[johnyzee]

Ugh, I've had the exact same problem in a Java project, which meant I had to go through thousands and thousands of lines of code and make sure that all 'toLowerCase()' on enum names included Locale.ENGLISH as parameter.

As the article demonstrates, the error manifests in a completely inscrutable way. But once I saw the bug from a couple of users with Turkish sounding names, I zeroed in on it. And cursed a few times under my breath whoever messed up that character table so bad.

[nradov]

Were you not using static analysis tools? All of the popular ones will warn about that issue with locales.

[lucumo]

They do. But a generic warning about locale-dependence doesn't really tell you that ASCII-strings will be broken. For nearly every purpose ASCII is the same in every locale. If you have a string that is guaranteed to be ASCII (like an enum constant is in most code styles), it's easy to think "not a problem here" and move on.