bug#74981: 29.4; X11 crash when minibuffer text scale is increased greatly

bug#74981: 29.4; X11 crash when minibuffer text scale is increased greatly

[Joseph Turner via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Tested on two window managers, exwm and dwm, with emacs -Q:

Open the minibuffer, e.g., with M-x eval-expression.  Run
text-scale-adjust with C-x C-=. The minibuffer text gets
bigger. Repeatedly press C-= until X11 crashes, bringing you back to the
login prompt.

In GNU Emacs 29.4 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.41,
cairo version 1.18.0)
Windowing system distributor 'The X.Org Foundation', version 11.0.12101007
System Description: Debian GNU/Linux 12 (bookworm)

Configured using:
 'configure
 CONFIG_SHELL=/gnu/store/3jhfhxdf6v5ms10x5zmnl166dh3yhbr1-bash-minimal-5.1.16/bin/bash
 SHELL=/gnu/store/3jhfhxdf6v5ms10x5zmnl166dh3yhbr1-bash-minimal-5.1.16/bin/bash
 --prefix=/gnu/store/9kbz86680cd5m7m7qz5vj7q6kc994rrj-emacs-29.4
 --enable-fast-install --with-cairo --with-modules
 --with-native-compilation=aot --disable-build-details'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GPM GSETTINGS HARFBUZZ JPEG
JSON LCMS2 LIBOTF LIBSELINUX LIBSYSTEMD LIBXML2 M17N_FLT MODULES
NATIVE_COMP NOTIFY INOTIFY PDUMPER PNG RSVG SECCOMP SOUND SQLITE3
THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER X11 XDBE XIM XINPUT2 XPM
GTK3 ZLIB

Important settings:
  value of $EMACSLOADPATH: /home/joseph/.guix-extra-profiles/emacs/emacs/share/emacs/site-lisp:/gnu/store/9kbz86680cd5m7m7qz5vj7q6kc994rrj-emacs-29.4/share/emacs/29.4/lisp
  value of $EMACSNATIVELOADPATH: /home/joseph/.guix-extra-profiles/emacs/emacs/lib/emacs/native-site-lisp
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

bug#74981: 29.4; X11 crash when minibuffer text scale is increased greatly

[Eli Zaretskii]

> Date: Thu, 19 Dec 2024 14:06:59 -0800
> From:  Joseph Turner via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Tested on two window managers, exwm and dwm, with emacs -Q:
> 
> Open the minibuffer, e.g., with M-x eval-expression.  Run
> text-scale-adjust with C-x C-=. The minibuffer text gets
> bigger. Repeatedly press C-= until X11 crashes, bringing you back to the
> login prompt.

Thanks.

I can't reproduce this, but I'm not on X11.  What happens here is that
after many "C-x C-= C-=" presses, the minibuffer (whose contents
becomes illegible long before that) starts blinking, and I need to C-g
out of it (or C-x C-c to kill Emacs).  This seems harmless enough,
since the enlarged font is not useful past the point where the
minibuffer no longer shows the minibuffer text.

Can you run this under GDB, and when Emacs crashes, type

  (gdb) thread apply all bt

and post everything GDB produces as result?