Tracking issue for associated const equality · Issue #92827 · rust-lang/rust (original) (raw)

This is a tracking issue for the experimental feature associated const equality brought up in #702561 (RFC pending).
The feature gate for the issue is #![feature(associated_const_equality)].

About experimental features

An experimental feature is one that has not yet had an RFC. The idea is to allow implementation work to proceed to better inform an upcoming RFC. Experimental features cannot be stabilized without first having an RFC. The existence of an experimental feature does not indicate lang team consensus that the feature is desirable, only that there is a problem that is worthy of being solved and that the idea has enough merit to consider exploring. See the lang team process page for more details.

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

• Fully implement the feature
  • Address important open F-associated_const_equality `#![feature(associated_const_equality)]` issues
  • Support const projections in the next trait solver
  • Address all blocking FIXME(associated_const_equality)
• Write an RFC
• Adjust documentation (see instructions on rustc-dev-guide)
• Formatting for new syntax has been added to the Style Guide (nightly-style-procedure)
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

None so far.

Implementation history

• allow eq constraints on associated constants #876482
• Continue work on associated const equality #932853
• Resolve associated item bindings by namespace #118668
• Fix type resolution of associated const equality bounds (take 2) #119385
• Reject overly generic assoc const binding types #121258

1. Original proposal with support but no official RFC, but implementation delayed. ↩
2. Initial effort to implement which includes parsing and use of term throughout the codebase, but still lacking a complete implementation. ↩
3. More thorough implementation which works for basic cases. This allowed for consts to actually be bound, more than just parsing them. ↩