re PR c++/39608 ('expr' cannot appear in a constant-expression.)

        PR c++/39608
        * semantics.c (finish_id_expression): Don't assume a dependent
        member of the current instantiation isn't a valid integral
        constant expression.  Check dependent_scope_p.
        * pt.c (dependent_scope_p): Check TYPE_P.

From-SVN: r145508

gcc/cp/ChangeLog

+2009-04-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/39608
+	* semantics.c (finish_id_expression): Don't assume a dependent
+	member of the current instantiation isn't a valid integral
+	constant expression.  Check dependent_scope_p.
+	* pt.c (dependent_scope_p): Check TYPE_P.
+	(tsubst_copy): If args is null, just return.
+
 2009-04-02  Jason Merrill  <jason@redhat.com>
 
 	PR c++/25185

gcc/cp/pt.c

@@ -9999,7 +9999,7 @@ tsubst_copy (tree t, tree args, tsubst_flags_t complain, tree in_decl)
   enum tree_code code;
   tree r;
 
-  if (t == NULL_TREE || t == error_mark_node)
+  if (t == NULL_TREE || t == error_mark_node || args == NULL_TREE)
     return t;
 
   code = TREE_CODE (t);
@@ -16168,7 +16168,8 @@ dependent_type_p (tree type)
 bool
 dependent_scope_p (tree scope)
 {
-  return dependent_type_p (scope) && !currently_open_class (scope);
+  return (scope && TYPE_P (scope) && dependent_type_p (scope)
+	  && !currently_open_class (scope));
 }
 
 /* Returns TRUE if EXPRESSION is dependent, according to CRITERION.  */

gcc/cp/semantics.c

@@ -2857,11 +2857,6 @@ finish_id_expression (tree id_expression,
 	     dependent.  */
 	  if (scope)
 	    {
-	      /* Since this name was dependent, the expression isn't
-		 constant -- yet.  No error is issued because it might
-		 be constant when things are instantiated.  */
-	      if (integral_constant_expression_p)
-		*non_integral_constant_expression_p = true;
 	      if (TYPE_P (scope))
 		{
 		  if (address_p && done)
@@ -2869,7 +2864,7 @@ finish_id_expression (tree id_expression,
 						     done, address_p,
 						     template_p,
 						     template_arg_p);
-		  else if (dependent_type_p (scope))
+		  else if (dependent_scope_p (scope))
 		    decl = build_qualified_name (/*type=*/NULL_TREE,
 						 scope,
 						 id_expression,

gcc/testsuite/ChangeLog

+2009-04-03  Jason Merrill  <jason@redhat.com>
+
+	PR c++/39608
+	* g++.dg/template/const2.C: New test.
+
 2009-04-03  Richard Guenther  <rguenther@suse.de>
 
 	PR tree-optimization/2480

gcc/testsuite/g++.dg/template/const2.C

+// PR c++/39608
+// We were improperly considering dependent members of the current
+// instantiation to be non-constant (and therefore invalid template
+// non-type arguments).
+
+template <int I>
+struct C {};
+
+template <class T>
+struct A
+{
+  static const T x = 1;
+  C<A<T>::x> c;			// { dg-bogus "invalid" }
+};
+
+A<int> a;