--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/torture/pr87997.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+template <typename, typename> struct a;
+template <template <typename> class b, typename c, typename f, typename... d>
+struct a<b<f, d...>, c> {
+  using e = b<c>;
+};
+template <typename f> class h {
+public:
+  typedef f g;
+};
+template <typename j, typename c> using k = typename a<j, c>::e;
+template <typename j> struct l { template <typename f> using m = k<j, f>; };
+template <typename j> struct n {
+  typedef typename j::g o;
+  template <typename f> struct p {
+    typedef typename l<j>::template m<f> other;
+  };
+};
+template <typename f, typename j> struct F {
+  typedef typename n<j>::template p<f>::other q;
+};
+template <typename f, typename j = h<f>> class r {
+public:
+  typename n<typename F<f, j>::q>::o operator[](long);
+  f *t() noexcept;
+};
+class s {
+  void m_fn2();
+  r<int (s::*)()> u;
+};
+void s::m_fn2() try {
+  for (int i;;)
+    (this->*u[i])();
+} catch (...) {
+}