[Bug bootstrap/92008] Build failure on cygwin

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92008

--- Comment #14 from CVS 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:437eea66a4b010d8e94aa81c2b40ccf0588e5fab

commit r10-7752-g437eea66a4b010d8e94aa81c2b40ccf0588e5fab
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Apr 16 11:55:00 2020 +0200

    intl: Unbreak intl build with bison 3 when no regeneration is needed
[PR92008]

    As Iain reported, my change broke the case when one has bison >= 3,
    but make decides there is no reason to regenerate plural.c, unfortunately
    that seems to be a scenario I haven't tested.  The problem is that
    the pregenerated plural.c has been generated with bison 1.35, but when
    config.h says HAVE_BISON3, the code assumes it is the bison3 variant.
    What used to work fine is when one has bison >= 3 and plural.c has been
    regenerated (e.g. do touch intl/plural.y and it will work), or when
    one doesn't have any bison (then nothing is regenerated, but HAVE_BISON3
    isn't defined either), or when one has bison < 3 and doesn't need to
    regenerate, or when one has bison < 3 and it is regenerated.

    The following patch fixes this, by killing the HAVE_BISON3 macro from
    config.h, and instead remembering the fact whether plural.c has been
created
    with bison < 3 or bison >= 3 in a separate new plural-config.h header.
    The way this works:
    - user doesn't have bison
    - user has bison >= 3, but intl/{plural-config.h,plural.c} aren't older
than intl/plural.y
    - user has bison < 3, but intl/{plural-config.h,plural.c} aren't older than
intl/plural.y
            pregenerated !USE_BISON3 plural.c and plural-config.h from source
            dir is used, nothing in the objdir
    - user has bison >= 3 and intl/plural.y is newer
            Makefile generates plural.c and USE_BISON3 plural-config.h in the
            objdir, which is then used in preference to srcdir copies
    - user has bison < 3 and intl/plural.y is newer
            Makefile generates plural.c and !USE_BISON3 plural-config.h in the
            objdir, which is then used in preference to srcdir copies
    I have tested all these cases and make all-yes worked in all the cases.
    If one uses the unsupported ./configure where srcdir == objdir, I guess
    (though haven't tested) that it should still work, just it would be nice
    if such people didn't try to check in the plural{.c,-config.h} they have
    regenerated.
    What doesn't work, but didn't work before either (just tested gcc-9 branch
    too) is when one doesn't have bison and plural.y is newer than plural.c.
    Don't do that ;)

    2020-04-16  Jakub Jelinek  <jakub@redhat.com>

            PR bootstrap/92008
    intl/
            * configure.ac: Remove HAVE_BISON3 AC_DEFINE.
            * Makefile.in (HEADERS): Add plural-config.h.
            (.y.c): Also create plural-config.h.
            (dcigettext.o loadmsgcat.o plural.o plural-exp.o): Also depend
            on plural-config.h.
            (plural-config.h): Depend on plural.c.
            * plural-exp.h: Include plural-config.h.  Use USE_BISON3 instead
            of HAVE_BISON3.
            * plural.y: Use USE_BISON3 instead of HAVE_BISON3.
            * configure: Regenerated.
            * plural.c: Regenerated.
            * config.h.in: Regenerated.
            * plural-config.h: Generated.
    contrib/
            * gcc_update: Add intl/plural.y dependency for
intl/plural-config.h.