Fix #14308 FP nullPointerRedundantCheck with pointer reference parameter (*&)

[chrchr-github]

[pfultz2]

This is not really the correct fix. ValueFlowForward will check for variable changes.

The problem is that this comes from reverse analysis, so we need to traverse the subfunction in reverse as well. We don't really have a way to do that but we can skip the values that come from reverse analysis for now though.

[chrchr-github]

[...] but we can skip the values that come from reverse analysis for now though.

And how would we do that? Mark the values somehow?

[pfultz2]

[...] but we can skip the values that come from reverse analysis for now though.

And how would we do that? Mark the values somehow?

You could check the tokvlaue, but it is a little hacky how we use that for the starting point (I would like to add an origin field for this instead).

Another way is to mark them but we need to mark when it goes reverse and forward as we do forward analysis from reverse analysis so the state would need to switch back. It should probably be an enum of Forward. Reverse, and Unknown.

[chrchr-github]

Another way is to mark them but we need to mark when it goes reverse and forward as we do forward analysis from reverse analysis so the state would need to switch back. It should probably be an enum of Forward. Reverse, and Unknown.

There seem to be many places where values flow forward, so I haven't implemented the switching logic. We also have no tests that require it yet.

[pfultz2]

We could set the the direction of the value in the update method in the analyzer. That might be simpler than trying to do it for every forward.

[chrchr-github]

We could set the the direction of the value in the update method in the analyzer. That might be simpler than trying to do it for every forward.

I have tried that, but unless Reverse is set in makeReverseAnalyzer(), the FP still occurs. Maybe update() is not called for the value in question?

[sonarqubecloud[bot]]

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