--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/warn/pr94038-3.C	Mon May 25 07:50:57 2020 +0900
@@ -0,0 +1,15 @@
+// PR c++/94038
+// { dg-do compile { target c++20 } }
+// { dg-additional-options "-Wall" }
+
+template<typename T>
+constexpr int foo() {
+  return T::x;
+}
+
+constexpr bool bar(bool a) { return a; }
+
+template<typename T>
+concept C = foo<T>() == 0;
+
+static_assert(decltype(bar(C<int>)){} == false);