670     case TSK_ExplicitInstantiationDefinition:
6671       assert((PrevTSK == TSK_ImplicitInstantiation ||
6672               PrevPointOfInstantiation.isValid()) &&
6673              "Explicit instantiation without point of instantiation?");
6674 
6675       // C++ [temp.expl.spec]p6:
6676       //   If a template, a member template or the member of a class template
6677       //   is explicitly specialized then that specialization shall be declared
6678       //   before the first use of that specialization that would cause an
6679       //   implicit instantiation to take place, in every translation unit in
6680       //   which such a use occurs; no diagnostic is required.
6681       for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
6682         // Is there any previous explicit specialization declaration?
6683         if (getTemplateSpecializationKind(Prev) == TSK_ExplicitSpecialization)
6684           return false;
6685       }
6686 
6687       Diag(NewLoc, diag::err_specialization_after_instantiation)
6688         << PrevDecl;
6689       Diag(PrevPointOfInstantiation, diag::note_instantiation_required_here)
6690         << (PrevTSK != TSK_ImplicitInstantiation);
6691 
6692       return true;
6693     }
6694 
6695   case TSK_ExplicitInstantiationDeclaration:
6696     switch (PrevTSK) {
6697     case TSK_ExplicitInstantiationDeclaration:
6698       // This explicit instantiation declaration is redundant (that's okay).
6699       HasNoEffect = true;
6700       return false;
6701 
6702     case TSK_Undeclared:
6703     case TSK_ImplicitInstantiation:
6704       // We're explicitly instantiating something that may have already been
6705       // implicitly instantiated; that's fine.
6706       return false;
6707 
6708     case TSK_ExplicitSpecialization:
6709       // C++0x [temp.explicit]p4:
6710       //   For a given set of template parameters, if an explicit instantiation
6711       //   of a template appears after a declaration of an explicit
6712       //   specialization for that template, the explicit instantiation has no
6713       //   effect.
6714       HasNoEffect = true;
6715       return false;
6716 
6717     case TSK_ExplicitInstantiationDefinition:
6718       // C++0x [temp.explicit]p10:
6719       //   If an entity is the subject of both an explicit instantiation
6720       //   declaration and an explicit instantiation definition in the same
6721       //   translation unit, the definition shall follow the declaration.
6722       Diag(NewLoc,
6723            diag::err_explicit_instantiation_declaration_after_definition);
6724 
6725       // Explicit instantiations following a specialization have no effect and
6726       // hence no PrevPointOfInstantiation. In that case, walk decl backwards
6727       // until a valid name loc is found.
6728       Diag(DiagLocForExplicitInstantiation(PrevDecl, PrevPointOfInstantiation),
6729            diag::note_explicit_instantiation_definition_here);
6730       HasNoEffect = true;
6731       return false;
6732     }
6733 
6734   case TSK_ExplicitInstantiationDefinition:
6735     switch (PrevTSK) {
6736     case TSK_Undeclared:
6737     case TSK_ImplicitInstantiation:
6738       // We're explicitly instantiating something that may have already been
6739       // implicitly instantiated; that's fine.
6740       return false;
6741 
6742     case TSK_ExplicitSpecialization:
6743       // C++ DR 259, C++0x [temp.explicit]p4:
6744       //   For a given set of template parameters, if an explicit
6745       //   instantiation of a template appears after a declaration of
6746       //   an explicit specialization for that template, the explicit
6747       //   instantiation has no effect.
6748       //
6749       // In C++98/03 mode, we only give an extension warning here, because it
6750       // is not harmful to try to explicitly instantiate something that
6751       // has been explicitly specialized.
6752       Diag(NewLoc, getLangOpts().CPlusPlus11 ?
6753            diag::warn_cxx98_compat_explicit_instantiation_after_specialization :
6754            diag::ext_explicit_instantiation_after_specialization)
6755         << PrevDecl;
6756       Diag(PrevDecl->getLocation(),
6757            diag::note_previous_template_specialization);
6758       HasNoEffect = true;
6759       return false;
6760 
6761     case TSK_ExplicitInstantiationDeclaration:
6762       // We're explicity instantiating a definition for something for which we
6763       // were previously asked to suppress instantiations. That's fine.
6764 
6765       // C++0x [temp.explicit]p4:
6766       //   For a given set of template parameters, if an explicit instantiation
6767       //   of a template appears after a declaration of an explicit
6768       //   specialization for that template, the explicit instantiation has no
6769       //   effect.
6770       for (Decl *Prev = PrevDecl; Prev; Prev = Prev->getPreviousDecl()) {
6771         // Is there any previous explicit specialization declaration?
6772         if (getTemplateSpecializationKind(Prev) == TSK_ExplicitSpecialization) {
6773           HasNoEffect = true;
6774           break;
6775         }
6776       }
6777 
6778       return false;
6779 
6780     case TSK_ExplicitInstantiationDefinition:
6781       // C++0x [temp.spec]p5:
6782       //   For a given template and a given set of template-arguments,
6783       //     - an explicit instantiation definition shall appear at most once
6784       //       in a program,
6785 
6786       // MSVCCompat: MSVC silently ignores duplicate explicit instantiations.
6787       Diag(NewLoc, (getLangOpts().MSVCCompat)
6788                        ? diag::ext_explicit_instantiation_duplicate
6789                        : diag::err_explicit_instantiation_duplicate)
6790           << PrevDecl;
6791       Diag(DiagLocForExplicitInstantiation(PrevDecl, PrevPointOfInstantiation),
6792            diag::note_previous_explicit_instantiation);
6793       HasNoEffect = true;
6794       return false;
6795     }
6796   }
6797 
6798   llvm_unreachable("Missing specialization/instantiation case?");
6799 }
6800 
6801 /// \brief Perform semantic analysis for the given dependent function
6802 /// template specialization.
6803 ///
6804 /// The only possible way to get a dependent function template specialization
6805 /// is with a friend declaration, like so:
6806 ///
6807 /// \code
6808 ///   template \<class T> void foo(T);
6809 ///   template \<class T> class A {
6810 ///     friend void foo<>(T);
6811 ///   };
6812 /// \endcode
6813 ///
6814 /// There really isn't any useful analysis we can do here, so we
6815 /// just store the information.
6816 bool
CheckDependentFunctionTemplateSpecialization(FunctionDecl * FD,const TemplateArgumentListInfo & ExplicitTemplateArgs,LookupResult & Previous)6817 Sema::CheckDependentFunctionTemplateSpecialization(FunctionDecl *FD,
6818                    const TemplateArgumentListInfo &ExplicitTemplateArgs,
6819                                                    LookupResult &Previous) {
6820   // Remove anything from Previous that isn't a function template in
6821   // the correct context.
6822   DeclContext *FDLookupContext = FD->getDeclContext()->getRedeclContext();
6823   LookupResult::Filter F = Previous.makeFilter();
6824   while (F.hasNext()) {
6825     NamedDecl *D = F.next()->getUnderlyingDecl();
6826     if (!isa<FunctionTemplateDecl>(D) ||
6827         !FDLookupContext->InEnclosingNamespaceSetOf(
6828                               D->getDeclContext()->getRedeclContext()))
6829       F.erase();
6830   }
6831   F.done();
6832 
6833   // Should this be diagnosed here?
6834   if (Previous.empty()) return true;
6835 
6836   FD->setDependentTemplateSpecialization(Context, Previous.asUnresolvedSet(),
6837                                          ExplicitTemplateArgs);
6838   return false;
6839 }
6840 
6841 /// \brief Perform semantic analysis for the given function template
6842 /// specialization.
6843 ///
6844 /// This routine performs all of the semantic analysis required for an
6845 /// explicit function template specialization. On successful completion,
6846 /// the function declaration \p FD will become a function template
6847 /// specialization.
6848 ///
6849 /// \param FD the function declaration, which will be updated to become a
6850 /// function template specialization.
6851 ///
6852 /// \param ExplicitTemplateArgs the explicitly-provided template arguments,
6853 /// if any. Note that this may be valid info even when 0 arguments are
6854 /// explicitly provided as in, e.g., \c void sort<>(char*, char*);
6855 /// as it anyway contains info on the angle brackets locations.
6856 ///
6857 /// \param Previous the set of declarations that may be specialized by
6858 /// this function specialization.
CheckFunctionTemplateSpecialization(FunctionDecl * FD,TemplateArgumentListInfo * ExplicitTemplateArgs,LookupResult & Previous)6859 bool Sema::CheckFunctionTemplateSpecialization(
6860     FunctionDecl *FD, TemplateArgumentListInfo *ExplicitTemplateArgs,
6861     LookupResult &Previous) {
6862   // The set of function template specializations that could match this
6863   // explicit function template specialization.
6864   UnresolvedSet<8> Candidates;
6865   TemplateSpecCandidateSet FailedCandidates(FD->getLocation(),
6866                                             /*ForTakingAddress=*/false);
6867 
6868   llvm::SmallDenseMap<FunctionDecl *, TemplateArgumentListInfo, 8>
6869       ConvertedTemplateArgs;
6870 
6871   DeclContext *FDLookupContext = FD->getDeclContext()->getRedeclContext();
6872   for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
6873          I != E; ++I) {
6874     NamedDecl *Ovl = (*I)->getUnderlyingDecl();
6875     if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(Ovl)) {
6876       // Only consider templates found within the same semantic lookup scope as
6877       // FD.
6878       if (!FDLookupContext->InEnclosingNamespaceSetOf(
6879                                 Ovl->getDeclContext()->getRedeclContext()))
6880         continue;
6881 
6882       // When matching a constexpr member function template specialization
6883       // against the primary template, we don't yet know whether the
6884       // specialization has an implicit 'const' (because we don't know whether
6885       // it will be a static member function until we know which template it
6886       // specializes), so adjust it now assuming it specializes this template.
6887       QualType FT = FD->getType();
6888       if (FD->isConstexpr()) {
6889         CXXMethodDecl *OldMD =
6890           dyn_cast<CXXMethodDecl>(FunTmpl->getTemplatedDecl());
6891         if (OldMD && OldMD->isConst()) {
6892           const FunctionProtoType *FPT = FT->castAs<FunctionProtoType>();
6893           FunctionProtoType::ExtProtoInfo EPI = FPT->getExtProtoInfo();
6894           EPI.TypeQuals |= Qualifiers::Const;
6895           FT = Context.getFunctionType(FPT->getReturnType(),
6896                                        FPT->getParamTypes(), EPI);
6897         }
6898       }
6899 
6900       TemplateArgumentListInfo Args;
6901       if (ExplicitTemplateArgs)
6902         Args = *ExplicitTemplateArgs;
6903 
6904       // C++ [temp.expl.spec]p11:
6905       //   A trailing template-argument can be left unspecified in the
6906       //   template-id naming an explicit function template specialization
6907       //   provided it can be deduced from the function argument type.
6908       // Perform template argument deduction to determine whether we may be
6909       // specializing this template.
6910       // FIXME: It is somewhat wasteful to build
6911       TemplateDeductionInfo Info(FailedCandidates.getLocation());
6912       FunctionDecl *Specialization = nullptr;
6913       if (TemplateDeductionResult TDK = DeduceTemplateArguments(
6914               cast<FunctionTemplateDecl>(FunTmpl->getFirstDecl()),
6915               ExplicitTemplateArgs ? &Args : nullptr, FT, Specialization,
6916               Info)) {
6917         // Template argument deduction failed; record why it failed, so
6918         // that we can provide nifty diagnostics.
6919         FailedCandidates.addCandidate().set(
6920             I.getPair(), FunTmpl->getTemplatedDecl(),
6921             MakeDeductionFailureInfo(Context, TDK, Info));
6922         (void)TDK;
6923         continue;
6924       }
6925 
6926       // Record this candidate.
6927       if (ExplicitTemplateArgs)
6928         ConvertedTemplateArgs[Specialization] = std::move(Args);
6929       Candidates.addDecl(Specialization, I.getAccess());
6930     }
6931   }
6932 
6933   // Find the most specialized function template.
6934   UnresolvedSetIterator Result = getMostSpecialized(
6935       Candidates.begin(), Candidates.end(), FailedCandidates,
6936       FD->getLocation(),
6937       PDiag(diag::err_function_template_spec_no_match) << FD->getDeclName(),
6938       PDiag(diag::err_function_template_spec_ambiguous)
6939           << FD->getDeclName() << (ExplicitTemplateArgs != nullptr),
6940       PDiag(diag::note_function_template_spec_matched));
6941 
6942   if (Result == Candidates.end())
6943     return true;
6944 
6945   // Ignore access information;  it doesn't figure into redeclaration checking.
