Ligature rendering sometimes renders with extra spacing

[LukeXuan]

I confirm that...

• I have searched the issue tracker, documentation, FAQ, Discourse, and Google, in case this issue has already been reported/resolved.
• I have read "How to Debug Issues", and will use it to provide as much information about this issue as possible.
• The issue can be reproduced on the latest available commit of Doom.
• The issue can be reproduced on a stable release of Emacs, such as 27, 28, or 29. (Unstable versions end in .50, .60, or .9x)

Expected behavior

Ligature should look normal

Current behavior

When I open emacs, sometimes this is what I see

Notice the extra spacing at the end of each ligature. This behavior happens regardless whether I configure ligature.el directly or through doom module.

Steps to reproduce

1. open Emacs
2. stare at the extra spacing

System Information

https://gist.github.com/LukeXuan/7e1f0edaca4fa8ac3328d6f16f69b276

[LukeXuan]

I reported in upstream earlier. Since then I tested a few days with only ligature.el and no doom emacs, and the problem didn't occur once. Unless I'm extremely unlucky, this seems like a emacs only issue.

Also, my font configure:

(setq doom-theme 'doom-one
      doom-font (font-spec :family "JetBrains Mono" :size 16 :weight 'medium)
      doom-symbol-font (font-spec :family "JetBrains Mono" :weight 'medium)
      doom-variable-pitch-font (font-spec :family "JetBrains Mono" :weight 'medium)
      doom-emoji-font (font-spec :family "JetBrainsMono NF" :weight 'medium))

[upbqdn]

This happens to me with Iosevka, and I can't figure out why either.

[hlissner]

I'm unable to reproduce this.

I'm on 31.0.50, so I thought this might be a 29.x thing, but I couldn't reproduce it in 29.1 either.

These are in vanilla Doom configs with the :ui ligatures module.

I'll keep investigating.

[hlissner]

Perhaps try unsetting doom-symbol-font, doom-variable-pitch-font, and doom-emoji-font.

(And please update Doom, from your M-x doom/info, you're a couple weeks behind; it's possible it was fixed in that time)

[LukeXuan]

No it's not fixed. This problem happened to me at least once this week (I update doom emacs weekly).

I can try disabling the other fonts and see if it works. The irritating thing is it doesn't happen everytime, just occasionally.

[LukeXuan]

Sadly the proposed fix doesn't solve the problem. It appears again today.

[LukeXuan]

Perhaps the problem is related to latex mode? LaTeX and coq are my daily drives. I feel like this issue usually happens after a few hours of latex sessions, but I'm not confident that's always the case.