array pattern formatting does not honour column limit

[nagisa]

Consider following code:

fn main() {
    let [
        mut insert_count, 
        mut set_count, 
        mut update_rc_count, 
        mut delete_count, 
        mut delete_all_count, 
        mut delete_range_count
    ] = [0u64; 6];
}

playground

Rustfmt will put the whole pattern on a single line, even though it well exceeds the 100 columns rustfmt should target.

[ytmimi]

@nagisa this fixed when using Version=Two

[nagisa]

One thing I'm missing in the referenced issue is why Version=Two scheme was necessitated? Is there a writeup on this somewhere? Could that be linked from a message (ideally the first one) in the referenced issue?

[ytmimi]

@nagisa I tracked this down to #4994, and we needed version=Two because it would have been a breaking change to introduce this to all users at the time. See #4994 (comment). It's almost always the case that when version=Two is needed to introduce a formatting fix it's to avoid breaking stable formatting.