[Bug target/112397] Two persistent libstdc++ test failures on x86_64-apple-darwin

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112397

--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Iain D Sandoe
<iains@gcc.gnu.org>:

https://gcc.gnu.org/g:8c19cb9c6186b65f1858c91d423238a00ffe0c01

commit r11-11403-g8c19cb9c6186b65f1858c91d423238a00ffe0c01
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Thu Feb 8 17:54:31 2024 +0000

    libstdc++, Darwin: Handle a linker warning [PR112397].

    Darwin's linker warns when we make a direct branch to code that is
    in a weak definition (citing that if a different implementation of
    the weak function is chosen by the dynamic linker this would be an
    error).

    As the analysis in the PR shows, this can happen when we have hot/
    cold partitioning and there is an error path that is primarily cold
    but makes use of epilogue code in the hot section.  In this simple
    case, we can easily deduce that the code is in fact safe; however
    that is not something we can realistically implement in the linker.

    Since the user-replaceable allocators are implemented using weak
    definitions, this is a warning that is frequently flagged up in both
    the testsuite and end-user code.

    The chosen solution here is to suppress the hot/cold partitioning for
    these cases (it is unlikely to impact performance much c.f. the
    actual allocation).

            PR target/112397

    libstdc++-v3/ChangeLog:

            * configure: Regenerate.
            * configure.ac: Detect if we are building for Darwin.
            * libsupc++/Makefile.am: If we are building for Darwin, then
            suppress hot/cold partitioning for the array allocators.
            * libsupc++/Makefile.in: Regenerated.

    Signed-off-by: Iain Sandoe <iain@sandoe.co.uk>
    Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
    (cherry picked from commit 1609fdff16f17ead37666f6d0e801800ee3d04d2)