Imported Upstream version 6.4.0.137

Former-commit-id: 943baa9f16a098c33e129777827f3a9d20da00d6

mcs/class/corlib/corefx/SwitchExpressionException.cs

@@ -0,0 +1,66 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.Serialization;
+
+namespace System.Runtime.CompilerServices
+{
+    // MONO: this file was copied from CoreFX master for NS2.1
+
+    /// <summary>
+    /// Indicates that a switch expression that was non-exhaustive failed to match its input
+    /// at runtime, e.g. in the C# 8 expression <code>3 switch { 4 => 5 }</code>.
+    /// The exception optionally contains an object representing the unmatched value.
+    /// </summary>
+    [Serializable]
+    public sealed class SwitchExpressionException : InvalidOperationException
+    {
+        public SwitchExpressionException()
+            : base(SR.Arg_SwitchExpressionException) { }
+
+        public SwitchExpressionException(Exception innerException) :
+            base(SR.Arg_SwitchExpressionException, innerException) { }
+
+        public SwitchExpressionException(object unmatchedValue) : this()
+        {
+            UnmatchedValue = unmatchedValue;
+        }
+
+        private SwitchExpressionException(SerializationInfo info, StreamingContext context)
+            : base(info, context)
+        {
+            UnmatchedValue = info.GetValue(nameof(UnmatchedValue), typeof(object));
+        }
+
+        public SwitchExpressionException(string message) : base(message) { }
+
+        public SwitchExpressionException(string message, Exception innerException)
+            : base(message, innerException) { }
+
+        public object UnmatchedValue { get; }
+
+        public override void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+            base.GetObjectData(info, context);
+            info.AddValue(nameof(UnmatchedValue), UnmatchedValue, typeof(object));
+        }
+
+        public override string Message
+        {
+            get
+            {
+#if __MonoCS__
+                if (UnmatchedValue == null)
+#else
+                if (UnmatchedValue is null)
+#endif
+                {
+                    return base.Message;
+                }
+                string valueMessage = SR.Format(SR.SwitchExpressionException_UnmatchedValue, UnmatchedValue.ToString());
+                return base.Message + Environment.NewLine + valueMessage;
+            }
+        }
+    }
+}