2004-08-24  Nathan Sidwell  <nathan@codesourcery.com>

	PR c++/16889
	* (is_subobject_of_p): Resurrect & optimize.
	(lookup_field_r): Use it.

Index: cp/search.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cp/search.c,v
retrieving revision 1.308
diff -c -3 -p -r1.308 search.c
*** cp/search.c	15 Aug 2004 15:45:25 -0000	1.308
--- cp/search.c	24 Aug 2004 14:38:01 -0000
*************** struct vbase_info 
*** 45,50 ****
--- 45,51 ----
    tree inits;
  };
  
+ static int is_subobject_of_p (tree, tree);
  static tree dfs_check_overlap (tree, void *);
  static tree dfs_no_overlap_yet (tree, int, void *);
  static base_kind lookup_base_r (tree, tree, base_access, bool, tree *);
*************** template_self_reference_p (tree type, tr
*** 1002,1008 ****
  	   && DECL_NAME (decl) == constructor_name (type));
  }
  
- 
  /* Nonzero for a class member means that it is shared between all objects
     of that class.
  
--- 1003,1008 ----
*************** shared_member_p (tree t)
*** 1032,1037 ****
--- 1032,1057 ----
    return 0;
  }
  
+ /* Routine to see if the sub-object denoted by the binfo PARENT can be
+    found as a base class and sub-object of the object denoted by
+    BINFO.  */
+ 
+ static int
+ is_subobject_of_p (tree parent, tree binfo)
+ {
+   tree probe;
+   
+   for (probe = parent; probe; probe = BINFO_INHERITANCE_CHAIN (probe))
+     {
+       if (probe == binfo)
+ 	return 1;
+       if (BINFO_VIRTUAL_P (probe))
+ 	return (binfo_for_vbase (BINFO_TYPE (probe), BINFO_TYPE (binfo))
+ 		!= NULL_TREE);
+     }
+   return 0;
+ }
+ 
  /* DATA is really a struct lookup_field_info.  Look for a field with
     the name indicated there in BINFO.  If this function returns a
     non-NULL value it is the result of the lookup.  Called from
*************** lookup_field_r (tree binfo, void *data)
*** 1099,1110 ****
  
    /* If the lookup already found a match, and the new value doesn't
       hide the old one, we might have an ambiguity.  */
!   if (lfi->rval_binfo && !original_binfo (lfi->rval_binfo, binfo))
      {
        if (nval == lfi->rval && shared_member_p (nval))
  	/* The two things are really the same.  */
  	;
!       else if (original_binfo (binfo, lfi->rval_binfo))
  	/* The previous value hides the new one.  */
  	;
        else
--- 1119,1132 ----
  
    /* If the lookup already found a match, and the new value doesn't
       hide the old one, we might have an ambiguity.  */
!   if (lfi->rval_binfo
!       && !is_subobject_of_p (lfi->rval_binfo, binfo))
!     
      {
        if (nval == lfi->rval && shared_member_p (nval))
  	/* The two things are really the same.  */
  	;
!       else if (is_subobject_of_p (binfo, lfi->rval_binfo))
  	/* The previous value hides the new one.  */
  	;
        else