font-patcher: Cover alternate unicode encodings

[nathanielevan]

Description

[why]
As described in this comment, issue #400 recently reoccurred with the latest build of Input font, and it turns out the dotless-j part of the small j now points to U+0237, which in turn has an alternate unicode encoding to U+F6BE; overwriting U+F6BE effectively overwrites U+0237, and in turn, alters the small j. This patch aims to fix that.

[how]
In addition to references, the patcher also checks for alternate unicode encodings which are returned by the glyph.altuni attribute, adds those to the essential set of glyphs, and in turn recursively searches for their references/alternate unicode encodings, making sure to handle circular references if they appear (for example: U+2010 and U+2011 in Input Mono).

Fixes: #400

Requirements / Checklist

• Read the Contributing Guidelines
• Verified the license of any newly added font, glyph, or glyph set

What does this Pull Request (PR) do?

Make font-patcher also check for alternate unicode encodings in addition to references so they won't be overwritten.

How should this be manually tested?

Input Mono so far is the only font I've had this issue with, and this patch successfully prevents font-patcher from overwriting or altering those essential glyphs, but should work with most if not all fonts.

What are the relevant tickets (if any)?

#400

[Finii]

Thanks for reporting and of course for the nice PR!
Really appreciate the commit style 🎉 etc.

I will have a closer look at the weekend.

[Finii]

I wonder if the altuni part needs to be handled at all in self.essential, of if the check while patching should be "check if this glyph's codepoint or any of its alternative codepoints is in essential".

But then, that would probably be more work because we need to check more often. And the altuni bindings will not go away or something, so yes, probably this is best.

[Finii]

This looks good, thank you.

Feel free to add some more comment in the code and/or use list comprehension if you like 😬

Tell me if I shall merge or if you want to add something before.
Again your commit style and the thought you put into this 👍 💚

[Finii]

Ah I forgot, would be good to increase the script version.

[nathanielevan]

Done! Let me know if you have any more recommendations, or whether I introduced bugs etc

[Finii]

Did you test it with Input? I do not have that avail right away 😬

Looks very good ❤️

[nathanielevan]

I did, and the glyph that was previously broken seems to have been fixed! But if you do have the font in hand you might want to test it just to make sure I didn't mess anything up. If you do decide to merge, you'd want to change the version number as it's now outdated -- that's where the branch conflict is from

[Finii]

Rebase on master, force push

[Finii]

Tried to switch this to some kind of tail-recursion, but the code will end up very ugly.

Also noticed that Input Mono indeed contains refs and alt-codes in the extended latin range.

Very nice code and PR, thanks again.

[nathanielevan]

Sweet! I basically rely on Nerd Fonts for my day-to-day computer usage, so a little code is the least I can give back. Should I invoke the contributors bot as described here?

[Finii]

*lauch* yes please, I just searched for that syntax also, to add you :-)

[Finii]

Hey @all-contributors please add @nathanielevan for code

[allcontributors]

@Finii

I've put up a pull request to add @nathanielevan! 🎉

[Finii]

I'm not very knowledgeable with Python

To be honest .. I really struggle to take Python seriously, and Nerd Fonts is the only project where I actually use it.

🤔 No, meson uses it also I and contributed there. But not much.

[Finii]

Thinking... Hope my release workflow will not break, because we added your contributor commit.
There was a problem when the repo is touched after the release has been started 🤔 😒
Wanted to save time by not always pulling again before pushing.
Lets see...
https://github.com/ryanoasis/nerd-fonts/actions/runs/3984511030

[Finii]

😭