[Bug c++/124417] [reflection] constexpr exceptions v. -fno-exceptions

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124417

--- Comment #6 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:f233f787c2cef68282976cc6a507eba4e62827cb

commit r16-7996-gf233f787c2cef68282976cc6a507eba4e62827cb
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Mar 11 07:54:36 2026 +0100

    c++: Emit error if not quiet and set *non_constant_p for -fno-exceptions
metafn error cases [PR124417]

    For -fno-exceptions, we reject throw statements in the source, and a lot
    of code in the header has #ifdef __cpp_exceptions guarded stuff and the
    FE for !flag_exceptions doesn't emit some parts of the IL needed for
    exceptions.  For the errors in metafns, we had just a todo to handle it
    in the source but no actual implementation, so we allowed throwing
    an exception and sometimes it worked to some extent and sometimes
    it didn't.

    The following patch fixes it by not throwing an exception if user
    asked for -fno-exceptions - instead we just emit an error including
    the planned what () (unless ctx->quiet) and make the evaluation
    non-constant.

    2026-03-11  Jakub Jelinek  <jakub@redhat.com>

            PR c++/124417
            * reflect.cc (get_meta_exception_object): Add CTX argument.  For
            !flag_exceptions emit error unless ctx->quiet, set *non_constant_p
            to true and return NULL_TREE instead of throwing an exception.
            (throw_exception): Adjust get_meta_exception_object caller.

            * g++.dg/reflect/no-exceptions1.C: New test.

    Reviewed-by: Jason Merrill <jason@redhat.com>