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Implement coercions between &pin (mut|const) T and &(mut) T when T: Unpin #149130

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Implement coercions between &pin (mut|const) T and &(mut) T when T: Unpin #149130

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@frank-king frank-king commented Nov 20, 2025 •
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This allows the following (mutual) coercions when T: Unpin:

  • &T <-> Pin<&T>
  • &mut T <-> Pin<&mut T>
  • &mut T -> Pin<&T>
  • Pin<&mut T> -> &T

Part of Pin Ergonomics.

@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Nov 20, 2025
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@rustbot rustbot added the T-clippy Relevant to the Clippy team. label Nov 20, 2025
@frank-king frank-king marked this pull request as ready for review November 20, 2025 11:57
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rustbot commented Nov 20, 2025

Some changes occurred in need_type_info.rs

cc @lcnr

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

Some changes occurred in exhaustiveness checking

cc @Nadrieril

@rustbot 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 Nov 20, 2025
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rustbot commented Nov 20, 2025

r? @nnethercote

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nnethercote commented Nov 21, 2025

I am not a good person to review this. How about...

r? @lcnr

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lcnr commented Nov 24, 2025

r? types

@rustbot rustbot added the T-types Relevant to the types team, which will review and decide on the PR/issue. label Nov 24, 2025
@rustbot rustbot assigned spastorino and unassigned lcnr Nov 24, 2025
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spastorino commented Nov 24, 2025

r? types

@rustbot rustbot assigned jackh726 and unassigned spastorino Nov 24, 2025
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bors commented Dec 5, 2025

☔ The latest upstream changes (presumably #148602) made this pull request unmergeable. Please resolve the merge conflicts.

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rustbot commented Dec 15, 2025

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.

@frank-king frank-king mentioned this pull request Dec 18, 2025
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bors commented Dec 18, 2025

☔ The latest upstream changes (presumably #150115) made this pull request unmergeable. Please resolve the merge conflicts.

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jackh726 requested changes Jan 23, 2026
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Incredibly sorry about the review latency here.

Overall, the changes look not bad. That being said, there are two very mechanical changes that would be useful to split into a separate PR (or really, a separate commit is fine, but I prefer a separate PR since they stand alone well).

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compiler/rustc_middle/src/ty/adjustment.rs
}

#[derive(Copy, Clone, Debug, TyEncodable, TyDecodable, HashStable, TypeFoldable, TypeVisitable)]
pub enum DerefAdjustKind {
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(btw, small change that could be split out, but I like the addition of an enum even over Option)

compiler/rustc_middle/src/ty/sty.rs
}
}

pub fn pinned_ref(self) -> Option<(Ty<'tcx>, ty::Mutability)> {
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This deletion, can you too split into a separate PR?

@rustbot rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 23, 2026
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rustbot commented Jan 23, 2026

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

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