[-cxx-abi microsoft] Mangle local TagDecls appropriately

Summary:
When selecting a mangling for an anonymous tag type:
- We should first try it's typedef'd name.
- If that doesn't work, we should mangle in the name of the declarator
  that specified it as a declaration specifier.
- If that doesn't work, fall back to a static mangling of
  <unnamed-type>.

This should make our anonymous type mangling compatible.

This partially fixes PR16994; we would need to have an implementation of
scope numbering to get it right (a separate issue).

Reviewers: rnk, rsmith, rjmccall, cdavis5x

CC: cfe-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1540

llvm-svn: 190892

1 files changed, 13 insertions, 0 deletions

diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index cc9cb6317a1..8cd37258b6a 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -3356,6 +3356,19 @@ void Sema::BuildVariableInstantiation(
     NewVar->setReferenced(OldVar->isReferenced());
   }
 
+  // See if the old variable had a type-specifier that defined an anonymous tag.
+  // If it did, mark the new variable as being the declarator for the new
+  // anonymous tag.
+  if (const TagType *OldTagType = OldVar->getType()->getAs<TagType>()) {
+    TagDecl *OldTag = OldTagType->getDecl();
+    if (OldTag->getDeclaratorForAnonDecl() == OldVar) {
+      TagDecl *NewTag = NewVar->getType()->castAs<TagType>()->getDecl();
+      assert(!NewTag->hasNameForLinkage() &&
+             !NewTag->hasDeclaratorForAnonDecl());
+      NewTag->setDeclaratorForAnonDecl(NewVar);
+    }
+  }
+
   InstantiateAttrs(TemplateArgs, OldVar, NewVar, LateAttrs, StartingScope);
 
   if (NewVar->hasAttrs())