6946   FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
6947 
6948   // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare [...]
6949   // an explicit specialization (14.8.3) [...] of a concept definition.
6950   if (Specialization->getPrimaryTemplate()->isConcept()) {
6951     Diag(FD->getLocation(), diag::err_concept_specialized)
6952         << 0 /*function*/ << 1 /*explicitly specialized*/;
6953     Diag(Specialization->getLocation(), diag::note_previous_declaration);
6954     return true;
6955   }
6956 
6957   FunctionTemplateSpecializationInfo *SpecInfo
6958     = Specialization->getTemplateSpecializationInfo();
6959   assert(SpecInfo && "Function template specialization info missing?");
6960 
6961   // Note: do not overwrite location info if previous template
6962   // specialization kind was explicit.
6963   TemplateSpecializationKind TSK = SpecInfo->getTemplateSpecializationKind();
6964   if (TSK == TSK_Undeclared || TSK == TSK_ImplicitInstantiation) {
6965     Specialization->setLocation(FD->getLocation());
6966     // C++11 [dcl.constexpr]p1: An explicit specialization of a constexpr
6967     // function can differ from the template declaration with respect to
6968     // the constexpr specifier.
6969     Specialization->setConstexpr(FD->isConstexpr());
6970   }
6971 
6972   // FIXME: Check if the prior specialization has a point of instantiation.
6973   // If so, we have run afoul of .
6974 
6975   // If this is a friend declaration, then we're not really declaring
6976   // an explicit specialization.
6977   bool isFriend = (FD->getFriendObjectKind() != Decl::FOK_None);
6978 
6979   // Check the scope of this explicit specialization.
6980   if (!isFriend &&
6981       CheckTemplateSpecializationScope(*this,
6982                                        Specialization->getPrimaryTemplate(),
6983                                        Specialization, FD->getLocation(),
6984                                        false))
6985     return true;
6986 
6987   // C++ [temp.expl.spec]p6:
6988   //   If a template, a member template or the member of a class template is
6989   //   explicitly specialized then that specialization shall be declared
6990   //   before the first use of that specialization that would cause an implicit
6991   //   instantiation to take place, in every translation unit in which such a
6992   //   use occurs; no diagnostic is required.
6993   bool HasNoEffect = false;
6994   if (!isFriend &&
6995       CheckSpecializationInstantiationRedecl(FD->getLocation(),
6996                                              TSK_ExplicitSpecialization,
6997                                              Specialization,
6998                                    SpecInfo->getTemplateSpecializationKind(),
6999                                          SpecInfo->getPointOfInstantiation(),
7000                                              HasNoEffect))
7001     return true;
7002 
7003   // Mark the prior declaration as an explicit specialization, so that later
7004   // clients know that this is an explicit specialization.
7005   if (!isFriend) {
7006     // Since explicit specializations do not inherit '=delete' from their
7007     // primary function template - check if the 'specialization' that was
7008     // implicitly generated (during template argument deduction for partial
7009     // ordering) from the most specialized of all the function templates that
7010     // 'FD' could have been specializing, has a 'deleted' definition.  If so,
7011     // first check that it was implicitly generated during template argument
7012     // deduction by making sure it wasn't referenced, and then reset the deleted
7013     // flag to not-deleted, so that we can inherit that information from 'FD'.
7014     if (Specialization->isDeleted() && !SpecInfo->isExplicitSpecialization() &&
7015         !Specialization->getCanonicalDecl()->isReferenced()) {
7016       assert(
7017           Specialization->getCanonicalDecl() == Specialization &&
7018           "This must be the only existing declaration of this specialization");
7019       Specialization->setDeletedAsWritten(false);
7020     }
7021     SpecInfo->setTemplateSpecializationKind(TSK_ExplicitSpecialization);
7022     MarkUnusedFileScopedDecl(Specialization);
7023   }
7024 
7025   // Turn the given function declaration into a function template
7026   // specialization, with the template arguments from the previous
7027   // specialization.
7028   // Take copies of (semantic and syntactic) template argument lists.
7029   const TemplateArgumentList* TemplArgs = new (Context)
7030     TemplateArgumentList(Specialization->getTemplateSpecializationArgs());
7031   FD->setFunctionTemplateSpecialization(
7032       Specialization->getPrimaryTemplate(), TemplArgs, /*InsertPos=*/nullptr,
7033       SpecInfo->getTemplateSpecializationKind(),
7034       ExplicitTemplateArgs ? &ConvertedTemplateArgs[Specialization] : nullptr);
7035 
7036   // The "previous declaration" for this function template specialization is
7037   // the prior function template specialization.
7038   Previous.clear();
7039   Previous.addDecl(Specialization);
7040   return false;
7041 }
7042 
7043 /// \brief Perform semantic analysis for the given non-template member
7044 /// specialization.
7045 ///
7046 /// This routine performs all of the semantic analysis required for an
7047 /// explicit member function specialization. On successful completion,
7048 /// the function declaration \p FD will become a member function
7049 /// specialization.
7050 ///
7051 /// \param Member the member declaration, which will be updated to become a
7052 /// specialization.
7053 ///
7054 /// \param Previous the set of declarations, one of which may be specialized
7055 /// by this function specialization;  the set will be modified to contain the
7056 /// redeclared member.
7057 bool
CheckMemberSpecialization(NamedDecl * Member,LookupResult & Previous)7058 Sema::CheckMemberSpecialization(NamedDecl *Member, LookupResult &Previous) {
7059   assert(!isa<TemplateDecl>(Member) && "Only for non-template members");
7060 
7061   // Try to find the member we are instantiating.
7062   NamedDecl *FoundInstantiation = nullptr;
7063   NamedDecl *Instantiation = nullptr;
7064   NamedDecl *InstantiatedFrom = nullptr;
7065   MemberSpecializationInfo *MSInfo = nullptr;
7066 
7067   if (Previous.empty()) {
7068     // Nowhere to look anyway.
7069   } else if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Member)) {
7070     for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
7071            I != E; ++I) {
7072       NamedDecl *D = (*I)->getUnderlyingDecl();
7073       if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
7074         QualType Adjusted = Function->getType();
7075         if (!hasExplicitCallingConv(Adjusted))
7076           Adjusted = adjustCCAndNoReturn(Adjusted, Method->getType());
7077         if (Context.hasSameType(Adjusted, Method->getType())) {
7078           FoundInstantiation = *I;
7079           Instantiation = Method;
7080           InstantiatedFrom = Method->getInstantiatedFromMemberFunction();
7081           MSInfo = Method->getMemberSpecializationInfo();
7082           break;
7083         }
7084       }
7085     }
7086   } else if (isa<VarDecl>(Member)) {
7087     VarDecl *PrevVar;
7088     if (Previous.isSingleResult() &&
7089         (PrevVar = dyn_cast<VarDecl>(Previous.getFoundDecl())))
7090       if (PrevVar->isStaticDataMember()) {
7091         FoundInstantiation = Previous.getRepresentativeDecl();
7092         Instantiation = PrevVar;
7093         InstantiatedFrom = PrevVar->getInstantiatedFromStaticDataMember();
7094         MSInfo = PrevVar->getMemberSpecializationInfo();
7095       }
7096   } else if (isa<RecordDecl>(Member)) {
7097     CXXRecordDecl *PrevRecord;
7098     if (Previous.isSingleResult() &&
7099         (PrevRecord = dyn_cast<CXXRecordDecl>(Previous.getFoundDecl()))) {
7100       FoundInstantiation = Previous.getRepresentativeDecl();
7101       Instantiation = PrevRecord;
7102       InstantiatedFrom = PrevRecord->getInstantiatedFromMemberClass();
7103       MSInfo = PrevRecord->getMemberSpecializationInfo();
7104     }
7105   } else if (isa<EnumDecl>(Member)) {
7106     EnumDecl *PrevEnum;
7107     if (Previous.isSingleResult() &&
7108         (PrevEnum = dyn_cast<EnumDecl>(Previous.getFoundDecl()))) {
7109       FoundInstantiation = Previous.getRepresentativeDecl();
7110       Instantiation = PrevEnum;
7111       InstantiatedFrom = PrevEnum->getInstantiatedFromMemberEnum();
7112       MSInfo = PrevEnum->getMemberSpecializationInfo();
7113     }
7114   }
7115 
7116   if (!Instantiation) {
7117     // There is no previous declaration that matches. Since member
7118     // specializations are always out-of-line, the caller will complain about
7119     // this mismatch later.
7120     return false;
7121   }
7122 
7123   // If this is a friend, just bail out here before we start turning
7124   // things into explicit specializations.
7125   if (Member->getFriendObjectKind() != Decl::FOK_None) {
7126     // Preserve instantiation information.
7127     if (InstantiatedFrom && isa<CXXMethodDecl>(Member)) {
7128       cast<CXXMethodDecl>(Member)->setInstantiationOfMemberFunction(
7129                                       cast<CXXMethodDecl>(InstantiatedFrom),
7130         cast<CXXMethodDecl>(Instantiation)->getTemplateSpecializationKind());
7131     } else if (InstantiatedFrom && isa<CXXRecordDecl>(Member)) {
7132       cast<CXXRecordDecl>(Member)->setInstantiationOfMemberClass(
7133                                       cast<CXXRecordDecl>(InstantiatedFrom),
7134         cast<CXXRecordDecl>(Instantiation)->getTemplateSpecializationKind());
7135     }
7136 
7137     Previous.clear();
7138     Previous.addDecl(FoundInstantiation);
7139     return false;
7140   }
7141 
7142   // Make sure that this is a specialization of a member.
7143   if (!InstantiatedFrom) {
7144     Diag(Member->getLocation(), diag::err_spec_member_not_instantiated)
7145       << Member;
7146     Diag(Instantiation->getLocation(), diag::note_specialized_decl);
7147     return true;
7148   }
7149 
7150   // C++ [temp.expl.spec]p6:
7151   //   If a template, a member template or the member of a class template is
7152   //   explicitly specialized then that specialization shall be declared
7153   //   before the first use of that specialization that would cause an implicit
7154   //   instantiation to take place, in every translation unit in which such a
7155   //   use occurs; no diagnostic is required.
7156   assert(MSInfo && "Member specialization info missing?");
7157 
7158   bool HasNoEffect = false;
7159   if (CheckSpecializationInstantiationRedecl(Member->getLocation(),
7160                                              TSK_ExplicitSpecialization,
7161                                              Instantiation,
7162                                      MSInfo->getTemplateSpecializationKind(),
7163                                            MSInfo->getPointOfInstantiation(),
7164                                              HasNoEffect))
7165     return true;
7166 
7167   // Check the scope of this explicit specialization.
7168   if (CheckTemplateSpecializationScope(*this,
7169                                        InstantiatedFrom,
7170                                        Instantiation, Member->getLocation(),
7171                                        false))
7172     return true;
7173 
7174   // Note that this is an explicit instantiation of a member.
7175   // the original declaration to note that it is an explicit specialization
7176   // (if it was previously an implicit instantiation). This latter step
7177   // makes bookkeeping easier.
7178   if (isa<FunctionDecl>(Member)) {
7179     FunctionDecl *InstantiationFunction = cast<FunctionDecl>(Instantiation);
7180     if (InstantiationFunction->getTemplateSpecializationKind() ==
7181           TSK_ImplicitInstantiation) {
7182       InstantiationFunction->setTemplateSpecializationKind(
7183                                                   TSK_ExplicitSpecialization);
7184       InstantiationFunction->setLocation(Member->getLocation());
7185       // Explicit specializations of member functions of class templates do not
7186       // inherit '=delete' from the member function they are specializing.
