IDEA-119663 false positive Constant conditions & exceptions: "Argument ... might be null"

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

@@ -1849,13 +1849,12 @@ public class ControlFlowAnalyzer extends JavaElementVisitor {
       return null;
     }
 
-    PsiExpression qualifier = refExpr.getQualifierExpression();
-    if (qualifier == null) {
+    if (DfaValueFactory.isEffectivelyUnqualified(refExpr)) {
       return myFactory.getVarFactory().createVariableValue(var, refExpr.getType(), false, null);
     }
 
     if (!(var instanceof PsiField) || !var.hasModifierProperty(PsiModifier.TRANSIENT) && !var.hasModifierProperty(PsiModifier.VOLATILE)) {
-      DfaVariableValue qualifierValue = createChainedVariableValue(qualifier);
+      DfaVariableValue qualifierValue = createChainedVariableValue(refExpr.getQualifierExpression());
       if (qualifierValue != null) {
         return myFactory.getVarFactory().createVariableValue(var, refExpr.getType(), false, qualifierValue);
       }

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

@@ -0,0 +1,46 @@
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+public class TestInspection {
+
+  private static class StringWrapper {
+    private String inner = null;
+
+    @Nullable
+    public String getString() {
+      return inner;
+    }
+  }
+
+  @NotNull
+  private final StringWrapper wrapper;
+
+  @Nullable
+  private String string = null;
+
+  public TestInspection() {
+    wrapper = new StringWrapper();
+  }
+
+  public void doTest() {
+    if (this.wrapper.getString() != null) {
+      doSomething(this.wrapper.getString());
+    }
+    if (this.wrapper.getString() != null) {
+      doSomething(wrapper.getString());
+    }
+    if (wrapper.getString() != null) {
+      doSomething(this.wrapper.getString());
+    }
+    if (wrapper.getString() != null) {
+      doSomething(wrapper.getString());
+    }
+    if (this.string != null) {
+      doSomething(this.string);
+    }
+  }
+
+  private void doSomething(@NotNull String s) {
+    //...
+  }
+}

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

@@ -104,6 +104,7 @@ public class DataFlowInspectionTest extends LightCodeInsightFixtureTestCase {
   public void testChainedFinalFieldAccessorsDfa() throws Throwable { doTest(); }
   public void testAccessorPlusMutator() throws Throwable { doTest(); }
   public void testClosureVariableField() throws Throwable { doTest(); }
+  public void testOptionalThis() { doTest(); }
 
   public void testAssigningNullableToNotNull() throws Throwable { doTest(); }
   public void testAssigningUnknownToNullable() throws Throwable { doTest(); }