re PR c++/56998 (ICE in value_dependent_expression_p, at cp/pt.c:19598)

	PR c++/56998
	* semantics.c (potential_constant_expression_1): Make sure the
	called function is potentially constant.
	* call.c (null_ptr_cst_p): Revert earlier change.

From-SVN: r198881

gcc/cp/ChangeLog

+2013-05-14  Jason Merrill  <jason@redhat.com>
+
+	PR c++/56998
+	* semantics.c (potential_constant_expression_1): Make sure the
+	called function is potentially constant.
+	* call.c (null_ptr_cst_p): Revert earlier change.
+
 2013-05-13  Jason Merrill  <jason@redhat.com>
 
 	PR c++/56998

gcc/cp/call.c

@@ -554,7 +554,7 @@ null_ptr_cst_p (tree t)
   if (CP_INTEGRAL_TYPE_P (TREE_TYPE (t)))
     {
       /* Core issue 903 says only literal 0 is a null pointer constant.  */
-      if (cxx_dialect < cxx0x && !TREE_SIDE_EFFECTS (t))
+      if (cxx_dialect < cxx0x)
 	t = maybe_constant_value (fold_non_dependent_expr_sfinae (t, tf_none));
       STRIP_NOPS (t);
       if (integer_zerop (t) && !TREE_OVERFLOW (t))

gcc/cp/semantics.c

@@ -8476,7 +8476,11 @@ potential_constant_expression_1 (tree t, bool want_rval, tsubst_flags_t flags)
 		  }
 	      }
 	    else
-	      fun = get_first_fn (fun);
+	      {
+		if (!potential_constant_expression_1 (fun, true, flags))
+		  return false;
+		fun = get_first_fn (fun);
+	      }
 	    /* Skip initial arguments to base constructors.  */
 	    if (DECL_BASE_CONSTRUCTOR_P (fun))
 	      i = num_artificial_parms_for (fun);