Implement Objective-C Related Result Type semantics.

Related result types apply Cocoa conventions to the type of message
sends and property accesses to Objective-C methods that are known to
always return objects whose type is the same as the type of the
receiving class (or a subclass thereof), such as +alloc and
-init. This tightens up static type safety for Objective-C, so that we
now diagnose mistakes like this:

t.m:4:10: warning: incompatible pointer types initializing 'NSSet *'
with an
      expression of type 'NSArray *' [-Wincompatible-pointer-types]
  NSSet *array = [[NSArray alloc] init];
         ^       ~~~~~~~~~~~~~~~~~~~~~~
/System/Library/Frameworks/Foundation.framework/Headers/NSObject.h:72:1:
note: 
      instance method 'init' is assumed to return an instance of its
      receiver
      type ('NSArray *')
- (id)init;
^

It also means that we get decent type inference when writing code in
Objective-C++0x:

  auto array = [[NSMutableArray alloc] initWithObjects:@"one",  @"two",nil];
  //    ^ now infers NSMutableArray* rather than id




git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@132868 91177308-0d34-0410-b5e6-96231b3b80d8

7 files changed, 429 insertions, 31 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 9967fd3ebf..c2fee32aea 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1936,7 +1936,9 @@ void Sema::mergeObjCMethodDecls(ObjCMethodDecl *newMethod,
   for (ObjCMethodDecl::param_iterator oi = oldMethod->param_begin(),
          ni = newMethod->param_begin(), ne = newMethod->param_end();
        ni != ne; ++ni, ++oi)
-    mergeParamDeclAttributes(*ni, *oi, Context);    
+    mergeParamDeclAttributes(*ni, *oi, Context);
+  
+  CheckObjCMethodOverride(newMethod, oldMethod, true);
 }
 
 /// MergeVarDeclTypes - We parsed a variable 'New' which has the same name and
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 4e41aa93e5..de9097e98b 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -24,6 +24,141 @@
 
 using namespace clang;
 