7187       if (InstantiationFunction->isDeleted()) {
7188         assert(InstantiationFunction->getCanonicalDecl() ==
7189                InstantiationFunction);
7190         InstantiationFunction->setDeletedAsWritten(false);
7191       }
7192     }
7193 
7194     cast<FunctionDecl>(Member)->setInstantiationOfMemberFunction(
7195                                         cast<CXXMethodDecl>(InstantiatedFrom),
7196                                                   TSK_ExplicitSpecialization);
7197     MarkUnusedFileScopedDecl(InstantiationFunction);
7198   } else if (isa<VarDecl>(Member)) {
7199     VarDecl *InstantiationVar = cast<VarDecl>(Instantiation);
7200     if (InstantiationVar->getTemplateSpecializationKind() ==
7201           TSK_ImplicitInstantiation) {
7202       InstantiationVar->setTemplateSpecializationKind(
7203                                                   TSK_ExplicitSpecialization);
7204       InstantiationVar->setLocation(Member->getLocation());
7205     }
7206 
7207     cast<VarDecl>(Member)->setInstantiationOfStaticDataMember(
7208         cast<VarDecl>(InstantiatedFrom), TSK_ExplicitSpecialization);
7209     MarkUnusedFileScopedDecl(InstantiationVar);
7210   } else if (isa<CXXRecordDecl>(Member)) {
7211     CXXRecordDecl *InstantiationClass = cast<CXXRecordDecl>(Instantiation);
7212     if (InstantiationClass->getTemplateSpecializationKind() ==
7213           TSK_ImplicitInstantiation) {
7214       InstantiationClass->setTemplateSpecializationKind(
7215                                                    TSK_ExplicitSpecialization);
7216       InstantiationClass->setLocation(Member->getLocation());
7217     }
7218 
7219     cast<CXXRecordDecl>(Member)->setInstantiationOfMemberClass(
7220                                         cast<CXXRecordDecl>(InstantiatedFrom),
7221                                                    TSK_ExplicitSpecialization);
7222   } else {
7223     assert(isa<EnumDecl>(Member) && "Only member enums remain");
7224     EnumDecl *InstantiationEnum = cast<EnumDecl>(Instantiation);
7225     if (InstantiationEnum->getTemplateSpecializationKind() ==
7226           TSK_ImplicitInstantiation) {
7227       InstantiationEnum->setTemplateSpecializationKind(
7228                                                    TSK_ExplicitSpecialization);
7229       InstantiationEnum->setLocation(Member->getLocation());
7230     }
7231 
7232     cast<EnumDecl>(Member)->setInstantiationOfMemberEnum(
7233         cast<EnumDecl>(InstantiatedFrom), TSK_ExplicitSpecialization);
7234   }
7235 
7236   // Save the caller the trouble of having to figure out which declaration
7237   // this specialization matches.
7238   Previous.clear();
7239   Previous.addDecl(FoundInstantiation);
7240   return false;
7241 }
7242 
7243 /// \brief Check the scope of an explicit instantiation.
7244 ///
7245 /// \returns true if a serious error occurs, false otherwise.
CheckExplicitInstantiationScope(Sema & S,NamedDecl * D,SourceLocation InstLoc,bool WasQualifiedName)7246 static bool CheckExplicitInstantiationScope(Sema &S, NamedDecl *D,
7247                                             SourceLocation InstLoc,
7248                                             bool WasQualifiedName) {
7249   DeclContext *OrigContext= D->getDeclContext()->getEnclosingNamespaceContext();
7250   DeclContext *CurContext = S.CurContext->getRedeclContext();
7251 
7252   if (CurContext->isRecord()) {
7253     S.Diag(InstLoc, diag::err_explicit_instantiation_in_class)
7254       << D;
7255     return true;
7256   }
7257 
7258   // C++11 [temp.explicit]p3:
7259   //   An explicit instantiation shall appear in an enclosing namespace of its
7260   //   template. If the name declared in the explicit instantiation is an
7261   //   unqualified name, the explicit instantiation shall appear in the
7262   //   namespace where its template is declared or, if that namespace is inline
7263   //   (7.3.1), any namespace from its enclosing namespace set.
7264   //
7265   // This is DR275, which we do not retroactively apply to C++98/03.
7266   if (WasQualifiedName) {
7267     if (CurContext->Encloses(OrigContext))
7268       return false;
7269   } else {
7270     if (CurContext->InEnclosingNamespaceSetOf(OrigContext))
7271       return false;
7272   }
7273 
7274   if (NamespaceDecl *NS = dyn_cast<NamespaceDecl>(OrigContext)) {
7275     if (WasQualifiedName)
7276       S.Diag(InstLoc,
7277              S.getLangOpts().CPlusPlus11?
7278                diag::err_explicit_instantiation_out_of_scope :
7279                diag::warn_explicit_instantiation_out_of_scope_0x)
7280         << D << NS;
7281     else
7282       S.Diag(InstLoc,
7283              S.getLangOpts().CPlusPlus11?
7284                diag::err_explicit_instantiation_unqualified_wrong_namespace :
7285                diag::warn_explicit_instantiation_unqualified_wrong_namespace_0x)
7286         << D << NS;
7287   } else
7288     S.Diag(InstLoc,
7289            S.getLangOpts().CPlusPlus11?
7290              diag::err_explicit_instantiation_must_be_global :
7291              diag::warn_explicit_instantiation_must_be_global_0x)
7292       << D;
7293   S.Diag(D->getLocation(), diag::note_explicit_instantiation_here);
7294   return false;
7295 }
7296 
7297 /// \brief Determine whether the given scope specifier has a template-id in it.
ScopeSpecifierHasTemplateId(const CXXScopeSpec & SS)7298 static bool ScopeSpecifierHasTemplateId(const CXXScopeSpec &SS) {
7299   if (!SS.isSet())
7300     return false;
7301 
7302   // C++11 [temp.explicit]p3:
7303   //   If the explicit instantiation is for a member function, a member class
7304   //   or a static data member of a class template specialization, the name of
7305   //   the class template specialization in the qualified-id for the member
7306   //   name shall be a simple-template-id.
7307   //
7308   // C++98 has the same restriction, just worded differently.
7309   for (NestedNameSpecifier *NNS = SS.getScopeRep(); NNS;
7310        NNS = NNS->getPrefix())
7311     if (const Type *T = NNS->getAsType())
7312       if (isa<TemplateSpecializationType>(T))
7313         return true;
7314 
7315   return false;
7316 }
7317 
7318 // Explicit instantiation of a class template specialization
7319 DeclResult
ActOnExplicitInstantiation(Scope * S,SourceLocation ExternLoc,SourceLocation TemplateLoc,unsigned TagSpec,SourceLocation KWLoc,const CXXScopeSpec & SS,TemplateTy TemplateD,SourceLocation TemplateNameLoc,SourceLocation LAngleLoc,ASTTemplateArgsPtr TemplateArgsIn,SourceLocation RAngleLoc,AttributeList * Attr)7320 Sema::ActOnExplicitInstantiation(Scope *S,
7321                                  SourceLocation ExternLoc,
7322                                  SourceLocation TemplateLoc,
7323                                  unsigned TagSpec,
7324                                  SourceLocation KWLoc,
7325                                  const CXXScopeSpec &SS,
7326                                  TemplateTy TemplateD,
7327                                  SourceLocation TemplateNameLoc,
7328                                  SourceLocation LAngleLoc,
7329                                  ASTTemplateArgsPtr TemplateArgsIn,
7330                                  SourceLocation RAngleLoc,
7331                                  AttributeList *Attr) {
7332   // Find the class template we're specializing
7333   TemplateName Name = TemplateD.get();
7334   TemplateDecl *TD = Name.getAsTemplateDecl();
7335   // Check that the specialization uses the same tag kind as the
7336   // original template.
7337   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
7338   assert(Kind != TTK_Enum &&
7339          "Invalid enum tag in class template explicit instantiation!");
7340 
7341   ClassTemplateDecl *ClassTemplate = dyn_cast<ClassTemplateDecl>(TD);
7342 
7343   if (!ClassTemplate) {
7344     unsigned ErrorKind = 0;
7345     if (isa<TypeAliasTemplateDecl>(TD)) {
7346       ErrorKind = 4;
7347     } else if (isa<TemplateTemplateParmDecl>(TD)) {
7348       ErrorKind = 5;
7349     }
7350 
7351     Diag(TemplateNameLoc, diag::err_tag_reference_non_tag) << ErrorKind;
7352     Diag(TD->getLocation(), diag::note_previous_use);
7353     return true;
7354   }
7355 
7356   if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(),
7357                                     Kind, /*isDefinition*/false, KWLoc,
7358                                     ClassTemplate->getIdentifier())) {
7359     Diag(KWLoc, diag::err_use_with_wrong_tag)
7360       << ClassTemplate
7361       << FixItHint::CreateReplacement(KWLoc,
7362                             ClassTemplate->getTemplatedDecl()->getKindName());
7363     Diag(ClassTemplate->getTemplatedDecl()->getLocation(),
7364          diag::note_previous_use);
7365     Kind = ClassTemplate->getTemplatedDecl()->getTagKind();
7366   }
7367 
7368   // C++0x [temp.explicit]p2:
7369   //   There are two forms of explicit instantiation: an explicit instantiation
7370   //   definition and an explicit instantiation declaration. An explicit
7371   //   instantiation declaration begins with the extern keyword. [...]
7372   TemplateSpecializationKind TSK = ExternLoc.isInvalid()
7373                                        ? TSK_ExplicitInstantiationDefinition
7374                                        : TSK_ExplicitInstantiationDeclaration;
7375 
7376   if (TSK == TSK_ExplicitInstantiationDeclaration) {
7377     // Check for dllexport class template instantiation declarations.
7378     for (AttributeList *A = Attr; A; A = A->getNext()) {
7379       if (A->getKind() == AttributeList::AT_DLLExport) {
7380         Diag(ExternLoc,
7381              diag::warn_attribute_dllexport_explicit_instantiation_decl);
7382         Diag(A->getLoc(), diag::note_attribute);
7383         break;
7384       }
7385     }
7386 
7387     if (auto *A = ClassTemplate->getTemplatedDecl()->getAttr<DLLExportAttr>()) {
7388       Diag(ExternLoc,
7389            diag::warn_attribute_dllexport_explicit_instantiation_decl);
7390       Diag(A->getLocation(), diag::note_attribute);
7391     }
7392   }
7393 
7394   // In MSVC mode, dllimported explicit instantiation definitions are treated as
7395   // instantiation declarations for most purposes.
7396   bool DLLImportExplicitInstantiationDef = false;
7397   if (TSK == TSK_ExplicitInstantiationDefinition &&
7398       Context.getTargetInfo().getCXXABI().isMicrosoft()) {
7399     // Check for dllimport class template instantiation definitions.
7400     bool DLLImport =
7401         ClassTemplate->getTemplatedDecl()->getAttr<DLLImportAttr>();
7402     for (AttributeList *A = Attr; A; A = A->getNext()) {
7403       if (A->getKind() == AttributeList::AT_DLLImport)
7404         DLLImport = true;
7405       if (A->getKind() == AttributeList::AT_DLLExport) {
7406         // dllexport trumps dllimport here.
7407         DLLImport = false;
7408         break;
7409       }
7410     }
7411     if (DLLImport) {
7412       TSK = TSK_ExplicitInstantiationDeclaration;
7413       DLLImportExplicitInstantiationDef = true;
7414     }
7415   }
7416 
7417   // Translate the parser's template argument list in our AST format.
7418   TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
7419   translateTemplateArguments(TemplateArgsIn, TemplateArgs);
7420 
7421   // Check that the template argument list is well-formed for this
7422   // template.
7423   SmallVector<TemplateArgument, 4> Converted;
7424   if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc,
7425                                 TemplateArgs, false, Converted))
7426     return true;
7427 
7428   // Find the class template specialization declaration that
7429   // corresponds to these arguments.
7430   void *InsertPos = nullptr;
7431   ClassTemplateSpecializationDecl *PrevDecl
7432     = ClassTemplate->findSpecialization(Converted, InsertPos);
7433 
7434   TemplateSpecializationKind PrevDecl_TSK
7435     = PrevDecl ? PrevDecl->getTemplateSpecializationKind() : TSK_Undeclared;
7436 
7437   // C++0x [temp.explicit]p2:
7438   //   [...] An explicit instantiation shall appear in an enclosing
7439   //   namespace of its template. [...]
7440   //
7441   // This is C++ DR 275.
7442   if (CheckExplicitInstantiationScope(*this, ClassTemplate, TemplateNameLoc,
7443                                       SS.isSet()))
7444     return true;
7445 
7446   ClassTemplateSpecializationDecl *Specialization = nullptr;
7447 
7448   bool HasNoEffect = false;
7449   if (PrevDecl) {
7450     if (CheckSpecializationInstantiationRedecl(TemplateNameLoc, TSK,
7451                                                PrevDecl, PrevDecl_TSK,
7452                                             PrevDecl->getPointOfInstantiation(),
7453                                                HasNoEffect))
7454       return PrevDecl;
7455 
7456     // Even though HasNoEffect == true means that this explicit instantiation
7457     // has no effect on semantics, we go on to put its syntax in the AST.
