[Bug c++/110808] [modules] Internal Compiler Error in check_mergeable_decl

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110808

--- Comment #2 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathaniel Shead <nshead@gcc.gnu.org>:

https://gcc.gnu.org/g:7f24446a3cf67d1346c78b4667fba74b73a23302

commit r14-6977-g7f24446a3cf67d1346c78b4667fba74b73a23302
Author: Nathaniel Shead <nathanieloshead@gmail.com>
Date:   Fri Nov 24 16:26:43 2023 +1100

    c++: Follow module grammar more closely [PR110808]

    This patch cleans up the parsing of module-declarations and
    import-declarations to more closely follow the grammar defined by the
    standard.

    For instance, currently we allow declarations like 'import A:B', even
    from an unrelated source file (not part of module A), which causes
    errors in merging declarations. However, the syntax in [module.import]
    doesn't even allow this form of import, so this patch prevents this from
    parsing at all and avoids the error that way.

    Additionally, we sometimes allow statements like 'import :X' or
    'module :X' even when not in a named module, and this causes segfaults,
    so we disallow this too.

            PR c++/110808

    gcc/cp/ChangeLog:

            * parser.cc (cp_parser_module_name): Rewrite to handle
            module-names and module-partitions independently.
            (cp_parser_module_partition): New function.
            (cp_parser_module_declaration): Parse module partitions
            explicitly. Don't change state if parsing module decl failed.
            (cp_parser_import_declaration): Handle different kinds of
            import-declarations locally.

    gcc/testsuite/ChangeLog:

            * g++.dg/modules/part-hdr-1_c.C: Fix syntax.
            * g++.dg/modules/part-mac-1_c.C: Likewise.
            * g++.dg/modules/mod-invalid-1.C: New test.
            * g++.dg/modules/part-8_a.C: New test.
            * g++.dg/modules/part-8_b.C: New test.
            * g++.dg/modules/part-8_c.C: New test.

    Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>