Trailing whitespace remains when passing `--edition 2024`

[mmottl]

❯ rustfmt --version
rustfmt 1.8.0-stable (4d91de4e48 2025-02-17)

Consider the following file foo.rs:

fn f() {} // This has trailing whitespace  

The trailing whitespace remains when calling rustfmt --edition 2024 foo.rs but rustfmt foo.rs removes it.

[ytmimi]

Thanks! confirming that I can reproduce this behavior with rustfmt 1.8.0-nightly (fd0ea74 2025-04-12) (built from source).

Running cargo run --bin rustfmt -- --style-edition={2015|2018|2021} all remove the trailing whitespace, while running rustfmt with --style-edition=2024 keeps the trailing whitespace.

error[internal]: left behind trailing whitespace
 --> <stdin>:1:1:42
  |
1 | fn f() {} // This has trailing whitespace  
  |                                          ^^
  |
  = note: set `error_on_unformatted = false` to suppress the warning against comments or string literals