Implement `pin!()` using `super let` #139114

m-ou-se · 2025-03-29T17:05:27Z

Tracking issue for super let: #139076

This uses super let to implement pin!().

This means we can remove the hack we had to put in to fix #138596.

It also means we can remove the original hack to make pin!() work, which used a questionable public-but-unstable field rather than a proper private field.

While super let is still unstable and subject to change, it seems safe to assume that future Rust will always have a way to express pin!() in a compatible way, considering pin!() is already stable.

It'd help the experiment to have pin!() use super let, so we can get some more experience with it.

library/core/src/pin.rs

bors · 2025-04-01T11:41:06Z

☔ The latest upstream changes (presumably #138740) made this pull request unmergeable. Please resolve the merge conflicts.

m-ou-se · 2025-04-09T13:08:38Z

r? compiler

tests/ui/sanitizer/cfi/coroutine.rs

matthiaskrgr · 2025-04-18T19:36:15Z

@bors retry

2025-04-18T19:12:34.8633667Z    Compiling foo v0.1.0 (D:\a\rust\rust\build\x86_64-pc-windows-msvc\stage1-tools\x86_64-pc-windows-msvc\tmp\cit\t245\foo)
2025-04-18T19:12:34.8634860Z    Compiling bar v0.1.0 (D:\a\rust\rust\build\x86_64-pc-windows-msvc\stage1-tools\x86_64-pc-windows-msvc\tmp\cit\t245\foo\bar)
2025-04-18T19:12:34.8636135Z error: couldn't create a temp dir: Access is denied. (os error 5) at path "C:\\Users\\RUNNER~1\\AppData\\Local\\Temp\\rustccfrkMc"
2025-04-18T19:12:34.8636837Z
2025-04-18T19:12:34.8637137Z error: could not compile `foo` (bin "foo") due to 1 previous error

``

Implement `pin!()` using `super let` Tracking issue for super let: rust-lang#139076 This uses `super let` to implement `pin!()`. This means we can remove [the hack](rust-lang#138717) we had to put in to fix rust-lang#138596. It also means we can remove the original hack to make `pin!()` work, which used a questionable public-but-unstable field rather than a proper private field. While `super let` is still unstable and subject to change, it seems safe to assume that future Rust will always have a way to express `pin!()` in a compatible way, considering `pin!()` is already stable. It'd help [the experiment](rust-lang#139076) to have `pin!()` use `super let`, so we can get some more experience with it.

bors · 2025-04-18T20:19:11Z

⌛ Testing commit 5523c87 with merge 349aee2...

bors · 2025-04-18T23:27:15Z

💔 Test failed - checks-actions

rust-log-analyzer · 2025-04-18T23:27:20Z

A job failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

m-ou-se · 2025-04-19T07:19:48Z

@bors retry

bors · 2025-04-19T08:01:57Z

⌛ Testing commit 5523c87 with merge a7c39b6...

bors · 2025-04-19T11:10:22Z

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing a7c39b6 to master...

github-actions · 2025-04-19T11:11:58Z

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 2ef7858 (parent) -> a7c39b6 (this PR)

Test differences

Show 49 test diffs

Stage 0

pin_macro::temp_lifetime: pass -> [missing] (J1)

Stage 1

[ui] tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs: pass -> [missing] (J2)
[ui] tests/ui/pin-macro/cant_access_internals.rs: pass -> [missing] (J2)

Stage 2

[ui] tests/ui/feature-gates/feature-gate-unsafe_pin_internals.rs: pass -> [missing] (J0)
[ui] tests/ui/pin-macro/cant_access_internals.rs: pass -> [missing] (J0)

