Ergonomic Clone Support

[shadowcatzero]

The following code errors with rust analyzer, but builds and runs with cargo:

#![feature(ergonomic_clones)]
// ...
let mut y = use || {
    // ...
};

specifically:

1. Syntax Error: expected expression [syntax-error] (on the 'u' in 'use')
2. Syntax Error: expected SEMICOLON [syntax-error] (on the space after 'use')

with nightly (2025-08-24) rust analyzer using rustup and rustaceanvim.

The other x.use syntax also fails as well, but the UseCloned trait works as expected.

It's an incomplete feature, so sorry if this is too early. I have no clue if those are supported or if it makes more sense to wait (couldn't find clear info on this). I thought I'd make this issue anyways in case someone else comes across this.

[ChayimFriedman2]

This feature is very new (and also an experiment AFAIK). We don't hurry to support new features, but if the maintenance effort is not too great and someone creates a PR we will accept it. I won't recommend doing that now though as we're during a migration to the next trait solver, so the PR could sit for a long time.