Use slightly smaller code for String.Concat(object, object, ...) (#44133)

C#, IL, and asm are all a bit smaller.  We don't need to set the arguments to Empty if they're null, as the called function checks for null.

diff --git a/src/libraries/System.Private.CoreLib/src/System/String.Manipulation.cs b/src/libraries/System.Private.CoreLib/src/System/String.Manipulation.cs
index 336f511..1175778 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/String.Manipulation.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/String.Manipulation.cs
@@ -30,41 +30,14 @@ namespace System
                 elementCount: (uint)src.Length);
         }
 
-        public static string Concat(object? arg0) => arg0?.ToString() ?? string.Empty;
+        public static string Concat(object? arg0) =>
+            arg0?.ToString() ?? Empty;
 
-        public static string Concat(object? arg0, object? arg1)
-        {
-            if (arg0 == null)
-            {
-                arg0 = string.Empty;
-            }
-
-            if (arg1 == null)
-            {
-                arg1 = string.Empty;
-            }
-            return Concat(arg0.ToString(), arg1.ToString());
-        }
-
-        public static string Concat(object? arg0, object? arg1, object? arg2)
-        {
-            if (arg0 == null)
-            {
-                arg0 = string.Empty;
-            }
-
-            if (arg1 == null)
-            {
-                arg1 = string.Empty;
-            }
+        public static string Concat(object? arg0, object? arg1) =>
+            Concat(arg0?.ToString(), arg1?.ToString());
 
-            if (arg2 == null)
-            {
-                arg2 = string.Empty;
-            }
-
-            return Concat(arg0.ToString(), arg1.ToString(), arg2.ToString());
-        }
+        public static string Concat(object? arg0, object? arg1, object? arg2) =>
+            Concat(arg0?.ToString(), arg1?.ToString(), arg2?.ToString());
 
         public static string Concat(params object?[] args)
         {