PR c++/81671 - nullptr_t template parameter

	* pt.c (convert_nontype_argument): Fix nullptr_t check.

From-SVN: r251046

gcc/cp/ChangeLog

+2017-08-11  Jason Merrill  <jason@redhat.com>
+
+	PR c++/81671 - nullptr_t template parameter
+	* pt.c (convert_nontype_argument): Fix nullptr_t check.
+
 2017-08-10  Jason Merrill  <jason@redhat.com>
 
 	PR c++/81359 - Unparsed NSDMI error from SFINAE context.

gcc/cp/pt.c

@@ -6879,7 +6879,7 @@ convert_nontype_argument (tree type, tree expr, tsubst_flags_t complain)
     }
   else if (NULLPTR_TYPE_P (type))
     {
-      if (expr != nullptr_node)
+      if (!NULLPTR_TYPE_P (TREE_TYPE (expr)))
 	{
 	  if (complain & tf_error)
 	    error ("%qE is not a valid template argument for type %qT "

gcc/testsuite/g++.dg/cpp0x/nullptr39.C

+// PR c++/81671
+// { dg-do compile { target c++11 } }
+
+namespace std { typedef decltype(nullptr) nullptr_t; }
+
+template<class R, class CB> struct Bar
+{};
+template<class R> struct Bar<R, std::nullptr_t>
+{
+    template<std::nullptr_t> struct Bind { constexpr static int const cb = 0; };
+};
+int foo()
+{
+  return Bar<int, decltype(nullptr)>::Bind<nullptr>::cb;
+}