From 815dda57fb99b9a07596020e84c1d95dfb0170d0 Mon Sep 17 00:00:00 2001
From: Tagir Valeev <Tagir.Valeev@jetbrains.com>
Date: Mon, 14 Jan 2019 10:04:23 +0700
Subject: [PATCH] MismatchedArrayReadWrite: do not consider compound
 assignments/increments as reads (IDEA-CR-41955)

---
 .../ig/bugs/MismatchedArrayReadWriteInspection.java      | 3 ++-
 .../MismatchedArrayReadWrite.java                        | 9 ++++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/MismatchedArrayReadWriteInspection.java b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/MismatchedArrayReadWriteInspection.java
index f19cb7f23911..07421cab47ec 100644
--- a/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/MismatchedArrayReadWriteInspection.java
+++ b/plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/MismatchedArrayReadWriteInspection.java
@@ -256,8 +256,9 @@ public class MismatchedArrayReadWriteInspection extends BaseInspection {
           }
           if (PsiUtil.isAccessedForWriting(arrayAccessExpression)) {
             myWritten = true;
+            // compound writes like += are not considered as reads, because result result goes to the same array as well
           }
-          if (PsiUtil.isAccessedForReading(arrayAccessExpression) && !goesToSameArray(arrayAccessExpression)) {
+          else if (PsiUtil.isAccessedForReading(arrayAccessExpression) && !goesToSameArray(arrayAccessExpression)) {
             myRead = true;
           }
         }
diff --git a/plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/mismatched_array_read_write/MismatchedArrayReadWrite.java b/plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/mismatched_array_read_write/MismatchedArrayReadWrite.java
index 97f63152270a..73f98b15cc65 100644
--- a/plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/mismatched_array_read_write/MismatchedArrayReadWrite.java
+++ b/plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/mismatched_array_read_write/MismatchedArrayReadWrite.java
@@ -109,9 +109,10 @@ public class MismatchedArrayReadWrite {
     }
     
     void reuseSelf() {
-      int[] arr = new int[10];
+      int[] <warning descr="Contents of array 'arr' are written to, but never read">arr</warning> = new int[10];
       for(int i=0; i<arr.length; i++) arr[i] = i;
       for(int i=1; i<arr.length; i++) arr[i] += arr[i-1];
+      for(int i=1; i<arr.length; i++) arr[i] = arr[i-1] + 1;
     }
     
     void objectType(Object x) {
@@ -135,8 +136,14 @@ class Test{
     }
 
     private void testStuff() {
+        int[][] <warning descr="Contents of array 'array' are written to, but never read">array</warning> = new int[2][2];
+        array[0][1]++;
+    }
+
+    private void testStuff2() { // IDEA-47651
         int[][] array = new int[2][2];
         array[0][1]++;
+        System.out.println(array[0][1]);
     }
 
     void foo1() {