Comprehension segfault

[wldhx]

Hi, here's a repro:

array[1..2] of var set of 1..2: xy_shapes;

array[int] of var opt set of 1..2: x_roff =
    [ {1}
    | l in 1..2, sh in xy_shapes[l] ];

MiniZinc error: Memory violation detected (segmentation fault).
This is a bug. Please file a bug report using the MiniZinc bug tracker.

> minizinc --version
MiniZinc to FlatZinc converter, version 2.8.2
Copyright (C) 2014-1980 Monash University, NICTA, Data61

[cyderize]

Unfortunately MiniZinc doesn't currently support opt set types.

In this case the comprehension iterates over a var set, and gets transformed into an array of opt under the hood - but since the comprehension returns {1} it tries to create a var opt set which is not supported.

Of course, this shouldn't crash with a segfault, so we'll have to fix the type checker to properly disallow the var opt set declaration, and the var comprehension with the set inside. In the future, we may have a look at trying to add support for opt sets so that this would be allowed.