--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/concepts/variadic1.C	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,25 @@
+// PR c++/66712
+// { dg-options "-std=c++17 -fconcepts" }
+
+template <class T, class...Args>
+concept bool _Constructible_ =
+  requires (Args&&...args)
+  {
+    T{ ((Args&&)(args))... };
+  };
+
+template <class T, class...Args>
+constexpr bool _constructible_() { return false; }
+
+_Constructible_{T, ...Args}
+constexpr bool _constructible_() { return true; }
+
+struct S
+{
+  S(int, char const *);
+};
+
+int main()
+{
+  static_assert(_constructible_<S, int, char const *>(), "");
+}