Cameron McCormack:
Trailing undefineds are treated as "not passed" in the overload resolution algorithm (step 4).
Boris Zbarsky:
Only if explicit [TreatUndefinedAs=Missing] is being used, no?
Yes. If we do as the note says, IIUC, it would mean that [TreatUndefinedAs=Missing] would be normal behaviour, and that explicit undefined values even in the middle of a list of actual arguments would get treated as the argument's default value, if it has one. Is that right?
