mzn2fzn duplicates non-empty array and loses type of empty array

[kfranc]

Hi,
When I compile the following minizinc model, the flatzinc has an extra copy of the non-empty array and type array [1..0] of bot for the empty one.

MiniZinc:

predicate fakepred(array[int] of int: a1, array[int] of int: a2, var int: result);
var 1..5: x;
array[int] of int: a1 = [2, 3];
array[int] of int: a2 = [];
constraint fakepred(a1, a2, x);
solve minimize x;

Flatzinc produced by mzn2fzn 2.0.1:

predicate fakepred(array [int] of int: a1,array [int] of int: a2,var int: result);
array [1..0] of bot: a2 = [];
array [1..2] of int: a1 = [2,3];
array [1..2] of int: X_INTRODUCED_0 = [2,3];
var 1..5: x:: output_var;
constraint fakepred(a1,a2,x);
solve  minimize x;