Lint for .clone().into_boxed_str()

[lolbinarycat]

What it does

Suggest turning s.clone().into_boxed_str() into Box::from(s.as_str()).

Possibly could be grouped together with other inefficient string conversions.

Advantage

Removes a call to __rust_realloc

Drawbacks

No response

Example

fn foo(s: &String) -> Box<str> {
    s.clone().into_boxed_str()
}

Could be written as:

fn foo(s: &String) -> Box<str> {
    Box::from(s.as_str())
}

Comparison with existing lints

redundant_clone generally doesn't consider the semantics of the

Additional Context

A GitHub search shows this unoptimal pattern is actually used fairly often.

[Jarcho]

Would probably name this something like clones_into_boxed_slices. This is definitely not redundant_clone since the clone is used and __rustc_realloc will never actually be called (the length and capacity or a clone are always equal).

[zihan0822]

kind of similar to #15373