[Bug fortran/66089] [6 Regression] elemental dependency mishandling when derived types are involved

[mikael at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66089

--- Comment #14 from Mikael Morin <mikael at gcc dot gnu.org> ---
Created attachment 37613
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37613&action=edit
Fix for comment #10

This is sufficient to fix comment #10.
It removes the optional attribute on c(1) if c is optional.
Then the can_be_null_ref attribute is not set during scalarization, and
gfc_scalar_elemental_arg_saved_as_reference returns false.
I'm not sure this is actually correct; should we consider c(1) optional if c is
optional?