RE: Add Nullif case for eval_const_expressions_mutator

[houzj.f...@fujitsu.com]

> +                             if (!has_nonconst_input)
> +                                     return ece_evaluate_expr(expr);
> 
> That's not okay without a further check to see if the comparison function used
> by the node is immutable.  Compare ScalarArrayOpExpr, for instance.

Thanks for pointing it out.
Attaching new patch with this change.

Best regards,
houzj

v4-0001-add-nullif-case-for-eval_const_expressions.patch
Description: v4-0001-add-nullif-case-for-eval_const_expressions.patch