From 79ae1b3fde730dd29bb65804eda422c3663694d0 Mon Sep 17 00:00:00 2001
From: Maryam Ariyan <maryam.ariyan@microsoft.com>
Date: Mon, 28 Jan 2019 14:07:37 -0800
Subject: [PATCH] Add SwitchExpressionException

Fixes: #33284
---
 .../ref/System.Runtime.Extensions.cs          | 11 +++++
 .../src/Resources/Strings.resx                |  3 ++
 .../src/System.Runtime.Extensions.csproj      |  1 +
 .../SwitchExpressionException.cs              | 41 +++++++++++++++++++
 .../System.Runtime.Extensions.Tests.csproj    |  1 +
 .../SwitchExpressionExceptionTests.cs         | 29 +++++++++++++
 6 files changed, 86 insertions(+)
 create mode 100644 src/System.Runtime.Extensions/src/System/Runtime/CompilerServices/SwitchExpressionException.cs
 create mode 100644 src/System.Runtime.Extensions/tests/System/Runtime/CompilerServices/SwitchExpressionExceptionTests.cs

diff --git a/src/System.Runtime.Extensions/ref/System.Runtime.Extensions.cs b/src/System.Runtime.Extensions/ref/System.Runtime.Extensions.cs
index ceab9463af72..74fdf9090e6b 100644
--- a/src/System.Runtime.Extensions/ref/System.Runtime.Extensions.cs
+++ b/src/System.Runtime.Extensions/ref/System.Runtime.Extensions.cs
@@ -1842,6 +1842,17 @@ public static class ProfileOptimization
         public static void StartProfile(string profile) { throw null; }
     }
 }
+namespace System.Runtime.CompilerServices
+{
+    [Serializable]
+    public sealed class SwitchExpressionException : System.InvalidOperationException
+    {
+        public SwitchExpressionException() { }
+        public SwitchExpressionException(object unmatchedValue) { }
+        public object UnmatchedValue { get { throw null; } }
+        public override void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System.Runtime.Serialization.StreamingContext context) { }
+    }
+}
 namespace System.Runtime.Versioning
 {
     public sealed partial class FrameworkName : System.IEquatable<System.Runtime.Versioning.FrameworkName>
diff --git a/src/System.Runtime.Extensions/src/Resources/Strings.resx b/src/System.Runtime.Extensions/src/Resources/Strings.resx
index 525c175c7a00..20981ccb5fc1 100644
--- a/src/System.Runtime.Extensions/src/Resources/Strings.resx
+++ b/src/System.Runtime.Extensions/src/Resources/Strings.resx
@@ -166,6 +166,9 @@
   <data name="Arg_AppDomainUnloadedException" xml:space="preserve">
     <value>Attempted to access an unloaded AppDomain.</value>
   </data>
+  <data name="Arg_SwitchExpressionException" xml:space="preserve">
+    <value>Non-exhaustive switch expression failed to match its input.</value>
+  </data>
   <data name="ZeroLengthString" xml:space="preserve">
     <value>String cannot have zero length.</value>
   </data>
diff --git a/src/System.Runtime.Extensions/src/System.Runtime.Extensions.csproj b/src/System.Runtime.Extensions/src/System.Runtime.Extensions.csproj
index 107a833b0969..4a09272b3ac7 100644
--- a/src/System.Runtime.Extensions/src/System.Runtime.Extensions.csproj
+++ b/src/System.Runtime.Extensions/src/System.Runtime.Extensions.csproj
@@ -44,6 +44,7 @@
     <Compile Include="System\IO\InvalidDataException.cs" />
     <Compile Include="System\Net\WebUtility.cs" />
     <Compile Include="System\Reflection\AssemblyNameProxy.cs" />
+    <Compile Include="System\Runtime\CompilerServices\SwitchExpressionException.cs" />
     <Compile Include="System\Runtime\ProfileOptimization.cs" />
     <Compile Include="System\Runtime\Versioning\FrameworkName.cs" />
     <Compile Include="System\Runtime\Versioning\ComponentGuaranteesAttribute.cs" />
