cp:

	PR c++/16889
	* (is_subobject_of_p): Resurrect & optimize.
	(lookup_field_r): Use it.
testsuite:
	PR c++/16889
	* g++.dg/lookup/ambig[12].C: New.


git-svn-id: https://gcc.gnu.org/svn/gcc/trunk@86488 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 25 insertions, 3 deletions

diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index 81226d13d33..4aadf78adf8 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -45,6 +45,7 @@ struct vbase_info
   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 *);
@@ -1018,7 +1019,6 @@ template_self_reference_p (tree type, tree decl)
 	   && DECL_NAME (decl) == constructor_name (type));
 }
 
-
 /* Nonzero for a class member means that it is shared between all objects
    of that class.
 
@@ -1048,6 +1048,26 @@ shared_member_p (tree t)
   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
@@ -1115,12 +1135,14 @@ lookup_field_r (tree binfo, void *data)
 
   /* 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 (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 (original_binfo (binfo, lfi->rval_binfo))
+      else if (is_subobject_of_p (binfo, lfi->rval_binfo))
 	/* The previous value hides the new one.  */
 	;
       else