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implement StructuralPartialEq for MaybeDangling#154891

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WaffleLapkin:deregress-manually-drop-matching
Apr 7, 2026
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implement StructuralPartialEq for MaybeDangling#154891
rust-bors[bot] merged 1 commit intorust-lang:mainfrom
WaffleLapkin:deregress-manually-drop-matching

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@WaffleLapkin WaffleLapkin commented Apr 6, 2026 •
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This fixes -- a stable-to-stable regression where constants of type ManuallyDrop<T> would not be allowed to be used as a pattern due to MaybeDangling<T> in ManuallyDrop<T> not implementing StructuralPartialEq.

Fixes #154890

I'm sorry, @theemathas, I forgot to address your comment 😭

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r=me once CI passes

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@WaffleLapkin
implement StructuralPartialEq for MaybeDangling
d5f98fb 
This fixes a stable-to-stable regression where constants of type
`ManuallyDrop<T>` would not be allowed to be used as a pattern due to
`MaybeDangling<T>` in `ManuallyDrop<T>` not implementing
`StructuralPartialEq`.
@WaffleLapkin WaffleLapkin force-pushed the deregress-manually-drop-matching branch from 68bcf7c to d5f98fb Compare April 6, 2026 16:19
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Jules-Bertholet commented Apr 6, 2026

Why not just derive(PartialEq, Eq, PartialOrd, Ord, Hash) for MaybeDangling? That way, ManuallyDrop can revert to derived impls also.

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Jules-Bertholet commented Apr 6, 2026

Filed a PR: #154905

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WaffleLapkin commented Apr 6, 2026

@bors r=JohnTitor

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rust-bors bot commented Apr 6, 2026

📌 Commit d5f98fb has been approved by JohnTitor

It is now in the queue for this repository.

@rust-bors rust-bors bot 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 Apr 6, 2026
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Apr 6, 2026
@JonathanBrouwer
Rollup merge of rust-lang#154891 - WaffleLapkin:deregress-manually-dr…
679fa1f 
…op-matching, r=JohnTitor

implement `StructuralPartialEq` for `MaybeDangling`

This fixes -- a stable-to-stable regression where constants of type `ManuallyDrop<T>` would not be allowed to be used as a pattern due to `MaybeDangling<T>` in `ManuallyDrop<T>` not implementing `StructuralPartialEq`.

Fixes rust-lang#154890

I'm sorry, @theemathas, I forgot to address your [comment](rust-lang#149614 (comment)) 😭
@JonathanBrouwer JonathanBrouwer mentioned this pull request Apr 6, 2026
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@jhpratt jhpratt mentioned this pull request Apr 6, 2026
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rust-bors bot pushed a commit that referenced this pull request Apr 7, 2026
@bors
Auto merge of #154916 - jhpratt:rollup-RkdDmtW, r=jhpratt
49b6ac0 
Rollup of 6 pull requests

Successful merges:

 - #154627 (Move `rustc_middle::mir::mono` to `rustc_middle::mono`)
 - #154729 (de-non_const some `Iterator` methods)
 - #154891 (implement `StructuralPartialEq` for `MaybeDangling`)
 - #154894 (Slightly refactor mplace<->ptr conversions)
 - #154751 (compiletest: Remove `rfail` support from incremental tests)
 - #154901 (Update books)
@rust-bors rust-bors bot merged commit 7913288 into rust-lang:main Apr 7, 2026
11 checks passed
@rustbot rustbot added this to the 1.96.0 milestone Apr 7, 2026
rust-timer added a commit that referenced this pull request Apr 7, 2026
@rust-timer
Unrolled build for #154891
2d2475f 
Rollup merge of #154891 - WaffleLapkin:deregress-manually-drop-matching, r=JohnTitor

implement `StructuralPartialEq` for `MaybeDangling`

This fixes -- a stable-to-stable regression where constants of type `ManuallyDrop<T>` would not be allowed to be used as a pattern due to `MaybeDangling<T>` in `ManuallyDrop<T>` not implementing `StructuralPartialEq`.

Fixes #154890

I'm sorry, @theemathas, I forgot to address your [comment](#149614 (comment)) 😭
@WaffleLapkin WaffleLapkin deleted the deregress-manually-drop-matching branch April 7, 2026 11:42
@WaffleLapkin WaffleLapkin added the relnotes Marks issues that should be documented in the release notes of the next release. label Apr 7, 2026
@rustbot rustbot mentioned this pull request Apr 7, 2026
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github-actions bot pushed a commit to rust-lang/miri that referenced this pull request Apr 8, 2026
@bors
Auto merge of #154916 - jhpratt:rollup-RkdDmtW, r=jhpratt
07f121f 
Rollup of 6 pull requests

Successful merges:

 - rust-lang/rust#154627 (Move `rustc_middle::mir::mono` to `rustc_middle::mono`)
 - rust-lang/rust#154729 (de-non_const some `Iterator` methods)
 - rust-lang/rust#154891 (implement `StructuralPartialEq` for `MaybeDangling`)
 - rust-lang/rust#154894 (Slightly refactor mplace<->ptr conversions)
 - rust-lang/rust#154751 (compiletest: Remove `rfail` support from incremental tests)
 - rust-lang/rust#154901 (Update books)
github-actions bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Apr 8, 2026
@bors
Auto merge of #154916 - jhpratt:rollup-RkdDmtW, r=jhpratt
a51f720 
Rollup of 6 pull requests

Successful merges:

 - rust-lang/rust#154627 (Move `rustc_middle::mir::mono` to `rustc_middle::mono`)
 - rust-lang/rust#154729 (de-non_const some `Iterator` methods)
 - rust-lang/rust#154891 (implement `StructuralPartialEq` for `MaybeDangling`)
 - rust-lang/rust#154894 (Slightly refactor mplace<->ptr conversions)
 - rust-lang/rust#154751 (compiletest: Remove `rfail` support from incremental tests)
 - rust-lang/rust#154901 (Update books)
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ManuallyDrop can't be used as a constant in match since 1.94

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