Use `drop_guard` in some places in {core,alloc,std} by GrigorenkoPV · Pull Request #161702 · rust-lang/rust

GrigorenkoPV · 2026-08-24T21:37:43Z

Tracking issue: Tracking Issue for core::mem::DropGuard #144426
Will conflict with Stabilize core::mem::DropGuard #161520
Add no-value DropGuard::new(|| ...) #161550 would also be cool occasionally

Didn't touch the places where manual impl Drops had #[inline] on their fn drop or where the guard type had other impls beside Drop and/or was named a lot.

No LLMs used, only pure human slop.

rustbot · 2026-08-24T21:37:48Z

r? @clarfonthey

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clarfonthey · 2026-08-25T02:15:45Z

The way the code was moved around makes this a bit more difficult to review, but otherwise, it looks good to me. Just a limitation of how diffs work.

I think this is a strict improvement regardless of stabilisation. I don't think this should require more than a rebase from Yosh, so, it should be fine that this conflicts with the stabilisation PR.

@bors r+ rollup

Thank you!

rust-bors · 2026-08-25T02:15:47Z

📌 Commit a5a9d5d has been approved by clarfonthey

It is now in the queue for this repository.

…they Use `drop_guard` in some places in {core,alloc,std} - Tracking issue: rust-lang#144426 - Will conflict with rust-lang#161520 - rust-lang#161550 would also be cool occasionally Didn't touch the places where manual `impl Drop`s had `#[inline]` on their `fn drop` or where the guard type had other `impl`s beside `Drop` and/or was named a lot. No LLMs used, only pure human slop.

Rollup of 9 pull requests Successful merges: - #160533 (dirfd dir operations (3/4)) - #161294 (add crashtests [6/N]) - #160392 (library: motor: bump moto-rt ABI ver to 17) - #161646 (interpret: fix after_local_read handling) - #160819 (Rework `div_ceil` for nonzero integers) - #161591 (run `classify-runtime-const` test for `f128`) - #161680 (renovate: add lockfile update warning) - #161702 (Use `drop_guard` in some places in {core,alloc,std}) - #161709 (Stop rustfmt deleting attributes in fn params)

JonathanBrouwer · 2026-08-25T05:04:55Z

💔 I suspect this PR failed tests as part of a rollup
@bors r-

After fixing the problem, consider running a try job for the failed job before re-approving.

Link to failure: #161715 (comment)

rust-bors · 2026-08-25T05:05:02Z

This pull request was unapproved.

This PR was contained in a rollup (#161715), which was unapproved.

View changes since this unapproval

GrigorenkoPV · 2026-08-25T09:40:07Z

@rustbot ready

yoshuawuyts · 2026-08-25T11:28:19Z

@GrigorenkoPV thank you for filing this PR; this is really cool to see and a very helpful reference for how DropGuard actually ends up working out in real codebases. I'm loving the 40% code reduction compared to manually creating guards for each instance. Imo it validates the usefulness of the API.

GrigorenkoPV · 2026-08-25T16:42:27Z

I'm loving the 40% code reduction compared to manually creating guards for each instance.

Not sure how accurate that metric is, but yeah, code reduction is definitely real.

It is especially nice to not have to write all the types out again for the struct fields. And the generics for both the struct and the Drop impl (since those cannot be reused from the outer scope; in one place the old approach even required a PhantomData just to capture one of the generic parameters, which, with this change, is not needed anymore).

Imo it validates the usefulness of the API.

Absolutely. I remember touching std (something to do with Drain or CloneUninit) at some point a few years ago and wondering why there was no "canonical" way to to scope guards.

rustbot · 2026-08-26T16:11:04Z

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.

clarfonthey · 2026-08-27T00:00:38Z

@bors try

…they Use `drop_guard` in some places in {core,alloc,std} - Tracking issue: rust-lang#144426 - Will conflict with rust-lang#161520 - rust-lang#161550 would also be cool occasionally Didn't touch the places where manual `impl Drop`s had `#[inline]` on their `fn drop` or where the guard type had other `impl`s beside `Drop` and/or was named a lot. No LLMs used, only pure human slop.

Rollup of 7 pull requests Successful merges: - #150075 (Implement clamp_to) - #161034 (Add SVE-accelerated Vec::retain_mut for aarch64) - #161628 (interpret: ensure that calls via no-unwind ABIs do not unwind) - #161012 (borrowck: Normalize non-rigid aliases in NLL type relating) - #161702 (Use `drop_guard` in some places in {core,alloc,std}) - #161813 (Change `is_eligible_for_coverage` from a hook to a query) - #161842 (chore: fix cargo lints)

…they Use `drop_guard` in some places in {core,alloc,std} - Tracking issue: rust-lang#144426 - Will conflict with rust-lang#161520 - rust-lang#161550 would also be cool occasionally Didn't touch the places where manual `impl Drop`s had `#[inline]` on their `fn drop` or where the guard type had other `impl`s beside `Drop` and/or was named a lot. No LLMs used, only pure human slop.

