clippy could suggest .is_empty() for more things

[matthiaskrgr]

What it does

https://rust-lang.github.io/rust-clippy/master/index.html#/comparison_to
covers things like string = "", but we could also perhaps catch things like get the first element and check if that's SomeorNone`

        let v: &[i32] = &[1,2,3];
        if let Some(_) = v.get(0) {
                eprintln!("not_empty");
        }

        let v: &[i32] = &[1,2,3];
        if let Some(_) = v.get(0) { // !is_empty()
                eprintln!("not_empty");
        }

        let v: &[i32] = &[1,2,3];
        if let Some(_) = v.first() { // !is_empty()
                eprintln!("not_empty");
        }

        let v: &[i32] = &[1,2,3];
        if  v.get(0).is_some() {
                eprintln!("not_empty");
        }

        let v: &[i32] = &[1,2,3];
        if  v.first().is_some() {
                eprintln!("not_empty");
        }

[y21]

I think for all of these cases, clippy already leads you to writing v.first().is_some() through other lints, so maybe it just needs to lint that one case and suggest !v.is_empty()?

[matthiaskrgr]

yeah, exactly