--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/nontype-class28.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,37 @@
+// PR c++/92948 - Fix class NTTP with template arguments.
+// { dg-do compile { target c++2a } }
+
+struct A {
+  constexpr A(int) { }
+};
+
+template<A>
+struct B {
+  using U = unsigned;
+};
+
+template<A a>
+using U = B<a>;
+
+template<int X, typename Y = typename B<X>::U>
+void foo()
+{
+}
+
+template<int X, typename Y = typename U<X>::U>
+void foo2()
+{
+}
+
+template<typename Y = typename B<1>::U>
+void foo3()
+{
+}
+
+void
+g ()
+{
+  foo<1>();
+  foo2<1>();
+  foo3<>();
+}