Wish to have some new options about line break style

version

rustfmt 1.7.1-nightly (94885bc6 2024-09-01)

rustfmt.toml

max_width = 80
use_small_heuristics = "Max"

example

fn _hincrbyex(
    _a: &mut i64,
    _key: &i64,
    _field: &i64,
    _delta: i64,
    _iexpsec: i64,
    _b0: bool,
) -> bool {
    false
}

fn test() {
    let mut conn: i64 = 0;
    let key: i64 = 0;
    let field: i64 = 0;
    let delta: i64 = 0;
    let iexpsec: i64 = 0;

    let is_xxxxxxxx: bool = false;
    let is_xxxxxxxxx: bool = false;
    let is_xxxxxxxxxxxxxxx: bool = false;
    let is_xxxxxxxxxxxxxxxx: bool = false;

    // single line: exactly 80 ------------------------------------------------|
    let _fut = _hincrbyex(&mut conn, &key, &field, delta, iexpsec, is_xxxxxxxx);

    // style 1: 81 ------------------------------------------------------------|
    let _fut =
        _hincrbyex(&mut conn, &key, &field, delta, iexpsec, is_xxxxxxxxx);

    // style 1: exactly 80 for the second line --------------------------------|
    let _fut =
        _hincrbyex(&mut conn, &key, &field, delta, iexpsec, is_xxxxxxxxxxxxxxx);

    // style 2: 81 for the second line in style 1 -----------------------------|
    let _fut = _hincrbyex(
        &mut conn,
        &key,
        &field,
        delta,
        iexpsec,
        is_xxxxxxxxxxxxxxxx,
    );
}

According to the above example, rustfmt have two line break styles for long statement. But I really don't like the style 1 because it looks strange in some cases. I have to make some tricky adjustments such as rename the function name / rename some argument names / ... to change the style 1 to single line or style 2. And it bothers me too in some other situations such as match-arms.
I wish to have some new options in rustfmt.toml to disable the style 1, a statement should directly be formatted to the style 2 from single line if it's too long. Thanks~

Start by reproducing the two line-break styles from the issue's rustfmt.toml configuration and Rust example. Read the formatter logic for long statements and match arms, then determine where an option would control the choice. Done means the option is documented and the examples format directly from a single line to the fully broken style, with tests covering both enabled and default behavior.