+bool Sema::CheckObjCMethodOverride(ObjCMethodDecl *NewMethod, 
+                                   const ObjCMethodDecl *Overridden,
+                                   bool IsImplementation) {
+  if (Overridden->hasRelatedResultType() && 
+      !NewMethod->hasRelatedResultType()) {
+    // This can only happen when the method follows a naming convention that
+    // implies a related result type, and the original (overridden) method has
+    // a suitable return type, but the new (overriding) method does not have
+    // a suitable return type.
+    QualType ResultType = NewMethod->getResultType();
+    SourceRange ResultTypeRange;
+    if (const TypeSourceInfo *ResultTypeInfo 
+        = NewMethod->getResultTypeSourceInfo())
+      ResultTypeRange = ResultTypeInfo->getTypeLoc().getSourceRange();
+    
+    // Figure out which class this method is part of, if any.
+    ObjCInterfaceDecl *CurrentClass 
+      = dyn_cast<ObjCInterfaceDecl>(NewMethod->getDeclContext());
+    if (!CurrentClass) {
+      DeclContext *DC = NewMethod->getDeclContext();
+      if (ObjCCategoryDecl *Cat = dyn_cast<ObjCCategoryDecl>(DC))
+        CurrentClass = Cat->getClassInterface();
+      else if (ObjCImplDecl *Impl = dyn_cast<ObjCImplDecl>(DC))
+        CurrentClass = Impl->getClassInterface();
+      else if (ObjCCategoryImplDecl *CatImpl
+               = dyn_cast<ObjCCategoryImplDecl>(DC))
+        CurrentClass = CatImpl->getClassInterface();
+    }
+    
+    if (CurrentClass) {
+      Diag(NewMethod->getLocation(), 
+           diag::warn_related_result_type_compatibility_class)
+        << Context.getObjCInterfaceType(CurrentClass)
+        << ResultType
+        << ResultTypeRange;
+    } else {
+      Diag(NewMethod->getLocation(), 
+           diag::warn_related_result_type_compatibility_protocol)
+        << ResultType
+        << ResultTypeRange;
+    }
+    
+    Diag(Overridden->getLocation(), diag::note_related_result_type_overridden)
+      << Overridden->getMethodFamily();
+  }
+  
+  return false;
+}
+
+
+static bool CheckObjCMethodOverrides(Sema &S, ObjCMethodDecl *NewMethod,
+                                     DeclContext *DC, 
+                                     bool SkipCurrent = true) {
+  if (!DC)
+    return false;
+  
+  if (!SkipCurrent) {
+    // Look for this method. If we find it, we're done.
+    Selector Sel = NewMethod->getSelector();
+    bool IsInstance = NewMethod->isInstanceMethod();
+    DeclContext::lookup_const_iterator Meth, MethEnd;
+    for (llvm::tie(Meth, MethEnd) = DC->lookup(Sel); Meth != MethEnd; ++Meth) {
+      ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(*Meth);
+      if (MD && MD->isInstanceMethod() == IsInstance)
+        return S.CheckObjCMethodOverride(NewMethod, MD, false);
+    }
+  }
+  
+  if (ObjCInterfaceDecl *Class = llvm::dyn_cast<ObjCInterfaceDecl>(DC)) {
+    // Look through categories.
+    for (ObjCCategoryDecl *Category = Class->getCategoryList();
+         Category; Category = Category->getNextClassCategory()) {
+      if (CheckObjCMethodOverrides(S, NewMethod, Category, false))
+        return true;
+    }
+    
+    // Look through protocols.
+    for (ObjCList<ObjCProtocolDecl>::iterator I = Class->protocol_begin(),
+         IEnd = Class->protocol_end();
+         I != IEnd; ++I)
+      if (CheckObjCMethodOverrides(S, NewMethod, *I, false))
+        return true;
+    
+    // Look in our superclass.
+    return CheckObjCMethodOverrides(S, NewMethod, Class->getSuperClass(), 
+                                    false);
+  }
+  
+  if (ObjCCategoryDecl *Category = dyn_cast<ObjCCategoryDecl>(DC)) {
+    // Look through protocols.
+    for (ObjCList<ObjCProtocolDecl>::iterator I = Category->protocol_begin(),
+         IEnd = Category->protocol_end();
+         I != IEnd; ++I)
+      if (CheckObjCMethodOverrides(S, NewMethod, *I, false))
+        return true;
+    
+    return false;
+  }
+  
+  if (ObjCProtocolDecl *Protocol = dyn_cast<ObjCProtocolDecl>(DC)) {
+    // Look through protocols.
+    for (ObjCList<ObjCProtocolDecl>::iterator I = Protocol->protocol_begin(),
+         IEnd = Protocol->protocol_end();
+         I != IEnd; ++I)
+      if (CheckObjCMethodOverrides(S, NewMethod, *I, false))
+        return true;
+    
+    return false;
+  }
+  
+  return false;
+}
+
+bool Sema::CheckObjCMethodOverrides(ObjCMethodDecl *NewMethod, 
+                                    DeclContext *DC) {
+  if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(DC))
+    return ::CheckObjCMethodOverrides(*this, NewMethod, Class);
+  
+  if (ObjCCategoryDecl *Category = dyn_cast<ObjCCategoryDecl>(DC))
+    return ::CheckObjCMethodOverrides(*this, NewMethod, Category);
+  
+  if (ObjCProtocolDecl *Protocol = dyn_cast<ObjCProtocolDecl>(DC))
+    return ::CheckObjCMethodOverrides(*this, NewMethod, Protocol);
+  
+  if (ObjCImplementationDecl *Impl = dyn_cast<ObjCImplementationDecl>(DC))
+    return ::CheckObjCMethodOverrides(*this, NewMethod, 
+                                      Impl->getClassInterface());
+  
+  if (ObjCCategoryImplDecl *CatImpl = dyn_cast<ObjCCategoryImplDecl>(DC))
+    return ::CheckObjCMethodOverrides(*this, NewMethod, 
+                                      CatImpl->getClassInterface());
+  
+  return ::CheckObjCMethodOverrides(*this, NewMethod, CurContext);
+}
+
 static void DiagnoseObjCImplementedDeprecations(Sema &S,
                                                 NamedDecl *ND,
                                                 SourceLocation ImplLoc,
@@ -1717,11 +1852,71 @@ bool containsInvalidMethodImplAttribute(const AttrVec &A) {
   return false;
 }
 
