bug#75275: 30.0.92; `make-thread` bug on macOS 15.2

["Gerd Möllmann" <gerd.moellmann@gmail.com>]

Stefan Kangas <stefankangas@gmail.com> writes:

> I have run into a bug with make-thread on macOS 15.2, running on an M2.
>
> I can reproduce the issue consistently both on emacs-30 and master by
> evaluating this in emacs -Q:
>
>     (make-thread (lambda () (sleep-for 1)) "bug")
>
> This leads to Emacs freezing up completely within a fraction of a
> second.  I have time to move point once or maybe twice before it gets
> non-responsive, let's say within a few tenths of a second.

Curious question: Do you see a beach ball?

> When I kill the process in the lldb window with Ctrl+C, I can get the
> following (this is on emacs-30):
>
>     frame #12: 0x0000000100403fec emacs`-[EmacsApp
> run](self=0x0000000156610fe0, _cmd="run") at nsterm.m:5938:7
>     frame #13: 0x00000001004024b0 emacs`ns_select_1(nfds=0,
> readfds=0x00000001708c26bc, writefds=0x00000001708c263c,
> exceptfds=0x0000000000000000, timeout=0x00000001708c2610,
> sigmask=0x0000000000000000, run_loop_only=NO) at nsterm.m:4954:3
>     frame #14: 0x000000010040202c emacs`ns_select(nfds=0,
> readfds=0x00000001708c26bc, writefds=0x00000001708c263c,
> exceptfds=0x0000000000000000, timeout=0x00000001708c2610,
> sigmask=0x0000000000000000) at nsterm.m:5006:10

I'm asking because of bug#72496. The part of the backtrace above reminds
me a bit of what I trued to describe in that bug: EmacsApp.run never
returning to ns_select_1. Can you see if it ever returns?