[Bug c++/114685] [modules] ICE when exporting a type through a different alias then one declared in GMF

["nshead at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114685

Nathaniel Shead <nshead at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=114683
             Status|UNCONFIRMED                 |NEW
                 CC|                            |nshead at gcc dot gnu.org
   Last reconfirmed|                            |2024-04-11
     Ever confirmed|0                           |1

--- Comment #2 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
This fails on

      if (data->hash->add_namespace_entities (decl, data->partitions))
        {
          /* It contains an exported thing, so it is exported.  */
          gcc_checking_assert (DECL_MODULE_PURVIEW_P (decl));
          DECL_MODULE_EXPORT_P (decl) = true;
        }

ultimately for a very similar reason to PR114683: non-functions brought in by
using-decls currently just bind the value directly which means that there's
nothing to indicate that they should be exported from this scope (and not their
original one).

I've been playing around with making use of the existing STAT_HACK machinery to
try to get this working, but it looks like we'll probably need to overhaul a
fair chunk of the name lookup code to handle this correctly.