Constify `DropGuard::dismiss` and trait impls #148755

nxsaken · 2025-11-09T17:39:01Z

Feature: drop_guard (#144426), const_convert (#143773), const_drop_guard (no tracking issue yet)

Constifies DropGuard::dismiss and trait impls.
I reused const_convert (#143773) for the Deref* impls.

rustbot · 2025-11-09T17:39:06Z

rustbot has assigned @joboet.
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joboet · 2025-11-13T19:10:21Z

r? libs-api
@rustbot label +S-blocked -S-waiting-on-review

nxsaken · 2025-11-17T11:55:43Z

#148752 has been merged.

@rustbot label -S-blocked

yoshuawuyts · 2025-11-27T11:11:40Z

#148589 Was just approved and renames into_inner to dismiss. Once that PR gets through the Bors queue this PR will need to be updated.

bors · 2025-11-27T20:38:27Z

☔ The latest upstream changes (presumably #149387) made this pull request unmergeable. Please resolve the merge conflicts.

rustbot · 2025-11-28T17:05:20Z

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.

tisonkun · 2025-12-02T03:23:37Z

library/core/src/mem/drop_guard.rs

+    pub const fn dismiss(self) -> T
+    where
+        F: [const] Destruct,


I agree with what @orlp mentioned in #144426 (comment) that dismiss should take guard: Self rather than self since it implements Deref as well.

Perhaps you can include it in this patch. Or if it's more desired to do separately, I can prepare a patch dedicated to the signature change.

Seems cleaner to include the change here. I'll wait for a response to the original comment first.

@nxsaken Who are you waiting for? I'm afraid an unspecified wait will never get noticed. (i.e., fewer maintainers know you are waiting here)

I checked the PR and it provides a motivation for the change:

This PR also changes the signature from an static method to an instance method. This also matches the Linux kernel's API, and seems alright since dismiss is not nearly as ubiquitous as into_inner. This makes it more convenient to use, with a much lower risk of conflicting.

The libs-api team has discussed the rename (#148589 (comment)), but according to the minutes, nobody brought up the receiver change.

cc @yoshuawuyts @joshtriplett

I think it hinges on what gets decided for the associated function name. If this API is stabilized as unguard(), then allowing method syntax seems fine because having guard objects (or something else with an unguard method?) inside of guard objects is sufficiently obscure. Whereas if it is stabilized as into_inner(), I think method syntax is unambiguously off the table. dismiss() would be somewhere in between.

Since changing from guard: Self to self after stabilization is not a breaking change while the reverse is, switching this back to guard: Self would put it closer to stabilization, so feel free to go ahead with that.

nxsaken · 2025-12-13T05:49:02Z

r? libs-api

library/core/src/mem/drop_guard.rs

dtolnay · 2025-12-13T06:52:52Z

library/core/src/mem/drop_guard.rs

+    pub const fn dismiss(self) -> T
+    where
+        F: [const] Destruct,


I think it hinges on what gets decided for the associated function name. If this API is stabilized as unguard(), then allowing method syntax seems fine because having guard objects (or something else with an unguard method?) inside of guard objects is sufficiently obscure. Whereas if it is stabilized as into_inner(), I think method syntax is unambiguously off the table. dismiss() would be somewhere in between.

Since changing from guard: Self to self after stabilization is not a breaking change while the reverse is, switching this back to guard: Self would put it closer to stabilization, so feel free to go ahead with that.

rustbot · 2025-12-13T06:53:00Z

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

nxsaken · 2025-12-13T11:38:15Z

@rustbot ready

dtolnay

Thanks!

View changes since this review

dtolnay · 2025-12-13T13:09:44Z

@bors r+

bors · 2025-12-13T13:09:47Z

📌 Commit 0ecf91a has been approved by dtolnay

It is now in the queue for this repository.

Constify `DropGuard::dismiss` and trait impls Feature: `drop_guard` (rust-lang#144426), `const_convert` (rust-lang#143773), `const_drop_guard` (no tracking issue yet) Constifies `DropGuard::dismiss` and trait impls. I reused `const_convert` (rust-lang#143773) for the `Deref*` impls.

…uwer Rollup of 5 pull requests Successful merges: - #148755 (Constify `DropGuard::dismiss` and trait impls) - #148825 (Add SystemTime::{MIN, MAX}) - #149894 (Update to mdbook 0.5) - #149930 (std: small `sys` refactor) - #149949 (Cleanup of attribute parsing errors) r? `@ghost` `@rustbot` modify labels: rollup

Constify `DropGuard::dismiss` and trait impls Feature: `drop_guard` (rust-lang#144426), `const_convert` (rust-lang#143773), `const_drop_guard` (no tracking issue yet) Constifies `DropGuard::dismiss` and trait impls. I reused `const_convert` (rust-lang#143773) for the `Deref*` impls.

bjorn3 · 2025-12-13T19:23:24Z

library/core/src/mem/drop_guard.rs

+    #[rustc_const_unstable(feature = "const_drop_guard", issue = "none")]
    #[inline]
-    pub fn dismiss(self) -> T {
+    pub const fn dismiss(guard: Self) -> T


Rc::into_raw and Arc::into_raw use this as arg name. Box::into_raw however uses b as arg name.

