[m-rev.] for review: Make is_type_a_dummy_loop handle abstractly imported dummy types.

[Julien Fischer]

On Wed, 7 Apr 2021, Peter Wang wrote:

> compiler/type_util.m:
>    Make is_type_a_dummy_loop return is_dummy_type for an
>    abstractly imported subtype whose base type is a dummy type.
>
>    Make is_type_a_dummy_loop return is_dummy_type for abstract dummy
>    types. (I believe this currently has no effect because the bodies
>    of abstractly exported dummy types will be available from the .int
>    or .int2 file of the module they are defined in.)
>
> tests/hard_coded/subtype_pack.exp:
>    Enable field with abstractly imported subtype. Previously the
>    compiler would generate a unify/compare predicate which tried to
>    unify/compare the dummy field, which either caused and exception
>    later, or generated target code that would not compile.

That's fine.

Julien.