Reproduction
These are the precise steps I took, using this code @ b6e7e4a6462644d83642ef2b1fae0a937c2fb339 : 1. With working directory in 'bpm.c/', start GUI Emacs in the background with `emacs &`
2. Enter `C-x 3` to get vertical split, click into the right window, and enter `C-x 2`.
3. From there, `M-x shell` to get a shell (zsh) in the bottom right corner.
4. Click into top right corner, `C-x C-f inc/parser.h`
5. Click into left half, `C-x C-f src/parser.c`
6. Append `// Continue checking if line is a comment (`.
Emacs will hang, not showing `(` or responding to clicks, commands, or GUI interaction.
I had to `kill -9` it to get rid of it completely.
ps -a shows stat of emacs as RNl
$ uname -a
Linux workstation 4.19.1-arch1-1-ARCH #1 SMP PREEMPT Sun Nov 4 16:49:26 UTC 2018 x86_64 GNU/Linux
Thank you for looking into this.