From e907de8eb85b8f0e06ee05c60b3a75f01080e628 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Fri, 21 Feb 2025 16:46:49 -0500
Subject: [PATCH] Backport hash improvements from Scala 2.13.16's MurmurHash3

---
 .../src/main/scala-2.13+/cats/kernel/compat/HashCompat.scala  | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/src/main/scala-2.13+/cats/kernel/compat/HashCompat.scala b/kernel/src/main/scala-2.13+/cats/kernel/compat/HashCompat.scala
index 471d16958a..a0838682db 100644
--- a/kernel/src/main/scala-2.13+/cats/kernel/compat/HashCompat.scala
+++ b/kernel/src/main/scala-2.13+/cats/kernel/compat/HashCompat.scala
@@ -89,7 +89,7 @@ private[kernel] class HashCompat {
           rangeDiff = hash - prev
           rangeState = 2
         case 2 =>
-          if (rangeDiff != hash - prev) rangeState = 3
+          if (rangeDiff != hash - prev || rangeDiff == 0) rangeState = 3
         case _ =>
       }
       prev = hash
@@ -120,7 +120,7 @@ private[kernel] class HashCompat {
     while (it.hasNext) {
       h = mix(h, prev)
       val hash = A.hash(it.next())
-      if (rangeDiff != hash - prev) {
+      if (rangeDiff != hash - prev || rangeDiff == 0) {
         h = mix(h, hash)
         i += 1
         while (it.hasNext) {