From 744d5ee012a6f25cc6328de2d90b6069fceb2802 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <tagir.valeev@jetbrains.com>
Date: Fri, 4 Mar 2022 14:16:30 +0700
Subject: [PATCH] [java-dfa] Assume that pure call may still flush private
 fields

Fixes IDEA-288570 Constant conditions & exceptions thinks that Iterator.hasNext() cannot modify a private field

GitOrigin-RevId: 116a0ca754004574fe6d789db1889a52d9057bfd
---
 .../dataFlow/DfaCallArguments.java            |  8 ++++++
 .../dataFlow/java/JavaDfaValueFactory.java    |  5 +++-
 .../IteratorHasNextModifiesPrivateField.java  | 27 +++++++++++++++++++
 .../DataFlowInspection8Test.java              |  1 +
 4 files changed, 40 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/IteratorHasNextModifiesPrivateField.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaCallArguments.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaCallArguments.java
index 6471fcc98fb8..2e712d40eb40 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaCallArguments.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaCallArguments.java
@@ -19,6 +19,7 @@ import com.intellij.codeInspection.dataFlow.java.JavaDfaValueFactory;
 import com.intellij.codeInspection.dataFlow.memory.DfaMemoryState;
 import com.intellij.codeInspection.dataFlow.value.DfaValue;
 import com.intellij.codeInspection.dataFlow.value.DfaValueFactory;
+import com.intellij.codeInspection.dataFlow.value.DfaVariableValue;
 import com.intellij.psi.*;
 import com.intellij.util.ArrayUtil;
 import com.siyeh.ig.psiutils.MethodCallUtils;
@@ -76,6 +77,13 @@ public final class DfaCallArguments {
       return;
     }
     if (myMutation.isPure()) {
+      if (myQualifier instanceof DfaVariableValue) {
+        DfaVariableValue qualifier = (DfaVariableValue)myQualifier;
+        // We assume that even pure call may modify private fields (e.g., to cache something)
+        state.flushVariables(v -> v.getQualifier() == qualifier &&
+                                  v.getPsiVariable() instanceof PsiMember &&
+                                  ((PsiMember)v.getPsiVariable()).hasModifierProperty(PsiModifier.PRIVATE));
+      }
       return;
     }
     if (myMutation == MutationSignature.UNKNOWN || myArguments == null) {
diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/JavaDfaValueFactory.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/JavaDfaValueFactory.java
index 5dede8e29030..0cc047396009 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/JavaDfaValueFactory.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/java/JavaDfaValueFactory.java
@@ -152,7 +152,10 @@ public class JavaDfaValueFactory {
         PsiClass memberClass = ((PsiMember)element).getContainingClass();
         if (memberClass != null && currentClass != null) {
           PsiClass target;
-          if (currentClass == memberClass || InheritanceUtil.isInheritorOrSelf(currentClass, memberClass, true)) {
+          PsiElement refName = refExpr.getReferenceNameElement();
+          if (currentClass == memberClass ||
+              (!(refName instanceof PsiKeyword && ((PsiKeyword)refName).getTokenType() == JavaTokenType.SUPER_KEYWORD) &&
+               InheritanceUtil.isInheritorOrSelf(currentClass, memberClass, true))) {
             target = currentClass;
           }
           else {
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/IteratorHasNextModifiesPrivateField.java b/java/java-tests/testData/inspection/dataFlow/fixture/IteratorHasNextModifiesPrivateField.java
new file mode 100644
index 000000000000..d9b3cc7a44a9
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/IteratorHasNextModifiesPrivateField.java
@@ -0,0 +1,27 @@
+import java.util.*;
+
+class Test implements Iterator<String> {
+  String myNext;
+
+  public boolean hasNext() {
+    myNext = "test";
+    return true;
+  }
+
+  public String next() {
+    if (!hasNext()) throw new NoSuchElementException();
+    return myNext;
+  }
+
+  void test() {
+    int merged = 0;
+    while (hasNext()) {
+      assert myNext != null;
+      merged++;
+      if (<warning descr="Condition 'merged > 50' is always 'false'">merged > 50</warning>) {
+        break;
+      }
+      myNext = <warning descr="Assigning 'null' value to non-annotated field">null</warning>;
+    }
+  }
+}
diff --git a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
index b5da831db2a2..d776892a56db 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
@@ -355,6 +355,7 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
   public void testReturnOrElseNull() { doTestWith(insp -> insp.REPORT_NULLABLE_METHODS_RETURNING_NOT_NULL = true); }
   public void testArrayIntersectionType() { doTest(); }
   public void testFunctionType() { doTest(); }
+  public void testIteratorHasNextModifiesPrivateField() { doTest(); }
   public void testJsr305TypeUseNoLocal() {
     DataFlowInspectionTest.addJavaxNullabilityAnnotations(myFixture);
     DataFlowInspectionTest.addJavaxDefaultNullabilityAnnotations(myFixture);