Index: resolve.c
===================================================================
--- resolve.c	(revision 115827)
+++ resolve.c	(working copy)
@@ -1012,7 +1012,8 @@
 	    && arg->expr->symtree->n.sym->attr.optional
 	    && formal_optional
 	    && arg->expr->rank
-	    && (set_by_optional || arg->expr->rank != rank)) 
+	    && (set_by_optional || arg->expr->rank != rank)
+	    && !(isym && isym->generic_id == GFC_ISYM_CONVERSION))
 	{
 	  gfc_error ("'%s' at %L is an array and OPTIONAL; it cannot "
 		     "therefore be an actual argument of an ELEMENTAL "