naming a variable starting with a '+' crashes all MiniZinc's subsolvers

Solver: all Minizinc’s subsolvers CPMpy: version v0.9.9 commit e79b3afedc934a9437c2ddb3a9f54d7e2d7bd3ee minizinc-python release version 0.7.0 commit {https://github.com/MiniZinc/minizinc-python/commit/a195cf63fcfbc98665d70ab64efb5424db25bd7e)

This one was a fun one to find, I made a typo when naming a variable and the MiniZinc subsolvers crashed. It works with other symbols as well, I tried -, #, %, * and more. It does not occur with ‘ortools’ or ‘gurobi’.

from cpmpy import *

b = boolvar(name="+")
m = Model()
m += b==0
m.solve(solver="minizinc:ortools")

expected behavior: Treat the variable name as a name instead of code.

Bug found while working on my master thesis.

[Wout4]

So we decided not to clean the variables because this can lead to duplicate names (for example ‘6var’ and ‘5var’ would both be cleaned to var because names cannot start with a number)

However this can still occur for names with any of the following characters: ‘,’ ’ ’ ‘.’ ‘[’ and ‘]’ (not much we can do about that because these get introduced with np arrays)

[Wout4]

@tias Already had a bit of code in there that cleaned the variable name from some illegal characters (but only a handful of them).

Do you think it’s best to clean all possible variable names, or to throw an exception saying which names are allowed?