Under -fms-extensions, only inject a friend tag name when we didn't see a tag with that name in an enclosing scope.

r177473 made us correctly consider only those declarations in the
enclosing namespace scope when looking for a friend declaration. Under
ms-extensions mode, where we do some level of friend injection, this
meant that we were introducing a new tag type into a different scope
than what Microsoft actually does. Address this by only doing the
friend injection when we didn't see any tag with that name in any
outer scope. Fixes <rdar://problem/14250378>.

llvm-svn: 185100

1 files changed, 7 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 08e8cb798ac..a87cf61ccfe 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9614,7 +9614,7 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
     Redecl = NotForRedeclaration;
 
   LookupResult Previous(*this, Name, NameLoc, LookupTagName, Redecl);
-
+  bool FriendSawTagOutsideEnclosingNamespace = false;
   if (Name && SS.isNotEmpty()) {
     // We have a nested-name tag ('struct foo::bar').
 
@@ -9707,8 +9707,11 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
       while (F.hasNext()) {
         NamedDecl *ND = F.next();
         DeclContext *DC = ND->getDeclContext()->getRedeclContext();
-        if (DC->isFileContext() && !EnclosingNS->Encloses(ND->getDeclContext()))
+        if (DC->isFileContext() &&
+            !EnclosingNS->Encloses(ND->getDeclContext())) {
           F.erase();
+          FriendSawTagOutsideEnclosingNamespace = true;
+        }
       }
       F.done();
     }
@@ -10208,7 +10211,8 @@ CreateNewDecl:
   // the tag name visible.
   if (TUK == TUK_Friend)
     New->setObjectOfFriendDecl(/* PreviouslyDeclared = */ !Previous.empty() ||
-                               getLangOpts().MicrosoftExt);
+                               (!FriendSawTagOutsideEnclosingNamespace &&
+                                getLangOpts().MicrosoftExt));
 
   // Set the access specifier.
   if (!Invalid && SearchDC->isRecord())