I use it with parenthesized clarification. So `# XXX(dependency-version): Reason why we can't have nice things` is code that can be updated when `dependency` of at least `version` can be assumed. The clarification is there so that if the reason itself goes away, we can just remove the conditional. Repeat for things like `cmake-3.23`, `macos-10.14`, `python-3.8` and so on. It's just an easily greppable string and Vim highlights it differently.
