This is a tracking issue for precise capturing of type and lifetime parameters in impl Trait opaque types.

The feature gate for the issue is #![feature(precise_capturing)].

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

• Implement.
  • Implement syntax for impl Trait to specify its captures explicitly (feature(precise_capturing)) #123468
• Write/accept an RFC.
  • Precise capturing rfcs#3617
• Implement migration lints.
  • Warn against changes in opaque lifetime captures in 2024  #124228
• Remove incomplete_features lint from use<..> syntax.
• Add error for use of use<..> within RPITIT.
  • Deny use<> for RPITITs #126746
• Resolve bikeshed on impl use<..> vs use<..> impl.
  • Syntax for precise capturing: impl Trait + use<..> #125836
• Switch to final chosen syntax.
  • Rework feature(precise_capturing) to represent use<...> as a syntactical bound #126049
• Implement formatting in rustfmt.
  • Implement use<> formatting in rustfmt #126754
• Stabilize use<..> syntax.
  • Stabilize opaque type precise capturing (RFC 3617) #127672
• N/A: Add documentation to the dev guide.
  • See the instructions.
• Add documentation to the reference.
  • Add capturing and precise capturing rules reference#1577
  • Be sure to update the name-resolution example in impl trait restrictions.
• Add documentation to the edition guide.
  • Add chapter for Lifetime Capture Rules 2024 edition-guide#316
• Add formatting for new syntax to the style guide.
  • Add nightly style guide section for precise_capturing use<> syntax #126753
• Ensure ready for Rust 2024 stabilization.

Related

• Parse precise capturing syntax dtolnay/syn#1677
• Parse use<'a, T> precise capturing bounds as verbatim dtolnay/syn#1707
• Design meeting: Precise capturing lang-team#261
• Design meeting: impl use<..> Trait vs use<..> impl Trait lang-team#269
• Lifetime Capture Rules 2024 rfcs#3498
• Precise capturing rfcs#3617
• Stabilize associated type position impl Trait (ATPIT) #120700
• Syntax for precise capturing: impl Trait + use<..> #125836
• Deny use<> for RPITITs #126746
• Add nightly style guide section for precise_capturing use<> syntax #126753
• Implement use<> formatting in rustfmt #126754
• Give RPITITs variances, so they can (not) capture lifetimes #124029
• rustdoc: support for precise capturing #127228
• Suggest using precise capturing for hidden type that captures region #127619
• Implement precise_capturing support for rustdoc #127632
• Add cross-crate precise capturing support to rustdoc #127658
• Fix precise capturing suggestion for hidden regions when we have APITs #127664
• Stabilize opaque type precise capturing (RFC 3617) #127672
• Support for + use<..> precise_capturing syntax rust-analyzer#17598
• feat: add preliminary support for + use<..> precise_capturing syntax rust-analyzer#17676

Implementation history

• Implement syntax for impl Trait to specify its captures explicitly (feature(precise_capturing)) #123468
• Warn against changes in opaque lifetime captures in 2024  #124228

cc @oli-obk @compiler-errors @rust-lang/style