DFA Optional.orElse handling improved (splitting states)

java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/StandardInstructionVisitor.java

@@ -287,10 +287,12 @@ public class StandardInstructionVisitor extends InstructionVisitor {
               result = argValues[0];
               break;
             case UNSURE:
-              Nullness nullness =
-                memState.isNotNull(argValues[0]) ? Nullness.NOT_NULL : memState.isNull(argValues[0]) ? Nullness.NULLABLE : Nullness.UNKNOWN;
-              result = runner.getFactory().createTypeValue(instruction.getResultType(), nullness);
-              break;
+              DfaMemoryState falseState = memState.createCopy();
+              memState.push(runner.getFactory().createTypeValue(instruction.getResultType(), Nullness.NOT_NULL));
+              memState.applyIsPresentCheck(true, qualifier);
+              falseState.push(argValues[0]);
+              falseState.applyIsPresentCheck(false, qualifier);
+              return Arrays.asList(memState, falseState);
           }
         }
         break;

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

@@ -42,4 +42,11 @@ class OptionalOrElse {
       return "";
     }
   }
+
+  void isPresentCheck(Optional<String> opt) {
+    String result = opt.orElse(null);
+    if(<warning descr="Condition 'result == null && opt.isPresent()' is always 'false'">result == null && <warning descr="Condition 'opt.isPresent()' is always 'false' when reached">opt.isPresent()</warning></warning>) {
+      System.out.println("Impossible");
+    }
+  }
 }