[java-dfa] IDEA-354336 Java DFA fails to report nullable var passed to notnull arg after instanceof

GitOrigin-RevId: 2fada677a054fbd049e12e9b585a5f08711a5b26

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

@@ -0,0 +1,22 @@
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+class Main {
+  Record foo() {
+    PsiFile file = fooBar();
+    if (file instanceof PsiCompiledFile compiledFile) {
+      return new Record(compiledFile);
+    }
+    return new Record(<warning descr="Argument 'file' might be null">file</warning>);
+  }
+
+  @Nullable
+  private PsiFile fooBar() {
+    return null;
+  }
+
+  interface PsiFile {}
+  interface PsiCompiledFile extends PsiFile {}
+
+  private record Record(@NotNull PsiFile file) {}
+}

java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection21Test.java

@@ -130,4 +130,6 @@ public class DataFlowInspection21Test extends DataFlowInspectionTestCase {
 
   public void testArrayElementWrappedInPureMethod() { doTest(); }
   public void testArrayAddedIntoCollection() { doTest(); }
+  
+  public void testInstanceOfPatternAffectNullity() { doTest(); }
 }

platform/analysis-impl/src/com/intellij/codeInspection/dataFlow/memory/DfaMemoryStateImpl.java

@@ -1290,7 +1290,7 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
       type = type.fromRelation(RelationType.EQ);
       for (DfaVariableValue value : eqClass.asList()) {
         if (value != dfaVar) {
-          recordVariableType(value, type.meet(value.getInherentType()));
+          recordVariableType(value, type.meet(getDfType(value)));
           if (!updateQualifierOnEquality(value, value)) return false;
         }
       }