diff --git a/src/System.Runtime.Extensions/src/System/Runtime/CompilerServices/SwitchExpressionException.cs b/src/System.Runtime.Extensions/src/System/Runtime/CompilerServices/SwitchExpressionException.cs
new file mode 100644
index 000000000000..f227cf3cfd4b
--- /dev/null
+++ b/src/System.Runtime.Extensions/src/System/Runtime/CompilerServices/SwitchExpressionException.cs
@@ -0,0 +1,41 @@
+// 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
+{
+    /// <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]
+    [System.Runtime.CompilerServices.TypeForwardedFrom("mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089")]
+    public sealed class SwitchExpressionException : InvalidOperationException//, ISerializable
+    {
+        public SwitchExpressionException()
+            : base(SR.Arg_SwitchExpressionException) { }
+
+        public SwitchExpressionException(object unmatchedValue)
+            : base()
+        {
+            UnmatchedValue = unmatchedValue;
+        }
+
+        private SwitchExpressionException(SerializationInfo info, StreamingContext context) 
+            : base(info, context)
+        {
+            info.AddValue(nameof(UnmatchedValue), UnmatchedValue, typeof(object));
+        }
+
+        public object UnmatchedValue { get; }
+
+        public override void GetObjectData(SerializationInfo info, StreamingContext context)
+        {
+           base.GetObjectData(info, context);
+            info.AddValue(nameof(UnmatchedValue), UnmatchedValue, typeof(object));
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/System.Runtime.Extensions/tests/System.Runtime.Extensions.Tests.csproj b/src/System.Runtime.Extensions/tests/System.Runtime.Extensions.Tests.csproj
index 623e2520f7c4..64b7682300cd 100644
--- a/src/System.Runtime.Extensions/tests/System.Runtime.Extensions.Tests.csproj
+++ b/src/System.Runtime.Extensions/tests/System.Runtime.Extensions.Tests.csproj
@@ -50,6 +50,7 @@
     <Compile Include="System\Diagnostics\Stopwatch.cs" />
     <Compile Include="System\Environment.MachineName.cs" />
     <Compile Include="System\IO\PathTests_Combine.cs" />
+    <Compile Include="System\Runtime\CompilerServices\SwitchExpressionExceptionTests.cs" />
     <Compile Include="System\Runtime\Versioning\FrameworkName.cs" />
     <Compile Include="System\IO\PathTestsBase.cs" />
     <Compile Include="System\Net\WebUtility.cs" />
diff --git a/src/System.Runtime.Extensions/tests/System/Runtime/CompilerServices/SwitchExpressionExceptionTests.cs b/src/System.Runtime.Extensions/tests/System/Runtime/CompilerServices/SwitchExpressionExceptionTests.cs
new file mode 100644
index 000000000000..e7622a2cbd77
--- /dev/null
+++ b/src/System.Runtime.Extensions/tests/System/Runtime/CompilerServices/SwitchExpressionExceptionTests.cs
@@ -0,0 +1,29 @@
+// 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.CompilerServices;
+using Xunit;
+
+namespace System.Runtime.CompilerServices.Tests
+{
+    public class SwitchExpressionExceptionTests
+    {
+        [Fact]
+        public void UnmatchedValue()
+        {
+            var ex = new SwitchExpressionException(34);
+            Assert.Equal(34, ex.UnmatchedValue);
+
+            var data = new byte[] { 1, 2, 3 };
+            ex = new SwitchExpressionException(data);
+            Assert.Equal(data, ex.UnmatchedValue);
+
+            ex = new SwitchExpressionException(true);
+            Assert.Equal(true, ex.UnmatchedValue);
+
+            ex = new SwitchExpressionException("34");
+            Assert.Equal("34", ex.UnmatchedValue);
+        }
+    }
+}