Tracking Issue for RFC 3591: `use`ing a function from a trait

[clubby789]

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)].

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
  • Implement use associated items of traits #134754
• 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

[crumblingstatue]

Might be worth noting that there is an orthogonal implementation of using a trait function through the unstable fn_delegation feature.

#![feature(fn_delegation)]

reuse Default::default;

fn main() {
    let s: i32 = default();
    dbg!(s);
}

Although my understanding is that this is just some kind of experiment, and will not be stabilized?
Might be worth taking a look at the implementation though.

[joshtriplett]

We were discussing this feature in a @rust-lang/libs-api meeting. We were wondering if the infrastructure that enables this feature would make it straightforward to provide a (separate) feature allowing use of an inherent function or associated constant/type from a concrete type.