--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1y/pr87410.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,19 @@
+// PR c++/87410
+// { dg-do compile { target c++14 } }
+
+template <long a> using b = const char[a];
+template <typename, int c, int e, typename f>
+constexpr auto g(b<c> &, b<e> &, f) {}
+template <typename d, int a> auto h(b<a> &) {
+  auto i = j(static_cast<d **>(nullptr));
+  return **i;
+}
+class k {
+  using l = k;
+  const int &m() const;
+  friend constexpr auto j(l **n) -> decltype(n) {
+    g<int>("", "", static_cast<const int &(k::*)() const>(&k::m));
+    return n;
+  }
+};
+k o = h<k, 1>("");