CheckObjCInstMethSignature.cpp revision 55fc873017f10f6f566b182b70f6fc22aefa3464 
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
45  QualType ResDerived  = MethDerived->getResultType();
46  QualType ResAncestor = MethAncestor->getResultType();
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().getAsString()
58       << "' whose return type is '"
59       << ResDerived.getAsString()
60       << "'.  A method with the same name (same selector) is also defined in "
61          "class '"
62       << *MethAncestor->getClassInterface()
63       << "' and has a return type of '"
64       << ResAncestor.getAsString()
65       << "'.  These two types are incompatible, and may result in undefined "
66          "behavior for clients of these classes.";
67
68    PathDiagnosticLocation MethDLoc =
69      PathDiagnosticLocation::createBegin(MethDerived,
70                                          BR.getSourceManager());
71
72    BR.EmitBasicReport(MethDerived,
73                       "Incompatible instance method return type",
74                       categories::CoreFoundationObjectiveC,
75                       os.str(), MethDLoc);
76  }
77}
78
79static void CheckObjCInstMethSignature(const ObjCImplementationDecl *ID,
80                                       BugReporter& BR) {
81
82  const ObjCInterfaceDecl *D = ID->getClassInterface();
83  const ObjCInterfaceDecl *C = D->getSuperClass();
84
85  if (!C)
86    return;
87
88  ASTContext &Ctx = BR.getContext();
89
90  // Build a DenseMap of the methods for quick querying.
91  typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
92  MapTy IMeths;
93  unsigned NumMethods = 0;
94
95  for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
96       E=ID->instmeth_end(); I!=E; ++I) {
97
98    ObjCMethodDecl *M = *I;
99    IMeths[M->getSelector()] = M;
100    ++NumMethods;
101  }
102
103  // Now recurse the class hierarchy chain looking for methods with the
104  // same signatures.
105  while (C && NumMethods) {
106    for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
107         E=C->instmeth_end(); I!=E; ++I) {
108
109      ObjCMethodDecl *M = *I;
110      Selector S = M->getSelector();
111
112      MapTy::iterator MI = IMeths.find(S);
113
114      if (MI == IMeths.end() || MI->second == 0)
115        continue;
116
117      --NumMethods;
118      ObjCMethodDecl *MethDerived = MI->second;
119      MI->second = 0;
120
121      CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
122    }
123
124    C = C->getSuperClass();
125  }
126}
127
128//===----------------------------------------------------------------------===//
129// ObjCMethSigsChecker
130//===----------------------------------------------------------------------===//
131
132namespace {
133class ObjCMethSigsChecker : public Checker<
134                                      check::ASTDecl<ObjCImplementationDecl> > {
135public:
136  void checkASTDecl(const ObjCImplementationDecl *D, AnalysisManager& mgr,
137                    BugReporter &BR) const {
138    CheckObjCInstMethSignature(D, BR);
139  }
140};
141}
142
143void ento::registerObjCMethSigsChecker(CheckerManager &mgr) {
144  mgr.registerChecker<ObjCMethSigsChecker>();
145}
146