FIX: ArrayHelpers.Merge used the comparer incorrectly [ISXB-1790]

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/InputSystem/Utilities/ArrayHelpers.cs

@@ -120,7 +120,7 @@ public static bool HaveDuplicateReferences<TFirst>(this TFirst[] first, int inde
             for (var i = 0; i < count; ++i)
             {
                 var element = first[i];
-                for (var n = i + 1; n < count - i; ++n)
+                for (var n = i + 1; n < count; ++n)
                 {
                     if (ReferenceEquals(element, first[n]))
                         return true;
@@ -552,7 +552,7 @@ 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)))
+                if (!merged.Exists(x => comparer.Equals(x, secondValue)))
                 {
                     merged.Add(secondValue);
                 }