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/StaticAnalyzer/Core/Checker.h"
18 #include "clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h"
19 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
20 #include "clang/AST/DeclObjC.h"
21 #include "clang/AST/Type.h"
22 #include "clang/AST/ASTContext.h"
23
24 #include "llvm/ADT/DenseMap.h"
25 #include "llvm/Support/raw_ostream.h"
26
27 using namespace clang;
28 using namespace ento;
29
AreTypesCompatible(QualType Derived,QualType Ancestor,ASTContext & C)30 static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
31 ASTContext& C) {
32
33 // Right now don't compare the compatibility of pointers. That involves
34 // looking at subtyping relationships. FIXME: Future patch.
35 if (Derived->isAnyPointerType() && Ancestor->isAnyPointerType())
36 return true;
37
38 return C.typesAreCompatible(Derived, Ancestor);
39 }
40
CompareReturnTypes(const ObjCMethodDecl * MethDerived,const ObjCMethodDecl * MethAncestor,BugReporter & BR,ASTContext & Ctx,const ObjCImplementationDecl * ID)41 static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
42 const ObjCMethodDecl *MethAncestor,
43 BugReporter &BR, ASTContext &Ctx,
44 const ObjCImplementationDecl *ID) {
45
46 QualType ResDerived = MethDerived->getResultType();
47 QualType ResAncestor = MethAncestor->getResultType();
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().getAsString()
59 << "' 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 BR.EmitBasicReport("Incompatible instance method return type",
70 os.str(), MethDerived->getLocStart());
71 }
72 }
73
CheckObjCInstMethSignature(const ObjCImplementationDecl * ID,BugReporter & BR)74 static void CheckObjCInstMethSignature(const ObjCImplementationDecl* ID,
75 BugReporter& BR) {
76
77 const ObjCInterfaceDecl* D = ID->getClassInterface();
78 const ObjCInterfaceDecl* C = D->getSuperClass();
79
80 if (!C)
81 return;
82
83 ASTContext& Ctx = BR.getContext();
84
85 // Build a DenseMap of the methods for quick querying.
86 typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
87 MapTy IMeths;
88 unsigned NumMethods = 0;
89
90 for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
91 E=ID->instmeth_end(); I!=E; ++I) {
92
93 ObjCMethodDecl* M = *I;
94 IMeths[M->getSelector()] = M;
95 ++NumMethods;
96 }
97
98 // Now recurse the class hierarchy chain looking for methods with the
99 // same signatures.
100 while (C && NumMethods) {
101 for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
102 E=C->instmeth_end(); I!=E; ++I) {
103
104 ObjCMethodDecl* M = *I;
105 Selector S = M->getSelector();
106
107 MapTy::iterator MI = IMeths.find(S);
108
109 if (MI == IMeths.end() || MI->second == 0)
110 continue;
111
112 --NumMethods;
113 ObjCMethodDecl* MethDerived = MI->second;
114 MI->second = 0;
115
116 CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
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);
134 }
135 };
136 }
137
registerObjCMethSigsChecker(CheckerManager & mgr)138 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
139 mgr.registerChecker<ObjCMethSigsChecker>();
140 }
141