Make PinCoerceUnsized require Deref

[theemathas]

View all comments

Also, delete impls on non-Deref types.

Pin doesn't do anything useful for non-Deref types, so PinCoerceUnsized on such types makes no sense.

This is a breaking change, since stable code can observe the deleted PinCoerceUnsized impls by uselessly coercing between such types inside a Pin.

There is still some strange behavior, such as Pin<&mut i32> being able to coerce to Pin<&dyn Send>, but not being able to coerce to Pin<&i32>. However, I don't think it's possible to fix this.

Fixes #145081

[rustbot]

r? @tgross35

rustbot has assigned @tgross35.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[jdonszelmann]

@bors try

[rust-bors]

☀️ Try build successful (CI)
Build commit: 94e8487 (94e848735e78b58442e0b82e9c60f8f430840389, parent: e0e204f3e97ad5f79524b9c259dc38df606ed82c)

[saethlin]

@craterbot check

[craterbot]

👌 Experiment pr-149218 created and queued.
🤖 Automatically detected try build 94e8487
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[craterbot]

🚧 Experiment pr-149218 is now running

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[Darksonn]

I added these impls because otherwise the introduction of PinCoerceUnsized would have been a breaking change. I'm in favor of removing them.

[craterbot]

🎉 Experiment pr-149218 is completed!
📊 6 regressed and 5 fixed (743358 total)
📊 1966 spurious results on the retry-regessed-list.txt, consider a retry¹ if this is a significant amount.
📰 Open the summary report.

⚠️ If you notice any spurious failure please add them to the denylist!
ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

Footnotes

1. re-run the experiment with crates=https://crater-reports.s3.amazonaws.com/pr-149218/retry-regressed-list.txt ↩

[workingjubilee]

@craterbot check crates=https://crater-reports.s3.amazonaws.com/pr-149218/retry-regressed-list.txt

[craterbot]

👌 Experiment pr-149218-1 created and queued.
🤖 Automatically detected try build 94e8487
🔍 You can check out the queue and this experiment's details.

ℹ️ Crater is a tool to run experiments across parts of the Rust ecosystem. Learn more

[JonathanBrouwer]

@bors r-
#154312 (comment)

[rust-bors]

This pull request was unapproved.

This PR was contained in a rollup (#154312), which was unapproved.

Auto build was cancelled due to unapproval. Cancelled workflows:

• https://github.com/rust-lang/rust/actions/runs/23496789264

[rustbot]

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.

[theemathas]

The UserRef type in the SGX code seemingly is meant to be used as &UserRef<T> and &mut UserRef<T>. It's never meant to be used as a by-value UserRef<T>. Therefore, the PinCoerceUnsized impl for it doesn't make much sense, as users aren't meant to be making a Pin<UserRef<T>>. Therefore, I've removed the impl.

@rustbot ready

[oli-obk]

@bors r+

[rust-bors]

📌 Commit f55c8cc has been approved by oli-obk

It is now in the queue for this repository.

[rust-bors]

☀️ Test successful - CI
Approved by: oli-obk
Duration: 3h 44m 40s
Pushing 64d5cb6 to main...

[github-actions]

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing 8a70352 (parent) -> 64d5cb6 (this PR)

Test differences

Show 562 test diffs

562 doctest diffs were found. These are ignored, as they are noisy.

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 64d5cb603b9caf9063d27d64fdfa61fa7af3b98f --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

1. dist-apple-various: 1h 33m -> 2h 10m (+38.8%)
2. aarch64-apple: 2h 39m -> 3h 35m (+35.4%)
3. dist-aarch64-apple: 1h 33m -> 1h 57m (+24.9%)
4. dist-x86_64-apple: 1h 58m -> 2h 24m (+21.5%)
5. pr-check-1: 31m 37s -> 25m 9s (-20.5%)
6. x86_64-gnu-llvm-22-2: 1h 39m -> 1h 23m (-15.6%)
7. aarch64-gnu-llvm-21-1: 59m 24s -> 51m 21s (-13.6%)
8. dist-aarch64-llvm-mingw: 1h 53m -> 1h 39m (-12.5%)
9. x86_64-gnu-tools: 1h 3m -> 55m 54s (-12.3%)
10. x86_64-gnu-gcc: 1h 9m -> 1h 1m (-11.8%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

[rust-timer]

Finished benchmarking commit (64d5cb6): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

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

Max RSS (memory usage)

Results (primary -2.3%)

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)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-2.3%	[-2.3%, -2.3%]	1

Cycles

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

Binary size

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

Bootstrap: 482.838s -> 483.648s (0.17%)
Artifact size: 394.91 MiB -> 394.87 MiB (-0.01%)