--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/cpp1z/class-deduction12.C	Fri Oct 27 22:46:09 2017 +0900
@@ -0,0 +1,17 @@
+// { dg-options -std=c++17 }
+
+template <class T>
+struct A
+{
+  template<class U, template<U u> class P>
+  A(T,U,P<42>);
+};
+
+template <int I> struct B { };
+
+int i;
+A a(&i,2,B<42>());
+
+template <class,class> class same;
+template <class T> class same<T,T> {};
+same<decltype(a), A<int*>> s;