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
25using namespace clang;
26using namespace ento;
27
28static 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(T1: Derived, T2: Ancestor);
37}
38
39static 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(Derived: ResDerived, Ancestor: ResAncestor, C&: 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&: 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(D: MethDerived,
68 SM: BR.getSourceManager());
69
70 BR.EmitBasicReport(
71 DeclWithIssue: MethDerived, Checker, BugName: "Incompatible instance method return type",
72 BugCategory: categories::CoreFoundationObjectiveC, BugStr: os.str(), Loc: MethDLoc);
73 }
74}
75
76static 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(Val: 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, MethAncestor: M, BR, Ctx, ID, Checker);
114 }
115
116 C = C->getSuperClass();
117 }
118}
119
120//===----------------------------------------------------------------------===//
121// ObjCMethSigsChecker
122//===----------------------------------------------------------------------===//
123
124namespace {
125class ObjCMethSigsChecker : public Checker<
126 check::ASTDecl<ObjCImplementationDecl> > {
127public:
128 void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
129 BugReporter &BR) const {
130 CheckObjCInstMethSignature(ID: D, BR, Checker: this);
131 }
132};
133}
134
135void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
136 mgr.registerChecker<ObjCMethSigsChecker>();
137}
138
139bool ento::shouldRegisterObjCMethSigsChecker(const CheckerManager &mgr) {
140 return true;
141}
142