The optional subject of an imperative is usually the second person pronoun. I've found something quite peculiar in Malay, where the utterance is an imperative and is passive but the subject is not the second person.
Benda yang pelik jangan di-tegur (*[oleh kamu]) Thing COMP weird NEG PASS-mention (*[by 2.SG]) Don't mention things that are weird
The context of this utterance is one where 2 persons notice something weird, thinking that it's a ghostly entity or something paranormal and one person mentions what s/he sees, smells or hears. It's something like the 'knock on wood' gesture. The active counterpart of this utterance is the following:
(Kamu) jangan tegur benda yang pelik (2.SG) NEG mention thing COMP weird (You) don't mention things that are weird
One can also focus-move the arguments:
Benda yang pelik jangan ditegur.
Jangan ditegur, benda yang pelik.
Benda yang pelik, jangan tegur.
Jangan tegur benda yang pelik.
In transformational grammar, it is said that the internal argument is raised and the thematic subject is turned into an optional adjunct by-phrase. Using the by-phrase in the utterance above is anomalous. However, an imperative necessarily needs a second person subject in English and Malay, but the utterance above demonstrates that there is a mix up somehow.
The negator "jangan" is a direct order which means "do not". This means that the subject absolutely has to be the second person. In English, it would be very strange to use "do not" with a 3rd person subject.
How is this utterance possibly an imperative when the grammatical subject is not the second person?
How can one register this utterance as an imperative when SpecIP has been occupied by the moved internal argument, not the second person?