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 (fd0ea742f8 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

[jblachly]

I have the same issue, except that running

cargo fmt -- --style-edition=2021

does not remove the whitespace and rustfmt still returns errors:

error[internal]: left behind trailing whitespace
   --> /Users/james/src/blachlylab/wodehouse/src/lib/routes/layout.rs:129:129:81
    |
129 |         (layout.visibility == crate::models::userdef::Visibility::AccountWide && 
    |                                                                                 ^

Version: rustfmt 1.8.0-nightly (f3db63916e 2025-06-17)

Code in question is:

    // Check permissions based on visibility
    let can_access =
        // User owns the layout
        layout.user_id == uid ||
        // Layout is public
        layout.visibility == crate::models::userdef::Visibility::Public ||
        // Layout is account-wide and user is in the same account
        (layout.visibility == crate::models::userdef::Visibility::AccountWide && 
         user.account_id.is_some() &&
         conn.run(move |c| {
             use diesel::prelude::*;
             use crate::schema::users::dsl::*;

             users
...

and the trailing whitespace is after the boolean operators || and &&

[ytmimi]

@jblachly you're issue is off topic. It's a duplicate of #3591 and other linked issues. rustfmt won't format binary expressions if they contain comments in the because they would otherwise be deleted.