Subject: bug#43177: Bug: Emacs 27.1 hangs forever in `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1'

From: Robert Pluim <[email-masked]>
Date: Thu, 03 Sep 2020 09:28:23 +0200

>>>>> On Thu, 3 Sep 2020 09:18:53 +0200, Alexander Shukaev <[email-masked]> said:

    Alexander> Hi,
    Alexander> With latest Emacs, I have a sporadic hang issue when either opening a
    Alexander> file or scrolling a buffer.  The best part is that it's impossible to
    Alexander> get break back to evaluation loop of Emacs even with 'USR2'
    Alexander> signal. That is when 'USR2' is sent, it does show "Entering
    Alexander> debugger...", though it remains frozen afterwards.  Resending 'USR2'
    Alexander> leads to the same outcome.  One thing is for certain, every time
    Alexander> 'USR2' is sent into such a hang, the stack traceback leads to
    Alexander> `FcCharSetSubtractCount' from '/usr/lib/libfontconfig.so.1':

If you've still got this in gdb, can you go to frame #6 and do

pp entity

(this is assuming you've sourced the .gdbinit in src/)

That will tell us which font weʼre trying to open. Perhaps itʼs a bad
font or fontconfig configuration.

Robert