Rustfmt causes compilation error by inserting illegal trailing comma in macro

[Aloso]

Describe the bug

Struct patterns that end with .. can't have a trailing comma. However, rustfmt on nightly inserts one within macro_rules!.

To Reproduce

Run rustup default nightly, then format this code:

macro_rules! foo {
    ($s:ident ( $p:pat )) => {
        Foo {
            name: Name::$s($p),
            ..
        }
    };
}

Expected behavior

The comma should not be inserted to ensure that expanded code compiles.

Meta

• rustfmt version: rustfmt 1.4.32-nightly (216a643 2021-01-16)
• From where did you install rustfmt? Via rustup
• How do you run rustfmt: Either with cargo fmt or with rust-analyzer (makes no difference)

[Aloso]

@calebcartwright Thanks for fixing this so quickly!

[calebcartwright]

@calebcartwright Thanks for fixing this so quickly!

Sure! It was really just a case of exceptionally fortuitous timing, as this popped up right as I was preparing to update rustfmt on nightly and it only needed a trivial fix.

Any future issues will almost certainly not have the same turnaround 😄