Format issue on supertrait with bounds on associated types.

[gui1117]

For all version I could tests (master and nightly)

this code:

pub trait MyLongTraitName:
    MyLongBoundName<
        MyLongAssociatedType:
            SomeAnotherBound<
                YetAnotherType: YetAnotherBound,
                YetAnotherType2: YetAnotherBound2
            >,
        OtherType: SmallBound
            + SmallBound2
            + AnotherLongBound<
                WithSomeType: BeingBound,
                WithSomeType2: BeingBound,
                WithSomeType3: BeingBound
            >
            + SmallBound3
            + AnotherLongBound2<
                WithSomeType: BeingBound,
                WithSomeType2: BeingBound,
                WithSomeType3: BeingBound
            >,
    >
{
}

fn main() {}

gets formatted into:

pub trait MyLongTraitName:
    MyLongBoundName<
    MyLongAssociatedType: SomeAnotherBound<
        YetAnotherType: YetAnotherBound,
        YetAnotherType2: YetAnotherBound2,
    >,
    OtherType: SmallBound
                   + SmallBound2
                   + AnotherLongBound<
        WithSomeType: BeingBound,
        WithSomeType2: BeingBound,
        WithSomeType3: BeingBound,
    > + SmallBound3
                   + AnotherLongBound2<
        WithSomeType: BeingBound,
        WithSomeType2: BeingBound,
        WithSomeType3: BeingBound,
    >,
>
{
}

fn main() {}

[ytmimi]

Thanks for the report. Confirming I can reproduce this the latest master rustfmt 1.7.1-nightly (1a70f40d7f 2024-09-03)

[gui1117]

It seems those types are formatted with the overflow formatting, do you suggest to change the overflow formatting or change formatting so it doesn't go into overflow?

[ytmimi]

@gui1117 have you started looking into this issue?

[gui1117]

@gui1117 have you started looking into this issue?

Not really, and I would prefer not because I struggle to understand the code. But I look a bit when I have free time.

[ytmimi]

@gui1117 no worries. Based on https://github.com/rust-lang/rustfmt/issues/6316#issuecomment-2339597525 I thought maybe you'd looked through the code.

Not really, and I would prefer not because I struggle to understand the code.

It's quite a tricky part of the codebase. Definitely don't feel obligated to dive in.

[jrose-signal]

Smaller example without any nesting, though I'm sure the nesting doesn't help:

pub trait Example<Inner = ()>:
    ExampleImplementation<
    Inner,
    MoreParam,
    AnotherParam,
    AnotherParamAgain,
    YetAnotherParam,
    AFurtherParam,
>
{
}