[cannam]

QString::toUpper/toLower are not locale-aware (https://doc.qt.io/qt-6/qstring.html#toLower)

Qt does have a locale-aware equivalent (QLocale::toUpper/toLower) which calls out to ICU if available. Otherwise it falls back to the QString functions, so you have to be confident about how your build is configured. Whether it works or not has very little to do with the design of QString.

[ahartmetz]

I don't see a problem with that. You can have it done locale-aware or not and "not" seems like a sane default. QString will uppercase 'ü' to 'Ü' just fine without locale-awareness whereas std::string doesn't handle non-ASCII according to the article. The cases where locale matters are probably very rare and the result will probably be reasonable anyway.

[account42]

That attitude is how you end up with exploits because your case folding is different from some other system you interact with.