NullDereference is missing non-null case about simplecfg HOT 2 OPEN

This false positive seems difficult to solve in the current architecture of the NullableDereference analyzer. It think a general solution to this would require some kind of constraint solver to know that x == null means that y != null after the first if-statement.

It might be possible to solve this problem for this specific case without a constraint solver, but it seems like a more general solution would need a constraint solver.

An idea for a constraint solving solution would be to build a set of constraints for each node in the control flow graph, for example the node following the else-part of the if-statement has the constraint !(x == null && y == null), then the else-part of the conditional expression adds a constraint x == null to that set, leading to y != null being true.

from simplecfg.

Yes, I agree. This is a tricky case to solve and I think any constraint-like solution would require a lot of work. Due to this, I think there needs to be a way to filter out files we don't want to report findings for to avoid reporting the same false positive each time a file goes for review.

from simplecfg.