"internal error: left behind trailing whitespace" with long lines

[Naddiseo]

Using rustfmt-nightly (1.0.1-nightly) I get "internal error: left behind trailing whitespace" for the following sample program:

use std::fmt::{self, Display};
pub enum FooLongEnum { AVeryLongEnumName ,BNotherLongEnumName }
impl Display for Foo {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		let description = match self {
			FooLongEnum::AVeryLongEnumName => String::from("this is a very very very very very very very very very very very very very very very very long string"),
			
		
		};
		write!(f, "{}", description)
	}
}

[scampi]

do you have any custom configuration ?

[Naddiseo]

Not to my knowledge. I found it in a project I started yesterday, and hadn't configured anything.

[rchaser53]

I'd like to work on this.
I created a small reproducible code like below.

pub enum TestEnum {
    a,
    b,
}

fn test_fn(input: TestEnum) {
    match input {
        TestEnum::a => String::from("aaa"),
        TestEnum::b => String::from("this is a very very very very very very very very very very very very very very very ong string"),
        
    };
}

I found format_expr return None in rewrite_match_body.
Maybe I can resolve this issue.

[topecongiro]

cc #3206.