PreferSameLine brace_style with where_single_line = true causes inconsistent braces for function declarations

[lukewilson2002]

Function declarations that had their parameters "multi-lined" were forcing the brace after the where clause to the next line like so:

fn fn_with_everything_long_and_body<T, U, 'a>(
    aaaa: f64,
    bbbb: f64,
    cccc: f64,
    dddd: f64,
    eeee: f64,
    ffff: f64,       // Note: multiple arguments here
) -> Result<
    HashMap<String, Vec<(SomeLongTypeName, AnotherLongTypeName, YetAnotherType)>>,
    Box<dyn Error + Send + Sync + 'static>,
>
where
    T: Debug + Display + Clone + Send + Sync + 'static,
    U: Iterator<Item = &'a T> + ExactSizeIterator,
{     // <- brace here, incorrect ?
}

Whereas for an equivalent function that had no multi-lined arguments the brace would be on the same line as the last where predicate:

fn fn_with_long_return_and_where_and_body<T, U, 'a>(
    a: f64,       // Note: single argument here
) -> Result<
    HashMap<String, Vec<(SomeLongTypeName, AnotherLongTypeName, YetAnotherType)>>,
    Box<dyn Error + Send + Sync + 'static>,
>
where
    T: Debug + Display + Clone + Send + Sync + 'static,
    U: Iterator<Item = &'a T> + ExactSizeIterator, {            // <- brace here, correct by PreferSameLine
}

I've tracked it down to these lines of code:

rustfmt/src/items.rs

Lines 2750 to 2751 in 0332da0

	force_new_line_for_brace |=
	is_params_multi_lined && context.config.where_single_line() && !where_clause_str.is_empty();

---

With PreferSameLine, should the opening brace always be on the same line as the last where predicate? If so, then a condition can be added to not force the brace to a new line if brace_style is PreferSameLine:

- force_new_line_for_brace |=
-     is_params_multi_lined && context.config.where_single_line() && !where_clause_str.is_empty();
+ force_new_line_for_brace |= is_params_multi_lined
+    && context.config.where_single_line()
+    && !where_clause_str.is_empty()
+    && context.config.brace_style() != BraceStyle::PreferSameLine;