Enable the internal -x-lang CSS property

[Loirooriol]

The behavior of text-transform can be affected by the language of the text, e.g.

<div style="text-transform: uppercase">
  <span lang="tr">i</span> <!-- İ -->
  <span lang="en">i</span> <!-- I -->
</div>

Therefore, we need some way to track the language.

Gecko uses an internal -x-lang CSS property for that, so it seems a good idea to do the same (especially since we use the same style engine).

To do that,

1. Clone a fork of https://github.com/servo/stylo/
2. Enable -x-lang not just for gecko but also servo.
   https://github.com/servo/stylo/blob/7dd884031d6b97d801d50f8fcdff69bbeb292ae0/style/properties/longhands/font.mako.rs#L257-L266
3. Run cargo build --features servo to ensure it builds fine
4. Open a PR at https://github.com/servo/stylo/
5. Here in Servo, update Cargo.toml to take the various style-related crates from your PR. Compile, this will automatically update Cargo.lock. See 871e36f for reference.
6. In this case I don't expect anything to break, but otherwise you would need to do the changes necessary so that it still compiles fine.
7. Open a PR with the Servo changes, so that we can run the tests and ensure everything is fine. -x-lang is an internal property, so I don't expect any test to complain.
8. Then we can land the PR for Stylo
9. Then update the PR for Servo, reverting the changes from Cargo.toml, but bumping Cargo.lock to point to the new upstream rev. See 0935bf5 for reference.
10. Finally we can land the PR for Servo

[servo-highfive]

cc @emilio

[MunishMummadi]

@servo-highfive assign me

[servo-highfive]

Hey @MunishMummadi! Thanks for your interest in working on this issue. It's now assigned to you!

[MunishMummadi]

Hello @Loirooriol,

I encountered an error while trying to build:

munish@Zoro:~/servo$ cargo build --features servo
error: none of the selected packages contains these features: servo
munish@Zoro:~/servo$

I'm wondering if I've missed something. I added the necessary local paths of my stylo repo to cargo.toml and uncommented the patch.crates-io for stylo. Here's the change I made to stylo:

${helpers.predefined_type(
    "-x-lang",
    "XLang",
    engines="gecko",
    initial_value="computed::XLang::get_initial_value()",
    animation_value_type="none",
    enabled_in="servo",
    has_effect_on_gecko_scrollbars=False,
    spec="Internal (not web-exposed)",
)}

I greatly appreciate your time and would be grateful for any guidance you could provide.

[sandeepB3]

I think you have to replace engines="gecko" with engines="gecko servo", similar to other predefined_type like "font-family" to enable -x-lang for servo. But I think before that you may have to make some other modifications too, to properly support -x-lang for servo.

[MunishMummadi]

Thanks for input @sandeepB3 . I will consider your suggestions and I will try to modify them.

[mrobinson]

This is part of the Outreachy project, so please don't work on this one yet. Thank you!

[Rhea-Eve]

Opened PR for step 7. See mentions above.

[Loirooriol]

@MunishMummadi The cargo build --features servo should be run on the Stylo repository, not on Servo.

[MunishMummadi]

@mrobinson I am an outreachy applicant. @Loirooriol I did the things and everything is working fine. Can I push a PR.

[MunishMummadi]

@Rhea-Eve Thank you for working on an issue assigned to me. I literally sat overnight and failed.

[Loirooriol]

@MunishMummadi Martin meant to defer the bulk of the Outreachy project work for the actual internship after the contribution phase. But for something small like this I guess it's fine to do it now.

Anyways you were assigned first but @Rhea-Eve already posted the PRs, so maybe one of you can land the Stylo patch and the other the Servo patch?

[Rhea-Eve]

Sorry! @Loirooriol linked me to this issue on Zulip, and I misread Martin's comment to say that this was now open for others. Would be happy to work with you on this. Let me know if you have any questions about my code. :).

[MunishMummadi]

@Loirooriol thanks for the suggestion. Hey @Rhea-Eve can we discuss the details over Zulip. I can't find you in Zulip. can you ping me there!!!

[Rhea-Eve]

@MunishMummadi How about you do the Stylo PR? As this seems to be the part that you have already started on. Then after that gets merged, I can update the PR for Servo.

If you need help with fixing the issues in your PR, you can look at the Stylo PR I did (servo/stylo#23).

[MunishMummadi]

@Rhea-Eve Thanks for the heads up. I will be on it.

[MunishMummadi]

hey @Rhea-Eve . I made the PR based on your suggestion. can u review it.

[Rhea-Eve]

@MunishMummadi it seems like Oriol requested some changes. Once you make those, it looks good.