Ligatures partially disappear over a line break

[kalaleq]

Here's a fun little issue - apologies if it's already covered elsewhere, but i searched and didn't see anything.

With the default logical line wrapping on, using Fira Code Retina, if the line splits in the middle of a ligature, the left part of the ligature (at the end of the first line) disappears entirely, and only the right part of the ligature at the start of the second line is visible.

This is true with ligatures involving more than two characters; whatever part(s) of the ligature are before the break will disappear and only the part(s) after the break will show.

In the attached example, the ligature "&&" effectively shows as a space on the second line and a "&" on the third line.

I also installed Cascadia Code to test. Interestingly, with Cascadia code it's the right side of the ligatures that disappears, so the start of the ligature shows on the first line, and a blank space appears on the next.

[mickeynp]

This is a display engine bug, and you should M-x report-emacs-bug. Ligature.el merely primes the display engine, it does no rendering of its own.