Error formatting with block comment after match scrutinee

[austenadler]

I am getting error[internal]: left behind trailing whitespace on the latest stable 1.90 and nightly rustc 1.92.0-nightly (4645a7988 2025-09-17)

Minimum example: https://play.rust-lang.org/?version=stable&mode=debug&edition=2024&gist=67d8495779f0d47760dff7bea024ad75

fn main() {
    match () /*x*/ {
     
        _ => {}
    }
}

The issue is caused by the comment after the scrutinee. If you remove the x (but keep the /**/), it will format, or if you replace x with any number of spaces, it formats fine.

Also fails if scrutinee is a variable name.

[shulaoda]

Same underlying issue as #6687: the block comment causes rustfmt to fail formatting the entire match expression, triggering a fallback to the original source which preserves trailing whitespace.