internal error: left behind trailing whitespace

[bjorn3]

Source: https://github.com/bjorn3/rustc_codegen_cranelift/tree/rustfmt_error

$ cargo fmt
internal error: left behind trailing whitespace
   --> /home/bjorn/Documenten/rustc_codegen_cranelift/src/lib.rs:416
    |
416 |                     
    | ^^^^^^^^^^^^^^^^^^^^

warning: rustfmt may have failed to format. See previous 1 errors.

[minno726]

Same issue for me. The minimal reproduction I have is two lines:

a_macro!(name<Param1, Param2>, 
);

The error points to the trailing space on the first line. Removing one or both of the generic parameters removes the error.

[topecongiro]

@bjorn3 This is likely due to the comment in the match arm. #1087 is a similar issue.

[theduke]

I have run into the same issue.

Sadly it occurs all over the place for me with using a macro to build HTML.