--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp2a/udlit-class-nttp-ctad.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,24 @@
+// PR c++/88095
+// Test class non-type template parameters for literal operator templates.
+// Validate support for class template argument deduction.
+// { dg-do compile { target c++2a } }
+
+namespace std {
+using size_t = decltype(sizeof(int));
+}
+
+template <typename CharT, std::size_t N>
+struct fixed_string {
+  constexpr static std::size_t length = N;
+  constexpr fixed_string(...) { }
+  // auto operator<=> (const fixed_string&) = default;
+};
+template <typename CharT, std::size_t N>
+fixed_string(const CharT (&str)[N]) -> fixed_string<CharT, N>;
+
+template <fixed_string fs>
+constexpr std::size_t operator"" _udl() {
+  return decltype(fs)::length;
+}
+
+static_assert("test"_udl == 5);