Strange formatting for closure with match

[jonhoo]

Take the following (manually formatted) code:

fn main() {
    let bar = Some(true);
    let foo = Some(true);
    let mut x = false;
    bar.and_then(|_| {
        match foo {
            None => None,
            Some(b) => {
                x = true;
                Some(b)
            }
        }
    });
}

rustfmt will currently turn that into

fn main() {
    let bar = Some(true);
    let foo = Some(true);
    let mut x = false;
    bar.and_then(|_| match foo {
                     None => None,
                     Some(b) => {
        x = true;
        Some(b)
    }
                 });
}

Which is much less visually clear. It almost seems like rustfmt forgets to carry along the indentation level?

[jonhoo]

I wonder if this is just another manifestation of #1332...

[aldanor]

#1405 could be the the same thing?

[jonhoo]

@aldanor in fact, I think these are all the result of the new visual indent rules for closures (in #1332). If you look at these cases, rustfmt does "the right thing" for all of them, in the sense of choosing to use visual indent for the closure body, and then block closure for some things inside the closure body. The bug seems to be that block indent inside a visual indent does not inherit the indentation level of the containing visual indent.

[nrc]

With the RFC style, this is currently formatted as:

fn main() {
    let bar = Some(true);
    let foo = Some(true);
    let mut x = false;
    bar.and_then(
        |_| match foo {
            None => None,
            Some(b) => {
                x = true;
                Some(b)
            }
        },
    );
}

Which is much better, but not quite perfect.

[aldanor]

Better indeed. However match lining up with the match arms (None and Some) is particularly unfortunate, since |_| happens to take exactly 4 spaces, same as the tab width...

In the original example, closure body was surrounded by braces -- were they removed by rustfmt?

[nrc]

In the original example, closure body was surrounded by braces -- were they removed by rustfmt?

Yes

[topecongiro]

Closed by #1454.