cp-tree.h (CLASSTYPE_VBASECLASSES): Improve documentation.

	* cp-tree.h (CLASSTYPE_VBASECLASSES): Improve documentation.
	* class.c (layout_basetypes): Don't set BINFO_INHERITANCE_CHAIN
	or unshare_base_binfos for virtual bases here.
	* search.c (dfs_get_vbase_types): Do it here.
	(get_vbase_types): Adjust.

From-SVN: r31184

gcc/cp/ChangeLog

+2000-01-03  Mark Mitchell  <mark@codesourcery.com>
+
+	* cp-tree.h (CLASSTYPE_VBASECLASSES): Improve documentation.
+	* class.c (layout_basetypes): Don't set BINFO_INHERITANCE_CHAIN
+	or unshare_base_binfos for virtual bases here.
+	* search.c (dfs_get_vbase_types): Do it here.
+	(get_vbase_types): Adjust.
+	
 2000-01-02  Mark Mitchell  <mark@codesourcery.com>
 
 	* cp-tree.h (CLASSTYPE_VFIELDS): Move definition.

gcc/cp/class.c

@@ -4379,8 +4379,6 @@ layout_basetypes (rec)
   for (vbase_types = CLASSTYPE_VBASECLASSES (rec); vbase_types;
        vbase_types = TREE_CHAIN (vbase_types))
     {
-      BINFO_INHERITANCE_CHAIN (vbase_types) = TYPE_BINFO (rec);
-      unshare_base_binfos (vbase_types);
       propagate_binfo_offsets (vbase_types, BINFO_OFFSET (vbase_types));
 
       if (extra_warnings)

gcc/cp/cp-tree.h

@@ -1408,7 +1408,20 @@ struct lang_type
 #define CLASSTYPE_VSIZE(NODE) (TYPE_LANG_SPECIFIC(NODE)->vsize)
 
 /* A chain of BINFOs for the direct and indirect virtual base classes
-   that this type uses in depth-first left-to-right order.  */
+   that this type uses in depth-first left-to-right order.  These
+   BINFOs are distinct from those in the TYPE_BINFO hierarchy.  So,
+   given: 
+
+     struct A {};
+     struct B : public A {};
+     struct C : virtual public B {};
+     struct D : virtual public B {};
+     struct E : public C, public D {};
+
+   there will be two copies of `A' and `B' in the TYPE_BINFO hierarchy
+   for `E'.  On the CLASSTYPE_VBASECLASSES list, there will be just
+   one copy of `A' (distinct from the other two) with its own copy of `B'
+   (also distinct from the copies in the TYPE_BINFO hierarchy.)  */
 #define CLASSTYPE_VBASECLASSES(NODE) (TYPE_LANG_SPECIFIC(NODE)->vbases)
 
 /* The BINFO (if any) for the virtual baseclass T of the class C.  */

gcc/cp/search.c

@@ -2907,33 +2907,32 @@ dfs_get_vbase_types (binfo, data)
      tree binfo;
      void *data;
 {
-  tree *vbase_types = (tree *) data;
+  tree type = (tree) data;
 
   if (TREE_VIA_VIRTUAL (binfo) && ! BINFO_VBASE_MARKED (binfo))
     {
       tree new_vbase = make_binfo (integer_zero_node, binfo,
 				   BINFO_VTABLE (binfo),
 				   BINFO_VIRTUALS (binfo));
-      TREE_CHAIN (new_vbase) = *vbase_types;
+      unshare_base_binfos (new_vbase);
       TREE_VIA_VIRTUAL (new_vbase) = 1;
-      *vbase_types = new_vbase;
+      BINFO_INHERITANCE_CHAIN (new_vbase) = TYPE_BINFO (type);
+      TREE_CHAIN (new_vbase) = CLASSTYPE_VBASECLASSES (type);
+      CLASSTYPE_VBASECLASSES (type) = new_vbase;
       SET_BINFO_VBASE_MARKED (binfo);
     }
   SET_BINFO_MARKED (binfo);
   return NULL_TREE;
 }
 
-/* Return a list of binfos for the virtual base classes for TYPE, in
-   depth-first search order.  The list is freshly allocated, so
-   no modification is made to  the current binfo hierarchy.  */
+/* Set CLASSTYPE_VBASECLASSES for TYPE.  */
 
 void
 get_vbase_types (type)
      tree type;
 {
   CLASSTYPE_VBASECLASSES (type) = NULL_TREE;
-  dfs_walk (TYPE_BINFO (type), dfs_get_vbase_types, unmarkedp,
-	    &CLASSTYPE_VBASECLASSES (type));
+  dfs_walk (TYPE_BINFO (type), dfs_get_vbase_types, unmarkedp, type);
   /* Rely upon the reverse dfs ordering from dfs_get_vbase_types, and now
      reverse it so that we get normal dfs ordering.  */
   CLASSTYPE_VBASECLASSES (type) = nreverse (CLASSTYPE_VBASECLASSES (type));