> Diagnostic printf message in some embedded firmware. Do you need to drag Unicode into it?
Why not? The firmware itself would usually have no reason to care about the details of a diagnostic message's encoding, whether that be ASCII or UTF-8 - it can mostly just treat strings as bags of bytes. There might be some byte values that are special (nul terminator, % for printf, etc.), but UTF-8 is a superset of ASCII and represents extended characters using only bytes with the highest bit set, so there will never be 'false positives' of the special byte values. Other than that, the bytes can stay uninterpreted as they go over whatever serial port or diagnostic protocol the device is using, until they eventually show up on - most likely - some sort of terminal application on a modern computer, which probably supports UTF-8 already. So in most cases it should 'just work'.
Of course, there are situations where it won't just work, such as if the firmware needs to display the diagnostic message on a screen (by itself), but from what I've seen those are the minority.
edit: As for Git, what's wrong with people writing log messages in their language of choice? (Other than the social issue of it making it harder for English speakers to use the codebase.)
Not specifically trying to weigh in on the overall conversation, but aren't git commands generally UTF-8?
> git commit and git commit-tree issues a warning if the commit log message given to it does not look like a valid UTF-8 string, unless you explicitly say your project uses a legacy encoding.
> git log, git show, git blame and friends look at the encoding header of a commit object, and try to re-code the log message into UTF-8 unless otherwise specified.
