Perhaps the ICU or parts of it should be integrated into the standard library?   There are lots of cases (in the past or currently), where features were tested as a library first or successful libraries or at least their interfaces were incorporated into the standard. Why should it differ from linear algebra, dates and times and physical units?   Text processing is a basic functionality.   We want to do more and more at compile-time, make constexpr everything, even do metaprogramming. So of course it should work at constexpr time.   If the statefulness of the current locale is a problem, either  - we have a locale-independent recommendation in the unicode standard  - we can provide the locale as a second argument to the case conversion function     So we have an official well-designed standard for the functionality, the information can be stored in just a few KiB. There is a huge customer need for text processing in programming languages. It is a basic functionality, which normally (at least for non-international text in the past) does not need external libraries. C++ wants to adhere to Unicode.   -----Ursprüngliche Nachricht----- Von:Thiago Macieira via Std-Proposals <std-proposals_at_[hidden]> But I also don't think it should simply try to be another ICU, even just the Unicode support.