Current behavior is to treat = as assignment inside []

julia> Meta.@lower x[a=1] = 3
:(begin
      a = 1
      setindex!(x, 3, 1)
      return 3
  end)

But for consistency with (), I would like to have it parse as a kwcall

setindex!(x, 3; a=1)

Currently, that has to be written:

x[(a = 1,)] = 3

which is much less nice.