7458 
7459     if (PrevDecl_TSK == TSK_ImplicitInstantiation ||
7460         PrevDecl_TSK == TSK_Undeclared) {
7461       // Since the only prior class template specialization with these
7462       // arguments was referenced but not declared, reuse that
7463       // declaration node as our own, updating the source location
7464       // for the template name to reflect our new declaration.
7465       // (Other source locations will be updated later.)
7466       Specialization = PrevDecl;
7467       Specialization->setLocation(TemplateNameLoc);
7468       PrevDecl = nullptr;
7469     }
7470 
7471     if (PrevDecl_TSK == TSK_ExplicitInstantiationDeclaration &&
7472         DLLImportExplicitInstantiationDef) {
7473       // The new specialization might add a dllimport attribute.
7474       HasNoEffect = false;
7475     }
7476   }
7477 
7478   if (!Specialization) {
7479     // Create a new class template specialization declaration node for
7480     // this explicit specialization.
7481     Specialization
7482       = ClassTemplateSpecializationDecl::Create(Context, Kind,
7483                                              ClassTemplate->getDeclContext(),
7484                                                 KWLoc, TemplateNameLoc,
7485                                                 ClassTemplate,
7486                                                 Converted,
7487                                                 PrevDecl);
7488     SetNestedNameSpecifier(Specialization, SS);
7489 
7490     if (!HasNoEffect && !PrevDecl) {
7491       // Insert the new specialization.
7492       ClassTemplate->AddSpecialization(Specialization, InsertPos);
7493     }
7494   }
7495 
7496   // Build the fully-sugared type for this explicit instantiation as
7497   // the user wrote in the explicit instantiation itself. This means
7498   // that we'll pretty-print the type retrieved from the
7499   // specialization's declaration the way that the user actually wrote
7500   // the explicit instantiation, rather than formatting the name based
7501   // on the "canonical" representation used to store the template
7502   // arguments in the specialization.
7503   TypeSourceInfo *WrittenTy
7504     = Context.getTemplateSpecializationTypeInfo(Name, TemplateNameLoc,
7505                                                 TemplateArgs,
7506                                   Context.getTypeDeclType(Specialization));
7507   Specialization->setTypeAsWritten(WrittenTy);
7508 
7509   // Set source locations for keywords.
7510   Specialization->setExternLoc(ExternLoc);
7511   Specialization->setTemplateKeywordLoc(TemplateLoc);
7512   Specialization->setRBraceLoc(SourceLocation());
7513 
7514   if (Attr)
7515     ProcessDeclAttributeList(S, Specialization, Attr);
7516 
7517   // Add the explicit instantiation into its lexical context. However,
7518   // since explicit instantiations are never found by name lookup, we
7519   // just put it into the declaration context directly.
7520   Specialization->setLexicalDeclContext(CurContext);
7521   CurContext->addDecl(Specialization);
7522 
7523   // Syntax is now OK, so return if it has no other effect on semantics.
7524   if (HasNoEffect) {
7525     // Set the template specialization kind.
7526     Specialization->setTemplateSpecializationKind(TSK);
7527     return Specialization;
7528   }
7529 
7530   // C++ [temp.explicit]p3:
7531   //   A definition of a class template or class member template
7532   //   shall be in scope at the point of the explicit instantiation of
7533   //   the class template or class member template.
7534   //
7535   // This check comes when we actually try to perform the
7536   // instantiation.
7537   ClassTemplateSpecializationDecl *Def
7538     = cast_or_null<ClassTemplateSpecializationDecl>(
7539                                               Specialization->getDefinition());
7540   if (!Def)
7541     InstantiateClassTemplateSpecialization(TemplateNameLoc, Specialization, TSK);
7542   else if (TSK == TSK_ExplicitInstantiationDefinition) {
7543     MarkVTableUsed(TemplateNameLoc, Specialization, true);
7544     Specialization->setPointOfInstantiation(Def->getPointOfInstantiation());
7545   }
7546 
7547   // Instantiate the members of this class template specialization.
7548   Def = cast_or_null<ClassTemplateSpecializationDecl>(
7549                                        Specialization->getDefinition());
7550   if (Def) {
7551     TemplateSpecializationKind Old_TSK = Def->getTemplateSpecializationKind();
7552     // Fix a TSK_ExplicitInstantiationDeclaration followed by a
7553     // TSK_ExplicitInstantiationDefinition
7554     if (Old_TSK == TSK_ExplicitInstantiationDeclaration &&
7555         (TSK == TSK_ExplicitInstantiationDefinition ||
7556          DLLImportExplicitInstantiationDef)) {
7557       // FIXME: Need to notify the ASTMutationListener that we did this.
7558       Def->setTemplateSpecializationKind(TSK);
7559 
7560       if (!getDLLAttr(Def) && getDLLAttr(Specialization) &&
7561           Context.getTargetInfo().getCXXABI().isMicrosoft()) {
7562         // In the MS ABI, an explicit instantiation definition can add a dll
7563         // attribute to a template with a previous instantiation declaration.
7564         // MinGW doesn't allow this.
7565         auto *A = cast<InheritableAttr>(
7566             getDLLAttr(Specialization)->clone(getASTContext()));
7567         A->setInherited(true);
7568         Def->addAttr(A);
7569 
7570         // We reject explicit instantiations in class scope, so there should
7571         // never be any delayed exported classes to worry about.
7572         assert(DelayedDllExportClasses.empty() &&
7573                "delayed exports present at explicit instantiation");
7574         checkClassLevelDLLAttribute(Def);
7575         referenceDLLExportedClassMethods();
7576 
7577         // Propagate attribute to base class templates.
7578         for (auto &B : Def->bases()) {
7579           if (auto *BT = dyn_cast_or_null<ClassTemplateSpecializationDecl>(
7580                   B.getType()->getAsCXXRecordDecl()))
7581             propagateDLLAttrToBaseClassTemplate(Def, A, BT, B.getLocStart());
7582         }
7583       }
7584     }
7585 
7586     // Set the template specialization kind. Make sure it is set before
7587     // instantiating the members which will trigger ASTConsumer callbacks.
7588     Specialization->setTemplateSpecializationKind(TSK);
7589     InstantiateClassTemplateSpecializationMembers(TemplateNameLoc, Def, TSK);
7590   } else {
7591 
7592     // Set the template specialization kind.
7593     Specialization->setTemplateSpecializationKind(TSK);
7594   }
7595 
7596   return Specialization;
7597 }
7598 
7599 // Explicit instantiation of a member class of a class template.
7600 DeclResult
ActOnExplicitInstantiation(Scope * S,SourceLocation ExternLoc,SourceLocation TemplateLoc,unsigned TagSpec,SourceLocation KWLoc,CXXScopeSpec & SS,IdentifierInfo * Name,SourceLocation NameLoc,AttributeList * Attr)7601 Sema::ActOnExplicitInstantiation(Scope *S,
7602                                  SourceLocation ExternLoc,
7603                                  SourceLocation TemplateLoc,
7604                                  unsigned TagSpec,
7605                                  SourceLocation KWLoc,
7606                                  CXXScopeSpec &SS,
7607                                  IdentifierInfo *Name,
7608                                  SourceLocation NameLoc,
7609                                  AttributeList *Attr) {
7610 
7611   bool Owned = false;
7612   bool IsDependent = false;
7613   Decl *TagD = ActOnTag(S, TagSpec, Sema::TUK_Reference,
7614                         KWLoc, SS, Name, NameLoc, Attr, AS_none,
7615                         /*ModulePrivateLoc=*/SourceLocation(),
7616                         MultiTemplateParamsArg(), Owned, IsDependent,
7617                         SourceLocation(), false, TypeResult(),
7618                         /*IsTypeSpecifier*/false);
7619   assert(!IsDependent && "explicit instantiation of dependent name not yet handled");
7620 
7621   if (!TagD)
7622     return true;
7623 
7624   TagDecl *Tag = cast<TagDecl>(TagD);
7625   assert(!Tag->isEnum() && "shouldn't see enumerations here");
7626 
7627   if (Tag->isInvalidDecl())
7628     return true;
7629 
7630   CXXRecordDecl *Record = cast<CXXRecordDecl>(Tag);
7631   CXXRecordDecl *Pattern = Record->getInstantiatedFromMemberClass();
7632   if (!Pattern) {
7633     Diag(TemplateLoc, diag::err_explicit_instantiation_nontemplate_type)
7634       << Context.getTypeDeclType(Record);
7635     Diag(Record->getLocation(), diag::note_nontemplate_decl_here);
7636     return true;
7637   }
7638 
7639   // C++0x [temp.explicit]p2:
7640   //   If the explicit instantiation is for a class or member class, the
7641   //   elaborated-type-specifier in the declaration shall include a
7642   //   simple-template-id.
7643   //
7644   // C++98 has the same restriction, just worded differently.
7645   if (!ScopeSpecifierHasTemplateId(SS))
7646     Diag(TemplateLoc, diag::ext_explicit_instantiation_without_qualified_id)
7647       << Record << SS.getRange();
7648 
7649   // C++0x [temp.explicit]p2:
7650   //   There are two forms of explicit instantiation: an explicit instantiation
7651   //   definition and an explicit instantiation declaration. An explicit
7652   //   instantiation declaration begins with the extern keyword. [...]
7653   TemplateSpecializationKind TSK
7654     = ExternLoc.isInvalid()? TSK_ExplicitInstantiationDefinition
7655                            : TSK_ExplicitInstantiationDeclaration;
7656 
7657   // C++0x [temp.explicit]p2:
7658   //   [...] An explicit instantiation shall appear in an enclosing
7659   //   namespace of its template. [...]
7660   //
7661   // This is C++ DR 275.
7662   CheckExplicitInstantiationScope(*this, Record, NameLoc, true);
7663 
7664   // Verify that it is okay to explicitly instantiate here.
7665   CXXRecordDecl *PrevDecl
7666     = cast_or_null<CXXRecordDecl>(Record->getPreviousDecl());
7667   if (!PrevDecl && Record->getDefinition())
7668     PrevDecl = Record;
7669   if (PrevDecl) {
7670     MemberSpecializationInfo *MSInfo = PrevDecl->getMemberSpecializationInfo();
7671     bool HasNoEffect = false;
7672     assert(MSInfo && "No member specialization information?");
7673     if (CheckSpecializationInstantiationRedecl(TemplateLoc, TSK,
7674                                                PrevDecl,
7675                                         MSInfo->getTemplateSpecializationKind(),
7676                                              MSInfo->getPointOfInstantiation(),
7677                                                HasNoEffect))
7678       return true;
7679     if (HasNoEffect)
7680       return TagD;
7681   }
7682 
7683   CXXRecordDecl *RecordDef
7684     = cast_or_null<CXXRecordDecl>(Record->getDefinition());
7685   if (!RecordDef) {
7686     // C++ [temp.explicit]p3:
7687     //   A definition of a member class of a class template shall be in scope
7688     //   at the point of an explicit instantiation of the member class.
7689     CXXRecordDecl *Def
7690       = cast_or_null<CXXRecordDecl>(Pattern->getDefinition());
7691     if (!Def) {
7692       Diag(TemplateLoc, diag::err_explicit_instantiation_undefined_member)
7693         << 0 << Record->getDeclName() << Record->getDeclContext();
7694       Diag(Pattern->getLocation(), diag::note_forward_declaration)
7695         << Pattern;
7696       return true;
7697     } else {
7698       if (InstantiateClass(NameLoc, Record, Def,
7699                            getTemplateInstantiationArgs(Record),
7700                            TSK))
7701         return true;
7702 
7703       RecordDef = cast_or_null<CXXRecordDecl>(Record->getDefinition());
7704       if (!RecordDef)
7705         return true;
7706     }
7707   }
7708 
7709   // Instantiate all of the members of the class.
7710   InstantiateClassMembers(NameLoc, RecordDef,
7711                           getTemplateInstantiationArgs(Record), TSK);
7712 
7713   if (TSK == TSK_ExplicitInstantiationDefinition)
7714     MarkVTableUsed(NameLoc, RecordDef, true);
7715 
7716   // FIXME: We don't have any representation for explicit instantiations of
7717   // member classes. Such a representation is not needed for compilation, but it
7718   // should be available for clients that want to see all of the declarations in
7719   // the source code.
