[Sema] Transform a templated name before looking it up in
FindInstantiatedDecl or passing it to RebuildMemberExpr.

This fixes PR30361.

rdar://problem/17341274

Differential Revision: https://reviews.llvm.org/D24969

llvm-svn: 293678
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 46de4a1..1c69208 100644
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4990,8 +4990,12 @@
     NamedDecl *Result = nullptr;
     // FIXME: If the name is a dependent name, this lookup won't necessarily
     // find it. Does that ever matter?
-    if (D->getDeclName()) {
-      DeclContext::lookup_result Found = ParentDC->lookup(D->getDeclName());
+    if (auto Name = D->getDeclName()) {
+      DeclarationNameInfo NameInfo(Name, D->getLocation());
+      Name = SubstDeclarationNameInfo(NameInfo, TemplateArgs).getName();
+      if (!Name)
+        return nullptr;
+      DeclContext::lookup_result Found = ParentDC->lookup(Name);
       Result = findInstantiationOf(Context, D, Found.begin(), Found.end());
     } else {
       // Since we don't have a name for the entity we're looking for,