bug#75199: 30.0.93; Emacs crashes when completing with corfu

[Eli Zaretskii <eliz@gnu.org>]

> From: Zhengyi Fu <i@fuzy.me>
> Cc: Po Lu <luangruo@yahoo.com>,  75199@debbugs.gnu.org
> Date: Mon, 30 Dec 2024 23:04:44 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > I don't understand how 'event', which was 0x7fffffffba70 in
> > x_error_handler became a NULL pointer inside x_error_quitter, which
> > x_error_handler calls.
> >
> > Po Lu, any ideas?
> >
> > Zhengyi Fu, can you configure Emacs 30.0.93 with --enable-checking and
> > compile it with -O0, and see if you get more detailed diagnostics?
> >
> > Also, does disabling the X input method help in any way?  (I see you
> > are using fcitx.)
> 
> This the backtrace I got after rebuilding Emacs with --enable-checking
> and -O0 and disabling fcitx:
> 
> 
> (gdb) r
> Starting program: /home/zhengyi/src/emacs/src/emacs -Q -l \~/.emacs.d/straight/repos/corfu/corfu.el
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library "/lib64/libthread_db.so.1".
> [New Thread 0x7ffff1bfe6c0 (LWP 58332)]
> [New Thread 0x7ffff126e6c0 (LWP 58333)]
> [New Thread 0x7fffebfff6c0 (LWP 58334)]
> [New Thread 0x7fffeb66f6c0 (LWP 58335)]
> [Detaching after vfork from child process 58338]
> [Detaching after vfork from child process 58343]
> [Detaching after vfork from child process 58350]
> [Detaching after vfork from child process 58351]
> [Detaching after vfork from child process 58352]
> [Detaching after vfork from child process 58353]
> [Detaching after vfork from child process 58357]
> [Detaching after vfork from child process 58361]
> [Detaching after vfork from child process 58366]
> [Detaching after vfork from child process 58370]
> [Detaching after vfork from child process 58374]
> [Detaching after vfork from child process 58379]
> 
> Thread 1 "emacs" hit Breakpoint 1, x_error_quitter (display=0x104d5d0, event=0x7fffffffb8c0) at xterm.c:27111
> 27111	  if (event->error_code == BadName)

Thanks, but now it doesn't seem to be a crash?  What is the value of
event->error_code?

Earlier you wrote:

> The error is probably caused by the width value of 0 passed to 
> XCreatePixmapFromBitmapData().
> 
> It seems gui_intersect_rectangles() returns true even if the resulted 
> rectangle is empty.  Is that correct behavior?

Can you tell how this happens?  Is corfu doing something special with
the fringes?