1 files changed, 5 insertions, 2 deletions
diff --git a/gcc/cp/search.c b/gcc/cp/search.c
index d6521fb6f82..3adf9e0a1ab 100644
--- a/gcc/cp/search.c
+++ b/gcc/cp/search.c
@@ -214,9 +214,12 @@ lookup_base (tree t, tree base, base_access access, base_kind *kind_ptr)
       t_binfo = TYPE_BINFO (t);
     }
 
-  base = complete_type (TYPE_MAIN_VARIANT (base));
+  base = TYPE_MAIN_VARIANT (base);
 
-  if (t_binfo)
+  /* If BASE is incomplete, it can't be a base of T--and instantiating it
+     might cause an error.  */
+  if (t_binfo && CLASS_TYPE_P (base)
+      && (COMPLETE_TYPE_P (base) || TYPE_BEING_DEFINED (base)))
     {
       struct lookup_base_data_s data;