dfa: method can still return unknown value if its arguments satisfy nullity conditions (IDEA-106205)

java/java-impl/src/com/intellij/codeInspection/dataFlow/ControlFlowAnalyzer.java

@@ -1347,6 +1347,17 @@ class ControlFlowAnalyzer extends JavaElementVisitor {
         } else if (type == ConditionChecker.Type.IS_NULL_METHOD || type == ConditionChecker.Type.IS_NOT_NULL_METHOD) {
           addInstruction(new PushInstruction(myFactory.getConstFactory().getNull(), null));
           addInstruction(new BinopInstruction(type == ConditionChecker.Type.IS_NULL_METHOD ? JavaTokenType.EQEQ : JavaTokenType.NE, null, expression.getProject()));
+          
+          ConditionalGotoInstruction ifFails = new ConditionalGotoInstruction(-1, true, null);
+          GotoInstruction gotoEnd = new GotoInstruction(exitPoint);
+
+          addInstruction(ifFails);
+          pushUnknown();
+          addInstruction(gotoEnd);
+          ifFails.setOffset(myCurrentFlow.getInstructionCount());
+          addInstruction(new PushInstruction(myFactory.getConstFactory().getFalse(), null));
+          gotoEnd.setOffset(myCurrentFlow.getInstructionCount());
+
         } else { //assertTrue or assertFalse
           conditionalExit(exitPoint, type == ConditionChecker.Type.ASSERT_FALSE_METHOD);
         }

java/java-tests/testData/inspection/dataFlow/fixture/IsNotNullCheck.java

@@ -4,6 +4,13 @@ public class IsNotNullCheck {
      if (Value.isNotNull(v)) {
        if(<warning descr="Condition 'v == null' is always 'false'">v == null</warning>) {}
      }
+   }
+   void bar2() {
+     final Value v = call();
+     System.out.println(v.hashCode());
+     if (Value.isNotNull(v)) {
+
+     }
    }
     Value call() {return new Value();}
 }