[analyzer] Add missing state transition in IteratorChecker

[rnkovacs]

Summary

After cleaning up program state maps in checkDeadSymbols(), a transition should be added to generate the new state.

[MTC]

lib/StaticAnalyzer/Checkers/IteratorChecker.cpp

399 ↗

(On Diff #148735)

I have two questions may need @NoQ or @xazax.hun who is more familiar with the analyzer engine help to answer.

• State may not change at all, do we need a check here like if (state != originalState)
• A more basic problem is that do we need originalState = State trick. It seems that addTransitionImpl() has a check about same state transition, see addTransitionImp().

Thanks in advance!

[NoQ]

Nice catch!

lib/StaticAnalyzer/Checkers/IteratorChecker.cpp

399 ↗

(On Diff #148735)

It seems that addTransitionImpl() has a check about same state transition, see addTransitionImp().

Yep, you pretty much answered your question. The check in the checker code is unnecessary.

[MTC]

lib/StaticAnalyzer/Checkers/IteratorChecker.cpp

399 ↗

(On Diff #148735)

Thanks, NoQ! It seems that if (state != originalState) in some checkers is misleading and may need to be cleaned up.

[baloghadamsoftware]

Oh, it slipped through somehow. Thanks for fixing this!

[baloghadamsoftware]

Did the tests execute? I am not sure. First problem is the the container may become dead before the iterator, so its Begin and End symbols may be inaccessible. This is easy to solve by marking the container of the iterator as live. However, there is a second problem that disables correct tracking of iterators: memory regions are marked as dead, however there are LazyCompoundVals referring to them. Is this maybe a bug in SymbolReaper?

cfe/trunk/lib/StaticAnalyzer/Checkers/IteratorChecker.cpp

void IteratorChecker::checkDeadSymbols(SymbolReaper &SR,
   }
 
   auto ComparisonMap = State->get<IteratorComparisonMap>();
   for (const auto Comp : ComparisonMap) {
     if (!SR.isLive(Comp.first)) {
       State = State->remove<IteratorComparisonMap>(Comp.first);
     }
   }
+
+  C.addTransition(State);
 }
 
 ProgramStateRef IteratorChecker::evalAssume(ProgramStateRef State, SVal Cond,
                                             bool Assumption) const {
   // Load recorded comparison and transfer iterator state between sides
   // according to comparison operator and assumption
   const auto *SE = Cond.getAsSymExpr();
   if (!SE)