[patch] Fix PR c++/28051

[Lee Millward]

Hi,

The C++ front-end currently fails on the following invalid testcase
with a tree check failure in
mangle_conv_op_name_for_type:

template<int> struct A {};
template<int N> struct B : A<N>
{
    using A<N>::operator typename A::X;
};

B<0> b;

This is because error_mark_node gets passed into
mangle_conv_op_name_for_type from tsubst_copy which can't handle it.
The proposed patch fixes this ICE by checking the return value from
tsubst in tsubst_copy before calling mangle_conv_op_name_for_type,
avoiding the ICE.

The second part of the patch addresses some follow up issues by making
push_class_level_binding and do_class_using_decl more robust in the
presence of error_mark_nodes.

Bootstrapped and regression tested on i686-pc-linux-gnu with no new
failures. Ok for mainline?

Cheers,
Lee.

:ADDPATCH c++:

cp/

2006-06-18  Lee Millward  <lee.millward@gmail.com>

	PR c++/28051
	* pt.c (tsubst_copy): Check for tsubst
	returning error_mark_node before calling
	mangle_conv_op_name_for_type.
	* name-lookup.c (push_class_level_binding): Robustify.
	(do_class_using_decl): Likewise.

testsuite/

2006-06-18  Lee Millward  <lee.millward@gmail.com>

	PR c++/28051
	* g++.dg/template/using13.C: New test.
-------------- next part --------------
Index: gcc/testsuite/g++.dg/template/using13.C
===================================================================
--- gcc/testsuite/g++.dg/template/using13.C	(revision 0)
+++ gcc/testsuite/g++.dg/template/using13.C	(revision 0)
@@ -0,0 +1,11 @@
+//PR c++/28051
+
+template<int> struct A {};
+
+template<int N> struct B : A<N>
+{
+    using A<N>::operator typename A<N>::X; // { dg-error "no type named" }
+};
+
+B<0> b;
+
Index: gcc/cp/pt.c
===================================================================
--- gcc/cp/pt.c	(revision 114756)
+++ gcc/cp/pt.c	(working copy)
@@ -8085,6 +8085,10 @@ tsubst_copy (tree t, tree args, tsubst_f
       if (IDENTIFIER_TYPENAME_P (t))
 	{
 	  tree new_type = tsubst (TREE_TYPE (t), args, complain, in_decl);
+
+          if(new_type == error_mark_node)
+            return error_mark_node;
+
 	  return mangle_conv_op_name_for_type (new_type);
 	}
       else
Index: gcc/cp/name-lookup.c
===================================================================
--- gcc/cp/name-lookup.c	(revision 114756)
+++ gcc/cp/name-lookup.c	(working copy)
@@ -2609,6 +2609,9 @@ push_class_level_binding (tree name, tre
   if (!class_binding_level)
     POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, true);
 
+  if(name == error_mark_node)
+    POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, false);
+
   /* Check for invalid member names.  */
   gcc_assert (TYPE_BEING_DEFINED (current_class_type));
   /* We could have been passed a tree list if this is an ambiguous
@@ -2826,7 +2829,7 @@ do_class_using_decl (tree scope, tree na
 	  return NULL_TREE;
 	}
 
-      if (!name_dependent_p)
+      if (!name_dependent_p && name != error_mark_node)
 	{
 	  decl = lookup_member (binfo, name, 0, false);
 	  if (!decl)