`sfAddrTaken` not set for array `a` on `a[0].addr`

[timotheecour]

@Araq low priority but I noticed the following while working on some PR; is the following a bug?
sfAddrTaken is not set for array a on a[0].addr even though a and a[0].addr have the same address.

when true: # D20200711T150822
  proc main() =
    var a = [0,1]
    let a1 = a[0].addr # this does not set `sfAddrTaken` on `a`address
    let a2 = a.addr # this does set `sfAddrTaken` on `a`

[Clyybber]

sfAddrTaken will probably be removed: nim-lang/Nim#14881 (comment)

[Araq]

Exactly.