+/// \brief Check whether the declared result type of the given Objective-C
+/// method declaration is compatible with the method's class.
+///
+static bool 
+CheckRelatedResultTypeCompatibility(Sema &S, ObjCMethodDecl *Method,
+                                    ObjCInterfaceDecl *CurrentClass) {
+  QualType ResultType = Method->getResultType();
+  SourceRange ResultTypeRange;
+  if (const TypeSourceInfo *ResultTypeInfo = Method->getResultTypeSourceInfo())
+    ResultTypeRange = ResultTypeInfo->getTypeLoc().getSourceRange();
+  
+  // If an Objective-C method inherits its related result type, then its 
+  // declared result type must be compatible with its own class type. The
+  // declared result type is compatible if:
+  if (const ObjCObjectPointerType *ResultObjectType
+                                = ResultType->getAs<ObjCObjectPointerType>()) {
+    //   - it is id or qualified id, or
+    if (ResultObjectType->isObjCIdType() ||
+        ResultObjectType->isObjCQualifiedIdType())
+      return false;
+  
+    if (CurrentClass) {
+      if (ObjCInterfaceDecl *ResultClass 
+                                      = ResultObjectType->getInterfaceDecl()) {
+        //   - it is the same as the method's class type, or
+        if (CurrentClass == ResultClass)
+          return false;
+        
+        //   - it is a superclass of the method's class type
+        if (ResultClass->isSuperClassOf(CurrentClass))
+          return false;
+      }      
+    }
+  }
+  
+  return true;
+}
+
+/// \brief Determine if any method in the global method pool has an inferred 
+/// result type.
+static bool 
+anyMethodInfersRelatedResultType(Sema &S, Selector Sel, bool IsInstance) {
+  Sema::GlobalMethodPool::iterator Pos = S.MethodPool.find(Sel);
+  if (Pos == S.MethodPool.end()) {
+    if (S.ExternalSource)
+      Pos = S.ReadMethodPool(Sel);
+    else
+      return 0;
+  }
+  
+  ObjCMethodList &List = IsInstance ? Pos->second.first : Pos->second.second;
+  for (ObjCMethodList *M = &List; M; M = M->Next) {
+    if (M->Method && M->Method->hasRelatedResultType())
+      return true;
+  }  
+  
+  return false;
+}
+
 Decl *Sema::ActOnMethodDeclaration(
     Scope *S,
     SourceLocation MethodLoc, SourceLocation EndLoc,
     tok::TokenKind MethodType, Decl *ClassDecl,
     ObjCDeclSpec &ReturnQT, ParsedType ReturnType,
+    SourceLocation SelectorStartLoc,
     Selector Sel,
     // optional arguments. The number of types/arguments is obtained
     // from the Sel.getNumArgs().
@@ -1746,7 +1941,7 @@ Decl *Sema::ActOnMethodDeclaration(
       Diag(MethodLoc, diag::err_object_cannot_be_passed_returned_by_value)
         << 0 << resultDeclType;
       return 0;
-    }
+    }    
   } else // get the type for "id".
     resultDeclType = Context.getObjCIdType();
 
@@ -1756,9 +1951,10 @@ Decl *Sema::ActOnMethodDeclaration(
                            cast<DeclContext>(ClassDecl),
                            MethodType == tok::minus, isVariadic,
                            false, false,
-                           MethodDeclKind == tok::objc_optional ?
-                           ObjCMethodDecl::Optional :
-                           ObjCMethodDecl::Required);
+                           MethodDeclKind == tok::objc_optional 
+                             ? ObjCMethodDecl::Optional
+                             : ObjCMethodDecl::Required,
+                           false);
 
   llvm::SmallVector<ParmVarDecl*, 16> Params;
 
@@ -1854,6 +2050,7 @@ Decl *Sema::ActOnMethodDeclaration(
     }
     InterfaceMD = ImpDecl->getClassInterface()->getMethod(Sel,
                                                    MethodType == tok::minus);
+    
     if (ObjCMethod->hasAttrs() &&
         containsInvalidMethodImplAttribute(ObjCMethod->getAttrs()))
       Diag(EndLoc, diag::warn_attribute_method_def);
@@ -1866,6 +2063,10 @@ Decl *Sema::ActOnMethodDeclaration(
       PrevMethod = CatImpDecl->getClassMethod(Sel);
       CatImpDecl->addClassMethod(ObjCMethod);
     }
+
+    if (ObjCCategoryDecl *Cat = CatImpDecl->getCategoryDecl())
+      InterfaceMD = Cat->getMethod(Sel, MethodType == tok::minus);
+
     if (ObjCMethod->hasAttrs() &&
         containsInvalidMethodImplAttribute(ObjCMethod->getAttrs()))
       Diag(EndLoc, diag::warn_attribute_method_def);
@@ -1879,10 +2080,65 @@ Decl *Sema::ActOnMethodDeclaration(
     Diag(PrevMethod->getLocation(), diag::note_previous_declaration);
   }
 
