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 PathDiagnosticLocation MethDLoc =
70 PathDiagnosticLocation::createBegin(MethDerived,
71 BR.getSourceManager());
72
73 BR.EmitBasicReport(MethDerived,
74 "Incompatible instance method return type",
75 categories::CoreFoundationObjectiveC,
76 os.str(), MethDLoc);
77 }
78 }
79
CheckObjCInstMethSignature(const ObjCImplementationDecl * ID,BugReporter & BR)80 static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
81 BugReporter& BR) {
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 (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
97 E=ID->instmeth_end(); I!=E; ++I) {
98
99 ObjCMethodDecl *M = *I;
100 IMeths[M->getSelector()] = M;
101 ++NumMethods;
102 }
103
104 // Now recurse the class hierarchy chain looking for methods with the
105 // same signatures.
106 while (C && NumMethods) {
107 for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
108 E=C->instmeth_end(); I!=E; ++I) {
109
110 ObjCMethodDecl *M = *I;
111 Selector S = M->getSelector();
112
113 MapTy::iterator MI = IMeths.find(S);
114
115 if (MI == IMeths.end() || MI->second == 0)
116 continue;
117
118 --NumMethods;
119 ObjCMethodDecl *MethDerived = MI->second;
120 MI->second = 0;
121
122 CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
123 }
124
125 C = C->getSuperClass();
126 }
127 }
128
129 //===----------------------------------------------------------------------===//
130 // ObjCMethSigsChecker
131 //===----------------------------------------------------------------------===//
132
133 namespace {
134 class ObjCMethSigsChecker : public Checker<
135 check::ASTDecl<ObjCImplementationDecl> > {
136 public:
checkASTDecl(const ObjCImplementationDecl * D,AnalysisManager & mgr,BugReporter & BR) const137 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
138 BugReporter &BR) const {
139 CheckObjCInstMethSignature(D, BR);
140 }
141 };
142 }
143
registerObjCMethSigsChecker(CheckerManager & mgr)144 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
145 mgr.registerChecker<ObjCMethSigsChecker>();
146 }
147