Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin` by frank-king · Pull Request #149130 · rust-lang/rust

frank-king · 2025-11-20T09:23:55Z

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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 · 2025-11-20T11:57:14Z

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 · 2025-11-20T11:57:17Z

r? @nnethercote

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nnethercote · 2025-11-21T10:52:54Z

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

r? @lcnr

lcnr · 2025-11-24T18:57:32Z

r? types

spastorino · 2025-11-24T21:03:36Z

r? types

bors · 2025-12-05T16:16:58Z

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

bors · 2025-12-18T04:09:04Z

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

jackh726

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).

View changes since this review

compiler/rustc_middle/src/ty/adjustment.rs

compiler/rustc_middle/src/ty/sty.rs

rustbot · 2026-01-23T07:21:47Z

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

frank-king · 2026-03-10T11:08:54Z

@bors r=jackh726

rust-bors · 2026-03-10T11:09:00Z

📌 Commit d38c8c0 has been approved by jackh726

It is now in the queue for this repository.

🌲 The tree is currently closed for pull requests below priority 1000. This pull request will be tested once the tree is reopened.

…ackh726 Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin` 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](rust-lang#130494).

…uwer Rollup of 8 pull requests Successful merges: - #149130 (Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin`) - #152457 (Pass -pg to linker when using -Zinstrument-mcount) - #153143 (Allow `./x test` to run tests without doc tests and without benchmarks) - #153653 (scalable vector: type renames and simple checks) - #152302 (fix: don't suggest replacing `env!("CARGO_BIN_NAME")` with itself) - #153641 (Move `Spanned`.) - #153643 (Avoid projection-only suggestions for inherent assoc types) - #153657 (triagebot: remove myself from some mention groups)

…ackh726 Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin` 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](rust-lang#130494).

…uwer Rollup of 13 pull requests Successful merges: - #149130 (Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin`) - #152457 (Pass -pg to linker when using -Zinstrument-mcount) - #153143 (Allow `./x test` to run tests without doc tests and without benchmarks) - #153471 (Refactor `ActiveJobGuard`) - #153595 (`QueryLatch` cleanups) - #153653 (scalable vector: type renames and simple checks) - #152302 (fix: don't suggest replacing `env!("CARGO_BIN_NAME")` with itself) - #153479 (Add rationale for intentional potential_query_instability allows) - #153600 (add test for proc-macros with custom panic payloads) - #153641 (Move `Spanned`.) - #153643 (Avoid projection-only suggestions for inherent assoc types) - #153657 (triagebot: remove myself from some mention groups) - #153659 (Mark an unreachable match arm as such)

…ackh726 Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin` 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](rust-lang#130494).

…uwer Rollup of 14 pull requests Successful merges: - #149130 (Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin`) - #152457 (Pass -pg to linker when using -Zinstrument-mcount) - #153143 (Allow `./x test` to run tests without doc tests and without benchmarks) - #153471 (Refactor `ActiveJobGuard`) - #153595 (`QueryLatch` cleanups) - #153653 (scalable vector: type renames and simple checks) - #152302 (fix: don't suggest replacing `env!("CARGO_BIN_NAME")` with itself) - #153283 (feat(rustdoc-json): Add optional support for rkyv (de)serialization) - #153479 (Add rationale for intentional potential_query_instability allows) - #153533 (Fix LegacyKeyValueFormat report from docker build: miscellaneous) - #153600 (add test for proc-macros with custom panic payloads) - #153643 (Avoid projection-only suggestions for inherent assoc types) - #153657 (triagebot: remove myself from some mention groups) - #153659 (Mark an unreachable match arm as such)

