lib/GR/Checkers/CheckObjCInstMethSignature.cpp

   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 "clang/GR/Checkers/LocalCheckers.h"
  17 #include "clang/GR/BugReporter/PathDiagnostic.h"
  18 #include "clang/GR/BugReporter/BugReporter.h"
  19 #include "clang/AST/DeclObjC.h"
  20 #include "clang/AST/Type.h"
  21 #include "clang/AST/ASTContext.h"
  22
  23 #include "llvm/ADT/DenseMap.h"
  24 #include "llvm/Support/raw_ostream.h"
  25
  26 using namespace clang;
  27 using namespace GR;
  28
  29 static 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
  40 static 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     BR.EmitBasicReport("Incompatible instance method return type",
  69                        os.str(), MethDerived->getLocStart());
  70   }
  71 }
  72
  73 void GR::CheckObjCInstMethSignature(const ObjCImplementationDecl* ID,
  74                                     BugReporter& BR) {
  75
  76   const ObjCInterfaceDecl* D = ID->getClassInterface();
  77   const ObjCInterfaceDecl* C = D->getSuperClass();
  78
  79   if (!C)
  80     return;
  81
  82   ASTContext& Ctx = BR.getContext();
  83
  84   // Build a DenseMap of the methods for quick querying.
  85   typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
  86   MapTy IMeths;
  87   unsigned NumMethods = 0;
  88
  89   for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
  90        E=ID->instmeth_end(); I!=E; ++I) {
  91
  92     ObjCMethodDecl* M = *I;
  93     IMeths[M->getSelector()] = M;
  94     ++NumMethods;
  95   }
  96
  97   // Now recurse the class hierarchy chain looking for methods with the
  98   // same signatures.
  99   while (C && NumMethods) {
 100     for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
 101          E=C->instmeth_end(); I!=E; ++I) {
 102
 103       ObjCMethodDecl* M = *I;
 104       Selector S = M->getSelector();
 105
 106       MapTy::iterator MI = IMeths.find(S);
 107
 108       if (MI == IMeths.end() || MI->second == 0)
 109         continue;
 110
 111       --NumMethods;
 112       ObjCMethodDecl* MethDerived = MI->second;
 113       MI->second = 0;
 114
 115       CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
 116     }
 117
 118     C = C->getSuperClass();
 119   }
 120 }