bug#54667: 29.0.50; posix_spawn breaks emacs-gdb

[Robert Pluim]

>>>>> On Fri, 1 Apr 2022 12:51:43 +0200, Herman@debbugs.gnu.org, Géza 
>>>>> <geza.herman@gmail.com> said:

    Herman> There's a gdb frontend: https://github.com/weirdNox/emacs-gdb
    Herman> With the emacs commit "a60053f836 Use posix_spawn if possible.",
    Herman> emacs-gdb doesn't work properly: when starting an executable, gdb 
says
    Herman> that it's running, but in reality, it doesn't start. The process
    Herman> itself is started, gdb attaches to it, but the process still not run
    Herman> for some reason.

    Herman> You can reproduce this:
    Herman> 1. install emacs-gdb
    Herman> 2. M-x gdb-executable, enter any executable, like "/bin/ls". 
emacs-gdb
    Herman> should open a new frame.
    Herman> 3. Then press f5 (this executes gdb-run-or-continue), this should
    Herman> start the process in gdb.

    Herman> Before the mentioned commit, this worked, and "ls" was run
    Herman> properly. But with this commit, "ls" isn't started.

    Herman> I checked this with a recent master
    Herman> (bd5d136777ef30f36807c7e690413846ed38fce1), and still happens. 
Adding

    Herman> #undef USABLE_POSIX_SPAWN
    Herman> #define USABLE_POSIX_SPAWN 0

    Herman> to callproc.c at line 49 fixes the issue.

Thereʼs a patch from Jürgen Hötzel in <86o82mvybj.fsf@hoetzel.info> on
emacs-devel that should fix it (I haven't had a chance to fully test
it).

Robert
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