dwarf2out.c (prune_unused_types): Handle unused top-level limbo dies.

	* dwarf2out.c (prune_unused_types): Handle unused top-level limbo
	dies.

From-SVN: r224391

gcc/ChangeLog

+2015-06-11  Jason Merrill  <jason@redhat.com>
+
+	* dwarf2out.c (prune_unused_types): Handle unused top-level limbo
+	dies.
+
 2015-06-11  Marek Polacek  <polacek@redhat.com>
 
 	* match.pd ((x & y) ^ (x | y)): Don't check for single_use.

gcc/dwarf2out.c

@@ -23789,8 +23789,17 @@ prune_unused_types (void)
   if (skeleton_debug_str_hash)
     skeleton_debug_str_hash->empty ();
   prune_unused_types_prune (comp_unit_die ());
-  for (node = limbo_die_list; node; node = node->next)
-    prune_unused_types_prune (node->die);
+  for (limbo_die_node **pnode = &limbo_die_list; *pnode; )
+    {
+      node = *pnode;
+      if (!node->die->die_mark)
+	*pnode = node->next;
+      else
+	{
+	  prune_unused_types_prune (node->die);
+	  pnode = &node->next;
+	}
+    }
   for (ctnode = comdat_type_list; ctnode; ctnode = ctnode->next)
     prune_unused_types_prune (ctnode->root_die);