Re: [PATCH] PR125527 submodule cannot access internal subprograms of, ancestor module via host association

Thanks Paul.

The master branch has been updated by Jerry DeLisle <[email protected]>:

https://gcc.gnu.org/g:d3d984e9a0670b8b1076089e2cbc85f9a58578b6

commit r17-1148-gd3d984e9a0670b8b1076089e2cbc85f9a58578b6
Author: Jerry DeLisle <[email protected]>
Date:   Mon May 25 09:29:33 2026 -0700

     fortran: submodule cannot access internal subprograms of ancestor module
via host association


On 6/1/26 2:15 PM, Paul Richard Thomas wrote:
> Hi Jerry,
> 
> The mea-bug is 121381, is it not?
> 
> The patch looks good to me and regtests just fine on FC44/x86_64.
> 
> OK for mainline and, after a decent interval, for backporting.
> 
> Cheers
> 
> Paul
> 
> On Mon, 1 Jun 2026 at 21:30, Jerry D <[email protected]> wrote:
>>
>> See attached patch.
>>
>> This fixes the problem as noted in the change log.
>>
>> This is one of the several listed in the meta bug PR125515.
>> I will be submitting these one at a time for review so we don;t get lost in it.
>>
>> Regression tested on x86_64.
>>
>> OK for mainline and then backport to 16 after a wait.
>>
>> Regards,
>>
>> Jerry
>>
>> ---
>>
>> fortran: submodule cannot access internal subprograms of
>>    ancestor module via host association
>>
>> A submodule could not access internal subprograms of its ancestor module
>> via host association.  References to such procedures were rejected with
>> "has no IMPLICIT type".  Fortran 2018 §14.6.1.3 requires submodules to
>> host-associate the specification part and the module subprogram part of
>> their ancestor module; Intel Fortran and NAG Fortran accept this usage.
>>
>> Root cause: when parse_module processes a submodule, gfc_current_ns->parent
>> is left NULL, so the host-association walk cannot reach the ancestor
>> module's namespace and its internal procedures.
>>
>> Fix (parse.cc, parse_module): after use_modules() and gfc_traverse_ns(),
>> strip the child suffix from the submodule's dotted name (e.g. "m.s" -> "m"),
>> search gfc_global_ns_list for the matching ancestor namespace, and set
>> gfc_current_ns->parent to it.
>>
>> Fix (parse.cc, clean_up_modules): before calling gfc_done_2(), reset
>> gfc_current_ns->parent to NULL to prevent gfc_symbol_done_2 from walking up
>> to and double-freeing the ancestor module namespace during teardown.
>>
>> The new parent link also required boundary guards in three places that walk
>> up the namespace chain:
>>
>> Fix (class.cc, gfc_find_derived_vtab): the vtab lookup walks up ns->parent
>> to find the top-level namespace.  Stop at module/submodule boundaries
>> (FL_MODULE flavor) so that vtables for types defined in a submodule are not
>> incorrectly placed in the ancestor module namespace.
>>
>> Fix (openmp.cc, gfc_omp_requires_add_clause, gfc_match_omp_requires,
>> gfc_match_omp_atomic): three OpenMP helpers walk ns->parent to find the
>> enclosing program unit.  Each acquired the same boundary guard so the
>> submodule is treated as its own program unit for OMP REQUIRES purposes.
>>
>> PR fortran/125527
>>
>> Assisted by: Claude Sonnet 4.6
>>
>> gcc/fortran/ChangeLog:
>>
>>          PR fortran/125527
>>          * class.cc (gfc_find_derived_vtab): Stop the top-level namespace
>>          walk at module/submodule boundaries to avoid escaping a submodule
>>          into its ancestor module namespace.
>>          * openmp.cc (gfc_omp_requires_add_clause): Likewise; treat the
>>          submodule as its own program unit for OMP REQUIRES.
>>          (gfc_match_omp_requires): Likewise; allow OMP REQUIRES in a submodule
>>          spec part even when gfc_current_ns->parent is now non-NULL.
>>          (gfc_match_omp_atomic): Likewise.
>>          * parse.cc (parse_module): After processing USE statements and
>>          host-association traversal, link the submodule namespace to its
>>          ancestor module namespace so internal subprograms are visible via
>>          host association (Fortran 2018, 14.6.1.3).
>>          (clean_up_modules): Reset gfc_current_ns->parent before gfc_done_2
>>          to prevent double-free of the ancestor module namespace.
>>
>> gcc/testsuite/ChangeLog:
>>
>>          PR fortran/125527
>>          * gfortran.dg/submodule_host_assoc_1.f90: New test.
>>          * gfortran.dg/submodule_host_assoc_1_aux.f90: New test.
>> ---