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Tracking Issue for Lifetime Capture Rules 2024 (RFC 3498) #117587

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traviscross opened this issue Nov 4, 2023 · 1 comment
Closed
9 of 10 tasks

Tracking Issue for Lifetime Capture Rules 2024 (RFC 3498) #117587

traviscross opened this issue Nov 4, 2023 · 1 comment
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A-edition-2024 Area: The 2024 edition B-RFC-approved Blocker: Approved by a merged RFC but not yet implemented. C-tracking-issue Category: A tracking issue for an RFC or an unstable feature. F-lifetime_capture_rules_2024 `#![feature(lifetime_capture_rules_2024)]` S-tracking-ready-for-edition Status: This issue is ready for inclusion in the edition. T-lang Relevant to the language team, which will review and decide on the PR/issue.

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@traviscross
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traviscross commented Nov 4, 2023

This is a tracking issue for the RFC 3498, "Lifetime Capture Rules 2024" (rust-lang/rfcs#3498). The feature gate for the issue is #![feature(lifetime_capture_rules_2024)].

In Rust 2024 and later editions, return position impl Trait (RPIT) opaque types will automatically capture all in-scope type and lifetime parameters. In preparation for this, new RPIT-like impl Trait features introduced into earlier editions will also automatically capture all in-scope type and lifetime parameters.

About tracking issues

Tracking issues are used to record the overall progress of implementation. They are also used as hubs connecting to other relevant issues, e.g., bugs or open design questions. A tracking issue is however not meant for large scale discussion, questions, or bug reports about a feature. Instead, open a dedicated issue for the specific matter and add the relevant feature gate label.

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@traviscross traviscross added B-RFC-approved Blocker: Approved by a merged RFC but not yet implemented. T-lang Relevant to the language team, which will review and decide on the PR/issue. C-tracking-issue Category: A tracking issue for an RFC or an unstable feature. F-lifetime_capture_rules_2024 `#![feature(lifetime_capture_rules_2024)]` labels Nov 4, 2023
@traviscross traviscross added the A-edition-2024 Area: The 2024 edition label Apr 10, 2024
@traviscross traviscross self-assigned this Apr 12, 2024
bors added a commit to rust-lang-ci/rust that referenced this issue Apr 15, 2024
…=oli-obk

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)

Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to rust-lang#117587.

We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? `@oli-obk`

Tracking issue:

- rust-lang#123432
bors added a commit to rust-lang-ci/rust that referenced this issue Apr 16, 2024
…=oli-obk

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)

Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to rust-lang#117587.

We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? `@oli-obk`

Tracking issue:

- rust-lang#123432
bors added a commit to rust-lang-ci/rust that referenced this issue Apr 16, 2024
…=oli-obk

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)

Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to rust-lang#117587.

We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? `@oli-obk`

Tracking issue:

- rust-lang#123432
bors added a commit to rust-lang-ci/rust that referenced this issue Apr 16, 2024
…=oli-obk

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)

Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to rust-lang#117587.

We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? `@oli-obk`

Tracking issue:

- rust-lang#123432
flip1995 pushed a commit to flip1995/rust that referenced this issue Apr 18, 2024
…=oli-obk

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)

Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to rust-lang#117587.

We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? `@oli-obk`

Tracking issue:

- rust-lang#123432
@traviscross traviscross added S-tracking-needs-documentation Status: Needs documentation. S-tracking-needs-migration-lint Status: This item needs a migration lint. labels May 21, 2024
calebcartwright pushed a commit to calebcartwright/rust that referenced this issue Jun 22, 2024
…=oli-obk

Implement syntax for `impl Trait` to specify its captures explicitly (`feature(precise_capturing)`)

Implements `impl use<'a, 'b, T, U> Sized` syntax that allows users to explicitly list the captured parameters for an opaque, rather than inferring it from the opaque's bounds (or capturing *all* lifetimes under 2024-edition capture rules). This allows us to exclude some implicit captures, so this syntax may be used as a migration strategy for changes due to rust-lang#117587.

We represent this list of captured params as `PreciseCapturingArg` in AST and HIR, resolving them between `rustc_resolve` and `resolve_bound_vars`. Later on, we validate that the opaques only capture the parameters in this list.

We artificially limit the feature to *require* mentioning all type and const parameters, since we don't currently have support for non-lifetime bivariant generics. This can be relaxed in the future.

We also may need to limit this to require naming *all* lifetime parameters for RPITIT, since GATs have no variance. I have to investigate this. This can also be relaxed in the future.

r? `@oli-obk`

Tracking issue:

- rust-lang#123432
@traviscross traviscross removed the S-tracking-needs-migration-lint Status: This item needs a migration lint. label Jul 30, 2024
@traviscross traviscross added the S-tracking-impl-incomplete Status: The implementation is incomplete. label Aug 20, 2024
matthiaskrgr added a commit to matthiaskrgr/rust that referenced this issue Aug 26, 2024
…captures-to-rust-2024, r=compiler-errors

Tie `impl_trait_overcaptures` lint to Rust 2024

The `impl_trait_overcaptures` lint is part of the migration to Rust 2024 and the Lifetime Capture Rules 2024.  Now that we've stabilized precise capturing (RFC 3617), let's tie this lint to the `rust_2024_compatibility` lint group.

Tracking:

- rust-lang#117587

r? `@compiler-errors`
rust-timer added a commit to rust-lang-ci/rust that referenced this issue Aug 26, 2024
Rollup merge of rust-lang#129600 - traviscross:TC/tie-impl_trait_overcaptures-to-rust-2024, r=compiler-errors

Tie `impl_trait_overcaptures` lint to Rust 2024

The `impl_trait_overcaptures` lint is part of the migration to Rust 2024 and the Lifetime Capture Rules 2024.  Now that we've stabilized precise capturing (RFC 3617), let's tie this lint to the `rust_2024_compatibility` lint group.

Tracking:

- rust-lang#117587

r? `@compiler-errors`
@traviscross traviscross removed S-tracking-impl-incomplete Status: The implementation is incomplete. S-tracking-needs-documentation Status: Needs documentation. labels Sep 3, 2024
@traviscross traviscross added the S-tracking-ready-for-edition Status: This issue is ready for inclusion in the edition. label Sep 3, 2024
@traviscross
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@rustbot labels +S-tracking-ready-for-edition

We discussed this item in the edition call today and concluded that this is ready for Rust 2024.

Huge thanks to @compiler-errors for moving the mountains needed to make this concept a reality.

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Labels
A-edition-2024 Area: The 2024 edition B-RFC-approved Blocker: Approved by a merged RFC but not yet implemented. C-tracking-issue Category: A tracking issue for an RFC or an unstable feature. F-lifetime_capture_rules_2024 `#![feature(lifetime_capture_rules_2024)]` S-tracking-ready-for-edition Status: This issue is ready for inclusion in the edition. T-lang Relevant to the language team, which will review and decide on the PR/issue.
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