Rob Shearman rob@codeweavers.com writes:
At present, if the size of the buffer passed to snprintfW is too small then the function returns -1, as opposed to the required size of the buffer (as per C snprintf). This greatly limits its usefulness and can give incorrect results for those using the function that don't explicitly check for -1 being returned. A grep of the source tree shows that nothing depends on this behaviour.
Actually, something does depend on it: it is used to implement _vsnwprintf in ntdll, so you can't change it.