IDEA-89964 Constant conditions & exceptions inspection is incorrect with instance checks in loops

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

@@ -736,7 +736,8 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
   }
 
   public void flushVariable(@NotNull DfaVariableValue variable) {
-    if (variable.getPsiVariable().hasModifierProperty(PsiModifier.FINAL)) {
+    PsiVariable psiVariable = variable.getPsiVariable();
+    if (psiVariable instanceof PsiField && psiVariable.hasModifierProperty(PsiModifier.FINAL)) {
       return;
     }
 

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

@@ -0,0 +1,16 @@
+public class Test {
+
+  public static void main(Object[] args) throws Exception {
+    boolean elvisLives = false;
+    for (final Object o : args) {
+      if (o instanceof Integer) {
+        elvisLives = true;
+      } else {
+        if (elvisLives) {
+          System.err.println("Elvis is alive!");
+        }
+      }
+    }
+  }
+
+}

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionFixtureTest.java

@@ -75,5 +75,6 @@ public class DataFlowInspectionFixtureTest extends JavaCodeInsightFixtureTestCas
   public void testNotEqualsDoesntImplyNotNullity() throws Throwable { doTest(); }
   public void testEqualsEnumConstant() throws Throwable { doTest(); }
   public void testEqualsConstant() throws Throwable { doTest(); }
+  public void testFinalLoopVariableInstanceof() throws Throwable { doTest(); }
 
 }