> It's also pretty telling that every article that tries to explain how to safely copy or concat strings in C, like this one, only ever works with ASCII, no attempt whatsoever to handle UTF-8 and keep code points together, let alone grapheme clusters.

Can you expand on this? Why does it matter to keep code points and grapheme clusters together in the case of truncation? If you’re already truncating the string, then you can just copy as many bytes as possible. Then, later when you interpret that string, you’ll hit a malformed codepoint and ignore it. I guess what you might be getting at is that if you have a codepoint sequence, then you shouldn’t copy the bytes if they can’t all fit in the truncated string?

I feel like this is an edge case and not “the reason almost all C software has problems with non-English strings”. 99% of the time, copying up until the null byte is fine, whether or not the string is UTF-8 or ASCII. The reason most C software doesn’t work with non-English strings is because the developer never added support. The bytes are still there, they just need to be interpreted correctly in the UI portions of the code.