7720   return TagD;
7721 }
7722 
ActOnExplicitInstantiation(Scope * S,SourceLocation ExternLoc,SourceLocation TemplateLoc,Declarator & D)7723 DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
7724                                             SourceLocation ExternLoc,
7725                                             SourceLocation TemplateLoc,
7726                                             Declarator &D) {
7727   // Explicit instantiations always require a name.
7728   // TODO: check if/when DNInfo should replace Name.
7729   DeclarationNameInfo NameInfo = GetNameForDeclarator(D);
7730   DeclarationName Name = NameInfo.getName();
7731   if (!Name) {
7732     if (!D.isInvalidType())
7733       Diag(D.getDeclSpec().getLocStart(),
7734            diag::err_explicit_instantiation_requires_name)
7735         << D.getDeclSpec().getSourceRange()
7736         << D.getSourceRange();
7737 
7738     return true;
7739   }
7740 
7741   // The scope passed in may not be a decl scope.  Zip up the scope tree until
7742   // we find one that is.
7743   while ((S->getFlags() & Scope::DeclScope) == 0 ||
7744          (S->getFlags() & Scope::TemplateParamScope) != 0)
7745     S = S->getParent();
7746 
7747   // Determine the type of the declaration.
7748   TypeSourceInfo *T = GetTypeForDeclarator(D, S);
7749   QualType R = T->getType();
7750   if (R.isNull())
7751     return true;
7752 
7753   // C++ [dcl.stc]p1:
7754   //   A storage-class-specifier shall not be specified in [...] an explicit
7755   //   instantiation (14.7.2) directive.
7756   if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef) {
7757     Diag(D.getIdentifierLoc(), diag::err_explicit_instantiation_of_typedef)
7758       << Name;
7759     return true;
7760   } else if (D.getDeclSpec().getStorageClassSpec()
7761                                                 != DeclSpec::SCS_unspecified) {
7762     // Complain about then remove the storage class specifier.
7763     Diag(D.getIdentifierLoc(), diag::err_explicit_instantiation_storage_class)
7764       << FixItHint::CreateRemoval(D.getDeclSpec().getStorageClassSpecLoc());
7765 
7766     D.getMutableDeclSpec().ClearStorageClassSpecs();
7767   }
7768 
7769   // C++0x [temp.explicit]p1:
7770   //   [...] An explicit instantiation of a function template shall not use the
7771   //   inline or constexpr specifiers.
7772   // Presumably, this also applies to member functions of class templates as
7773   // well.
7774   if (D.getDeclSpec().isInlineSpecified())
7775     Diag(D.getDeclSpec().getInlineSpecLoc(),
7776          getLangOpts().CPlusPlus11 ?
7777            diag::err_explicit_instantiation_inline :
7778            diag::warn_explicit_instantiation_inline_0x)
7779       << FixItHint::CreateRemoval(D.getDeclSpec().getInlineSpecLoc());
7780   if (D.getDeclSpec().isConstexprSpecified() && R->isFunctionType())
7781     // FIXME: Add a fix-it to remove the 'constexpr' and add a 'const' if one is
7782     // not already specified.
7783     Diag(D.getDeclSpec().getConstexprSpecLoc(),
7784          diag::err_explicit_instantiation_constexpr);
7785 
7786   // C++ Concepts TS [dcl.spec.concept]p1: The concept specifier shall be
7787   // applied only to the definition of a function template or variable template,
7788   // declared in namespace scope.
7789   if (D.getDeclSpec().isConceptSpecified()) {
7790     Diag(D.getDeclSpec().getConceptSpecLoc(),
7791          diag::err_concept_specified_specialization) << 0;
7792     return true;
7793   }
7794 
7795   // C++0x [temp.explicit]p2:
7796   //   There are two forms of explicit instantiation: an explicit instantiation
7797   //   definition and an explicit instantiation declaration. An explicit
7798   //   instantiation declaration begins with the extern keyword. [...]
7799   TemplateSpecializationKind TSK
7800     = ExternLoc.isInvalid()? TSK_ExplicitInstantiationDefinition
7801                            : TSK_ExplicitInstantiationDeclaration;
7802 
7803   LookupResult Previous(*this, NameInfo, LookupOrdinaryName);
7804   LookupParsedName(Previous, S, &D.getCXXScopeSpec());
7805 
7806   if (!R->isFunctionType()) {
7807     // C++ [temp.explicit]p1:
7808     //   A [...] static data member of a class template can be explicitly
7809     //   instantiated from the member definition associated with its class
7810     //   template.
7811     // C++1y [temp.explicit]p1:
7812     //   A [...] variable [...] template specialization can be explicitly
7813     //   instantiated from its template.
7814     if (Previous.isAmbiguous())
7815       return true;
7816 
7817     VarDecl *Prev = Previous.getAsSingle<VarDecl>();
7818     VarTemplateDecl *PrevTemplate = Previous.getAsSingle<VarTemplateDecl>();
7819 
7820     if (!PrevTemplate) {
7821       if (!Prev || !Prev->isStaticDataMember()) {
7822         // We expect to see a data data member here.
7823         Diag(D.getIdentifierLoc(), diag::err_explicit_instantiation_not_known)
7824             << Name;
7825         for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
7826              P != PEnd; ++P)
7827           Diag((*P)->getLocation(), diag::note_explicit_instantiation_here);
7828         return true;
7829       }
7830 
7831       if (!Prev->getInstantiatedFromStaticDataMember()) {
7832         // FIXME: Check for explicit specialization?
7833         Diag(D.getIdentifierLoc(),
7834              diag::err_explicit_instantiation_data_member_not_instantiated)
7835             << Prev;
7836         Diag(Prev->getLocation(), diag::note_explicit_instantiation_here);
7837         // FIXME: Can we provide a note showing where this was declared?
7838         return true;
7839       }
7840     } else {
7841       // Explicitly instantiate a variable template.
7842 
7843       // C++1y [dcl.spec.auto]p6:
7844       //   ... A program that uses auto or decltype(auto) in a context not
7845       //   explicitly allowed in this section is ill-formed.
7846       //
7847       // This includes auto-typed variable template instantiations.
7848       if (R->isUndeducedType()) {
7849         Diag(T->getTypeLoc().getLocStart(),
7850              diag::err_auto_not_allowed_var_inst);
7851         return true;
7852       }
7853 
7854       if (D.getName().getKind() != UnqualifiedId::IK_TemplateId) {
7855         // C++1y [temp.explicit]p3:
7856         //   If the explicit instantiation is for a variable, the unqualified-id
7857         //   in the declaration shall be a template-id.
7858         Diag(D.getIdentifierLoc(),
7859              diag::err_explicit_instantiation_without_template_id)
7860           << PrevTemplate;
7861         Diag(PrevTemplate->getLocation(),
7862              diag::note_explicit_instantiation_here);
7863         return true;
7864       }
7865 
7866       // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare an
7867       // explicit instantiation (14.8.2) [...] of a concept definition.
7868       if (PrevTemplate->isConcept()) {
7869         Diag(D.getIdentifierLoc(), diag::err_concept_specialized)
7870             << 1 /*variable*/ << 0 /*explicitly instantiated*/;
7871         Diag(PrevTemplate->getLocation(), diag::note_previous_declaration);
7872         return true;
7873       }
7874 
7875       // Translate the parser's template argument list into our AST format.
7876       TemplateArgumentListInfo TemplateArgs =
7877           makeTemplateArgumentListInfo(*this, *D.getName().TemplateId);
7878 
7879       DeclResult Res = CheckVarTemplateId(PrevTemplate, TemplateLoc,
7880                                           D.getIdentifierLoc(), TemplateArgs);
7881       if (Res.isInvalid())
7882         return true;
7883 
7884       // Ignore access control bits, we don't need them for redeclaration
7885       // checking.
7886       Prev = cast<VarDecl>(Res.get());
7887     }
7888 
7889     // C++0x [temp.explicit]p2:
7890     //   If the explicit instantiation is for a member function, a member class
7891     //   or a static data member of a class template specialization, the name of
7892     //   the class template specialization in the qualified-id for the member
7893     //   name shall be a simple-template-id.
7894     //
7895     // C++98 has the same restriction, just worded differently.
7896     //
7897     // This does not apply to variable template specializations, where the
7898     // template-id is in the unqualified-id instead.
7899     if (!ScopeSpecifierHasTemplateId(D.getCXXScopeSpec()) && !PrevTemplate)
7900       Diag(D.getIdentifierLoc(),
7901            diag::ext_explicit_instantiation_without_qualified_id)
7902         << Prev << D.getCXXScopeSpec().getRange();
7903 
7904     // Check the scope of this explicit instantiation.
7905     CheckExplicitInstantiationScope(*this, Prev, D.getIdentifierLoc(), true);
7906 
7907     // Verify that it is okay to explicitly instantiate here.
7908     TemplateSpecializationKind PrevTSK = Prev->getTemplateSpecializationKind();
7909     SourceLocation POI = Prev->getPointOfInstantiation();
7910     bool HasNoEffect = false;
7911     if (CheckSpecializationInstantiationRedecl(D.getIdentifierLoc(), TSK, Prev,
7912                                                PrevTSK, POI, HasNoEffect))
7913       return true;
7914 
7915     if (!HasNoEffect) {
7916       // Instantiate static data member or variable template.
7917 
7918       Prev->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
7919       if (PrevTemplate) {
7920         // Merge attributes.
7921         if (AttributeList *Attr = D.getDeclSpec().getAttributes().getList())
7922           ProcessDeclAttributeList(S, Prev, Attr);
7923       }
7924       if (TSK == TSK_ExplicitInstantiationDefinition)
7925         InstantiateVariableDefinition(D.getIdentifierLoc(), Prev);
7926     }
7927 
7928     // Check the new variable specialization against the parsed input.
7929     if (PrevTemplate && Prev && !Context.hasSameType(Prev->getType(), R)) {
7930       Diag(T->getTypeLoc().getLocStart(),
7931            diag::err_invalid_var_template_spec_type)
7932           << 0 << PrevTemplate << R << Prev->getType();
7933       Diag(PrevTemplate->getLocation(), diag::note_template_declared_here)
7934           << 2 << PrevTemplate->getDeclName();
7935       return true;
7936     }
7937 
7938     // FIXME: Create an ExplicitInstantiation node?
7939     return (Decl*) nullptr;
7940   }
7941 
7942   // If the declarator is a template-id, translate the parser's template
7943   // argument list into our AST format.
7944   bool HasExplicitTemplateArgs = false;
7945   TemplateArgumentListInfo TemplateArgs;
7946   if (D.getName().getKind() == UnqualifiedId::IK_TemplateId) {
7947     TemplateArgs = makeTemplateArgumentListInfo(*this, *D.getName().TemplateId);
7948     HasExplicitTemplateArgs = true;
7949   }
7950 
7951   // C++ [temp.explicit]p1:
7952   //   A [...] function [...] can be explicitly instantiated from its template.
7953   //   A member function [...] of a class template can be explicitly
7954   //  instantiated from the member definition associated with its class
7955   //  template.
7956   UnresolvedSet<8> Matches;
7957   TemplateSpecCandidateSet FailedCandidates(D.getIdentifierLoc());
7958   for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
7959        P != PEnd; ++P) {
7960     NamedDecl *Prev = *P;
7961     if (!HasExplicitTemplateArgs) {
7962       if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Prev)) {
7963         QualType Adjusted = adjustCCAndNoReturn(R, Method->getType());
7964         if (Context.hasSameUnqualifiedType(Method->getType(), Adjusted)) {
7965           Matches.clear();
7966 
7967           Matches.addDecl(Method, P.getAccess());
7968           if (Method->getTemplateSpecializationKind() == TSK_Undeclared)
7969             break;
7970         }
7971       }
7972     }
7973 
7974     FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(Prev);
7975     if (!FunTmpl)
7976       continue;
7977 
7978     TemplateDeductionInfo Info(FailedCandidates.getLocation());
7979     FunctionDecl *Specialization = nullptr;
7980     if (TemplateDeductionResult TDK
7981           = DeduceTemplateArguments(FunTmpl,
7982                                (HasExplicitTemplateArgs ? &TemplateArgs
7983                                                         : nullptr),
7984                                     R, Specialization, Info)) {
7985       // Keep track of almost-matches.
