[Bug gdb/24069] gdb on OSX Mojave hangs in darwin_decode_message

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

https://sourceware.org/bugzilla/show_bug.cgi?id=24069

--- Comment #46 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Simon Marchi <simark@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9cca177baec32a1ed1422a87a1f57cda2d2eb21a

commit 9cca177baec32a1ed1422a87a1f57cda2d2eb21a
Author: Dominique Quatravaux <dominique.quatravaux@epfl.ch>
Date:   Wed Feb 16 09:15:39 2022 -0500

    gdb/darwin: remove not-so-harmless spurious call to `wait4`

    As seen in https://sourceware.org/bugzilla/show_bug.cgi?id=24069 this
    code will typically wait4() a second time on the same process that was
    already wait4()'d a few lines above. While this used to be
    harmless/idempotent (when we assumed that the process already exited),
    this now causes a deadlock in the WIFSTOPPED case.

    The early (~2019) history of bug #24069 cautiously suggests to use
    WNOHANG instead of outright deleting the call. However, tests on the
    current version of Darwin (Big Sur) demonstrate that gdb runs just fine
    without a redundant call to wait4(), as would be expected.
    Notwithstanding the debatable value of conserving bug compatibility with
    an OS release that is more than a decade old, there is scant evidence of
    what that double-wait4() was supposed to achieve in the first place - A
    cursory investigation with `git blame` pinpoints commits bb00b29d7802
    and a80b95ba67e2 from the 2008-2009 era, but fails to answer the
    "why" question conclusively.

    Co-Authored-By: Philippe Blain <levraiphilippeblain@gmail.com>
    Change-Id: Id4e4415d66d6ff6b3552b60d761693f17015e4a0

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