Function wcstoumax 

#[unsafe(no_mangle)]
pub unsafe extern "C" fn wcstoumax(
    nptr: *const wchar_t,
    endptr: *mut *mut wchar_t,
    base: c_int,
) -> uintmax_t

See https://pubs.opengroup.org/onlinepubs/9799919799/functions/wcstoimax.html.

Equivalent to wctoul() and wctoull(), except that the initial portion of the wide string shall be converted to uintmax_t.

Upon success, returns the converted value. If no conversion could be performed, returns 0.