7986       FailedCandidates.addCandidate()
7987           .set(P.getPair(), FunTmpl->getTemplatedDecl(),
7988                MakeDeductionFailureInfo(Context, TDK, Info));
7989       (void)TDK;
7990       continue;
7991     }
7992 
7993     Matches.addDecl(Specialization, P.getAccess());
7994   }
7995 
7996   // Find the most specialized function template specialization.
7997   UnresolvedSetIterator Result = getMostSpecialized(
7998       Matches.begin(), Matches.end(), FailedCandidates,
7999       D.getIdentifierLoc(),
8000       PDiag(diag::err_explicit_instantiation_not_known) << Name,
8001       PDiag(diag::err_explicit_instantiation_ambiguous) << Name,
8002       PDiag(diag::note_explicit_instantiation_candidate));
8003 
8004   if (Result == Matches.end())
8005     return true;
8006 
8007   // Ignore access control bits, we don't need them for redeclaration checking.
8008   FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
8009 
8010   // C++11 [except.spec]p4
8011   // In an explicit instantiation an exception-specification may be specified,
8012   // but is not required.
8013   // If an exception-specification is specified in an explicit instantiation
8014   // directive, it shall be compatible with the exception-specifications of
8015   // other declarations of that function.
8016   if (auto *FPT = R->getAs<FunctionProtoType>())
8017     if (FPT->hasExceptionSpec()) {
8018       unsigned DiagID =
8019           diag::err_mismatched_exception_spec_explicit_instantiation;
8020       if (getLangOpts().MicrosoftExt)
8021         DiagID = diag::ext_mismatched_exception_spec_explicit_instantiation;
8022       bool Result = CheckEquivalentExceptionSpec(
8023           PDiag(DiagID) << Specialization->getType(),
8024           PDiag(diag::note_explicit_instantiation_here),
8025           Specialization->getType()->getAs<FunctionProtoType>(),
8026           Specialization->getLocation(), FPT, D.getLocStart());
8027       // In Microsoft mode, mismatching exception specifications just cause a
8028       // warning.
8029       if (!getLangOpts().MicrosoftExt && Result)
8030         return true;
8031     }
8032 
8033   if (Specialization->getTemplateSpecializationKind() == TSK_Undeclared) {
8034     Diag(D.getIdentifierLoc(),
8035          diag::err_explicit_instantiation_member_function_not_instantiated)
8036       << Specialization
8037       << (Specialization->getTemplateSpecializationKind() ==
8038           TSK_ExplicitSpecialization);
8039     Diag(Specialization->getLocation(), diag::note_explicit_instantiation_here);
8040     return true;
8041   }
8042 
8043   FunctionDecl *PrevDecl = Specialization->getPreviousDecl();
8044   if (!PrevDecl && Specialization->isThisDeclarationADefinition())
8045     PrevDecl = Specialization;
8046 
8047   if (PrevDecl) {
8048     bool HasNoEffect = false;
8049     if (CheckSpecializationInstantiationRedecl(D.getIdentifierLoc(), TSK,
8050                                                PrevDecl,
8051                                      PrevDecl->getTemplateSpecializationKind(),
8052                                           PrevDecl->getPointOfInstantiation(),
8053                                                HasNoEffect))
8054       return true;
8055 
8056     // FIXME: We may still want to build some representation of this
8057     // explicit specialization.
8058     if (HasNoEffect)
8059       return (Decl*) nullptr;
8060   }
8061 
8062   Specialization->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
8063   AttributeList *Attr = D.getDeclSpec().getAttributes().getList();
8064   if (Attr)
8065     ProcessDeclAttributeList(S, Specialization, Attr);
8066 
8067   if (Specialization->isDefined()) {
8068     // Let the ASTConsumer know that this function has been explicitly
8069     // instantiated now, and its linkage might have changed.
8070     Consumer.HandleTopLevelDecl(DeclGroupRef(Specialization));
8071   } else if (TSK == TSK_ExplicitInstantiationDefinition)
8072     InstantiateFunctionDefinition(D.getIdentifierLoc(), Specialization);
8073 
8074   // C++0x [temp.explicit]p2:
8075   //   If the explicit instantiation is for a member function, a member class
8076   //   or a static data member of a class template specialization, the name of
8077   //   the class template specialization in the qualified-id for the member
8078   //   name shall be a simple-template-id.
8079   //
8080   // C++98 has the same restriction, just worded differently.
8081   FunctionTemplateDecl *FunTmpl = Specialization->getPrimaryTemplate();
8082   if (D.getName().getKind() != UnqualifiedId::IK_TemplateId && !FunTmpl &&
8083       D.getCXXScopeSpec().isSet() &&
8084       !ScopeSpecifierHasTemplateId(D.getCXXScopeSpec()))
8085     Diag(D.getIdentifierLoc(),
8086          diag::ext_explicit_instantiation_without_qualified_id)
8087     << Specialization << D.getCXXScopeSpec().getRange();
8088 
8089   // C++ Concepts TS [dcl.spec.concept]p7: A program shall not declare an
8090   // explicit instantiation (14.8.2) [...] of a concept definition.
8091   if (FunTmpl && FunTmpl->isConcept() &&
8092       !D.getDeclSpec().isConceptSpecified()) {
8093     Diag(D.getIdentifierLoc(), diag::err_concept_specialized)
8094         << 0 /*function*/ << 0 /*explicitly instantiated*/;
8095     Diag(FunTmpl->getLocation(), diag::note_previous_declaration);
8096     return true;
8097   }
8098 
8099   CheckExplicitInstantiationScope(*this,
8100                    FunTmpl? (NamedDecl *)FunTmpl
8101                           : Specialization->getInstantiatedFromMemberFunction(),
8102                                   D.getIdentifierLoc(),
8103                                   D.getCXXScopeSpec().isSet());
8104 
8105   // FIXME: Create some kind of ExplicitInstantiationDecl here.
8106   return (Decl*) nullptr;
8107 }
8108 
8109 TypeResult
ActOnDependentTag(Scope * S,unsigned TagSpec,TagUseKind TUK,const CXXScopeSpec & SS,IdentifierInfo * Name,SourceLocation TagLoc,SourceLocation NameLoc)8110 Sema::ActOnDependentTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
8111                         const CXXScopeSpec &SS, IdentifierInfo *Name,
8112                         SourceLocation TagLoc, SourceLocation NameLoc) {
8113   // This has to hold, because SS is expected to be defined.
8114   assert(Name && "Expected a name in a dependent tag");
8115 
8116   NestedNameSpecifier *NNS = SS.getScopeRep();
8117   if (!NNS)
8118     return true;
8119 
8120   TagTypeKind Kind = TypeWithKeyword::getTagTypeKindForTypeSpec(TagSpec);
8121 
8122   if (TUK == TUK_Declaration || TUK == TUK_Definition) {
8123     Diag(NameLoc, diag::err_dependent_tag_decl)
8124       << (TUK == TUK_Definition) << Kind << SS.getRange();
8125     return true;
8126   }
8127 
8128   // Create the resulting type.
8129   ElaboratedTypeKeyword Kwd = TypeWithKeyword::getKeywordForTagTypeKind(Kind);
8130   QualType Result = Context.getDependentNameType(Kwd, NNS, Name);
8131 
8132   // Create type-source location information for this type.
8133   TypeLocBuilder TLB;
8134   DependentNameTypeLoc TL = TLB.push<DependentNameTypeLoc>(Result);
8135   TL.setElaboratedKeywordLoc(TagLoc);
8136   TL.setQualifierLoc(SS.getWithLocInContext(Context));
8137   TL.setNameLoc(NameLoc);
8138   return CreateParsedType(Result, TLB.getTypeSourceInfo(Context, Result));
8139 }
8140 
8141 TypeResult
ActOnTypenameType(Scope * S,SourceLocation TypenameLoc,const CXXScopeSpec & SS,const IdentifierInfo & II,SourceLocation IdLoc)8142 Sema::ActOnTypenameType(Scope *S, SourceLocation TypenameLoc,
8143                         const CXXScopeSpec &SS, const IdentifierInfo &II,
8144                         SourceLocation IdLoc) {
8145   if (SS.isInvalid())
8146     return true;
8147 
8148   if (TypenameLoc.isValid() && S && !S->getTemplateParamParent())
8149     Diag(TypenameLoc,
8150          getLangOpts().CPlusPlus11 ?
8151            diag::warn_cxx98_compat_typename_outside_of_template :
8152            diag::ext_typename_outside_of_template)
8153       << FixItHint::CreateRemoval(TypenameLoc);
8154 
8155   NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
8156   QualType T = CheckTypenameType(TypenameLoc.isValid()? ETK_Typename : ETK_None,
8157                                  TypenameLoc, QualifierLoc, II, IdLoc);
8158   if (T.isNull())
8159     return true;
8160 
8161   TypeSourceInfo *TSI = Context.CreateTypeSourceInfo(T);
8162   if (isa<DependentNameType>(T)) {
8163     DependentNameTypeLoc TL = TSI->getTypeLoc().castAs<DependentNameTypeLoc>();
8164     TL.setElaboratedKeywordLoc(TypenameLoc);
8165     TL.setQualifierLoc(QualifierLoc);
8166     TL.setNameLoc(IdLoc);
8167   } else {
8168     ElaboratedTypeLoc TL = TSI->getTypeLoc().castAs<ElaboratedTypeLoc>();
8169     TL.setElaboratedKeywordLoc(TypenameLoc);
8170     TL.setQualifierLoc(QualifierLoc);
8171     TL.getNamedTypeLoc().castAs<TypeSpecTypeLoc>().setNameLoc(IdLoc);
8172   }
8173 
8174   return CreateParsedType(T, TSI);
8175 }
8176 
8177 TypeResult
ActOnTypenameType(Scope * S,SourceLocation TypenameLoc,const CXXScopeSpec & SS,SourceLocation TemplateKWLoc,TemplateTy TemplateIn,SourceLocation TemplateNameLoc,SourceLocation LAngleLoc,ASTTemplateArgsPtr TemplateArgsIn,SourceLocation RAngleLoc)8178 Sema::ActOnTypenameType(Scope *S,
8179                         SourceLocation TypenameLoc,
8180                         const CXXScopeSpec &SS,
8181                         SourceLocation TemplateKWLoc,
8182                         TemplateTy TemplateIn,
8183                         SourceLocation TemplateNameLoc,
8184                         SourceLocation LAngleLoc,
8185                         ASTTemplateArgsPtr TemplateArgsIn,
8186                         SourceLocation RAngleLoc) {
8187   if (TypenameLoc.isValid() && S && !S->getTemplateParamParent())
8188     Diag(TypenameLoc,
8189          getLangOpts().CPlusPlus11 ?
8190            diag::warn_cxx98_compat_typename_outside_of_template :
8191            diag::ext_typename_outside_of_template)
8192       << FixItHint::CreateRemoval(TypenameLoc);
8193 
8194   // Translate the parser's template argument list in our AST format.
8195   TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
8196   translateTemplateArguments(TemplateArgsIn, TemplateArgs);
8197 
8198   TemplateName Template = TemplateIn.get();
8199   if (DependentTemplateName *DTN = Template.getAsDependentTemplateName()) {
8200     // Construct a dependent template specialization type.
8201     assert(DTN && "dependent template has non-dependent name?");
8202     assert(DTN->getQualifier() == SS.getScopeRep());
8203     QualType T = Context.getDependentTemplateSpecializationType(ETK_Typename,
8204                                                           DTN->getQualifier(),
8205                                                           DTN->getIdentifier(),
8206                                                                 TemplateArgs);
8207 
8208     // Create source-location information for this type.
8209     TypeLocBuilder Builder;
8210     DependentTemplateSpecializationTypeLoc SpecTL
8211     = Builder.push<DependentTemplateSpecializationTypeLoc>(T);
8212     SpecTL.setElaboratedKeywordLoc(TypenameLoc);
8213     SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
8214     SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
8215     SpecTL.setTemplateNameLoc(TemplateNameLoc);
8216     SpecTL.setLAngleLoc(LAngleLoc);
8217     SpecTL.setRAngleLoc(RAngleLoc);
8218     for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
8219       SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
8220     return CreateParsedType(T, Builder.getTypeSourceInfo(Context, T));
8221   }
8222 
8223   QualType T = CheckTemplateIdType(Template, TemplateNameLoc, TemplateArgs);
8224   if (T.isNull())
8225     return true;
8226 
8227   // Provide source-location information for the template specialization type.
