Introduce a new OpaquePtr<N> struct type, which is a simple POD wrapper for a
pointer.  Its purpose in life is to be a glorified void*, but which does not
implicitly convert to void* or other OpaquePtr's with a different UID.

Introduce Action::DeclPtrTy which is a typedef for OpaquePtr<0>.  Change the 
entire parser/sema interface to use DeclPtrTy instead of DeclTy*.  This
makes the C++ compiler enforce that these aren't convertible to other opaque
types.

We should also convert ExprTy, StmtTy, TypeTy, AttrTy, BaseTy, etc,
but I don't plan to do that in the short term.

The one outstanding known problem with this patch is that we lose the 
bitmangling optimization where ActionResult<DeclPtrTy> doesn't know how to
bitmangle the success bit into the low bit of DeclPtrTy.  I will rectify
this with a subsequent patch.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@67952 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index b3ec24f..dc57ac1 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -117,7 +117,7 @@
         // an operator and not as part of a simple-template-id.
       }
 
-      DeclTy *Template = 0;
+      DeclPtrTy Template;
       TemplateNameKind TNK = TNK_Non_template;
       // FIXME: If the nested-name-specifier thus far is dependent,
       // set TNK = TNK_Dependent_template_name and skip the