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 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 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 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: 131 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr, 132 BugReporter &BR) const { 133 CheckObjCInstMethSignature(D, BR, this); 134 } 135 }; 136 } 137 138 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) { 139 mgr.registerChecker<ObjCMethSigsChecker>(); 140 } 141