From 58bd65acee56c23dc37d342c1bb912fc4233fd1d Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Tue, 28 Nov 2017 10:12:08 +0700
Subject: [PATCH] DFA: do not flush array length on element write

---
 .../dataFlow/InstructionVisitor.java            |  4 +++-
 .../dataFlow/fixture/ArrayLength.java           | 17 +++++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/InstructionVisitor.java b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/InstructionVisitor.java
index 5ddf9cb0a570..2e5250d657d8 100644
--- a/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/InstructionVisitor.java
+++ b/java/java-analysis-impl/src/com/intellij/codeInspection/dataFlow/InstructionVisitor.java
@@ -139,7 +139,9 @@ public abstract class InstructionVisitor {
     if (variable != null) {
       if (instruction.isDependentsOnly()) {
         for (DfaVariableValue qualified : runner.getFactory().getVarFactory().getAllQualifiedBy(variable)) {
-          memState.flushVariable(qualified);
+          if (qualified.isFlushableByCalls()) {
+            memState.flushVariable(qualified);
+          }
         }
       }
       else {
diff --git a/java/java-tests/testData/inspection/dataFlow/fixture/ArrayLength.java b/java/java-tests/testData/inspection/dataFlow/fixture/ArrayLength.java
index 2250766f8d45..b1369090e356 100644
--- a/java/java-tests/testData/inspection/dataFlow/fixture/ArrayLength.java
+++ b/java/java-tests/testData/inspection/dataFlow/fixture/ArrayLength.java
@@ -1,6 +1,23 @@
 import java.util.Arrays;
 
 public final class ArrayLength {
+  void testEquality(int[] x) {
+    int len = x.length;
+    for(int i=0; i<100; i++) {
+      if (i == len) {
+        x[<warning descr="Array index is out of bounds">i</warning>] = 10;
+      }
+    }
+  }
+
+  int[] testFor(int length) {
+    int[] x = new int[length];
+    for(int i=0; i<=length; i++) {
+      x[i] = 1;
+    }
+    return x;
+  }
+
   public static void testArray2(Object[] x, Object[] y, int a) {
     if(<warning descr="Condition 'x[a] == null && a == x.length' is always 'false'">x[a] == null && <warning descr="Condition 'a == x.length' is always 'false' when reached">a == x.length</warning></warning>) {
       System.out.println("Impossible");