[modules] Properly look up the owning module for an instantiation of a merged template.

When looking for the template instantiation pattern of a templated entity,
consistently select the definition of the pattern if there is one. This means
we'll pick the same owning module when we start instantiating a template that
we'll later pick when determining which modules are visible during that
instantiation.

llvm-svn: 300650

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/test/Modules/Inputs/template-default-args/a.h b/clang/test/Modules/Inputs/template-default-args/a.h
index 532cbc8be03..0f4a39a1892 100644
--- a/clang/test/Modules/Inputs/template-default-args/a.h
+++ b/clang/test/Modules/Inputs/template-default-args/a.h
@@ -14,3 +14,11 @@ struct FriendL {
   template<typename T> friend struct L;
 };
 END
+
+namespace DeferredLookup {
+  template<typename T, typename U = T> using X = U;
+  template<typename T> void f() { (void) X<T>(); }
+  template<typename T> int n = X<T>();
+  template<typename T> struct S { X<T> xt; enum E : int; };
+  template<typename T> enum S<T>::E : int { a = X<T>() };
+}