8228   TypeLocBuilder Builder;
8229   TemplateSpecializationTypeLoc SpecTL
8230     = Builder.push<TemplateSpecializationTypeLoc>(T);
8231   SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
8232   SpecTL.setTemplateNameLoc(TemplateNameLoc);
8233   SpecTL.setLAngleLoc(LAngleLoc);
8234   SpecTL.setRAngleLoc(RAngleLoc);
8235   for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
8236     SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
8237 
8238   T = Context.getElaboratedType(ETK_Typename, SS.getScopeRep(), T);
8239   ElaboratedTypeLoc TL = Builder.push<ElaboratedTypeLoc>(T);
8240   TL.setElaboratedKeywordLoc(TypenameLoc);
8241   TL.setQualifierLoc(SS.getWithLocInContext(Context));
8242 
8243   TypeSourceInfo *TSI = Builder.getTypeSourceInfo(Context, T);
8244   return CreateParsedType(T, TSI);
8245 }
8246 
8247 
8248 /// Determine whether this failed name lookup should be treated as being
8249 /// disabled by a usage of std::enable_if.
isEnableIf(NestedNameSpecifierLoc NNS,const IdentifierInfo & II,SourceRange & CondRange)8250 static bool isEnableIf(NestedNameSpecifierLoc NNS, const IdentifierInfo &II,
8251                        SourceRange &CondRange) {
8252   // We must be looking for a ::type...
8253   if (!II.isStr("type"))
8254     return false;
8255 
8256   // ... within an explicitly-written template specialization...
8257   if (!NNS || !NNS.getNestedNameSpecifier()->getAsType())
8258     return false;
8259   TypeLoc EnableIfTy = NNS.getTypeLoc();
8260   TemplateSpecializationTypeLoc EnableIfTSTLoc =
8261       EnableIfTy.getAs<TemplateSpecializationTypeLoc>();
8262   if (!EnableIfTSTLoc || EnableIfTSTLoc.getNumArgs() == 0)
8263     return false;
8264   const TemplateSpecializationType *EnableIfTST =
8265     cast<TemplateSpecializationType>(EnableIfTSTLoc.getTypePtr());
8266 
8267   // ... which names a complete class template declaration...
8268   const TemplateDecl *EnableIfDecl =
8269     EnableIfTST->getTemplateName().getAsTemplateDecl();
8270   if (!EnableIfDecl || EnableIfTST->isIncompleteType())
8271     return false;
8272 
8273   // ... called "enable_if".
8274   const IdentifierInfo *EnableIfII =
8275     EnableIfDecl->getDeclName().getAsIdentifierInfo();
8276   if (!EnableIfII || !EnableIfII->isStr("enable_if"))
8277     return false;
8278 
8279   // Assume the first template argument is the condition.
8280   CondRange = EnableIfTSTLoc.getArgLoc(0).getSourceRange();
8281   return true;
8282 }
8283 
8284 /// \brief Build the type that describes a C++ typename specifier,
8285 /// e.g., "typename T::type".
8286 QualType
CheckTypenameType(ElaboratedTypeKeyword Keyword,SourceLocation KeywordLoc,NestedNameSpecifierLoc QualifierLoc,const IdentifierInfo & II,SourceLocation IILoc)8287 Sema::CheckTypenameType(ElaboratedTypeKeyword Keyword,
8288                         SourceLocation KeywordLoc,
8289                         NestedNameSpecifierLoc QualifierLoc,
8290                         const IdentifierInfo &II,
8291                         SourceLocation IILoc) {
8292   CXXScopeSpec SS;
8293   SS.Adopt(QualifierLoc);
8294 
8295   DeclContext *Ctx = computeDeclContext(SS);
8296   if (!Ctx) {
8297     // If the nested-name-specifier is dependent and couldn't be
8298     // resolved to a type, build a typename type.
8299     assert(QualifierLoc.getNestedNameSpecifier()->isDependent());
8300     return Context.getDependentNameType(Keyword,
8301                                         QualifierLoc.getNestedNameSpecifier(),
8302                                         &II);
8303   }
8304 
8305   // If the nested-name-specifier refers to the current instantiation,
8306   // the "typename" keyword itself is superfluous. In C++03, the
8307   // program is actually ill-formed. However, DR 382 (in C++0x CD1)
8308   // allows such extraneous "typename" keywords, and we retroactively
8309   // apply this DR to C++03 code with only a warning. In any case we continue.
8310 
8311   if (RequireCompleteDeclContext(SS, Ctx))
8312     return QualType();
8313 
8314   DeclarationName Name(&II);
8315   LookupResult Result(*this, Name, IILoc, LookupOrdinaryName);
8316   LookupQualifiedName(Result, Ctx, SS);
8317   unsigned DiagID = 0;
8318   Decl *Referenced = nullptr;
8319   switch (Result.getResultKind()) {
8320   case LookupResult::NotFound: {
8321     // If we're looking up 'type' within a template named 'enable_if', produce
8322     // a more specific diagnostic.
8323     SourceRange CondRange;
8324     if (isEnableIf(QualifierLoc, II, CondRange)) {
8325       Diag(CondRange.getBegin(), diag::err_typename_nested_not_found_enable_if)
8326         << Ctx << CondRange;
8327       return QualType();
8328     }
8329 
8330     DiagID = diag::err_typename_nested_not_found;
8331     break;
8332   }
8333 
8334   case LookupResult::FoundUnresolvedValue: {
8335     // We found a using declaration that is a value. Most likely, the using
8336     // declaration itself is meant to have the 'typename' keyword.
8337     SourceRange FullRange(KeywordLoc.isValid() ? KeywordLoc : SS.getBeginLoc(),
8338                           IILoc);
8339     Diag(IILoc, diag::err_typename_refers_to_using_value_decl)
8340       << Name << Ctx << FullRange;
8341     if (UnresolvedUsingValueDecl *Using
8342           = dyn_cast<UnresolvedUsingValueDecl>(Result.getRepresentativeDecl())){
8343       SourceLocation Loc = Using->getQualifierLoc().getBeginLoc();
8344       Diag(Loc, diag::note_using_value_decl_missing_typename)
8345         << FixItHint::CreateInsertion(Loc, "typename ");
8346     }
8347   }
8348   // Fall through to create a dependent typename type, from which we can recover
8349   // better.
8350 
8351   case LookupResult::NotFoundInCurrentInstantiation:
8352     // Okay, it's a member of an unknown instantiation.
8353     return Context.getDependentNameType(Keyword,
8354                                         QualifierLoc.getNestedNameSpecifier(),
8355                                         &II);
8356 
8357   case LookupResult::Found:
8358     if (TypeDecl *Type = dyn_cast<TypeDecl>(Result.getFoundDecl())) {
8359       // We found a type. Build an ElaboratedType, since the
8360       // typename-specifier was just sugar.
8361       MarkAnyDeclReferenced(Type->getLocation(), Type, /*OdrUse=*/false);
8362       return Context.getElaboratedType(ETK_Typename,
8363                                        QualifierLoc.getNestedNameSpecifier(),
8364                                        Context.getTypeDeclType(Type));
8365     }
8366 
8367     DiagID = diag::err_typename_nested_not_type;
8368     Referenced = Result.getFoundDecl();
8369     break;
8370 
8371   case LookupResult::FoundOverloaded:
8372     DiagID = diag::err_typename_nested_not_type;
8373     Referenced = *Result.begin();
8374     break;
8375 
8376   case LookupResult::Ambiguous:
8377     return QualType();
8378   }
8379 
8380   // If we get here, it's because name lookup did not find a
8381   // type. Emit an appropriate diagnostic and return an error.
8382   SourceRange FullRange(KeywordLoc.isValid() ? KeywordLoc : SS.getBeginLoc(),
8383                         IILoc);
8384   Diag(IILoc, DiagID) << FullRange << Name << Ctx;
8385   if (Referenced)
8386     Diag(Referenced->getLocation(), diag::note_typename_refers_here)
8387       << Name;
8388   return QualType();
8389 }
8390 
8391 namespace {
8392   // See Sema::RebuildTypeInCurrentInstantiation
8393   class CurrentInstantiationRebuilder
8394     : public TreeTransform<CurrentInstantiationRebuilder> {
8395     SourceLocation Loc;
8396     DeclarationName Entity;
8397 
8398   public:
8399     typedef TreeTransform<CurrentInstantiationRebuilder> inherited;
8400 
CurrentInstantiationRebuilder(Sema & SemaRef,SourceLocation Loc,DeclarationName Entity)8401     CurrentInstantiationRebuilder(Sema &SemaRef,
8402                                   SourceLocation Loc,
8403                                   DeclarationName Entity)
8404     : TreeTransform<CurrentInstantiationRebuilder>(SemaRef),
8405       Loc(Loc), Entity(Entity) { }
8406 
8407     /// \brief Determine whether the given type \p T has already been
8408     /// transformed.
8409     ///
8410     /// For the purposes of type reconstruction, a type has already been
8411     /// transformed if it is NULL or if it is not dependent.
AlreadyTransformed(QualType T)8412     bool AlreadyTransformed(QualType T) {
8413       return T.isNull() || !T->isDependentType();
8414     }
8415 
8416     /// \brief Returns the location of the entity whose type is being
8417     /// rebuilt.
getBaseLocation()8418     SourceLocation getBaseLocation() { return Loc; }
8419 
8420     /// \brief Returns the name of the entity whose type is being rebuilt.
getBaseEntity()8421     DeclarationName getBaseEntity() { return Entity; }
8422 
8423     /// \brief Sets the "base" location and entity when that
8424     /// information is known based on another transformation.
setBase(SourceLocation Loc,DeclarationName Entity)8425     void setBase(SourceLocation Loc, DeclarationName Entity) {
8426       this->Loc = Loc;
8427       this->Entity = Entity;
8428     }
8429 
TransformLambdaExpr(LambdaExpr * E)8430     ExprResult TransformLambdaExpr(LambdaExpr *E) {
8431       // Lambdas never need to be transformed.
8432       return E;
8433     }
8434   };
8435 } // end anonymous namespace
8436 
8437 /// \brief Rebuilds a type within the context of the current instantiation.
8438 ///
8439 /// The type \p T is part of the type of an out-of-line member definition of
8440 /// a class template (or class template partial specialization) that was parsed
8441 /// and constructed before we entered the scope of the class template (or
8442 /// partial specialization thereof). This routine will rebuild that type now
8443 /// that we have entered the declarator's scope, which may produce different
8444 /// canonical types, e.g.,
8445 ///
8446 /// \code
8447 /// template<typename T>
8448 /// struct X {
8449 ///   typedef T* pointer;
8450 ///   pointer data();
8451 /// };
8452 ///
8453 /// template<typename T>
8454 /// typename X<T>::pointer X<T>::data() { ... }
8455 /// \endcode
8456 ///
8457 /// Here, the type "typename X<T>::pointer" will be created as a DependentNameType,
8458 /// since we do not know that we can look into X<T> when we parsed the type.
8459 /// This function will rebuild the type, performing the lookup of "pointer"
8460 /// in X<T> and returning an ElaboratedType whose canonical type is the same
8461 /// as the canonical type of T*, allowing the return types of the out-of-line
8462 /// definition and the declaration to match.
RebuildTypeInCurrentInstantiation(TypeSourceInfo * T,SourceLocation Loc,DeclarationName Name)8463 TypeSourceInfo *Sema::RebuildTypeInCurrentInstantiation(TypeSourceInfo *T,
8464                                                         SourceLocation Loc,
8465                                                         DeclarationName Name) {
8466   if (!T || !T->getType()->isDependentType())
8467     return T;
8468 
8469   CurrentInstantiationRebuilder Rebuilder(*this, Loc, Name);
8470   return Rebuilder.TransformType(T);
8471 }
8472 
RebuildExprInCurrentInstantiation(Expr * E)8473 ExprResult Sema::RebuildExprInCurrentInstantiation(Expr *E) {
8474   CurrentInstantiationRebuilder Rebuilder(*this, E->getExprLoc(),
8475                                           DeclarationName());
8476   return Rebuilder.TransformExpr(E);
8477 }
8478 
RebuildNestedNameSpecifierInCurrentInstantiation(CXXScopeSpec & SS)8479 bool Sema::RebuildNestedNameSpecifierInCurrentInstantiation(CXXScopeSpec &SS) {
8480   if (SS.isInvalid())
8481     return true;
8482 
8483   NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
8484   CurrentInstantiationRebuilder Rebuilder(*this, SS.getRange().getBegin(),
8485                                           DeclarationName());
8486   NestedNameSpecifierLoc Rebuilt
8487     = Rebuilder.TransformNestedNameSpecifierLoc(QualifierLoc);
8488   if (!Rebuilt)
8489     return true;
8490 
8491   SS.Adopt(Rebuilt);
8492   return false;
8493 }
8494 
8495 /// \brief Rebuild the template parameters now that we know we're in a current
8496 /// instantiation.
