[Bug c++/122712] ADL search does not occur in a function exported from a module

[nshead at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122712

--- Comment #3 from Nathaniel Shead <nshead at gcc dot gnu.org> ---
(In reply to Egor Bychin from comment #2)
> I also came across this bug.
> Turns out that `foo` is invisible to ADL even if it is module-local (i.e.
> not part of a GMF)
> 
> https://godbolt.org/z/jx4PMsPKv

This example works with GCC 16.  GCC 15 unfortunately had a number of issues
with ADL due to a misunderstanding of how instantiation context was supposed to
function for ADL (see PR117658).