The Python C API has two very useful functions: _Py_char2wchar() and _Py_wchar2char(). They must be used to handle correctly undecodable byte sequences. _Py_char2wchar() and _Py_wchar2char() use the surrogateescape error handler (PEP-383). _Py_char2wchar() forces also the ASCII encoding on FreeBSD and Solaris when the LC_CTYPE locale is C.
Py_Main() expects an array of wide character strings (wchar_t*) for the command line argument, whereas main() gets an array or byte strings (char*). _Py_char2wchar() must be used to be able to call Py_Main().
How often do people need to convert to do platform independent locale encoding before Python is initialized? Encouraging use of platform dependent wchar_t's seems like a bad idea when PyUnicode abstracts away the difference ever since 3.3 released.