1 //===-- CheckObjCInstMethSignature.cpp - Check ObjC method signatures -----===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines a CheckObjCInstMethSignature, a flow-insensitive check
10 // that determines if an Objective-C class interface incorrectly redefines
11 // the method signature in a subclass.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
16 #include "clang/Analysis/PathDiagnostic.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/Checker.h"
22 #include "llvm/ADT/DenseMap.h"
23 #include "llvm/Support/raw_ostream.h"
24
25 using namespace clang;
26 using namespace ento;
27
AreTypesCompatible(QualType Derived,QualType Ancestor,ASTContext & C)28 static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
29 ASTContext &C) {
30
31 // Right now don't compare the compatibility of pointers. That involves
32 // looking at subtyping relationships. FIXME: Future patch.
33 if (Derived->isAnyPointerType() && Ancestor->isAnyPointerType())
34 return true;
35
36 return C.typesAreCompatible(Derived, Ancestor);
37 }
38
CompareReturnTypes(const ObjCMethodDecl * MethDerived,const ObjCMethodDecl * MethAncestor,BugReporter & BR,ASTContext & Ctx,const ObjCImplementationDecl * ID,const CheckerBase * Checker)39 static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
40 const ObjCMethodDecl *MethAncestor,
41 BugReporter &BR, ASTContext &Ctx,
42 const ObjCImplementationDecl *ID,
43 const CheckerBase *Checker) {
44
45 QualType ResDerived = MethDerived->getReturnType();
46 QualType ResAncestor = MethAncestor->getReturnType();
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().print(os);
58 os << "' whose return type is '" << ResDerived
59 << "'. A method with the same name (same selector) is also defined in "
60 "class '"
61 << *MethAncestor->getClassInterface() << "' and has a return type of '"
62 << ResAncestor
63 << "'. These two types are incompatible, and may result in undefined "
64 "behavior for clients of these classes.";
65
66 PathDiagnosticLocation MethDLoc =
67 PathDiagnosticLocation::createBegin(MethDerived,
68 BR.getSourceManager());
69
70 BR.EmitBasicReport(
71 MethDerived, Checker, "Incompatible instance method return type",
72 categories::CoreFoundationObjectiveC, os.str(), MethDLoc);
73 }
74 }
75
CheckObjCInstMethSignature(const ObjCImplementationDecl * ID,BugReporter & BR,const CheckerBase * Checker)76 static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
77 BugReporter &BR,
78 const CheckerBase *Checker) {
79
80 const ObjCInterfaceDecl *D = ID->getClassInterface();
81 const ObjCInterfaceDecl *C = D->getSuperClass();
82
83 if (!C)
84 return;
85
86 ASTContext &Ctx = BR.getContext();
87
88 // Build a DenseMap of the methods for quick querying.
89 typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
90 MapTy IMeths;
91 unsigned NumMethods = 0;
92
93 for (auto *M : ID->instance_methods()) {
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 (const auto *M : C->instance_methods()) {
102 Selector S = M->getSelector();
103
104 MapTy::iterator MI = IMeths.find(S);
105
106 if (MI == IMeths.end() || MI->second == nullptr)
107 continue;
108
109 --NumMethods;
110 ObjCMethodDecl *MethDerived = MI->second;
111 MI->second = nullptr;
112
113 CompareReturnTypes(MethDerived, M, BR, Ctx, ID, Checker);
114 }
115
116 C = C->getSuperClass();
117 }
118 }
119
120 //===----------------------------------------------------------------------===//
121 // ObjCMethSigsChecker
122 //===----------------------------------------------------------------------===//
123
124 namespace {
125 class ObjCMethSigsChecker : public Checker<
126 check::ASTDecl<ObjCImplementationDecl> > {
127 public:
checkASTDecl(const ObjCImplementationDecl * D,AnalysisManager & mgr,BugReporter & BR) const128 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
129 BugReporter &BR) const {
130 CheckObjCInstMethSignature(D, BR, this);
131 }
132 };
133 }
134
registerObjCMethSigsChecker(CheckerManager & mgr)135 void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
136 mgr.registerChecker<ObjCMethSigsChecker>();
137 }
138
shouldRegisterObjCMethSigsChecker(const CheckerManager & mgr)139 bool ento::shouldRegisterObjCMethSigsChecker(const CheckerManager &mgr) {
140 return true;
141 }
142