failed to format array with long string/identifier

[xxchan]

❯ cargo +nightly fmt
error[internal]: left behind trailing whitespace
 --> /private/tmp/tmp/src/main.rs:6:6:1
  |
6 |           
  | ^^^^^^^^^^
  |

fn main() {
    let aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa =
        1;
    let b = 2;
    let a = &[

                aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa,
        b,
    ];

    // or this
    // let a = &[

    //             "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa",
    //     "b",
    // ];
}

[ytmimi]

The max_width is a hard constraint for rustfmt. If it can't rewrite the identifier it'll fail to rewrite the let binding. Similarly, the long identifier in the list prevents it from being rewritten.

In this case there are two options to address the trailing whitespace error:

1. The developer can manually remove the trailing whitespace
2. increase the max_width to some sufficiently high value.