From 6ab52c9a991dddef638c4d8b6979ad491edde6b7 Mon Sep 17 00:00:00 2001
From: EgorBo <egorbo@gmail.com>
Date: Mon, 3 Sep 2018 20:30:13 +0300
Subject: [PATCH] Add old String.Concat with __arglist

---
 mcs/class/corlib/ReferenceSources/String.cs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/mcs/class/corlib/ReferenceSources/String.cs b/mcs/class/corlib/ReferenceSources/String.cs
index f45e78a031b..628fa968ffe 100644
--- a/mcs/class/corlib/ReferenceSources/String.cs
+++ b/mcs/class/corlib/ReferenceSources/String.cs
@@ -88,6 +88,13 @@ namespace System
 			return -1;
 		}
 
+		[CLSCompliant(false)] 
+		public static String Concat(Object arg0, Object arg1, Object arg2, Object arg3, __arglist) 
+		{
+			// Added to maintain backward compatibility, see https://github.com/mono/mono/issues/9996
+			throw new PlatformNotSupportedException();
+		}
+
 		internal unsafe int IndexOfUncheckedIgnoreCase (string value, int startIndex, int count)
 		{
 			int valueLen = value.Length;
-- 
2.11.4.GIT