From e266ca6f67ab081476a0990e36e67ab4f2554e2b Mon Sep 17 00:00:00 2001
From: Snowy <qmazon@outlook.com>
Date: Thu, 12 Mar 2026 04:23:22 +0800
Subject: [PATCH] Fix BackwardKillLine length calculation for multiline input
 (#5102)

---
 PSReadLine/KillYank.cs | 2 +-
 test/KillYankTest.cs   | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/PSReadLine/KillYank.cs b/PSReadLine/KillYank.cs
index 77fe33f..c282b14 100644
--- a/PSReadLine/KillYank.cs
+++ b/PSReadLine/KillYank.cs
@@ -135,7 +135,7 @@ namespace Microsoft.PowerShell
         public static void BackwardKillLine(ConsoleKeyInfo? key = null, object arg = null)
         {
             var start = GetBeginningOfLinePos(_singleton._current);
-            _singleton.Kill(start, _singleton._current, true);
+            _singleton.Kill(start, _singleton._current - start, true);
         }
 
         /// <summary>
diff --git a/test/KillYankTest.cs b/test/KillYankTest.cs
index 381e788..5c631d5 100644
--- a/test/KillYankTest.cs
+++ b/test/KillYankTest.cs
@@ -119,6 +119,8 @@ namespace Test
             PSConsoleReadLine.SetKeyHandler(new[] { "Shift+Tab" }, PSConsoleReadLine.BackwardKillLine, "", "");
 
             Test("", Keys("dir", _.Shift_Tab));
+
+            Test("abc\n123", Keys("abc", _.Shift_Enter, "123", _.Shift_Tab, _.Ctrl_y));
         }
 
         [SkippableFact]