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yeslogic / allsorts

Font parser, shaping engine, and subsetter implemented in Rust
https://yeslogic.com/blog/allsorts-rust-font-shaping-engine/
Apache License 2.0
706 stars 23 forks source link

Make allsorts run on no_std #42

Closed fschutt closed 2 years ago

fschutt commented 3 years ago

This is necessary to have a font shaper for embedded environments.

NOTE: WIP PR, some dependencies do not yet have no_std support, also compiling fails currently

TODO LIST:

fschutt commented 3 years ago

Okay, now everything should at least compile on no_std - I am still not 100% sure about the brotli decoder and the zlib decoder - they compile, but they probably don't work yet (i.e. they'll just emit a ParseError). As far as I can see, the brotli decoder needs a custom memory allocator and the API for that is very cumbersome.

Since rental is not maintained anymore, I've published a fork with a custom feature that allows rental to run on no_std. I've not removed it because it's good for what it does.

Aaron1011 commented 2 years ago

EDIT - I mistakenly thought that @fschutt was part of the yeslogic organization. cc @adrianwong @brendanzab @wezm - the comment below concerns the allsorts-rental crate.

strike>@fschutt</strike Would it be possible for you to make a new release of allsorts-rental that include this commit from rental: https://github.com/jpernst/rental/commit/61188eb97f5d99b10fc1fdd469b259c4ab4bf940. Doing so will allow allsorts-rental to continue to compile in future versions of Rust (after a backwards-compatibility hack is removed: https://github.com/rust-lang/rust/issues/83125).

Background: It looks like this PR (or something based off of it) was published to crates.io as allsorts_no_std. It was then added as a dependency by https://github.com/fschutt/rust-fontconfig, which is used by https://github.com/LtPeriwinkle/mist.

Unfortunately, once the backwards-compatibility hack https://github.com/rust-lang/rust/issues/83125 is removed from rustc, these crates will stop compiling. The simplest way to keep everything compiling would be to make a new point release of allsorts-rental that includes https://github.com/jpernst/rental/commit/61188eb97f5d99b10fc1fdd469b259c4ab4bf940. Specifically, all of the commas added by that commit need to present (they were previously 'generated' by rustc itself, and the rental proc-macro expects them to exist).

Feel free to ask me if you have any questions about this. Thank you for your time.

wezm commented 2 years ago

Hi @Aaron1011 we (YesLogic) don't own the allsorts-rental and allsorts_no_std crates. It would be great if @fschutt could edit the READMEs and crate metadata to make this clearer but they seem to be busy.

fschutt commented 2 years ago

Yeah, this PR is pretty old now, I think this can be closed for now. My original effort to make allsorts run on no_std was relatively pointless anyway, I wanted to reduce the binary size of azul, but in the end it's easier to use the upstream allsorts in order to not miss out on bugfixes. I could maybe rebase + re-publish (most of the PR is just replacing std::String with alloc::String), but I'm extremely busy atm.

The reason I like no_std crates is not just because of size, but also because of security. I can be relatively certain that allsorts doesn't contain malicious code if it runs on no_std and it just does font parsing. The more no_std, the better.

Yes, I did publish it as allsorts-no-std, since I needed an intermediate solution, but right now I am back to using the regular allsorts crate since I didn't manage to make azul run on no-std anyway (it needs access to the file system to load fonts + access to the windowing system).

The allsorts-rental is just a fork of the rental crate, since that crate was (is?) unmaintained.

wezm commented 2 years ago

Yes, I did publish it as allsorts-no-std, since I needed an intermediate solution

Any chance you could publish a new point release that changes the repo links etc. in the Cargo.toml and README to not point at our repo? A note about maintenance status and that it's fork would be super helpful for avoiding confusion too.

Aaron1011 commented 1 year ago

@fschutt Would you be able to publish that point release? It would be a big help in removing the back-compat hack from rustc.

fschutt commented 1 year ago

What back-compat hack? And yeah, sorry about not publishing a release, I forgot, sorry.

wezm commented 1 year ago

What back-compat hack?

I think it was this one from Aaron1011's comment:

the backwards-compatibility hack rust-lang/rust#83125

Aaron1011 commented 1 year ago

@fschutt Sorry to keep bothering you - would you be able to publish that release? It would be a huge help in removing the backward-compatibility hack from rustc.