Can't have single line let-else and control braces on next line

[fedenator]

let-else always expands to multiple lines if control_brace_style = "AlwaysNextLine". I don't know if this is a bug or simply not supported.

[calebcartwright]

When you get a chance could you please share some minimal code snippets, specifically what you were anticipating and what you're actually seeing?

The former in particular isn't clear to me, but I will say that a let-else statement will only be formatted on a single line provided it's possible to put the entire statement on one line. If that's not the case (either due to a non-default config option or due to one or more of the requirements articulated in the style guide not being met) then the multi-line formatting would apply.

[fedenator]

Sure, this happened when I typed the line

let Some(position) = q_windows.single().cursor_position() else { return };

I use the next config (relevant lines only)

control_brace_style = "AlwaysNextLine"
single_line_let_else_max_width = 200

So the line gets expanded to this

let Some(position) = q_windows.single().cursor_position()
else
{
	return;
};

Though the let else statement fits in one line, it is being formatted to multiple lines. This is not necessarily wrong, given that I'm using control_brace_style = "AlwaysNextLine", but I'm not sure if not respecting single_line_let_else_max_width is intended the behavior. Also I'm wondering if having something like control_brace_style = "NextLineWhen" so only it's not expanded when single_line_let_else_max_width it's not exceeded would be something that should be added.

Note that having control_brace_style = "AlwaysSameLine" does keeps the statement in one line unless the limit it's exceeded, similar to what I want.

[ytmimi]

This is Interesting 🤔. personally I think the current formatting is correct given the use of control_brace_style = "AlwaysNextLine", though checking similar behavior using single_line_if_else_max_width would suggest that the single_line_if_else_max_width value should take precedence.

input:

fn main() {
    if lorem
    {
        println!("ipsum!")
    }
    else
    {
        println!("dolor!")
    }
}

output: (using control_brace_style=AlwaysNextLine,single_line_if_else_max_width=100)

fn main() {
    if lorem { println!("ipsum!") } else { println!("dolor!") }
}

[lukesneeringer]

It actually looks like control_brace_type = "ClosingNextLine" actually prevents any single-line if-else or let-else block.

For example:

let foo = if true { 0 } else { 1 };

This gets formatted to...

let foo = if true {
    0
}
else {
    1
};

I always wondered why rustfmt didn't allow me to have a single-line if/else (or let/else), but this option is what does it.