[Sema] Don't work around a malformed AST

We created a malformed TemplateSpecializationType: it was dependent but
had a RecordType as it's canonical type.  This would lead getAs to
crash.  r249090 worked around this but we should fix this for real by
providing a more appropriate template specialization type as the
canonical type.

This fixes PR24246.

llvm-svn: 253495

1 files changed, 11 insertions, 1 deletions

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 8821088baac..c4c28148834 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -6408,7 +6408,17 @@ Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
     if (!PrevDecl)
       ClassTemplate->AddSpecialization(Specialization, InsertPos);
 
-    CanonType = Context.getTypeDeclType(Specialization);
+    if (CurContext->isDependentContext()) {
+      // -fms-extensions permits specialization of nested classes without
+      // fully specializing the outer class(es).
+      assert(getLangOpts().MicrosoftExt &&
+             "Only possible with -fms-extensions!");
+      TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
+      CanonType = Context.getTemplateSpecializationType(
+          CanonTemplate, Converted.data(), Converted.size());
+    } else {
+      CanonType = Context.getTypeDeclType(Specialization);
+    }
   }
 
   // C++ [temp.expl.spec]p6: