Re: changing function slots should update compiler properties

[Richard Stallman]

    Functions which update symbols' function slots should remove compiler
    properties first.  E.g., if you redefine something with `defun' that
    previously was defined with `defsubst', it currently maintains the
    `byte-compile-inline-expand' property.

I agree with you in that case.

    Also I think that `defalias' should copy compiler properties where
    appropriate.  E.g. after `(defalias 'plus '+)', I think calls of
    `plus' should compile like calls of `+'.  I'm not completely sure it's
    safe, though.

I'd rather not try to go down this road.
It would lead to a lot of work that we can just as well avoid.