Additionally, 44 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Job duration changes

dist-aarch64-linux: 5282.2s -> 7591.8s (43.7%)
x86_64-apple-1: 8265.6s -> 6235.6s (-24.6%)
dist-x86_64-apple: 10601.5s -> 8293.5s (-21.8%)
x86_64-apple-2: 4845.3s -> 5766.6s (19.0%)
aarch64-apple: 3980.0s -> 3698.9s (-7.1%)
dist-ohos: 10661.5s -> 9945.9s (-6.7%)
dist-armv7-linux: 5781.1s -> 5413.6s (-6.4%)
dist-apple-various: 6128.4s -> 6504.5s (6.1%)
dist-x86_64-freebsd: 5136.0s -> 4879.8s (-5.0%)
dist-i686-linux: 5826.9s -> 6109.6s (4.9%)

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 · 2025-04-19T12:36:57Z

Finished benchmarking commit (a7c39b6): 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 -0.5%, secondary -2.7%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	1.2%	[0.4%, 2.0%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.8%	[-2.2%, -0.4%]	14
Improvements ✅ (secondary)	-2.7%	[-3.3%, -2.3%]	5
All ❌✅ (primary)	-0.5%	[-2.2%, 2.0%]	16

Cycles

Results (primary -0.6%, secondary -2.9%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.6%	[-0.8%, -0.4%]	15
Improvements ✅ (secondary)	-2.9%	[-3.4%, -2.0%]	8
All ❌✅ (primary)	-0.6%	[-0.8%, -0.4%]	15

Binary size

Results (primary 0.0%, secondary 0.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	0.0%	[0.0%, 0.0%]	3
Regressions ❌ (secondary)	0.1%	[0.0%, 0.1%]	9
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.0%	[0.0%, 0.0%]	3

Bootstrap: 774.105s -> 772.535s (-0.20%)
Artifact size: 365.05 MiB -> 364.98 MiB (-0.02%)

…Urgau Remove (now unused) #[rustc_macro_edition_2021] attribute Now that rust-lang#139114 has been merged, we no longer need the temporary hack (`#[rustc_macro_edition_2021]`) that we introduced in rust-lang#138717. Time to remove it.

Rollup merge of rust-lang#140067 - m-ou-se:remove-macro-2021-hack, r=Urgau Remove (now unused) #[rustc_macro_edition_2021] attribute Now that rust-lang#139114 has been merged, we no longer need the temporary hack (`#[rustc_macro_edition_2021]`) that we introduced in rust-lang#138717. Time to remove it.

Implement `pin!()` using `super let` Tracking issue for super let: rust-lang#139076 This uses `super let` to implement `pin!()`. This means we can remove [the hack](rust-lang#138717) we had to put in to fix rust-lang#138596. It also means we can remove the original hack to make `pin!()` work, which used a questionable public-but-unstable field rather than a proper private field. While `super let` is still unstable and subject to change, it seems safe to assume that future Rust will always have a way to express `pin!()` in a compatible way, considering `pin!()` is already stable. It'd help [the experiment](rust-lang#139076) to have `pin!()` use `super let`, so we can get some more experience with it.

m-ou-se self-assigned this Mar 29, 2025

m-ou-se mentioned this pull request Mar 29, 2025

Tracking Issue for super let #139076

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m-ou-se force-pushed the super-let-pin branch from 61a124a to c2a3a76 Compare March 29, 2025 18:11

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Parse super let rust-lang/rust-analyzer#19623

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Implement parsing of pinned borrows #135731

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This was referenced Apr 20, 2025

Original pin!() macro behavior cannot be expressed in Rust 2024 #138718

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Remove (now unused) #[rustc_macro_edition_2021] attribute #140067

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Implement `pin!()` using `super let` #139114

Implement `pin!()` using `super let` #139114

m-ou-se commented Mar 29, 2025 •

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Implement pin!() using super let #139114

Implement pin!() using super let #139114

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Test differences

Stage 0

Stage 1

Stage 2

Job duration changes

rust-timer commented Apr 19, 2025

Overall result: no relevant changes - no action needed

Instruction count

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Implement `pin!()` using `super let` #139114

Implement `pin!()` using `super let` #139114

m-ou-se commented Mar 29, 2025 •

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