CheckObjCInstMethSignature.cpp revision 6bcf27bb9a4b5c3f79cb44c0e4654a6d7619ad89 
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
26using namespace clang;
27using namespace ento;
28
29static 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
40static 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
79static 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
127namespace {
128class ObjCMethSigsChecker : public Checker<
129                                      check::ASTDecl<ObjCImplementationDecl> > {
130public:
131  void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
132                    BugReporter &BR) const {
133    CheckObjCInstMethSignature(D, BR, this);
134  }
135};
136}
137
138void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
139  mgr.registerChecker<ObjCMethSigsChecker>();
140}
141