[Bug fortran/121379] MODULE attribute required for submodule procedure with interface in parent module.

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121379

--- Comment #1 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Paul Thomas <pault@gcc.gnu.org>:

https://gcc.gnu.org/g:3872da84760f827365fc0f8d1fdc45ca25810f89

commit r17-1405-g3872da84760f827365fc0f8d1fdc45ca25810f89
Author: Paul Thomas <pault@gcc.gnu.org>
Date:   Sun Jun 7 15:11:20 2026 +0100

    Fortran: require MODULE prefix for separate module procedures [PR121379]

    set_syms_host_assoc clears the 'external' attribute on module procedures
    when making them accessible via host association in a submodule.  The
    existing check in get_proc_name for a missing MODULE prefix used
    'sym->attr.external' as a guard, so the diagnostic was silently
    suppressed and gfortran accepted â and incorrectly linked â a bare
    function definition as if it were a valid separate module procedure.

    Replace 'sym->attr.external' with 'sym->attr.module_procedure', which is
    not cleared by set_syms_host_assoc, to restore the intended diagnostic.
    Also update the error message to be clearer about what is required.

    Both errors have been corrected to avoid returning any value, thereby
    avoiding an error cascade. After all, these are OK for further
    processing and argument mismatches etc. can be caught. Additionally, a
    number of existing testcases contained this error. In order to avoid
    masking the intended fix, this has been corrected in all cases.

    2026-06-07  Paul Thomas  <pault@gcc.gnu.org>

    gcc/fortran
            PR fortran/121379
            * decl.cc (get_proc_name): Use module_procedure attr. instead
            of external to guard the missing-MODULE-prefix diagnostic. Use
            gfc_error_now and do not return, so that an error cascade does
            not occur.

    gcc/testsuite/ChangeLog
            PR fortran/121379
            * gfortran.dg/pdt_59.f03: Add module attribute as required.
            * gfortran.dg/pr87907.f90: Ditto.
            * gfortran.dg/pr93461.f90: Ditto.
            * gfortran.dg/submodule_10.f08: Ditto.
            * gfortran.dg/submodule_33.f08: Ditto.
            * gfortran.dg/submodule_36.f90: New test.
            * gfortran.dg/submodule_37.f90: Add module attribute.

    Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>