re PR c++/56428 ([C++11] "is not a constant expression" when comparing non-type template argument to nullptr)

PR c++/56428
	* g++.dg/cpp0x/nontype4.C: New test.

From-SVN: r274028

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2019-08-02  Marek Polacek  <polacek@redhat.com>
+
+	PR c++/56428
+	* g++.dg/cpp0x/nontype4.C: New test.
+
 2019-08-02  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/53009

gcc/testsuite/g++.dg/cpp0x/nontype4.C

@@ -0,0 +1,25 @@
+// PR c++/56428
+// { dg-do compile { target c++11 } }
+
+struct A { };
+
+template<bool B>
+  struct Builder
+  {
+    static A build() { return A(); }
+  };
+
+template<A (*F)()>
+  A f()
+  {
+    return Builder<F != nullptr>::build();
+  }
+
+A g();
+
+int main()
+{
+  f< &g >();
+  f< nullptr >();
+  f< &f<nullptr> >();
+}