Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it #138717

jdonszelmann · 2025-03-19T16:39:00Z

Fixes a regression, see issue below. This is a temporary fix, super let is the real solution.

rustbot · 2025-03-19T16:39:06Z

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WaffleLapkin · 2025-03-19T17:02:06Z

r? WaffleLapkin
r=me with green CI

petrochenkov · 2025-03-19T17:19:14Z

@petrochenkov do you have a constructive suggestion for this issue or just unconstructive complaints? The latter is not welcome.

I need to think.
(Not blocking since this is a regression fix.)

petrochenkov · 2025-03-19T17:21:41Z

One alternative not requiring compiler hacks is to put it into a separate 2021 edition crate and then reexport it from libcore, but that may (or may not) cause some larger build/infrastructure issues.

workingjubilee · 2025-03-19T17:42:40Z

Probably will. And no one wants to spend a day debugging the CI issues when it does. And speaking from my POV as libs reviewer, I strongly prefer core's current dependency graph to it having any dependencies at all.

m-ou-se · 2025-03-19T17:55:08Z

What are you people doing 🤦
I really hope this is temporary.

It really should be. If this isn't temporary, it means that Rust 2024 isn't as expressive as Rust 2021. That would be a problem!

Opened #138718 to track that.

m-ou-se · 2025-03-19T17:58:31Z

One alternative not requiring compiler hacks is to put it into a separate 2021 edition crate and then reexport it from libcore, but that may (or may not) cause some larger build/infrastructure issues.

Definitely considered that. But adding a dependency to core isn't trivial. And unfortunately we don't have :expr2024 in Rust 2021, so it wouldn't just be moving the enitr pin macro to a 2021 crate.

Luckily this attribute is very simple to implement, and thus simple to remove again. (It just sets the SyntaxExtension::edition field.)

theemathas · 2025-03-19T17:59:05Z

Is it reasonable to try running crater with the identity() fix to see how much code breaks? Broken code probably would need to look like pin!(&mut temporary()), which is kinda silly, and hopefully doesn't come up often enough to be an issue.

m-ou-se · 2025-03-19T18:07:33Z

Is it reasonable to try running crater with the identity() fix to see how much code breaks? Broken code probably would need to look like pin!(&mut temporary()), which is kinda silly, and hopefully doesn't come up often enough to be an issue.

Considering that pin!() is used often in aync application code (not just libraries), I think crater might not be very representative, as there might be a lot of uses in code that is not on (public) github or crates.io.

compiler/rustc_resolve/src/macros.rs

Rollup merge of rust-lang#138717 - jdonszelmann:pin-macro, r=WaffleLapkin Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it Fixes a regression, see issue below. This is a temporary fix, super let is the real solution. Closes rust-lang#138596

Put pin!() tests in the right file. In rust-lang#138717, these tests were put in `tests/pin.rs`, but they should go in `tests/pin_macro.rs`. r? `@jdonszelmann`

Rollup merge of rust-lang#139052 - m-ou-se:pin-macro-tests, r=joboet Put pin!() tests in the right file. In rust-lang#138717, these tests were put in `tests/pin.rs`, but they should go in `tests/pin_macro.rs`. r? `@jdonszelmann`

Add more tests for pin!(). This adds the tests suggested by `@danielhenrymantilla` in this comment: rust-lang#138717 (comment) by

Rollup merge of rust-lang#139097 - m-ou-se:pin-tests, r=WaffleLapkin Add more tests for pin!(). This adds the tests suggested by `@danielhenrymantilla` in this comment: rust-lang#138717 (comment) by

…pkin Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it Fixes a regression, see issue below. This is a temporary fix, super let is the real solution. Closes rust-lang#138596

Put pin!() tests in the right file. In rust-lang#138717, these tests were put in `tests/pin.rs`, but they should go in `tests/pin_macro.rs`. r? `@jdonszelmann`

Add more tests for pin!(). This adds the tests suggested by `@danielhenrymantilla` in this comment: rust-lang#138717 (comment) by

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.

Implement `pin!()` using `super let` Tracking issue for super let: rust-lang/rust#139076 This uses `super let` to implement `pin!()`. This means we can remove [the hack](rust-lang/rust#138717) we had to put in to fix rust-lang/rust#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/rust#139076) to have `pin!()` use `super let`, so we can get some more experience with it.

…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.

add rustc_macro_edition_2021

7c085f7

rustbot assigned Noratrieb Mar 19, 2025

jdonszelmann changed the title ~~Add an attribute that makes the spans from a macro edition 2021~~ Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it Mar 19, 2025

m-ou-se mentioned this pull request Mar 19, 2025

pin macro no longer lifetime extends argument #138596

Closed

Pin tests.

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This was referenced Mar 19, 2025

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

Open

Adapt pin! to the new lifespan-extension rules of 2024 edition #138622

Closed

WaffleLapkin approved these changes Mar 19, 2025

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Add cfg(not(bootstrap)) for new test.

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compiler-errors reviewed Mar 19, 2025

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compiler/rustc_resolve/src/macros.rs Outdated Show resolved Hide resolved

bors merged commit 7c2475e into rust-lang:master Mar 21, 2025
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rustbot added this to the 1.87.0 milestone Mar 21, 2025

m-ou-se deleted the pin-macro branch March 26, 2025 08:31

m-ou-se mentioned this pull request Mar 28, 2025

Put pin!() tests in the right file. #139052

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m-ou-se mentioned this pull request Mar 28, 2025

Tracking Issue for super let #139076

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

Add more tests for pin!(). #139097

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m-ou-se added beta-nominated Nominated for backporting to the compiler in the beta channel. and removed beta-nominated Nominated for backporting to the compiler in the beta channel. labels Mar 29, 2025

m-ou-se mentioned this pull request Apr 9, 2025

Implement pin!() using super let #139114

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m-ou-se mentioned this pull request Apr 20, 2025

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

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Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it #138717

Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it #138717

jdonszelmann commented Mar 19, 2025 •

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Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it #138717

Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it #138717

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