That sounds good, but when you start thinking about how to implement this practically, it seems like it would either be unfeasible or would fail to really address the problem.

Maybe the rule would be: Unicode is allowed only in resource files. It would make code comments awkward for many non-English-speaking programmers. But suppose you did it, then since URLs can include Unicode, it would become normal to put URLs in resource files. If the VCS flagged up Unicode commits in source code, it would have to give resource files a pass. So in any case where you're not hardcoding a URL it wouldn't flag up Unicode URL abuses like the one illustrated here. You wouldn't really have fixed the problem, just hidden it in a different way. You'd still need to flag up ambiguous Unicode characters in resource files.

That's exactly the solution from the article 👌

In the curl git repository most files and most content are plain old ASCII so we can “easily” whitelist a small set of UTF-8 sequences and some specific files, the rest of the files are simply not allowed to use UTF-8 at all as they will then fail the CI job and turn up red.