+  // If this Objective-C method does not have a related result type, but we
+  // are allowed to infer related result types, try to do so based on the
+  // method family.
+  ObjCInterfaceDecl *CurrentClass = dyn_cast<ObjCInterfaceDecl>(ClassDecl);
+  if (!CurrentClass) {
+    if (ObjCCategoryDecl *Cat = dyn_cast<ObjCCategoryDecl>(ClassDecl))
+      CurrentClass = Cat->getClassInterface();
+    else if (ObjCImplDecl *Impl = dyn_cast<ObjCImplDecl>(ClassDecl))
+      CurrentClass = Impl->getClassInterface();
+    else if (ObjCCategoryImplDecl *CatImpl
+                                   = dyn_cast<ObjCCategoryImplDecl>(ClassDecl))
+      CurrentClass = CatImpl->getClassInterface();
+  }
+  
   // Merge information down from the interface declaration if we have one.
-  if (InterfaceMD)
+  if (InterfaceMD) {
+    // Inherit the related result type, if we can.
+    if (InterfaceMD->hasRelatedResultType() &&
+        !CheckRelatedResultTypeCompatibility(*this, ObjCMethod, CurrentClass))
+      ObjCMethod->SetRelatedResultType();
+      
     mergeObjCMethodDecls(ObjCMethod, InterfaceMD);
-
+  }
+  
+  if (!ObjCMethod->hasRelatedResultType() && 
+      getLangOptions().ObjCInferRelatedResultType) {
+    bool InferRelatedResultType = false;
+    switch (ObjCMethod->getMethodFamily()) {
+    case OMF_None:
+    case OMF_copy:
+    case OMF_dealloc:
+    case OMF_mutableCopy:
+    case OMF_release:
+    case OMF_retainCount:
+      break;
+      
+    case OMF_alloc:
+    case OMF_new:
+      InferRelatedResultType = ObjCMethod->isClassMethod();
+      break;
+        
+    case OMF_init:
+    case OMF_autorelease:
+    case OMF_retain:
+    case OMF_self:
+      InferRelatedResultType = ObjCMethod->isInstanceMethod();
+      break;
+    }
+    
+    if (InferRelatedResultType &&
+        !CheckRelatedResultTypeCompatibility(*this, ObjCMethod, CurrentClass))
+      ObjCMethod->SetRelatedResultType();
+    
+    if (!InterfaceMD && 
+        anyMethodInfersRelatedResultType(*this, ObjCMethod->getSelector(),
+                                         ObjCMethod->isInstanceMethod()))
+      CheckObjCMethodOverrides(ObjCMethod, cast<DeclContext>(ClassDecl));
+  }
+    
   return ObjCMethod;
 }
 
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index bb6a414f44..dafd56bf34 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -4328,7 +4328,11 @@ Sema::LookupMemberExpr(LookupResult &R, ExprResult &BaseExpr,
           if (DiagnoseUseOfDecl(PD, MemberLoc))
             return ExprError();
 
-          return Owned(new (Context) ObjCPropertyRefExpr(PD, PD->getType(),
+          QualType T = PD->getType();
+          if (ObjCMethodDecl *Getter = PD->getGetterMethodDecl())
+            T = getMessageSendResultType(BaseType, Getter, false, false);
+         
+          return Owned(new (Context) ObjCPropertyRefExpr(PD, T,
                                                          VK_LValue,
                                                          OK_ObjCProperty,
                                                          MemberLoc, 
@@ -4346,7 +4350,8 @@ Sema::LookupMemberExpr(LookupResult &R, ExprResult &BaseExpr,
           if (Decl *SDecl = FindGetterSetterNameDecl(OPT, /*Property id*/0, 
                                                      SetterSel, Context))
             SMD = dyn_cast<ObjCMethodDecl>(SDecl);
-          QualType PType = OMD->getSendResultType();
+          QualType PType = getMessageSendResultType(BaseType, OMD, false, 
+                                                    false);
           
