brace_style option not respected on polyadic functions with multiline signatures under "where_single_line = true"

[meiomorphism]

Input

pub fn function_of_arity_one(
    parameter_one: Option<Option<Option<Option<Option<Option<bool>>>>>>,
) -> Option<bool> {
    None
}

pub fn function_of_arity_two(
    parameter_one: Option<Option<Option<Option<Option<Option<bool>>>>>>,
    parameter_two: Option<Option<Option<Option<Option<Option<bool>>>>>>,
) -> Option<bool> {
    None
}

pub fn function_of_arity_three(a: u8, b: u8, c: u8) -> Option<bool> {
    None
}

Output

The space after the second function's return type is converted to a newline:

pub fn function_of_arity_one(
    parameter_one: Option<Option<Option<Option<Option<Option<bool>>>>>>,
) -> Option<bool> {
    None
}

pub fn function_of_arity_two(
    parameter_one: Option<Option<Option<Option<Option<Option<bool>>>>>>,
    parameter_two: Option<Option<Option<Option<Option<Option<bool>>>>>>,
) -> Option<bool>
{
    None
}

pub fn function_of_arity_three(a: u8, b: u8, c: u8) -> Option<bool> {
    None
}

Expected output

Identical to input.

Meta

rustfmt 1.4.27-nightly (580d826 2020-11-16), installed via rustup, and invoked as cargo +nightly fmt -- ./test.rs.

rustfmt.toml contained no uncommented lines except where_single_line = true.

[calebcartwright]

Agreed. In cases where the fn signature has to be formatted across multiple lines then a present where clause would need to be formatted in the multiline form even if when where_single_line is true, but that rule shouldn't be applied in the absence of a where clause