Rustdoc label badge for notable traits by ThierryBerger · Pull Request #157058 · rust-lang/rust

ThierryBerger · 2026-05-28T12:04:38Z

Part of Tracking Issue for doc_label_trait #156865
reuse notable trait feature to feed badge data
render it in html
add some html tests
Render a color from a hash from its full path
fixed oklch hue-driven palette checked against wcag/apca

Should the following be out of scope ?

Parse color (#[doc(notable_trait(color="0xff0000")])
display a small colored indicator (with a hover/first letter?) when a type implementing a notable trait is listed outside of its main page
Some Integration with rust analyzer

Color discussion

I went for the higher chroma, even though some values use a fallback, I'm not opposed to go for a less chromatic palette, but that's very bikeshedding so I'll defer to authority.

with chroma 0.21:

with chroma 0.090:

History

Initially, this PR added a new feature "label_trait", it was then decided in rustdoc meeting to reuse current notable_trait feature.

rustbot · 2026-05-28T12:04:42Z

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @lolbinarycat

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

rustbot · 2026-05-28T12:04:45Z

r? @fmease

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rustdoc expanded to 9 candidates
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GuillaumeGomez · 2026-05-28T15:28:17Z

Render a color from a hash from DefId -> ⚠️ is that an issue? color won't be stable between releases.

I would generated the color hash from the trait path (so crate::Trait for current crate, etc). Like that it will be stable across releases.

GuillaumeGomez · 2026-05-28T15:35:16Z

+
+    let Some(impls) = cx.cache().impls.get(&did) else { return Vec::new() };
+
+    let mut out: Vec<LabelTraitInfo> = impls


Instead of using a Vec, would be better to use a BTreeMap. It's sorted on insert and prevents duplications.

View changes since the review

I changed to do that but then collect it to Vec, keeping this discussion opened as I'm not sure if you meant something else.

Veykril

Could you remove the two rust-analyzer changes please? They don't do anything as is so they will likely cause unnecessary conflicts for us

View changes since this review

GuillaumeGomez · 2026-06-29T12:10:36Z

+                // Evenly-spaced OKLCH hues at fixed light/chroma.
+                const BADGE_HUES: u64 = 8;
+                let hue = (h.finish() % BADGE_HUES) * 360 / BADGE_HUES;
+                let style_attr = format!("style=\"background: oklch(0.55 0.21 {hue})\"");


Please create CSS classes instead. We can iterate over the color of each class later on.

View changes since the review

By that I mean: you can put the current colors in the newly created CSS classes. There should be 6 colors from what we wrote in the rustdoc meeting, so 6 different CSS classes.

GuillaumeGomez

We're getting close to something finalized, great work! Once my comments have been resolved, let's see together for the color selection for each themes.

View changes since this review

rustbot · 2026-06-29T12:16:46Z

Reminder, once the PR becomes ready for a review, use @rustbot ready.

rustbot · 2026-06-29T21:05:28Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

GuillaumeGomez · 2026-06-30T21:04:00Z

+    name: String,
+    full_path: String,
+    /// Relative URL to the trait page, or `None` when not linkable.
+    href: Option<String>,


If the trait is not linkable, we should not generate a badge for it (I mentioned that here).

View changes since the review

By that I mean: you can put the current colors in the newly created CSS classes. There should be 6 colors from what we wrote in the rustdoc meeting, so 6 different CSS classes.

it does, yes ; we should probably decide what to do about the notable trait visibility on function return type to align behaviors ? I'd say keep it consistent and then unify behavior on a follow up pr ? But no strong feeling, can do here, I just fear controversial discussions on tangantial changes :p

rustbot assigned fmease May 28, 2026

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ThierryBerger commented May 28, 2026

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ThierryBerger commented May 28, 2026

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ThierryBerger commented May 28, 2026

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Comment thread src/doc/unstable-book/src/language-features/doc-label_trait.md Outdated

ThierryBerger commented May 28, 2026

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ThierryBerger commented May 28, 2026

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Comment thread compiler/rustc_feature/src/unstable.rs Outdated