           ExprValueKind VK = VK_LValue;
           if (!getLangOptions().CPlusPlus &&
@@ -4414,7 +4419,8 @@ Sema::LookupMemberExpr(LookupResult &R, ExprResult &BaseExpr,
 
         ExprValueKind VK = VK_LValue;
         if (Getter) {
-          PType = Getter->getSendResultType();
+          PType = getMessageSendResultType(QualType(OT, 0), Getter, true, 
+                                           false);
           if (!getLangOptions().CPlusPlus &&
               IsCForbiddenLValueType(Context, PType))
             VK = VK_RValue;
@@ -8345,20 +8351,31 @@ ExprResult Sema::ConvertPropertyForRValue(Expr *E) {
          E->getObjectKind() == OK_ObjCProperty);
   const ObjCPropertyRefExpr *PRE = E->getObjCProperty();
 
+  QualType T = E->getType();
+  QualType ReceiverType;
+  if (PRE->isObjectReceiver())
+    ReceiverType = PRE->getBase()->getType();
+  else if (PRE->isSuperReceiver())
+    ReceiverType = PRE->getSuperReceiverType();
+  else
+    ReceiverType = Context.getObjCInterfaceType(PRE->getClassReceiver());
+    
   ExprValueKind VK = VK_RValue;
   if (PRE->isImplicitProperty()) {
-    if (const ObjCMethodDecl *GetterMethod = 
+    if (ObjCMethodDecl *GetterMethod = 
           PRE->getImplicitPropertyGetter()) {
-      QualType Result = GetterMethod->getResultType();
-      VK = Expr::getValueKindForType(Result);
+      T = getMessageSendResultType(ReceiverType, GetterMethod, 
+                                   PRE->isClassReceiver(), 
+                                   PRE->isSuperReceiver());
+      VK = Expr::getValueKindForType(GetterMethod->getResultType());
     }
     else {
       Diag(PRE->getLocation(), diag::err_getter_not_found)
             << PRE->getBase()->getType();
     }
   }
-
-  E = ImplicitCastExpr::Create(Context, E->getType(), CK_GetObjCProperty,
+  
+  E = ImplicitCastExpr::Create(Context, T, CK_GetObjCProperty,
                                E, 0, VK);
   
   ExprResult Result = MaybeBindToTemporary(E);
@@ -9851,6 +9868,7 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
     *Complained = false;
 
   // Decode the result (notice that AST's are still created for extensions).
+  bool CheckInferredResultType = false;
   bool isInvalid = false;
   unsigned DiagKind;
   FixItHint Hint;
@@ -9867,6 +9885,8 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
   case IncompatiblePointer:
     MakeObjCStringLiteralFixItHint(*this, DstType, SrcExpr, Hint);
     DiagKind = diag::ext_typecheck_convert_incompatible_pointer;
+    CheckInferredResultType = DstType->isObjCObjectPointerType() &&
+      SrcType->isObjCObjectPointerType();
     break;
   case IncompatiblePointerSign:
     DiagKind = diag::ext_typecheck_convert_incompatible_pointer_sign;
@@ -9948,6 +9968,9 @@ bool Sema::DiagnoseAssignmentResult(AssignConvertType ConvTy,
 
   Diag(Loc, DiagKind) << FirstType << SecondType << Action
     << SrcExpr->getSourceRange() << Hint;
+  if (CheckInferredResultType)
+    EmitRelatedResultTypeNote(SrcExpr);
+  
   if (Complained)
     *Complained = true;
   return isInvalid;
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 2cd495bf14..27659f6507 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -2221,6 +2221,10 @@ Sema::PerformImplicitConversion(Expr *From, QualType ToType,
              diag::ext_typecheck_convert_incompatible_pointer)
           << From->getType() << ToType << Action
           << From->getSourceRange();
+      
+      if (From->getType()->isObjCObjectPointerType() &&
+          ToType->isObjCObjectPointerType())
+        EmitRelatedResultTypeNote(From);
     }
 
     CastKind Kind = CK_Invalid;
diff --git a/lib/Sema/SemaExprObjC.cpp b/lib/Sema/SemaExprObjC.cpp
index 3444cb5a49..cb5c1e0d0c 100644
--- a/lib/Sema/SemaExprObjC.cpp
+++ b/lib/Sema/SemaExprObjC.cpp
@@ -241,10 +241,72 @@ ObjCMethodDecl *Sema::tryCaptureObjCSelf() {
   return method;
 }
 
