Deref support

[mqudsi]

NB: This might be a duplicate as I'm surprised it's never been even brought up, but I can't find any issues matching Deref with GitHub search

It does not appear that autocompletion is recursively triggered for the target of a Deref operation, both when triggered implicitly or explicitly.

Given the following code, which compiles and runs correctly:

use std::ops::Deref;

struct DerefExample<T> {
    value: T
}

impl<T> Deref for DerefExample<T> {
    type Target = T;

    fn deref(&self) -> &T {
        &self.value
    }
}


fn main() -> () {
    let x = DerefExample { value: "a".to_string() };
    x.deref().starts_with("a");
}

Explicit Deref

On the line x.deref().starts_with..., autocompletion after x.deref(). suggests nothing. This is presumably tied to another bug, as the signature is clear (and rls itself is aware of x.deref() -> &T's existence).

Implicit Deref

On the same line, x. suggests value, deref() -> &T, and deref() -> &Self::Target. It does not suggest starts_with(...) -> bool.

[aloucks]

Auto-completion is currently powered by racer. It looks like there's an open issue for enhancements that includes better deref support.

From racer-rust/racer#829

use std::ops::Deref;

struct Foo {}

impl Foo {
    fn bar(&self) {
        println!("nights");
    }
}

struct Ref<'a, T: 'a> {
    obj: &'a T,
}

impl<'a, T> Deref for Ref<'a, T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        self.obj
    }
}

fn main() {
    let a = Ref { obj: &Foo {} };
    // a. // Auto-complete does not work here
}

[nrc]

Closing in favour of the Racer issue.