"type unstable" code

[Loong]

This issue is a list to track "type unstable" code, some of which will be fixed, but others won't.

[Loong]

In setclock, "type unstable" variables:

y::Any
xi::Union{DiscreteClock{Int64, Base.OneTo{Int64}}, Array{Int64, N} where N}
ft::Type

edit: fix by 086ce79

[Loong]

Return of _gettime and gettime which call _gettime. This "unstable" is similar to iterate and may be ignore.

edit:
In cc8e45e, _gettime renamed as _gettime_itr now, but return of _gettime_itr is still unstable.

[Loong]

This issue should be closed, and new "type unstable" code should be in a new issue.