Restore pre-r335182 behavior for naming inherited constructors as
members of dependent contexts.

This permits cases where the names before and after the '::' in a
dependent inherited constructor using-declaration do not match, but
where we can nonetheless tell when parsing the template that a
constructor is being named. Under (open) core language DR 2070, such
cases will probably be ill-formed, but r335182 does not quite give
that result and didn't intend to change this, so restore the old
behavior for now.

llvm-svn: 335381
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index d977ea3..59066ee 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -82,11 +82,20 @@
 
 ParsedType Sema::getConstructorName(IdentifierInfo &II,
                                     SourceLocation NameLoc,
-                                    Scope *S, CXXScopeSpec &SS) {
+                                    Scope *S, CXXScopeSpec &SS,
+                                    bool EnteringContext) {
   CXXRecordDecl *CurClass = getCurrentClass(S, &SS);
   assert(CurClass && &II == CurClass->getIdentifier() &&
          "not a constructor name");
 
+  // When naming a constructor as a member of a dependent context (eg, in a
+  // friend declaration or an inherited constructor declaration), form an
+  // unresolved "typename" type.
+  if (CurClass->isDependentContext() && !EnteringContext) {
+    QualType T = Context.getDependentNameType(ETK_None, SS.getScopeRep(), &II);
+    return ParsedType::make(T);
+  }
+
   if (SS.isNotEmpty() && RequireCompleteDeclContext(SS, CurClass))
     return ParsedType();