Rollup of 6 pull requests Successful merges: - #161034 (Add SVE-accelerated Vec::retain_mut for aarch64) - #161628 (interpret: ensure that calls via no-unwind ABIs do not unwind) - #161012 (borrowck: Normalize non-rigid aliases in NLL type relating) - #161702 (Use `drop_guard` in some places in {core,alloc,std}) - #161813 (Change `is_eligible_for_coverage` from a hook to a query) - #161842 (chore: fix cargo lints)

jhpratt · 2026-08-27T04:40:01Z

@bors r- #161846 (comment)

rust-bors · 2026-08-27T04:40:09Z

This pull request was unapproved.

This PR was contained in a rollup (#161846), which was unapproved.

View changes since this unapproval

clarfonthey · 2026-08-27T12:01:07Z

Right, I guess that isn't technically run in CI, so, it should be checked separately.

GrigorenkoPV · 2026-08-27T14:36:03Z

Failed two rollups award

@rustbot ready

clarfonthey · 2026-08-27T18:31:14Z

@bors try jobs=x86_64-msvc-1

Use `drop_guard` in some places in {core,alloc,std} try-job: x86_64-msvc-1

rust-bors · 2026-08-27T21:21:17Z

☀️ Try build successful (CI)
Build commit: 1f03391 (1f033914d3c1c7c6efb2663fe094aeae0f8b39d7)
Base parent: e457a7b (e457a7b0d326d67b4322ef0d11bd715cfaeda48f)

clarfonthey · 2026-08-27T23:00:12Z

@bors r+ rollup note="third time's a charm?"

rust-bors · 2026-08-27T23:00:15Z

📌 Commit d1c533b has been approved by clarfonthey

It is now in the queue for this repository.

…uwer Rollup of 21 pull requests Successful merges: - #158609 (Update sccache to 0.16.0) - #150075 (Implement clamp_to) - #159103 (fix(reborrow): recursive implementation) - #160562 (add target feature ABI checks for SPARC) - #160848 (std: avoid aliasing violations when wrapping opaque C types) - #161421 (Include startup crt objects on WASI for more outputs) - #161805 (Prefer ambiguous candidates when deduplicating traits in scope, so `ambiguous_glob_imported_traits` doesn't depend on import order) - #161862 (Put data segment in specified section with link_section on wasm) - #161866 (delegation: add tests fixating behavior of delegating to default trait implementations) - #161456 (reduce perf impact of scalar size checks) - #161528 (Add regression test to ensure optimal compilation) - #161666 (Print vendor instructions in `x vendor`) - #161730 (Improve type mismatch annotation for lets with block-wrapped initializers) - #161828 (Never type after-stabilization cleanup) - #161859 (Do not optimize MIR for comptime ConstFns) - #161860 (atomicptr.rs test: remove unused import) - #161870 (bind to [::1] instead of 127.0.0.1 in documentation examples for v6 UDP methods) - #161876 (rustdoc: Correctly handle when a macro generates multiple items in `--generate-macro-expansion`) - #161889 (Add link to ownership section in ptr::read docs) - #161890 (rustdoc: some clarifying comments) - #161891 (Mark `extern_item_impls` feature as incomplete) Failed merges: - #161702 (Use `drop_guard` in some places in {core,alloc,std})

…uwer Rollup of 21 pull requests Successful merges: - #150075 (Implement clamp_to) - #159103 (fix(reborrow): recursive implementation) - #160562 (add target feature ABI checks for SPARC) - #160848 (std: avoid aliasing violations when wrapping opaque C types) - #161421 (Include startup crt objects on WASI for more outputs) - #161805 (Prefer ambiguous candidates when deduplicating traits in scope, so `ambiguous_glob_imported_traits` doesn't depend on import order) - #161862 (Put data segment in specified section with link_section on wasm) - #161866 (delegation: add tests fixating behavior of delegating to default trait implementations) - #157218 (Track items behind `cfg_select` in the same way we do for `cfg`) - #161456 (reduce perf impact of scalar size checks) - #161528 (Add regression test to ensure optimal compilation) - #161666 (Print vendor instructions in `x vendor`) - #161730 (Improve type mismatch annotation for lets with block-wrapped initializers) - #161828 (Never type after-stabilization cleanup) - #161859 (Do not optimize MIR for comptime ConstFns) - #161860 (atomicptr.rs test: remove unused import) - #161870 (bind to [::1] instead of 127.0.0.1 in documentation examples for v6 UDP methods) - #161876 (rustdoc: Correctly handle when a macro generates multiple items in `--generate-macro-expansion`) - #161889 (Add link to ownership section in ptr::read docs) - #161890 (rustdoc: some clarifying comments) - #161891 (Mark `extern_item_impls` feature as incomplete) Failed merges: - #161702 (Use `drop_guard` in some places in {core,alloc,std})

rustbot assigned clarfonthey Aug 24, 2026

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Rollup of 9 pull requests #161715

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Add no-value DropGuard::new(|| ...) #161550

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Stabilize core::mem::DropGuard #161520

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Rollup of 7 pull requests #161844

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Rollup of 6 pull requests #161846

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Use drop_guard in some places in {core,alloc,std}

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Auto merge of #161702 - GrigorenkoPV:drop-guard, r=<try>

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Use `drop_guard` in some places in {core,alloc,std} try-job: x86_64-msvc-1

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Rollup of 18 pull requests #161901

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Rollup of 21 pull requests #161905

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Rollup of 21 pull requests #161906

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