Tracking Issue for RFC 3591: `use`ing associated items from traits

This is a tracking issue for the RFC "Add support for use Trait::func" (rust-lang/rfcs#3591).
The feature gate for the issue is #![feature(import_trait_associated_functions)].

[!IMPORTANT]
Differences from RFC: You are allowed to glob-import associated items (::*) and you're allowed to import associated types (however, referencing the import will always lead to an ambiguity since the self type & trait can't be deduced from context (and likely never will, at least not until <_>::AssocTy works, cc https://github.com/rust-lang/rust/issues/22519)). Context / rationale: rust-lang/rust#3591.

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.
Discussion comments will get marked as off-topic or deleted.
Repeated discussions on the tracking issue may lead to the tracking issue getting locked.

Steps

• Implement the 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

Implementation history

• https://github.com/rust-lang/rust/pull/134754
• https://github.com/rust-lang/rust/pull/138712

Start with the linked rustc-dev-guide documentation and stabilization-guide instructions, then review src/doc/style-guide and the nightly-style-procedure for the remaining documentation and formatting work. Done means the documentation is adjusted, new syntax has Style Guide formatting, and a stabilization PR is prepared.