nosets.mzn flattening error

[stevenhvtran]

Example code that fails on Chuffed 0.10.4 and COIN-BC 2.10/1.17:

set of int: edges = {1, 2, 3};
array[1..3] of set of edges: adj_list = [{3}, {}, {2}];
array[1..3] of var edges: path;

constraint forall(t in 1..3 where t < 3)(
    (path[t + 1] in adj_list[path[t]])
);

solve satisfy;

This same model works on Gecode 6.1.1. The following error output is printed to stdout when run:

MiniZinc: flattening error: 
/home/stran/Dropbox/Uni/FIT2082/Optimised Solver/test.mzn:5:
  in call 'forall'
  in array comprehension expression
    with t = 2
/home/stran/Dropbox/Uni/FIT2082/Optimised Solver/test.mzn:6:
  in binary 'in' operator expression
  in array access
/opt/minizinc/share/minizinc/std//builtins.mzn:2360:
  in if-then-else expression
  in let expression
/opt/minizinc/share/minizinc/std//builtins.mzn:2362:
  in call 'element_t'
/opt/minizinc/share/minizinc/std//builtins.mzn:2344:
  in let expression
/opt/minizinc/share/minizinc/std//builtins.mzn:2347:
  in call 'array_var_set_element_nonshifted'
/opt/minizinc/share/minizinc/std//redefinitions-2.0.2.mzn:45:
  in call 'array_var_set_element'
/opt/minizinc/share/minizinc/std//builtins.mzn:1930:
  in call 'array_set_element'
/opt/minizinc/share/minizinc/std//nosets.mzn:307:
  in let expression
/opt/minizinc/share/minizinc/std//nosets.mzn:314:
  in binary 'subset' operator expression
  cannot find matching declaration

Process finished with non-zero exit code 1

Expected output is:

Compiling test.mzn
Running test.mzn
path = array1d(1..3, [1, 3, 2]);
----------
Finished in 38msec

Issue originally posted here: chuffed/chuffed#47 (comment)

[Dekker1]

Something seems to be going wrong with the internal types somewhere. The compiler is looking for the subset operator for 1..0 subset 2, where 2 is an integer instead of a set.
This should either have been a type error or if this is meant to be {2}, then the type information is lost.