Calling _IntVarImpl makes model unsat

[Wout4]

you need the model matrix_element_test16650504392567291.bt from cpmpy/bigtest to reproduce this bug

example below prints true, then false.
For z3 it prints twice true
for minizinc it prints twice false
for ortools + mininzinc it returns twice true
for minizinc + ortools it returns false, true
...

import brotli
import pickle
from cpmpy.expressions.variables import _IntVarImpl
f = 'models\matrix_element_test16650504392567291.bt'
with open(f, 'rb') as fpcl:
model = pickle.loads(brotli.decompress(fpcl.read()))
print(model.solve('ortools'))
_IntVarImpl(0, 1)
print(model.solve('ortools'))

[Wout4]

minizinc no longer thinks this model is unsat, since bugfix #272

[Dimosts]

so is this fixed? Or besides minizinc it still crashes?

One way to get over this (and also similar problems with using directly _BoolVarImpl) we could check the function calling the constructor of _IntVarImpl (and _BoolVarImpl) with inspect and return an exception if it is not the expected function(s). However this would require to include inspect in the requirements etc., which I am not sure we want ..

[Wout4]

I think it still crashes, can verify later. The bug occurred without a user directly calling _intvarimpl, but because one of the transformations called it. I just tried to write a minimized bug report here ;)

[Wout4]

can confirm this bug is still active