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)40 static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
41 const ObjCMethodDecl *MethAncestor,
42 BugReporter &BR, ASTContext &Ctx,
43 const ObjCImplementationDecl *ID) {
44
45 QualType ResDerived = MethDerived->getResultType();
46 QualType ResAncestor = MethAncestor->getResultType();
47
48 if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
49 std::string sbuf;
50 llvm::raw_string_ostream os(sbuf);
51
52 os << "The Objective-C class '"
53 << *MethDerived->getClassInterface()
54 << "', which is derived from class '"
55 << *MethAncestor->getClassInterface()
56 << "', defines the instance method '"
57 << MethDerived->getSelector().getAsString()
58 << "' whose return type is '"
59 << ResDerived.getAsString()
60 << "'. A method with the same name (same selector) is also defined in "
61 "class '"
62 << *MethAncestor->getClassInterface()
63 << "' and has a return type of '"
64 << ResAncestor.getAsString()
65 << "'. These two types are incompatible, and may result in undefined "
66 "behavior for clients of these classes.";
67
68 PathDiagnosticLocation MethDLoc =
69 PathDiagnosticLocation::createBegin(MethDerived,
70 BR.getSourceManager());
71
72 BR.EmitBasicReport(MethDerived,
73 "Incompatible instance method return type",
74 categories::CoreFoundationObjectiveC,
75 os.str(), MethDLoc);
76 }
77 }
78
CheckObjCInstMethSignature(const ObjCImplementationDecl * ID,BugReporter & BR)79 static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
80 BugReporter& BR) {
81
82 const ObjCInterfaceDecl *D = ID->getClassInterface();
83 const ObjCInterfaceDecl *C = D->getSuperClass();
84
85 if (!C)
86 return;
87
88 ASTContext &Ctx = BR.getContext();
89
90 // Build a DenseMap of the methods for quick querying.
91 typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
92 MapTy IMeths;
93 unsigned NumMethods = 0;
94
95 for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
96 E=ID->instmeth_end(); I!=E; ++I) {
97
98 ObjCMethodDecl *M = *I;
99 IMeths[M->getSelector()] = M;
100 ++NumMethods;
101 }
102
103 // Now recurse the class hierarchy chain looking for methods with the
104 // same signatures.
105 while (C && NumMethods) {
106 for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
107 E=C->instmeth_end(); I!=E; ++I) {
108
109 ObjCMethodDecl *M = *I;
110 Selector S = M->getSelector();
111
112 MapTy::iterator MI = IMeths.find(S);
113
114 if (MI == IMeths.end() || MI->second == 0)
115 continue;
116
117 --NumMethods;
118 ObjCMethodDecl *MethDerived = MI->second;
119 MI->second = 0;
120
121 CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
122 }
123
124 C = C->getSuperClass();
125 }
126 }
127
128 //===----------------------------------------------------------------------===//
129 // ObjCMethSigsChecker
130 //===----------------------------------------------------------------------===//
131
132 namespace {
133 class ObjCMethSigsChecker : public Checker<
134 check::ASTDecl<ObjCImplementationDecl> > {
135 public:
checkASTDecl(const ObjCImplementationDecl * D,AnalysisManager & mgr,BugReporter & BR) const136 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
137 BugReporter &BR) const {
138 CheckObjCInstMethSignature(D, BR);
139 }
140 };
141 }
142
registerObjCMethSigsChecker(CheckerManager & mgr)143 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
144 mgr.registerChecker<ObjCMethSigsChecker>();
145 }
146