[MSVC2012] Allow 'mutable' references

Some standard header files from MSVC2012 use 'mutable' on references, though it is directly prohibited by the standard.
Fix for http://llvm.org/PR22444
Differential Revision: http://reviews.llvm.org/D7370

llvm-svn: 228113

1 files changed, 6 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index eb21dff766f..a5ce9a0277d 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -12348,7 +12348,8 @@ FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
   if (!InvalidDecl && Mutable) {
     unsigned DiagID = 0;
     if (T->isReferenceType())
-      DiagID = diag::err_mutable_reference;
+      DiagID = getLangOpts().MSVCCompat ? diag::ext_mutable_reference
+                                        : diag::err_mutable_reference;
     else if (T.isConstQualified())
       DiagID = diag::err_mutable_const;
 
@@ -12357,8 +12358,10 @@ FieldDecl *Sema::CheckFieldDecl(DeclarationName Name, QualType T,
       if (D && D->getDeclSpec().getStorageClassSpecLoc().isValid())
         ErrLoc = D->getDeclSpec().getStorageClassSpecLoc();
       Diag(ErrLoc, DiagID);
-      Mutable = false;
-      InvalidDecl = true;
+      if (DiagID != diag::ext_mutable_reference) {
+        Mutable = false;
+        InvalidDecl = true;
+      }
     }
   }