While implementing UI tests for a custom linter, a reviewer noted that it would easier to review rustfix'd files if they had a .rs extension, since that would enable code highlighting when reviewing on Github or other code editors. This would be useful, but would be a breaking change for existing users.

I believe the extension for rustfix'd files is currently hardcoded here:

Additionally, this would probably require default_file_filter() to be updated to skip .fixed.rs files.

Thanks!