RebuildTemplateParamsInCurrentInstantiation(TemplateParameterList * Params)8497 bool Sema::RebuildTemplateParamsInCurrentInstantiation(
8498                                                TemplateParameterList *Params) {
8499   for (unsigned I = 0, N = Params->size(); I != N; ++I) {
8500     Decl *Param = Params->getParam(I);
8501 
8502     // There is nothing to rebuild in a type parameter.
8503     if (isa<TemplateTypeParmDecl>(Param))
8504       continue;
8505 
8506     // Rebuild the template parameter list of a template template parameter.
8507     if (TemplateTemplateParmDecl *TTP
8508         = dyn_cast<TemplateTemplateParmDecl>(Param)) {
8509       if (RebuildTemplateParamsInCurrentInstantiation(
8510             TTP->getTemplateParameters()))
8511         return true;
8512 
8513       continue;
8514     }
8515 
8516     // Rebuild the type of a non-type template parameter.
8517     NonTypeTemplateParmDecl *NTTP = cast<NonTypeTemplateParmDecl>(Param);
8518     TypeSourceInfo *NewTSI
8519       = RebuildTypeInCurrentInstantiation(NTTP->getTypeSourceInfo(),
8520                                           NTTP->getLocation(),
8521                                           NTTP->getDeclName());
8522     if (!NewTSI)
8523       return true;
8524 
8525     if (NewTSI != NTTP->getTypeSourceInfo()) {
8526       NTTP->setTypeSourceInfo(NewTSI);
8527       NTTP->setType(NewTSI->getType());
8528     }
8529   }
8530 
8531   return false;
8532 }
8533 
8534 /// \brief Produces a formatted string that describes the binding of
8535 /// template parameters to template arguments.
8536 std::string
getTemplateArgumentBindingsText(const TemplateParameterList * Params,const TemplateArgumentList & Args)8537 Sema::getTemplateArgumentBindingsText(const TemplateParameterList *Params,
8538                                       const TemplateArgumentList &Args) {
8539   return getTemplateArgumentBindingsText(Params, Args.data(), Args.size());
8540 }
8541 
8542 std::string
getTemplateArgumentBindingsText(const TemplateParameterList * Params,const TemplateArgument * Args,unsigned NumArgs)8543 Sema::getTemplateArgumentBindingsText(const TemplateParameterList *Params,
8544                                       const TemplateArgument *Args,
8545                                       unsigned NumArgs) {
8546   SmallString<128> Str;
8547   llvm::raw_svector_ostream Out(Str);
8548 
8549   if (!Params || Params->size() == 0 || NumArgs == 0)
8550     return std::string();
8551 
8552   for (unsigned I = 0, N = Params->size(); I != N; ++I) {
8553     if (I >= NumArgs)
8554       break;
8555 
8556     if (I == 0)
8557       Out << "[with ";
8558     else
8559       Out << ", ";
8560 
8561     if (const IdentifierInfo *Id = Params->getParam(I)->getIdentifier()) {
8562       Out << Id->getName();
8563     } else {
8564       Out << '$' << I;
8565     }
8566 
8567     Out << " = ";
8568     Args[I].print(getPrintingPolicy(), Out);
8569   }
8570 
8571   Out << ']';
8572   return Out.str();
8573 }
8574 
MarkAsLateParsedTemplate(FunctionDecl * FD,Decl * FnD,CachedTokens & Toks)8575 void Sema::MarkAsLateParsedTemplate(FunctionDecl *FD, Decl *FnD,
8576                                     CachedTokens &Toks) {
8577   if (!FD)
8578     return;
8579 
8580   LateParsedTemplate *LPT = new LateParsedTemplate;
8581 
8582   // Take tokens to avoid allocations
8583   LPT->Toks.swap(Toks);
8584   LPT->D = FnD;
8585   LateParsedTemplateMap.insert(std::make_pair(FD, LPT));
8586 
8587   FD->setLateTemplateParsed(true);
8588 }
8589 
UnmarkAsLateParsedTemplate(FunctionDecl * FD)8590 void Sema::UnmarkAsLateParsedTemplate(FunctionDecl *FD) {
8591   if (!FD)
8592     return;
8593   FD->setLateTemplateParsed(false);
8594 }
8595 
IsInsideALocalClassWithinATemplateFunction()8596 bool Sema::IsInsideALocalClassWithinATemplateFunction() {
8597   DeclContext *DC = CurContext;
8598 
8599   while (DC) {
8600     if (CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(CurContext)) {
8601       const FunctionDecl *FD = RD->isLocalClass();
8602       return (FD && FD->getTemplatedKind() != FunctionDecl::TK_NonTemplate);
8603     } else if (DC->isTranslationUnit() || DC->isNamespace())
8604       return false;
8605 
8606     DC = DC->getParent();
8607   }
8608   return false;
8609 }
8610 
8611 /// \brief Walk the path from which a declaration was instantiated, and check
8612 /// that every explicit specialization along that path is visible. This enforces
8613 /// C++ [temp.expl.spec]/6:
8614 ///
8615 ///   If a template, a member template or a member of a class template is
8616 ///   explicitly specialized then that specialization shall be declared before
8617 ///   the first use of that specialization that would cause an implicit
8618 ///   instantiation to take place, in every translation unit in which such a
8619 ///   use occurs; no diagnostic is required.
8620 ///
8621 /// and also C++ [temp.class.spec]/1:
8622 ///
8623 ///   A partial specialization shall be declared before the first use of a
8624 ///   class template specialization that would make use of the partial
8625 ///   specialization as the result of an implicit or explicit instantiation
8626 ///   in every translation unit in which such a use occurs; no diagnostic is
8627 ///   required.
8628 class ExplicitSpecializationVisibilityChecker {
8629   Sema &S;
8630   SourceLocation Loc;
8631   llvm::SmallVector<Module *, 8> Modules;
8632 
8633 public:
ExplicitSpecializationVisibilityChecker(Sema & S,SourceLocation Loc)8634   ExplicitSpecializationVisibilityChecker(Sema &S, SourceLocation Loc)
8635       : S(S), Loc(Loc) {}
8636 
check(NamedDecl * ND)8637   void check(NamedDecl *ND) {
8638     if (auto *FD = dyn_cast<FunctionDecl>(ND))
8639       return checkImpl(FD);
8640     if (auto *RD = dyn_cast<CXXRecordDecl>(ND))
8641       return checkImpl(RD);
8642     if (auto *VD = dyn_cast<VarDecl>(ND))
8643       return checkImpl(VD);
8644     if (auto *ED = dyn_cast<EnumDecl>(ND))
8645       return checkImpl(ED);
8646   }
8647 
8648 private:
diagnose(NamedDecl * D,bool IsPartialSpec)8649   void diagnose(NamedDecl *D, bool IsPartialSpec) {
8650     auto Kind = IsPartialSpec ? Sema::MissingImportKind::PartialSpecialization
8651                               : Sema::MissingImportKind::ExplicitSpecialization;
8652     const bool Recover = true;
8653 
8654     // If we got a custom set of modules (because only a subset of the
8655     // declarations are interesting), use them, otherwise let
8656     // diagnoseMissingImport intelligently pick some.
8657     if (Modules.empty())
8658       S.diagnoseMissingImport(Loc, D, Kind, Recover);
8659     else
8660       S.diagnoseMissingImport(Loc, D, D->getLocation(), Modules, Kind, Recover);
8661   }
8662 
8663   // Check a specific declaration. There are three problematic cases:
8664   //
8665   //  1) The declaration is an explicit specialization of a template
8666   //     specialization.
8667   //  2) The declaration is an explicit specialization of a member of an
8668   //     templated class.
8669   //  3) The declaration is an instantiation of a template, and that template
8670   //     is an explicit specialization of a member of a templated class.
8671   //
8672   // We don't need to go any deeper than that, as the instantiation of the
8673   // surrounding class / etc is not triggered by whatever triggered this
8674   // instantiation, and thus should be checked elsewhere.
8675   template<typename SpecDecl>
checkImpl(SpecDecl * Spec)8676   void checkImpl(SpecDecl *Spec) {
8677     bool IsHiddenExplicitSpecialization = false;
8678     if (Spec->getTemplateSpecializationKind() == TSK_ExplicitSpecialization) {
8679       IsHiddenExplicitSpecialization =
8680           Spec->getMemberSpecializationInfo()
8681               ? !S.hasVisibleMemberSpecialization(Spec, &Modules)
8682               : !S.hasVisibleDeclaration(Spec);
8683     } else {
8684       checkInstantiated(Spec);
8685     }
8686 
8687     if (IsHiddenExplicitSpecialization)
8688       diagnose(Spec->getMostRecentDecl(), false);
8689   }
8690 
checkInstantiated(FunctionDecl * FD)8691   void checkInstantiated(FunctionDecl *FD) {
8692     if (auto *TD = FD->getPrimaryTemplate())
8693       checkTemplate(TD);
8694   }
8695 
checkInstantiated(CXXRecordDecl * RD)8696   void checkInstantiated(CXXRecordDecl *RD) {
8697     auto *SD = dyn_cast<ClassTemplateSpecializationDecl>(RD);
8698     if (!SD)
8699       return;
8700 
8701     auto From = SD->getSpecializedTemplateOrPartial();
8702     if (auto *TD = From.dyn_cast<ClassTemplateDecl *>())
8703       checkTemplate(TD);
8704     else if (auto *TD =
8705                  From.dyn_cast<ClassTemplatePartialSpecializationDecl *>()) {
8706       if (!S.hasVisibleDeclaration(TD))
8707         diagnose(TD, true);
8708       checkTemplate(TD);
8709     }
8710   }
8711 
checkInstantiated(VarDecl * RD)8712   void checkInstantiated(VarDecl *RD) {
8713     auto *SD = dyn_cast<VarTemplateSpecializationDecl>(RD);
8714     if (!SD)
8715       return;
8716 
8717     auto From = SD->getSpecializedTemplateOrPartial();
8718     if (auto *TD = From.dyn_cast<VarTemplateDecl *>())
8719       checkTemplate(TD);
8720     else if (auto *TD =
8721                  From.dyn_cast<VarTemplatePartialSpecializationDecl *>()) {
8722       if (!S.hasVisibleDeclaration(TD))
8723         diagnose(TD, true);
8724       checkTemplate(TD);
8725     }
8726   }
8727 
checkInstantiated(EnumDecl * FD)8728   void checkInstantiated(EnumDecl *FD) {}
8729 
8730   template<typename TemplDecl>
checkTemplate(TemplDecl * TD)8731   void checkTemplate(TemplDecl *TD) {
8732     if (TD->isMemberSpecialization()) {
8733       if (!S.hasVisibleMemberSpecialization(TD, &Modules))
8734         diagnose(TD->getMostRecentDecl(), false);
8735     }
8736   }
8737 };
8738 
checkSpecializationVisibility(SourceLocation Loc,NamedDecl * Spec)8739 void Sema::checkSpecializationVisibility(SourceLocation Loc, NamedDecl *Spec) {
8740   if (!getLangOpts().Modules)
8741     return;
8742 
8743   ExplicitSpecializationVisibilityChecker(*this, Loc).check(Spec);
8744 }
8745 
8746 /// \brief Check whether a template partial specialization that we've discovered
8747 /// is hidden, and produce suitable diagnostics if so.
checkPartialSpecializationVisibility(SourceLocation Loc,NamedDecl * Spec)8748 void Sema::checkPartialSpecializationVisibility(SourceLocation Loc,
8749                                                 NamedDecl *Spec) {
8750   llvm::SmallVector<Module *, 8> Modules;
8751   if (!hasVisibleDeclaration(Spec, &Modules))
8752     diagnoseMissingImport(Loc, Spec, Spec->getLocation(), Modules,
8753                           MissingImportKind::PartialSpecialization,
8754                           /*Recover*/true);
8755 }
8756