Tracking Issue for Lifetime Capture Rules 2024 (RFC 3498) #117587
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A-edition-2024
Area: The 2024 edition
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Feature: 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)]`
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Relevant to the language team, which will review and decide on the PR/issue.
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traviscross
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bors
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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
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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
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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
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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
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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
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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-likeimpl Traitfeatures 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.
Steps
async fnand return-positionimpl Traitin trait #115822The text was updated successfully, but these errors were encountered: