Support use Trait::method and/or Type::method?

[Rufflewind]

Currently Rust doesn’t support any of the following:

// Example A
use Default::default;
use f64::sin;

This means one can never write default() or sin(3.14) without qualification as individual methods can never be imported in isolation. The workaround is to have a prelude-like module where you write wrappers for such static methods as free functions:

// Example B
pub fn default<T: Default>() -> T { T::default() }
pub fn sin(x: f64) -> f64 { f64::sin(x) }

This is a lot of boilerplate. Perhaps it would useful to make Example A “just work”?

For static methods, the intent is pretty clear: it would enable

static_method(arg1, arg2, …)

This would be just a shorthand for calling Trait::static_method. It won’t work if Self is ambiguous.

For non-static methods, it’s not obvious what use Trait::method would do. Which among these would it enable? (Either or both?)

method(obj, arg1, arg2, …)
obj.method(arg1, arg2, …)

[abonander]

For what it's worth, sin(), cos() and tan() are all inherent methods, so you can do 3.14f64.sin().

[petrochenkov]

This is more an RFC material rather than a rust-lang/rust issue.

Adding use Trait::AssocItem; should be simple, it mostly needs motivation and decision.
use Type::AssocItem; is not possible with current organization of compilation stages.

[Rufflewind]

@petrochenkov Oops my bad. I thought this was the rfcs repository. Should I move the issue over there?

[Rufflewind]

Moved to: rust-lang/rfcs#1995