Check in LLVM r95781.
diff --git a/lib/Checker/CheckObjCInstMethSignature.cpp b/lib/Checker/CheckObjCInstMethSignature.cpp
new file mode 100644
index 0000000..8c43a45
--- /dev/null
+++ b/lib/Checker/CheckObjCInstMethSignature.cpp
@@ -0,0 +1,119 @@
+//=- CheckObjCInstMethodRetTy.cpp - Check ObjC method signatures -*- C++ -*-==//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines a CheckObjCInstMethSignature, a flow-insenstive check
+// that determines if an Objective-C class interface incorrectly redefines
+// the method signature in a subclass.
+//
+//===----------------------------------------------------------------------===//
+
+#include "clang/Checker/Checkers/LocalCheckers.h"
+#include "clang/Checker/BugReporter/PathDiagnostic.h"
+#include "clang/Checker/BugReporter/BugReporter.h"
+#include "clang/AST/DeclObjC.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/ASTContext.h"
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+
+static bool AreTypesCompatible(QualType Derived, QualType Ancestor,
+ ASTContext& C) {
+
+ // Right now don't compare the compatibility of pointers. That involves
+ // looking at subtyping relationships. FIXME: Future patch.
+ if (Derived->isAnyPointerType() && Ancestor->isAnyPointerType())
+ return true;
+
+ return C.typesAreCompatible(Derived, Ancestor);
+}
+
+static void CompareReturnTypes(const ObjCMethodDecl *MethDerived,
+ const ObjCMethodDecl *MethAncestor,
+ BugReporter &BR, ASTContext &Ctx,
+ const ObjCImplementationDecl *ID) {
+
+ QualType ResDerived = MethDerived->getResultType();
+ QualType ResAncestor = MethAncestor->getResultType();
+
+ if (!AreTypesCompatible(ResDerived, ResAncestor, Ctx)) {
+ std::string sbuf;
+ llvm::raw_string_ostream os(sbuf);
+
+ os << "The Objective-C class '"
+ << MethDerived->getClassInterface()->getNameAsString()
+ << "', which is derived from class '"
+ << MethAncestor->getClassInterface()->getNameAsString()
+ << "', defines the instance method '"
+ << MethDerived->getSelector().getAsString()
+ << "' whose return type is '"
+ << ResDerived.getAsString()
+ << "'. A method with the same name (same selector) is also defined in "
+ "class '"
+ << MethAncestor->getClassInterface()->getNameAsString()
+ << "' and has a return type of '"
+ << ResAncestor.getAsString()
+ << "'. These two types are incompatible, and may result in undefined "
+ "behavior for clients of these classes.";
+
+ BR.EmitBasicReport("Incompatible instance method return type",
+ os.str(), MethDerived->getLocStart());
+ }
+}
+
+void clang::CheckObjCInstMethSignature(const ObjCImplementationDecl* ID,
+ BugReporter& BR) {
+
+ const ObjCInterfaceDecl* D = ID->getClassInterface();
+ const ObjCInterfaceDecl* C = D->getSuperClass();
+
+ if (!C)
+ return;
+
+ ASTContext& Ctx = BR.getContext();
+
+ // Build a DenseMap of the methods for quick querying.
+ typedef llvm::DenseMap<Selector,ObjCMethodDecl*> MapTy;
+ MapTy IMeths;
+ unsigned NumMethods = 0;
+
+ for (ObjCImplementationDecl::instmeth_iterator I=ID->instmeth_begin(),
+ E=ID->instmeth_end(); I!=E; ++I) {
+
+ ObjCMethodDecl* M = *I;
+ IMeths[M->getSelector()] = M;
+ ++NumMethods;
+ }
+
+ // Now recurse the class hierarchy chain looking for methods with the
+ // same signatures.
+ while (C && NumMethods) {
+ for (ObjCInterfaceDecl::instmeth_iterator I=C->instmeth_begin(),
+ E=C->instmeth_end(); I!=E; ++I) {
+
+ ObjCMethodDecl* M = *I;
+ Selector S = M->getSelector();
+
+ MapTy::iterator MI = IMeths.find(S);
+
+ if (MI == IMeths.end() || MI->second == 0)
+ continue;
+
+ --NumMethods;
+ ObjCMethodDecl* MethDerived = MI->second;
+ MI->second = 0;
+
+ CompareReturnTypes(MethDerived, M, BR, Ctx, ID);
+ }
+
+ C = C->getSuperClass();
+ }
+}