Tracking Issue for `where T = U`

[JulianKnodt]

This is a tracking issue for the RFC "135" (rust-lang/rfcs#135).
The feature gate for the issue is #![feature(type_equality_constraint)].

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 the RFC: parse and handle where T = U predicate #87471
• Adjust documentation (see instructions on rustc-dev-guide)
• Stabilization PR (see instructions on rustc-dev-guide)

Unresolved Questions

XXX --- list all the "unresolved questions" found in the RFC to ensure they are
not forgotten

Implementation history

Implemented in #87471

[JulianKnodt]

Closed for now, as the implementation PR was deferred.