+QualType Sema::getMessageSendResultType(QualType ReceiverType,
+                                        ObjCMethodDecl *Method,
+                                    bool isClassMessage, bool isSuperMessage) {
+  assert(Method && "Must have a method");
+  if (!Method->hasRelatedResultType())
+    return Method->getSendResultType();
+  
+  // If a method has a related return type:
+  //   - if the method found is an instance method, but the message send
+  //     was a class message send, T is the declared return type of the method
+  //     found
+  if (Method->isInstanceMethod() && isClassMessage)
+    return Method->getSendResultType();
+  
+  //   - if the receiver is super, T is a pointer to the class of the 
+  //     enclosing method definition
+  if (isSuperMessage) {
+    if (ObjCMethodDecl *CurMethod = getCurMethodDecl())
+      if (ObjCInterfaceDecl *Class = CurMethod->getClassInterface())
+        return Context.getObjCObjectPointerType(
+                                        Context.getObjCInterfaceType(Class));
+  }
+    
+  //   - if the receiver is the name of a class U, T is a pointer to U
+  if (ReceiverType->getAs<ObjCInterfaceType>() ||
+      ReceiverType->isObjCQualifiedInterfaceType())
+    return Context.getObjCObjectPointerType(ReceiverType);
+  //   - if the receiver is of type Class or qualified Class type, 
+  //     T is the declared return type of the method.
+  if (ReceiverType->isObjCClassType() ||
+      ReceiverType->isObjCQualifiedClassType())
+    return  Method->getSendResultType();
+  
+  //   - if the receiver is id, qualified id, Class, or qualified Class, T
+  //     is the receiver type, otherwise
+  //   - T is the type of the receiver expression.
+  return ReceiverType;
+}
+
+void Sema::EmitRelatedResultTypeNote(const Expr *E) {
+  E = E->IgnoreParenImpCasts();
+  const ObjCMessageExpr *MsgSend = dyn_cast<ObjCMessageExpr>(E);
+  if (!MsgSend)
+    return;
+  
+  const ObjCMethodDecl *Method = MsgSend->getMethodDecl();
+  if (!Method)
+    return;
+  
+  if (!Method->hasRelatedResultType())
+    return;
+  
+  if (Context.hasSameUnqualifiedType(Method->getResultType()
+                                                        .getNonReferenceType(),
+                                     MsgSend->getType()))
+    return;
+  
+  Diag(Method->getLocation(), diag::note_related_result_type_inferred)
+    << Method->isInstanceMethod() << Method->getSelector()
+    << MsgSend->getType();
+}
 
-bool Sema::CheckMessageArgumentTypes(Expr **Args, unsigned NumArgs,
+bool Sema::CheckMessageArgumentTypes(QualType ReceiverType,
+                                     Expr **Args, unsigned NumArgs,
                                      Selector Sel, ObjCMethodDecl *Method,
-                                     bool isClassMessage,
+                                     bool isClassMessage, bool isSuperMessage,
                                      SourceLocation lbrac, SourceLocation rbrac,
                                      QualType &ReturnType, ExprValueKind &VK) {
   if (!Method) {
@@ -268,7 +330,8 @@ bool Sema::CheckMessageArgumentTypes(Expr **Args, unsigned NumArgs,
     return false;
   }
 
-  ReturnType = Method->getSendResultType();
+  ReturnType = getMessageSendResultType(ReceiverType, Method, isClassMessage, 
+                                        isSuperMessage);
   VK = Expr::getValueKindForType(Method->getResultType());
 
