Stabilize `rwlock_downgrade` library feature by connortsui20 · Pull Request #143191 · rust-lang/rust (original) (raw)

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Tracking Issue: #128203

Method to be stabilized:

impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> { pub fn downgrade(s: Self) -> RwLockReadGuard<'a, T> {} }

I would like to point out that my documentation comment is longer than ideal, but at the same time I don't really know how else to show why downgrade is actually necessary (instead of just unlocking and relocking). If anyone has ideas for making this more concise that would be great! I have made the documentation a bit more clear.

Stabilization report: #128203 (comment)

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rustbot added S-waiting-on-review

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Jun 29, 2025

This means that we can never go back to pthreads to back our locks, but that seems fine since the pthreads API has many issues around UB and movability.

@rfcbot merge

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Jul 1, 2025

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Team member @Amanieu has proposed to merge this. The next step is review by the rest of the tagged team members:

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Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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connortsui20 added a commit to connortsui20/rust that referenced this pull request

Jul 29, 2025

This commit is a purely cosmetic change to the documentation and ordering of items in the rwlock.rs file.

List of changes (lots of small things):

Clean up some of the existing field doc comments
Add documentation for every field in struct definitions
Consolidate related implementation blocks (1 implementation block per guard instead of 2)
Use the lifetime name 'rwlock instead of 'a
Reorder implementation blocks to be consistent across the entire file (follows the order ReadGuard, WriteGuard, MappedReadGuard, MappedWriteGuard`)
Move simple trait implementations to the bottom of the file
Rename the poison field in MappedRwLockWriteGuard to posion_guard`
Cut off comments at 100 columns
Update the documentation of downgrade to match https://github.com rust-lang/pull/143191

🔔 This is now entering its final comment period, as per the review above. 🔔

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

esote mentioned this pull request

Oct 11, 2025

📌 Commit 780319a has been approved by tgross35

It is now in the queue for this repository.

bors added the S-waiting-on-bors

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Oct 15, 2025

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request

Oct 15, 2025

…grade, r=tgross35

Stabilize rwlock_downgrade library feature

Tracking Issue: rust-lang#128203

Method to be stabilized:

impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
    pub fn downgrade(s: Self) -> RwLockReadGuard<'a, T> {}
}

Stabilization report: rust-lang#128203 (comment)

bors added a commit that referenced this pull request

Oct 15, 2025

Rollup of 5 pull requests

Successful merges:

#143191 (Stabilize rwlock_downgrade library feature)
#147000 (std: Add Motor OS std library port)
#147670 (some ErrorGuaranteed cleanups)
#147716 (Fix some comments)
#147718 (miri: use allocator_shim_contents codegen helper)

r? @ghost @rustbot modify labels: rollup

bors added a commit that referenced this pull request

Oct 15, 2025

Rollup of 5 pull requests

Successful merges:

#143191 (Stabilize rwlock_downgrade library feature)
#147000 (std: Add Motor OS std library port)
#147670 (some ErrorGuaranteed cleanups)
#147716 (Fix some comments)
#147718 (miri: use allocator_shim_contents codegen helper)

r? @ghost @rustbot modify labels: rollup

bors added a commit that referenced this pull request

Oct 15, 2025

Rollup of 11 pull requests

Successful merges:

#143191 (Stabilize rwlock_downgrade library feature)
#147444 (Allow printing a fully-qualified path in def_path_str)
#147527 (Update t-compiler beta nomination Zulip msg)
#147670 (some ErrorGuaranteed cleanups)
#147676 (Return spans out of is_doc_comment to reduce reliance on .span() on attributes)
#147708 (const mem::drop)
#147710 (Fix ICE when using contracts on async functions)
#147716 (Fix some comments)
#147718 (miri: use allocator_shim_contents codegen helper)
#147729 (ignore boring locals when explaining why a borrow contains a point due to drop of a live local under polonius)
#147742 (Revert unintentional whitespace changes to rustfmt-excluded file)

r? @ghost @rustbot modify labels: rollup

rust-timer added a commit that referenced this pull request

Oct 16, 2025

Rollup merge of #143191 - connortsui20:stabilize-rwlock-downgrade, r=tgross35

Stabilize rwlock_downgrade library feature

Tracking Issue: #128203

Method to be stabilized:

impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
    pub fn downgrade(s: Self) -> RwLockReadGuard<'a, T> {}
}

Stabilization report: #128203 (comment)

github-actions bot pushed a commit to rust-lang/miri that referenced this pull request

Oct 16, 2025

flip1995 pushed a commit to flip1995/rust-clippy that referenced this pull request

Oct 18, 2025

github-actions bot pushed a commit to model-checking/verify-rust-std that referenced this pull request

Nov 30, 2025

…grade, r=tgross35

Stabilize rwlock_downgrade library feature

Tracking Issue: rust-lang#128203

Method to be stabilized:

impl<'a, T: ?Sized> RwLockWriteGuard<'a, T> {
    pub fn downgrade(s: Self) -> RwLockReadGuard<'a, T> {}
}

Stabilization report: rust-lang#128203 (comment)

github-actions bot pushed a commit to model-checking/verify-rust-std that referenced this pull request

Nov 30, 2025

…iaskrgr

Rollup of 11 pull requests

Successful merges:

rust-lang#143191 (Stabilize rwlock_downgrade library feature)
rust-lang#147444 (Allow printing a fully-qualified path in def_path_str)
rust-lang#147527 (Update t-compiler beta nomination Zulip msg)
rust-lang#147670 (some ErrorGuaranteed cleanups)
rust-lang#147676 (Return spans out of is_doc_comment to reduce reliance on .span() on attributes)
rust-lang#147708 (const mem::drop)
rust-lang#147710 (Fix ICE when using contracts on async functions)
rust-lang#147716 (Fix some comments)
rust-lang#147718 (miri: use allocator_shim_contents codegen helper)
rust-lang#147729 (ignore boring locals when explaining why a borrow contains a point due to drop of a live local under polonius)
rust-lang#147742 (Revert unintentional whitespace changes to rustfmt-excluded file)

r? @ghost @rustbot modify labels: rollup

Stabilize rwlock_downgrade library feature by connortsui20 · Pull Request #143191 · rust-lang/rust (original) (raw)

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Stabilize `rwlock_downgrade` library feature by connortsui20 · Pull Request #143191 · rust-lang/rust (original) (raw)