1 files changed, 119 insertions, 0 deletions
diff --git a/lib/Checker/CheckObjCInstMethSignature.cpp b/lib/Checker/CheckObjCInstMethSignature.cpp
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index 000000000000..8c43a45d92c0
--- /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();
+  }
+}