Illegally adds comma to macro invocation

[Person-93]

Rustfmt adds a comma to the following and causes a compiler error.

macro_rules! idx {
    ($(#[$attr:meta])* $vis:vis struct $name:ident; $metadata:ident) => {
        $(#[$attr])*
        $vis struct $name(usize);
    };
}

idx!(
    #[derive(Debug)]
    pub struct FooIdx; // rustfmt adds a comma here
    Meta
);

[ytmimi]

Thanks for the report. Confirming I can reproduce this with rustfmt 1.8.0-nightly (c6c8159 2025-02-27)

Input:

idx!(
    #[derive(Debug)]
    pub struct FooIdx; // rustfmt adds a comma here
    Meta
);

Output:

idx!(
    #[derive(Debug)]
    pub struct FooIdx;, // rustfmt adds a comma here
    Meta
);