   unsigned NumNamedArgs = Sel.getNumArgs();
@@ -456,9 +519,12 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
     ResTy = ResTy.getNonLValueExprType(Context);
     Selector Sel = PP.getSelectorTable().getNullarySelector(Member);
     ObjCMethodDecl *Getter = IFace->lookupInstanceMethod(Sel);
-    if (DiagnosePropertyAccessorMismatch(PD, Getter, MemberLoc))
-      ResTy = Getter->getResultType();
-
+    if (Getter &&
+        (Getter->hasRelatedResultType()
+         || DiagnosePropertyAccessorMismatch(PD, Getter, MemberLoc)))
+        ResTy = getMessageSendResultType(QualType(OPT, 0), Getter, false, 
+                                         Super);
+             
     if (Super)
       return Owned(new (Context) ObjCPropertyRefExpr(PD, ResTy,
                                                      VK_LValue, OK_ObjCProperty,
@@ -476,14 +542,18 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
       // Check whether we can reference this property.
       if (DiagnoseUseOfDecl(PD, MemberLoc))
         return ExprError();
+      
+      QualType T = PD->getType();
+      if (ObjCMethodDecl *Getter = PD->getGetterMethodDecl())
+        T = getMessageSendResultType(QualType(OPT, 0), Getter, false, Super);
       if (Super)
-        return Owned(new (Context) ObjCPropertyRefExpr(PD, PD->getType(),
+        return Owned(new (Context) ObjCPropertyRefExpr(PD, T,
                                                        VK_LValue,
                                                        OK_ObjCProperty,
                                                        MemberLoc, 
                                                        SuperLoc, SuperType));
       else
-        return Owned(new (Context) ObjCPropertyRefExpr(PD, PD->getType(),
+        return Owned(new (Context) ObjCPropertyRefExpr(PD, T,
                                                        VK_LValue,
                                                        OK_ObjCProperty,
                                                        MemberLoc,
@@ -540,7 +610,7 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
   if (Getter || Setter) {
     QualType PType;
     if (Getter)
-      PType = Getter->getSendResultType();
+      PType = getMessageSendResultType(QualType(OPT, 0), Getter, false, Super);
     else {
       ParmVarDecl *ArgDecl = *Setter->param_begin();
       PType = ArgDecl->getType();
@@ -614,10 +684,14 @@ ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
   IdentifierInfo *receiverNamePtr = &receiverName;
   ObjCInterfaceDecl *IFace = getObjCInterfaceDecl(receiverNamePtr,
                                                   receiverNameLoc);
+
+  bool IsSuper = false;
   if (IFace == 0) {
     // If the "receiver" is 'super' in a method, handle it as an expression-like
     // property reference.
     if (receiverNamePtr->isStr("super")) {
+      IsSuper = true;
+
       if (ObjCMethodDecl *CurMethod = tryCaptureObjCSelf()) {
         if (CurMethod->isInstanceMethod()) {
           QualType T = 
@@ -686,7 +760,9 @@ ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
 
     ExprValueKind VK = VK_LValue;
     if (Getter) {
-      PType = Getter->getSendResultType();
+      PType = getMessageSendResultType(Context.getObjCInterfaceType(IFace),
+                                       Getter, true, 
+                                       receiverNamePtr->isStr("super"));
       if (!getLangOptions().CPlusPlus &&
           !PType.hasQualifiers() && PType->isVoidType())
         VK = VK_RValue;
@@ -699,6 +775,13 @@ ActOnClassPropertyRefExpr(IdentifierInfo &receiverName,
 
     ExprObjectKind OK = (VK == VK_RValue ? OK_Ordinary : OK_ObjCProperty);
 
+    if (IsSuper)
+    return Owned(new (Context) ObjCPropertyRefExpr(Getter, Setter,
+                                                   PType, VK, OK,
+                                                   propertyNameLoc,
+                                                   receiverNameLoc, 
+                                          Context.getObjCInterfaceType(IFace)));
+
     return Owned(new (Context) ObjCPropertyRefExpr(Getter, Setter,
                                                    PType, VK, OK,
                                                    propertyNameLoc,
@@ -955,8 +1038,9 @@ ExprResult Sema::BuildClassMessage(TypeSourceInfo *ReceiverTypeInfo,
 
   unsigned NumArgs = ArgsIn.size();
   Expr **Args = reinterpret_cast<Expr **>(ArgsIn.release());
-  if (CheckMessageArgumentTypes(Args, NumArgs, Sel, Method, true,
-                                LBracLoc, RBracLoc, ReturnType, VK))
+  if (CheckMessageArgumentTypes(ReceiverType, Args, NumArgs, Sel, Method, true,
+                                SuperLoc.isValid(), LBracLoc, RBracLoc, 
+                                ReturnType, VK))
     return ExprError();
 
