From 8aa936dc004f8dd6cd1c4e3f1dbaab048b210420 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Wed, 20 Feb 2019 16:35:45 +0700
Subject: [PATCH] Flush canonicalized variable if requested one not found

Fixes IDEA-207441 False-positive "variable is always null" on linked-list like data structure
---
 .../dataFlow/DfaMemoryStateImpl.java          |  7 ++-
 .../fixture/HashMapImplementation.java        | 45 +++++++++++++++++++
 .../DataFlowInspection8Test.java              |  1 +
 3 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 java/java-tests/testData/inspection/dataFlow/fixture/HashMapImplementation.java

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
index 29dc00a6a58b..41fb5c77f196 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/DfaMemoryStateImpl.java
@@ -1530,7 +1530,12 @@ public class DfaMemoryStateImpl implements DfaMemoryState {
   private void removeEquivalence(DfaValue var) {
     int varID = var.getID();
     Integer varClassIndex = myIdToEqClassesIndices.get(varID);
-    if (varClassIndex == null) return;
+    if (varClassIndex == null) {
+      var = canonicalize(var);
+      varID = var.getID();
+      varClassIndex = myIdToEqClassesIndices.get(varID);
+      if (varClassIndex == null) return;
+    }
 
     EqClass varClass = myEqClasses.get(varClassIndex);
 
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/HashMapImplementation.java b/java/java-tests/testData/inspection/dataFlow/fixture/HashMapImplementation.java
new file mode 100644
index 000000000000..8d4b3f99f30c
--- /dev/null
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/HashMapImplementation.java
@@ -0,0 +1,45 @@
+import org.jetbrains.annotations.Nullable;
+
+class IntHashMap {
+
+  public void minTest() {
+    initEntries();
+
+    for (Entry entry : table) {
+      if (entry != null) {
+        Entry tmp = entry;
+        Entry tmpNext;
+
+        while (tmp != null) {
+          tmpNext = tmp.next;
+          tmp.next = null;
+          tmp = tmpNext;
+          System.out.println("tmpNext " + ((tmpNext == null) ? "is null" : "is not null"));
+        }
+      }
+    }
+  }
+
+  private Entry[] table = new Entry[16];
+
+  private class Entry {
+    @Nullable Entry next;
+  }
+
+
+  private void initEntries() {
+    table[0] = new Entry();
+    table[0].next = new Entry();
+
+    table[1] = new Entry();
+
+    table[3] = new Entry();
+
+    table[5] = new Entry();
+    table[5].next = new Entry();
+  }
+  public static void main(String[] args) {
+    IntHashMap map = new IntHashMap();
+    map.minTest();
+  }
+}
\ No newline at end of file
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 28aada0591c5..fd8d0644bc29 100644
--- a/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
+++ b/java/java-tests/testSrc/com/intellij/java/codeInspection/DataFlowInspection8Test.java
@@ -214,6 +214,7 @@ public class DataFlowInspection8Test extends DataFlowInspectionTestCase {
   public void testPrimitiveGetters() { doTest(); }
   public void testUnknownOnStack() { doTest(); }
   public void testMapUpdateInlining() { doTestWithCustomAnnotations(); }
+  public void testHashMapImplementation() { doTest(); }
 
   public void testOptionalTooComplex() { doTest(); }