1 //=- CheckObjCInstMethodRetTy.cpp - Check ObjC method signatures -*- C++ -*-==//
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 //
10 // This file defines a CheckObjCInstMethSignature, a flow-insenstive check
11 // that determines if an Objective-C class interface incorrectly redefines
12 // the method signature in a subclass.
13 //
14 //===----------------------------------------------------------------------===//
15
16 #include "ClangSACheckers.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/DeclObjC.h"
19 #include "clang/AST/Type.h"
20 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
21 #include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
22 #include "clang/StaticAnalyzer/Core/Checker.h"
23 #include "llvm/ADT/DenseMap.h"
24 #include "llvm/Support/raw_ostream.h"
25
26 using namespace clang;
27 using namespace ento;
28
AreTypesCompatible(QualType Derived,QualType Ancestor,ASTContext & C)29 static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
30 ASTContext &C) {
31
32 // Right now don't compare the compatibility of pointers. That involves
33 // looking at subtyping relationships. FIXME: Future patch.
34 if (Derived->isAnyPointerType() && Ancestor->isAnyPointerType())
35 return true;
36
37 return C.typesAreCompatible(Derived, Ancestor);
38 }
39
CompareReturnTypes(const ObjCMethodDecl * MethDerived,const ObjCMethodDecl * MethAncestor,BugReporter & BR,ASTContext & Ctx,const ObjCImplementationDecl * ID,const CheckerBase * Checker)40 static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
41 const ObjCMethodDecl *MethAncestor,
42 BugReporter &BR, ASTContext &Ctx,
43 const ObjCImplementationDecl *ID,
44 const CheckerBase *Checker) {
45
46 QualType ResDerived = MethDerived->getReturnType();
47 QualType ResAncestor = MethAncestor->getReturnType();
48
49 if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
50 std::string sbuf;
51 llvm::raw_string_ostream os(sbuf);
52
53 os << "The Objective-C class '"
54 << *MethDerived->getClassInterface()
55 << "', which is derived from class '"
56 << *MethAncestor->getClassInterface()
57 << "', defines the instance method '";
58 MethDerived->getSelector().print(os);
59 os << "' whose return type is '"
60 << ResDerived.getAsString()
61 << "'. A method with the same name (same selector) is also defined in "
62 "class '"
63 << *MethAncestor->getClassInterface()
64 << "' and has a return type of '"
65 << ResAncestor.getAsString()
66 << "'. These two types are incompatible, and may result in undefined "
67 "behavior for clients of these classes.";
68
69 PathDiagnosticLocation MethDLoc =
70 PathDiagnosticLocation::createBegin(MethDerived,
71 BR.getSourceManager());
72
73 BR.EmitBasicReport(
74 MethDerived, Checker, "Incompatible instance method return type",
75 categories::CoreFoundationObjectiveC, os.str(), MethDLoc);
76 }
77 }
78
CheckObjCInstMethSignature(const ObjCImplementationDecl * ID,BugReporter & BR,const CheckerBase * Checker)79 static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
80 BugReporter &BR,
81 const CheckerBase *Checker) {
82
83 const ObjCInterfaceDecl *D = ID->getClassInterface();
84 const ObjCInterfaceDecl *C = D->getSuperClass();
85
86 if (!C)
87 return;
88
89 ASTContext &Ctx = BR.getContext();
90
91 // Build a DenseMap of the methods for quick querying.
92 typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
93 MapTy IMeths;
94 unsigned NumMethods = 0;
95
96 for (auto *M : ID->instance_methods()) {
97 IMeths[M->getSelector()] = M;
98 ++NumMethods;
99 }
100
101 // Now recurse the class hierarchy chain looking for methods with the
102 // same signatures.
103 while (C && NumMethods) {
104 for (const auto *M : C->instance_methods()) {
105 Selector S = M->getSelector();
106
107 MapTy::iterator MI = IMeths.find(S);
108
109 if (MI == IMeths.end() || MI->second == nullptr)
110 continue;
111
112 --NumMethods;
113 ObjCMethodDecl *MethDerived = MI->second;
114 MI->second = nullptr;
115
116 CompareReturnTypes(MethDerived, M, BR, Ctx, ID, Checker);
117 }
118
119 C = C->getSuperClass();
120 }
121 }
122
123 //===----------------------------------------------------------------------===//
124 // ObjCMethSigsChecker
125 //===----------------------------------------------------------------------===//
126
127 namespace {
128 class ObjCMethSigsChecker : public Checker<
129 check::ASTDecl<ObjCImplementationDecl> > {
130 public:
checkASTDecl(const ObjCImplementationDecl * D,AnalysisManager & mgr,BugReporter & BR) const131 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
132 BugReporter &BR) const {
133 CheckObjCInstMethSignature(D, BR, this);
134 }
135 };
136 }
137
registerObjCMethSigsChecker(CheckerManager & mgr)138 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
139 mgr.registerChecker<ObjCMethSigsChecker>();
140 }
141