Are member functions of std::wstring_convert thread safe?
Because std::wstring_convert is part of the Standard Library, it follows certain rules when it comes to handling an object of such type from different threads.
In particular, because both to_bytes and from_bytes overloads are non-const, it is not possible to use those members on any one particular object from different threads without synchronization. This makes sense, as codecvt conversions typically make use of a state_type object. Using it without synchronization would lead to disaster.