…uwer Rollup of 5 pull requests Successful merges: - #148755 (Constify `DropGuard::dismiss` and trait impls) - #148825 (Add SystemTime::{MIN, MAX}) - #149894 (Update to mdbook 0.5) - #149949 (Cleanup of attribute parsing errors) - #149955 (Fix typo in armv7a-vex-v5 documentation) r? `@ghost` `@rustbot` modify labels: rollup

Constify `DropGuard::dismiss` and trait impls Feature: `drop_guard` (rust-lang#144426), `const_convert` (rust-lang#143773), `const_drop_guard` (no tracking issue yet) Constifies `DropGuard::dismiss` and trait impls. I reused `const_convert` (rust-lang#143773) for the `Deref*` impls.

Rollup of 8 pull requests Successful merges: - #148755 (Constify `DropGuard::dismiss` and trait impls) - #148825 (Add SystemTime::{MIN, MAX}) - #149272 (Fix vec iter zst alignment) - #149417 (tidy: Detect outdated workspaces in workspace list) - #149437 (Fix trailing newline in JUnit formatter) - #149773 (fix va_list test by adding a llvmir signext check) - #149894 (Update to mdbook 0.5) - #149955 (Fix typo in armv7a-vex-v5 documentation) r? `@ghost` `@rustbot` modify labels: rollup

Constify `DropGuard::dismiss` and trait impls Feature: `drop_guard` (rust-lang#144426), `const_convert` (rust-lang#143773), `const_drop_guard` (no tracking issue yet) Constifies `DropGuard::dismiss` and trait impls. I reused `const_convert` (rust-lang#143773) for the `Deref*` impls.

Rollup of 8 pull requests Successful merges: - #148755 (Constify `DropGuard::dismiss` and trait impls) - #148825 (Add SystemTime::{MIN, MAX}) - #149272 (Fix vec iter zst alignment) - #149417 (tidy: Detect outdated workspaces in workspace list) - #149773 (fix va_list test by adding a llvmir signext check) - #149894 (Update to mdbook 0.5) - #149955 (Fix typo in armv7a-vex-v5 documentation) - #149972 (Enable to ping LoongArch group via triagebot) r? `@ghost` `@rustbot` modify labels: rollup

rustbot assigned joboet Nov 9, 2025

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Nov 9, 2025

rustbot added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Nov 13, 2025

rustbot assigned the8472 and unassigned joboet Nov 13, 2025

rustbot added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Nov 13, 2025

nxsaken force-pushed the const_drop_guard branch from 3564847 to a86a557 Compare November 17, 2025 11:54

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rustbot removed the S-blocked Status: Blocked on something else such as an RFC or other implementation work. label Nov 17, 2025

bors added the S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. label Nov 27, 2025

nxsaken force-pushed the const_drop_guard branch from a86a557 to b273af3 Compare November 28, 2025 17:05

nxsaken changed the title ~~Constify DropGuard::into_inner and trait impls~~ Constify DropGuard::dismiss and trait impls Nov 28, 2025

Constify DropGuard methods

e163707

nxsaken force-pushed the const_drop_guard branch from b273af3 to e163707 Compare November 28, 2025 17:07

tisonkun reviewed Dec 2, 2025

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rustbot assigned dtolnay and unassigned the8472 Dec 13, 2025

dtolnay requested changes Dec 13, 2025

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Use an explicit receiver in DropGuard::dismiss

0ecf91a

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 13, 2025

nxsaken requested a review from dtolnay December 13, 2025 11:38

dtolnay approved these changes Dec 13, 2025

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bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 13, 2025

nxsaken mentioned this pull request Dec 13, 2025

Tracking Issue for core::mem::DropGuard #144426

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JonathanBrouwer mentioned this pull request Dec 13, 2025

Rollup of 5 pull requests #149953

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JonathanBrouwer mentioned this pull request Dec 13, 2025

Rollup of 5 pull requests #149956

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bjorn3 reviewed Dec 13, 2025

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ChrisDenton mentioned this pull request Dec 14, 2025

Rollup of 8 pull requests #149975

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ChrisDenton mentioned this pull request Dec 14, 2025

Rollup of 8 pull requests #149979

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Constify `DropGuard::dismiss` and trait impls #148755

Constify `DropGuard::dismiss` and trait impls #148755

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