FIX: ArrayHelpers.Merge used the comparer incorrectly [ISXB-1790] (#2377)

Author: K-Tone

Assets/Tests/InputSystem/Utilities/ArrayHelperTests.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Globalization;
 using NUnit.Framework;
 using Unity.Collections;
@@ -118,6 +119,35 @@ public void Utilities_IndexOfReference__IsUsingReferenceEqualsAndConstrainedBySt
         Assert.AreEqual(2, arr.IndexOfReference(arr[2], 1, 3));
     }
 
+    [Test]
+    [Category("Utilities")]
+    public void Utilities_HaveDuplicateReferences_DetectsDuplicatesInFullRange()
+    {
+        var withDup = new object[] { new object(), new object(), new object() };
+        withDup[2] = withDup[0]; // duplicate at 0 and 2
+        Assert.That(withDup.HaveDuplicateReferences(0, 3), Is.True);
+
+        var noDup = new object[] { new object(), new object(), new object() };
+        Assert.That(noDup.HaveDuplicateReferences(0, 3), Is.False);
+
+        // Regression test for ISXB-1792: inner loop was "n < count - i" so later pairs were never checked
+        var dupAtEnd = new object[] { new object(), new object(), new object(), new object() };
+        dupAtEnd[3] = dupAtEnd[2]; // duplicate at 2 and 3
+        Assert.That(dupAtEnd.HaveDuplicateReferences(0, 4), Is.True);
+    }
+
+    [Test]
+    [Category("Utilities")]
+    public void Utilities_MergeWithComparer_UsesComparerToDeduplicate()
+    {
+        // Regression test for ISXB-1790: Merge(IEqualityComparer) was calling comparer.Equals(secondValue)
+        // instead of comparer.Equals(x, secondValue), so it compared against the comparer instance.
+        var first = new[] { "a", "b" };
+        var second = new[] { "A", "c" }; // "A" equals "a" with case-insensitive comparer
+        var merged = ArrayHelpers.Merge(first, second, StringComparer.OrdinalIgnoreCase);
+        Assert.That(merged, Is.EqualTo(new[] { "a", "b", "c" }));
+    }
+
     [Test]
     [Category("Utilities")]
     public void Utilities_IndexOfPredicate__IsUsingPredicateForEqualityAndConstraintedByStartIndexAndCount()

Packages/com.unity.inputsystem/CHANGELOG.md

@@ -16,11 +16,13 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Improved New Input System warning dialog, Native Device Inputs Not Enabled [UUM-132151].
 - Fixed caching for InputControlPath display name [ISX-2501](https://jira.unity3d.com/browse/ISX-2501)
 - Fixed editor closing and not saving the input asset when clicking cancel in the dialog prompt [UUM-134748](https://jira.unity3d.com/browse/UUM-134748)
+- Fixed an incorrect ArraysHelper.Merge implementation that used the comparer incorrectly [ISXB-1790] (https://jira.unity3d.com/browse/ISXB-1790)
 - Fixed the input actions editor window entering a corrupt state when restarting Unity after the asset was edited. [UUM-134737](https://jira.unity3d.com/browse/UUM-134737)
 - Fixed the Input Actions Editor Window toolbar buttons overlapping each other when the window size is too small [ISXB-1783] (https://jira.unity3d.com/browse/ISXB-1783)
 - Fixed `buttonSouth` returning the state of the east button (and so on for all the compass named buttons) when using a Nintendo Switch Pro Controller on iOS [ISXB-1632](issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1632)
 - Fixed `aButton` returning the state of the east button (and so on for all the letter named buttons) when using a Nintendo Switch Pro Controller on Standalone & iOS [ISXB-1632](issuetracker.unity3d.com/product/unity/issues/guid/ISXB-1632)
 - Fixed an issue where `UIToolkit` `ClickEvent` could be fired on Android after device rotation due to inactive touch state being replayed during action initial state checks [UUM-100125](https://jira.unity3d.com/browse/UUM-100125).
+- Fixed an incorrect ArraysHelper.HaveDuplicateReferences implementation that didn't use its arguments right [ISXB-1792] (https://github.com/Unity-Technologies/InputSystem/pull/2376)
 
 ### Changed
 

Packages/com.unity.inputsystem/InputSystem/Utilities/ArrayHelpers.cs

@@ -114,13 +114,12 @@ public static bool ContainsReference<TFirst, TSecond>(this TFirst[] array, int s
             return IndexOfReference(array, value, startIndex, count) != -1;
         }
 
-        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA1801:ReviewUnusedParameters", MessageId = "index", Justification = "Keep this for future implementation")]
-        public static bool HaveDuplicateReferences<TFirst>(this TFirst[] first, int index, int count)
+        public static bool HaveDuplicateReferences<TFirst>(this TFirst[] first, int index, int count) where TFirst : class
         {
-            for (var i = 0; i < count; ++i)
+            for (var i = index; i < index + count; ++i)
             {
                 var element = first[i];
-                for (var n = i + 1; n < count - i; ++n)
+                for (var n = i + 1; n < index + count; ++n)
                 {
                     if (ReferenceEquals(element, first[n]))
                         return true;
@@ -552,7 +551,16 @@ public static TValue[] Merge<TValue>(TValue[] first, TValue[] second, IEqualityC
             for (var i = 0; i < second.Length; ++i)
             {
                 var secondValue = second[i];
-                if (!merged.Exists(x => comparer.Equals(secondValue)))
+                bool found = false;
+                foreach (var x in merged)
+                {
+                    if (comparer.Equals(x, secondValue))
+                    {
+                        found = true;
+                        break;
+                    }
+                }
+                if (!found)
                 {
                     merged.Add(secondValue);
                 }