rustfmt always inserts newline before `else` in let-else statement with attribute

[rhysd]

Repro

This is a code rustfmt formatted.

fn main() {
    #[cfg(target_os = "linux")]
    let x = 42
    else {
        todo!()
    };

    // #[cfg(target_os = "linux")]
    let x = 42 else { todo!() };
}

With some attribute on a let-else statement, rustfmt always inserts newline before else. When removing the attribute, this doesn't happen and rustfmt works as intended.

Expected behavior

My expectation is that rustfmt does not change formatting looking at the existence of attribute:

fn main() {
    #[cfg(target_os = "linux")]
    let x = 42 else { todo!() };

    // #[cfg(target_os = "linux")]
    let x = 42 else { todo!() };
}

Environment

• rustfmt: 1.6.0-stable (5680fa18 2023-08-23)
  • Installed via rustup's stable toolchain
• Rust: 1.72.0
• OS: Windows 10

[ytmimi]

Thanks for the report. Confirming I can reproduce this using rustfmt 1.6.0-nightly (b6367235 2023-08-30).

I wish I would have caught this when implementing let-else. I tried to be thorough with test cases but it didn't occur to me to test a let-else with an attribute 🤦

@calebcartwright I'm guessing we'll need to version gate this fix

[rhysd]

@ytmimi Thank you for triaging quickly. I'm looking at the implementation and trying to fix this issue. I'll make a PR.

[calebcartwright]

@calebcartwright I'm guessing we'll need to version gate this fix

Yeah we'll have to, can't rock formatting on stable again unfortunately. Mercifully the 2024 edition won't be too terribly far out so in practice this will get cleaned up by default before too long

[ytmimi]

Yup, that's what I thought

[rhysd]

@rustbot claim