…uwer Rollup of 13 pull requests Successful merges: - #149130 (Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin`) - #153143 (Allow `./x test` to run tests without doc tests and without benchmarks) - #153471 (Refactor `ActiveJobGuard`) - #153595 (`QueryLatch` cleanups) - #153653 (scalable vector: type renames and simple checks) - #152302 (fix: don't suggest replacing `env!("CARGO_BIN_NAME")` with itself) - #153283 (feat(rustdoc-json): Add optional support for rkyv (de)serialization) - #153479 (Add rationale for intentional potential_query_instability allows) - #153533 (Fix LegacyKeyValueFormat report from docker build: miscellaneous) - #153600 (add test for proc-macros with custom panic payloads) - #153643 (Avoid projection-only suggestions for inherent assoc types) - #153657 (triagebot: remove myself from some mention groups) - #153659 (Mark an unreachable match arm as such)

Rollup merge of #149130 - frank-king:feature/pin-coerce, r=jackh726 Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin` 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](#130494).

…nathanBrouwer Rollup of 13 pull requests Successful merges: - rust-lang#149130 (Implement coercions between `&pin (mut|const) T` and `&(mut) T` when `T: Unpin`) - rust-lang#153143 (Allow `./x test` to run tests without doc tests and without benchmarks) - rust-lang#153471 (Refactor `ActiveJobGuard`) - rust-lang#153595 (`QueryLatch` cleanups) - rust-lang#153653 (scalable vector: type renames and simple checks) - rust-lang#152302 (fix: don't suggest replacing `env!("CARGO_BIN_NAME")` with itself) - rust-lang#153283 (feat(rustdoc-json): Add optional support for rkyv (de)serialization) - rust-lang#153479 (Add rationale for intentional potential_query_instability allows) - rust-lang#153533 (Fix LegacyKeyValueFormat report from docker build: miscellaneous) - rust-lang#153600 (add test for proc-macros with custom panic payloads) - rust-lang#153643 (Avoid projection-only suggestions for inherent assoc types) - rust-lang#153657 (triagebot: remove myself from some mention groups) - rust-lang#153659 (Mark an unreachable match arm as such)

JonathanBrouwer · 2026-03-11T12:38:46Z

@rust-timer build 59484a8

rust-timer · 2026-03-11T13:58:50Z

Finished benchmarking commit (59484a8): comparison URL.

Overall result: ❌ regressions - please read the text below

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.3%	[0.1%, 0.5%]	17
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.0%	[2.0%, 2.0%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.0%	[2.0%, 2.0%]	1

Cycles

Results (secondary -2.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.4%	[-2.4%, -2.4%]	1
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 480.034s -> 487.723s (1.60%)
Artifact size: 394.90 MiB -> 395.00 MiB (0.03%)

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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frank-king force-pushed the feature/pin-coerce branch from 29a89ae to 92596db Compare November 20, 2025 09:56

rustbot added the T-clippy Relevant to the Clippy team. label Nov 20, 2025

frank-king marked this pull request as ready for review November 20, 2025 11:57

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 assigned lcnr and unassigned nnethercote Nov 21, 2025

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

rustbot assigned spastorino and unassigned lcnr Nov 24, 2025

rustbot assigned jackh726 and unassigned spastorino Nov 24, 2025

frank-king force-pushed the feature/pin-coerce branch from 92596db to 500d786 Compare December 15, 2025 02:53

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frank-king mentioned this pull request Dec 18, 2025

Continue Experimentation with Pin Ergonomics rust-lang/rust-project-goals#389

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jackh726 requested changes Jan 23, 2026

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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

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 10, 2026

JonathanBrouwer mentioned this pull request Mar 10, 2026

Rollup of 4 pull requests #153654

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Rollup of 8 pull requests #153658

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Rollup of 13 pull requests #153665

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Rollup of 14 pull requests #153669

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JonathanBrouwer mentioned this pull request Mar 10, 2026

Rollup of 13 pull requests #153672

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rust-bors bot merged commit 6419556 into rust-lang:main Mar 11, 2026
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rustbot added the perf-regression Performance regression. label Mar 11, 2026

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rust-timer commented Mar 11, 2026

Overall result: ❌ regressions - please read the text below

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