--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1z/fold10.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,17 @@
+// PR c++/89761
+// { dg-do compile { target c++17 } }
+
+template <int...> struct seq {};
+template <bool> struct S {
+    template <typename Args>
+    constexpr static void call(Args&&...) {}
+};
+
+template <int ...Idx,typename ...Args>
+auto foo (seq<Idx...>, Args&& ...args) {
+    return (S<Idx==sizeof...(args)>::call(args), ...);
+}
+
+void bar() {
+    foo(seq<0,1,2>{}, 1,2,3);
+}