From f2a04bf1689cd88dd04012c311ba86e9d8b2b1b2 Mon Sep 17 00:00:00 2001
From: Anders Carlsson <andersca@mac.com>
Date: Fri, 22 Jan 2010 17:37:20 +0000
Subject: [PATCH] No need to canonicalize the type and use dyn_cast. Also,
 correctly diagnose trying to override a function returning an lvalue
 reference with a function overriding an rvalue reference.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@94183 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Sema/SemaDeclCXX.cpp          | 22 ++++++++---------
 test/SemaCXX/virtual-override.cpp | 41 ++++++++++++++++++++++++++++++-
 2 files changed, 50 insertions(+), 13 deletions(-)

diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 289c0e024d..9ec95f3d17 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -5611,26 +5611,24 @@ bool Sema::CheckOverridingFunctionReturnType(const CXXMethodDecl *New,
   QualType NewTy = New->getType()->getAs<FunctionType>()->getResultType();
   QualType OldTy = Old->getType()->getAs<FunctionType>()->getResultType();
 
-  QualType CNewTy = Context.getCanonicalType(NewTy);
-  QualType COldTy = Context.getCanonicalType(OldTy);
-
-  if (CNewTy == COldTy &&
-      CNewTy.getLocalCVRQualifiers() == COldTy.getLocalCVRQualifiers())
+  if (Context.hasSameType(NewTy, OldTy))
     return false;
 
   // Check if the return types are covariant
   QualType NewClassTy, OldClassTy;
 
   /// Both types must be pointers or references to classes.
-  if (PointerType *NewPT = dyn_cast<PointerType>(CNewTy)) {
-    if (PointerType *OldPT = dyn_cast<PointerType>(COldTy)) {
+  if (const PointerType *NewPT = NewTy->getAs<PointerType>()) {
+    if (const PointerType *OldPT = OldTy->getAs<PointerType>()) {
       NewClassTy = NewPT->getPointeeType();
       OldClassTy = OldPT->getPointeeType();
     }
-  } else if (ReferenceType *NewRT = dyn_cast<ReferenceType>(CNewTy)) {
-    if (ReferenceType *OldRT = dyn_cast<ReferenceType>(COldTy)) {
-      NewClassTy = NewRT->getPointeeType();
-      OldClassTy = OldRT->getPointeeType();
+  } else if (const ReferenceType *NewRT = NewTy->getAs<ReferenceType>()) {
+    if (const ReferenceType *OldRT = OldTy->getAs<ReferenceType>()) {
+      if (NewRT->getTypeClass() == OldRT->getTypeClass()) {
+        NewClassTy = NewRT->getPointeeType();
+        OldClassTy = OldRT->getPointeeType();
+      }
     }
   }
 
@@ -5678,7 +5676,7 @@ bool Sema::CheckOverridingFunctionReturnType(const CXXMethodDecl *New,
   }
 
   // The qualifiers of the return types must be the same.
-  if (CNewTy.getLocalCVRQualifiers() != COldTy.getLocalCVRQualifiers()) {
+  if (NewTy.getLocalCVRQualifiers() != OldTy.getLocalCVRQualifiers()) {
     Diag(New->getLocation(),
          diag::err_covariant_return_type_different_qualifications)
     << New->getDeclName() << NewTy << OldTy;
diff --git a/test/SemaCXX/virtual-override.cpp b/test/SemaCXX/virtual-override.cpp
index a3d3f20f14..5e1e9b0899 100644
--- a/test/SemaCXX/virtual-override.cpp
+++ b/test/SemaCXX/virtual-override.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -faccess-control -verify %s
+// RUN: %clang_cc1 -fsyntax-only -faccess-control -verify %s -std=c++0x
 namespace T1 {
 
 class A {
@@ -214,3 +214,42 @@ namespace PR6110 {
   template <typename T1, typename T> class Y1 : public Y<T> { virtual T1 f(); };
   Y1<Derived*, Base*> y;
 }
+
+namespace T10 {
+  struct A { };
+  struct B : A { };
+
+  struct C { 
+    virtual A&& f();
+  };
+
+  struct D : C {
+    virtual B&& f();
+  };
+};
+
+namespace T11 {
+  struct A { };
+  struct B : A { };
+
+  struct C { 
+    virtual A& f(); // expected-note {{overridden virtual function is here}}
+  };
+
+  struct D : C {
+    virtual B&& f(); // expected-error {{virtual function 'f' has a different return type ('struct T11::B &&') than the function it overrides (which has return type 'struct T11::A &')}}
+  };
+};
+
+namespace T12 {
+  struct A { };
+  struct B : A { };
+
+  struct C { 
+    virtual A&& f(); // expected-note {{overridden virtual function is here}}
+  };
+
+  struct D : C {
+    virtual B& f(); // expected-error {{virtual function 'f' has a different return type ('struct T12::B &') than the function it overrides (which has return type 'struct T12::A &&')}}
+  };
+};
-- 
2.40.0