Use `impl` restrictions in `std`, `core` by jhpratt · Pull Request #157170 · rust-lang/rust

jhpratt · 2026-05-30T19:23:32Z

This should all be quite self-explanatory. I've used the tightest module permitted by current implementation, which is overwhelmingly self as I had expected.

r? @Urgau

fmease · 2026-05-30T19:47:22Z

 /// Trait to determine if a descriptor/handle refers to a terminal/tty.
 #[stable(feature = "is_terminal", since = "1.70.0")]
-pub trait IsTerminal: crate::sealed::Sealed {
+pub impl(crate) trait IsTerminal {


Don't we want to block this PR on rustdoc support?

IsTerminal is stable and AFAICT the docs don't mention anywhere that the trait is sealed, so if we were to merge your PR now, users would no longer know that the trait is sealed just by looking at the docs. That feels unfortunate.

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I'm not opposed to blocking it on such. I deliberately left any "this trait is sealed" comments for that reason. Once there's rustdoc support, all of those can be removed as well.

I don't think we need to wait for rustdoc as long as it's clear that the trait is sealed in the docs. We might have a rustdoc implementation soon enough¹ (EDIT: #157310).

I could also see a middleground and have both the Sealed trait and impl(..) restrictions.

Let's nominate it for T-libs to decide.

Footnotes

#t-rustdoc > Documenting `impl` restrictions ↩

We could temporarily add doc comments to each relevant trait.

jhpratt · 2026-05-30T22:59:31Z

CI will certainly fail again. x c core, x c std, and x c rustfmt all pass, but x t tidy fails at the rustfmt step. This is presumably due to the keyword order changing, but a bootstrap has taken place since that happened. What am I missing here?

Urgau · 2026-05-31T09:43:48Z

What am I missing here?

src/stage0 is still beta 1.96. It should be updated soon.

rustbot · 2026-05-31T21:00:07Z

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.

jhpratt · 2026-06-01T00:55:04Z

CI is now passing.

Urgau

Thanks for the PR. Looks good to me.

View changes since this review

Urgau · 2026-06-03T18:07:01Z

T-libs was +1 in the meeting and no objections to doing this were raised.

Let's go.

@bors r+
@rustbot labels -I-libs-nominated -S-waiting-on-t-libs

rust-bors · 2026-06-03T18:07:05Z

📋 This PR cannot be approved because it currently has the following label: S-waiting-on-t-libs.

Urgau · 2026-06-03T18:07:14Z

@bors r+

rust-bors · 2026-06-03T18:07:17Z

📌 Commit 0e69e90 has been approved by Urgau

It is now in the queue for this repository.

@clarfonthey

Rollup of 12 pull requests Successful merges: - #157085 (powerpc: warn against incorrect values for ABI-relevant target features) - #157170 (Use `impl` restrictions in `std`, `core`) - #157217 ([tiny] remove unecessary `.into()` calls) - #157262 (rustdoc: IXCRE: Preserve sizedness bounds on type params belonging to the parent item) - #157379 (Some more simple per-owner resolver changes) - #157381 (librustdoc: fix CSS border issue to support Firefox high contrast mode) - #155512 (interpreter: improve comments and error message in mir_assign_valid_types) - #157254 (Correct description of panic.rs) - #157290 (interpret: fix mir::UnOp layout computation) - #157332 (Rewrite target checking for `#[sanitize]`) - #157351 (Avoid leaking the query-job collection warning into the panic query stack) - #157389 (Add @clarfonthey to libs review rotation)

@Urgau

Rollup merge of #157170 - jhpratt:dogfood-restrictions, r=Urgau Use `impl` restrictions in `std`, `core` This should all be quite self-explanatory. I've used the tightest module permitted by current implementation, which is overwhelmingly `self` as I had expected. r? @Urgau

@clarfonthey

Rollup of 12 pull requests Successful merges: - rust-lang/rust#157085 (powerpc: warn against incorrect values for ABI-relevant target features) - rust-lang/rust#157170 (Use `impl` restrictions in `std`, `core`) - rust-lang/rust#157217 ([tiny] remove unecessary `.into()` calls) - rust-lang/rust#157262 (rustdoc: IXCRE: Preserve sizedness bounds on type params belonging to the parent item) - rust-lang/rust#157379 (Some more simple per-owner resolver changes) - rust-lang/rust#157381 (librustdoc: fix CSS border issue to support Firefox high contrast mode) - rust-lang/rust#155512 (interpreter: improve comments and error message in mir_assign_valid_types) - rust-lang/rust#157254 (Correct description of panic.rs) - rust-lang/rust#157290 (interpret: fix mir::UnOp layout computation) - rust-lang/rust#157332 (Rewrite target checking for `#[sanitize]`) - rust-lang/rust#157351 (Avoid leaking the query-job collection warning into the panic query stack) - rust-lang/rust#157389 (Add @clarfonthey to libs review rotation)

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jhpratt force-pushed the dogfood-restrictions branch 2 times, most recently from a6278c5 to 4bdbe8a Compare May 30, 2026 21:51

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jhpratt force-pushed the dogfood-restrictions branch from 4bdbe8a to ce88386 Compare May 30, 2026 22:56

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jhpratt mentioned this pull request May 30, 2026

Use impl restrictions over hand-sealed traits rust-lang/portable-simd#529

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Urgau added I-libs-nominated Nominated for discussion during a libs team meeting. S-waiting-on-t-libs Status: Awaiting decision from T-libs and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels May 31, 2026

fbstj reviewed May 31, 2026

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Comment thread library/core/src/marker/variance.rs

jhpratt added 2 commits May 31, 2026 16:59

Use impl restrictions in std

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Use impl restrictions in core

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jhpratt force-pushed the dogfood-restrictions branch from ce88386 to 478acf6 Compare May 31, 2026 21:00

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Update UI tests

0e69e90

Urgau approved these changes Jun 3, 2026

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rustbot removed I-libs-nominated Nominated for discussion during a libs team meeting. S-waiting-on-t-libs Status: Awaiting decision from T-libs labels Jun 3, 2026

rust-bors Bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Jun 3, 2026

jhpratt mentioned this pull request Jun 3, 2026

Rollup of 12 pull requests #157398

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rust-bors Bot merged commit feb69d6 into rust-lang:main Jun 3, 2026
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rustbot added this to the 1.98.0 milestone Jun 3, 2026

jhpratt deleted the dogfood-restrictions branch June 4, 2026 01:38

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