From ba7ce2e7d2ab9a16c83c7b77ddef9ed56f4c6796 Mon Sep 17 00:00:00 2001
From: ghm <ghm@google.com>
Date: Thu, 8 Dec 2022 14:35:51 -0800
Subject: [PATCH] Handle six-arg Arrays.equals in EqualsWrongThing

PiperOrigin-RevId: 493998416
---
 .../errorprone/bugpatterns/EqualsWrongThing.java   |  8 +++++---
 .../bugpatterns/EqualsWrongThingTest.java          | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/core/src/main/java/com/google/errorprone/bugpatterns/EqualsWrongThing.java b/core/src/main/java/com/google/errorprone/bugpatterns/EqualsWrongThing.java
index 16ddbad8058..ba63a295af7 100644
--- a/core/src/main/java/com/google/errorprone/bugpatterns/EqualsWrongThing.java
+++ b/core/src/main/java/com/google/errorprone/bugpatterns/EqualsWrongThing.java
@@ -91,9 +91,11 @@ public Void visitBinary(BinaryTree node, Void unused) {
 
       @Override
       public Void visitMethodInvocation(MethodInvocationTree node, Void unused) {
+        var args = node.getArguments();
         if (COMPARISON_METHOD.matches(node, state)) {
-          getDubiousComparison(
-                  classSymbol, node, node.getArguments().get(0), node.getArguments().get(1))
+          // args.size() / 2 handles the six-arg overload of Arrays.equals (the 0th and 3rd args are
+          // the arrays).
+          getDubiousComparison(classSymbol, node, args.get(0), args.get(args.size() / 2))
               .ifPresent(suspiciousComparisons::add);
         }
         if (instanceEqualsInvocation().matches(node, state)) {
@@ -102,7 +104,7 @@ public Void visitMethodInvocation(MethodInvocationTree node, Void unused) {
             // Special-case super, for odd cases like `super.equals(this)`.
             if (!(receiver instanceof IdentifierTree
                 && ((IdentifierTree) receiver).getName().contentEquals("super"))) {
-              getDubiousComparison(classSymbol, node, receiver, node.getArguments().get(0))
+              getDubiousComparison(classSymbol, node, receiver, args.get(0))
                   .ifPresent(suspiciousComparisons::add);
             }
           }
diff --git a/core/src/test/java/com/google/errorprone/bugpatterns/EqualsWrongThingTest.java b/core/src/test/java/com/google/errorprone/bugpatterns/EqualsWrongThingTest.java
index 5f40e14a943..7b5c02a850d 100644
--- a/core/src/test/java/com/google/errorprone/bugpatterns/EqualsWrongThingTest.java
+++ b/core/src/test/java/com/google/errorprone/bugpatterns/EqualsWrongThingTest.java
@@ -153,4 +153,18 @@ public void positiveEquals() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void negativeArraysEquals() {
+    helper
+        .addSourceLines(
+            "Test.java",
+            "import java.util.Arrays;",
+            "class Test {",
+            "  boolean test(int[] a, int[] b) {",
+            "    return Arrays.equals(a, 0, 1, b, 2, 3);",
+            "  }",
+            "}")
+        .doTest();
+  }
 }