C++ PATCH to add a test for c++/82231

[Marek Polacek]

This bug was fixed in r255430, but the test looks different enough so we better
add it.

Tested on x86_64-linux, ok for trunk?

2017-12-19  Marek Polacek  <pola...@redhat.com>

        PR c++/82231
        * g++.dg/cpp1z/nontype-auto14.C: New test.

--- gcc/testsuite/g++.dg/cpp1z/nontype-auto14.C
+++ gcc/testsuite/g++.dg/cpp1z/nontype-auto14.C
@@ -0,0 +1,14 @@
+// PR c++/82231
+// { dg-options -std=c++17 }
+
+template<int>
+struct x {};
+
+template <auto I, decltype(I) X>
+void f(x<X>) { }
+
+int
+main()
+{
+  f<0>(x<1>{});
+}

        Marek