[Bug target/107998] [13 Regression] gcc-13-20221204 failure to build on Cygwin No dirname for option: m32

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107998

--- Comment #23 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Yong <jyong@gcc.gnu.org>:

https://gcc.gnu.org/g:e3f8dfcd885d19d322b10fb4e36d50b60da2576b

commit r13-6578-ge3f8dfcd885d19d322b10fb4e36d50b60da2576b
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Feb 22 10:25:04 2023 +0100

    cygwin: Don't try to support multilibs [PR107998]

    As discussed in the PR, t-cygwin-w64 file has been introduced in 2013
    and has one important problem, two different multilib options -m64 and
-m32,
    but MULTILIB_DIRNAMES with just one word in it.
    Before the genmultilib sanity checking was added, my understanding is that
    this essentially resulted in effective --disable-multilib,
    $ gcc -print-multi-lib
    .;
    ;@m32
    $ gcc -print-multi-directory
    .
    $ gcc -print-multi-directory -m64
    .
    $ gcc -print-multi-directory -m32

    $ gcc -print-multi-os-directory
    ../lib
    $ gcc -print-multi-os-directory -m64
    ../lib
    $ gcc -print-multi-os-directory -m32
    ../lib32
    and because of the way e.g. config-ml.in operates
    multidirs=
    for i in `${CC-gcc} --print-multi-lib 2>/dev/null`; do
      dir=`echo $i | sed -e 's/;.*$//'`
      if [ "${dir}" = "." ]; then
        true
      else
        if [ -z "${multidirs}" ]; then
          multidirs="${dir}"
        else
          multidirs="${multidirs} ${dir}"
        fi
      fi
    done
    dir was . first time (and so nothing was done) and empty
    second time, multidirs empty too, so multidirs was set to empty
    like it would be with --disable-multilib.

    With the added sanity checking the build fails unless --disable-multilib
    is used in configure (dunno whether people usually configure that way
    on cygwin).

    >From what has been said in the PR, multilibs were not meant to be
supported
    and e.g. cygwin headers probably aren't ready for it.

    So the following patch just removes the file with the (incorrect) multilib
    stuff instead of fixing it (say by setting MULTILIB_DIRNAMES to 64 32).

    I have no way to test this though, no Windows around, can anyone please
    test this?  I just would like to get some progress on the P1s we have...

    2023-02-22  Jakub Jelinek  <jakub@redhat.com>

    gcc/ChangeLog:

            PR target/107998
            * config.gcc (x86_64-*-cygwin*): Don't add i386/t-cygwin-w64 into
            $tmake_file.
            * config/i386/t-cygwin-w64: Remove.

    Signed-off-by: Jonathan Yong <10walls@gmail.com>