Support font shaping in terms of ligatures
I started to track this particular font shaping feature in a new gist: https://gist.github.com/XVilka/070ed8b1c1186097cad65ef49220175a There exists an old bug https://bugzilla.gnome.org/show_bug.cgi?id=584160, but it's not particularly about ligatures, so I thought it might be helpful and easier to track separately.
So far the best example that handles them perfectly is kitty: https://github.com/kovidgoyal/kitty
FiraCode is one of the most used font for working with ligatures, so it's probably the best font to test the implementation with:
Another good example is Cascadia Code. And, of course, Iosevka:
Not particularily ligatures, but a good test case is also this article from JaneStreet about adding underlines or digits numbering using font shaping. The font sources available at GitHub repository. The online demo site is here.