re PR c++/55003 ([C++11] Member function pointer not working as constexpr initializer)

	PR c++/55003
	* decl.c (cp_finish_decl): Force instantiation of an
	auto static data member.

From-SVN: r196069

gcc/cp/ChangeLog

 2013-02-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/55003
+	* decl.c (cp_finish_decl): Force instantiation of an
+	auto static data member.
+
 	PR c++/55220
 	* pt.c (unify): A pack expansion that is not the last template
 	argument makes the entire template argument list non-deduced.

gcc/cp/decl.c

@@ -6111,6 +6111,15 @@ cp_finish_decl (tree decl, tree init, bool init_const_expr_p,
       tree d_init;
       if (init == NULL_TREE)
 	{
+	  if (DECL_TEMPLATE_INSTANTIATION (decl)
+	      && !DECL_TEMPLATE_INSTANTIATED (decl))
+	    {
+	      /* init is null because we're deferring instantiating the
+		 initializer until we need it.  Well, we need it now.  */
+	      instantiate_decl (decl, /*defer_ok*/true, /*expl*/false);
+	      return;
+	    }
+
 	  error ("declaration of %q#D has no initializer", decl);
 	  TREE_TYPE (decl) = error_mark_node;
 	  return;

gcc/testsuite/g++.dg/cpp0x/auto37.C

+// PR c++/55003
+// { dg-do compile { target c++11 } }
+
+template<typename T>
+struct A {
+  static const auto t
+    = (typename T::type)42;
+};
+
+struct X {
+  typedef int type;
+};
+
+A<X> a;