[Bug fortran/66227] [5/6/7 Regression] [OOP] EXTENDS_TYPE_OF n returns wrong result for polymorphic variable allocated to extended type

[janus at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66227

janus at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |janus at gcc dot gnu.org

--- Comment #4 from janus at gcc dot gnu.org ---
(In reply to janus from comment #3)
> Confirmed. What's funny is that all eight cases are simplified to
> compile-time constants. That clearly shouldn't be. Probably there's a bug in
> gfc_simplify_extends_type_of.

The regression is due to r168579. The following patch fixes it:

Index: simplify.c
===================================================================
--- simplify.c  (Revision 242412)
+++ simplify.c  (Arbeitskopie)
@@ -2531,11 +2531,7 @@
                         mold->ts.u.derived->components->ts.u.derived)
          && !gfc_type_is_extension_of
                        (mold->ts.u.derived->components->ts.u.derived,
-                        a->ts.u.derived))
-      || (a->ts.type == BT_CLASS && mold->ts.type == BT_DERIVED
-         && !gfc_type_is_extension_of
-                       (mold->ts.u.derived,
-                        a->ts.u.derived->components->ts.u.derived)))
+                        a->ts.u.derived)))
     return gfc_get_logical_expr (gfc_default_logical_kind, &a->where, false);

   if (mold->ts.type == BT_DERIVED