   if (Method && !Method->getResultType()->isVoidType() &&
@@ -1238,7 +1322,8 @@ ExprResult Sema::BuildInstanceMessage(Expr *Receiver,
   ExprValueKind VK = VK_RValue;
   bool ClassMessage = (ReceiverType->isObjCClassType() ||
                        ReceiverType->isObjCQualifiedClassType());
-  if (CheckMessageArgumentTypes(Args, NumArgs, Sel, Method, ClassMessage,
+  if (CheckMessageArgumentTypes(ReceiverType, Args, NumArgs, Sel, Method, 
+                                ClassMessage, SuperLoc.isValid(), 
                                 LBracLoc, RBracLoc, ReturnType, VK))
     return ExprError();
   
diff --git a/lib/Sema/SemaInit.cpp b/lib/Sema/SemaInit.cpp
index 11061d53f1..a33f5d0b2f 100644
--- a/lib/Sema/SemaInit.cpp
+++ b/lib/Sema/SemaInit.cpp
@@ -4322,6 +4322,9 @@ bool InitializationSequence::Diagnose(Sema &S,
       << Args[0]->isLValue()
       << Args[0]->getType()
       << Args[0]->getSourceRange();
+    if (DestType.getNonReferenceType()->isObjCObjectPointerType() &&
+        Args[0]->getType()->isObjCObjectPointerType())
+      S.EmitRelatedResultTypeNote(Args[0]);
     break;
 
   case FK_ConversionFailed: {
@@ -4332,6 +4335,9 @@ bool InitializationSequence::Diagnose(Sema &S,
       << Args[0]->isLValue()
       << FromType
       << Args[0]->getSourceRange();
+    if (DestType.getNonReferenceType()->isObjCObjectPointerType() &&
+        Args[0]->getType()->isObjCObjectPointerType())
+      S.EmitRelatedResultTypeNote(Args[0]);
     break;
   }
 
diff --git a/lib/Sema/SemaStmt.cpp b/lib/Sema/SemaStmt.cpp
index d4fc980e22..d7c0a543ee 100644
--- a/lib/Sema/SemaStmt.cpp
+++ b/lib/Sema/SemaStmt.cpp
@@ -1682,15 +1682,26 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
     return ActOnBlockReturnStmt(ReturnLoc, RetValExp);
 
   QualType FnRetType;
+  QualType DeclaredRetType;
   if (const FunctionDecl *FD = getCurFunctionDecl()) {
     FnRetType = FD->getResultType();
+    DeclaredRetType = FnRetType;
     if (FD->hasAttr<NoReturnAttr>() ||
         FD->getType()->getAs<FunctionType>()->getNoReturnAttr())
       Diag(ReturnLoc, diag::warn_noreturn_function_has_return_expr)
         << getCurFunctionOrMethodDecl()->getDeclName();
-  } else if (ObjCMethodDecl *MD = getCurMethodDecl())
-    FnRetType = MD->getResultType();
-  else // If we don't have a function/method context, bail.
+  } else if (ObjCMethodDecl *MD = getCurMethodDecl()) {
+    DeclaredRetType = MD->getResultType();
+    if (MD->hasRelatedResultType() && MD->getClassInterface()) {
+      // In the implementation of a method with a related return type, the
+      // type used to type-check the validity of return statements within the 
+      // method body is a pointer to the type of the class being implemented.
+      FnRetType = Context.getObjCInterfaceType(MD->getClassInterface());
+      FnRetType = Context.getObjCObjectPointerType(FnRetType);
+    } else {
+      FnRetType = DeclaredRetType;
+    }
+  } else // If we don't have a function/method context, bail.
     return StmtError();
 
   ReturnStmt *Result = 0;
@@ -1764,6 +1775,17 @@ Sema::ActOnReturnStmt(SourceLocation ReturnLoc, Expr *RetValExp) {
     }
 
     if (RetValExp) {
+      // If we type-checked an Objective-C method's return type based
+      // on a related return type, we may need to adjust the return
+      // type again. Do so now.
+      if (DeclaredRetType != FnRetType) {
+        ExprResult result = PerformImplicitConversion(RetValExp,
+                                                      DeclaredRetType,
+                                                      AA_Returning);
+        if (result.isInvalid()) return StmtError();
+        RetValExp = result.take();
+      }
+
       CheckImplicitConversions(RetValExp, ReturnLoc);
       RetValExp = MaybeCreateExprWithCleanups(RetValExp);
     }