Obsolete Socket.UseOnlyOverlappedIO

src/libraries/System.Net.Sockets/ref/System.Net.Sockets.cs

@@ -292,6 +292,8 @@ public Socket(System.Net.Sockets.SocketType socketType, System.Net.Sockets.Proto
         [System.ObsoleteAttribute("SupportsIPv6 is obsoleted for this type, please use OSSupportsIPv6 instead. https://go.microsoft.com/fwlink/?linkid=14202")]
         public static bool SupportsIPv6 { get { throw null; } }
         public short Ttl { get { throw null; } set { } }
+        [System.ObsoleteAttribute("This property has no effect in .NET Core")]
+        [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
         public bool UseOnlyOverlappedIO { get { throw null; } set { } }
         public System.Net.Sockets.Socket Accept() { throw null; }
         public System.Threading.Tasks.Task<System.Net.Sockets.Socket> AcceptAsync() { throw null; }
@@ -501,6 +503,8 @@ public enum SocketInformationOptions
         NonBlocking = 1,
         Connected = 2,
         Listening = 4,
+        [System.ObsoleteAttribute("This flag has no effect in .NET Core")]
+        [System.ComponentModel.EditorBrowsableAttribute(System.ComponentModel.EditorBrowsableState.Never)]
         UseOnlyOverlappedIO = 8,
     }
     public enum SocketOptionLevel

src/libraries/System.Net.Sockets/src/System/Net/Sockets/Socket.cs

@@ -3,6 +3,7 @@
 
 using System.Collections;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
 using System.IO;
@@ -415,6 +416,8 @@ public bool Blocking
         // allowing calls to DuplicateAndClose() even after performing asynchronous IO.
         // .NET (Core) Windows sockets are entirely IOCP-based, and the concept of "overlapped IO"
         // does not exist on other platforms, therefore UseOnlyOverlappedIO is a dummy, compat-only property.
+        [Obsolete("This property has no effect in .NET Core")]
+        [EditorBrowsable(EditorBrowsableState.Never)]
         public bool UseOnlyOverlappedIO
         {
             get { return false; }

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketInformationOptions.cs

@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.ComponentModel;
+
 namespace System.Net.Sockets
 {
     [Flags]
@@ -11,6 +13,8 @@ public enum SocketInformationOptions
         //disconnect doesn't update getpeername to return a failure.
         Connected = 0x2,
         Listening = 0x4,
+        [Obsolete("This flag has no effect in .NET Core")]
+        [EditorBrowsable(EditorBrowsableState.Never)]
         UseOnlyOverlappedIO = 0x8,
     }
 }

src/libraries/System.Net.Sockets/tests/FunctionalTests/CreateSocketTests.cs

@@ -378,7 +378,9 @@ public void Ctor_SafeHandle_BasicPropertiesPropagate_Success(AddressFamily addre
             Assert.Equal(orig.ReceiveTimeout, copy.ReceiveTimeout);
             Assert.Equal(orig.SendBufferSize, copy.SendBufferSize);
             Assert.Equal(orig.SendTimeout, copy.SendTimeout);
+#pragma warning disable 0618
             Assert.Equal(orig.UseOnlyOverlappedIO, copy.UseOnlyOverlappedIO);
+#pragma warning restore 0618
         }
 
         [Theory]
@@ -422,7 +424,6 @@ public async Task Ctor_SafeHandle_Tcp_SendReceive_Success(AddressFamily addressF
             Assert.Equal(orig.SendBufferSize, client.SendBufferSize);
             Assert.Equal(orig.SendTimeout, client.SendTimeout);
             Assert.Equal(orig.Ttl, client.Ttl);
-            Assert.Equal(orig.UseOnlyOverlappedIO, client.UseOnlyOverlappedIO);
 
             // Validate setting various properties on the new instance and seeing them roundtrip back to the original.
             client.ReceiveTimeout = 42;

src/libraries/System.Net.Sockets/tests/FunctionalTests/SocketDuplicationTests.cs

@@ -15,7 +15,7 @@
 
 namespace System.Net.Sockets.Tests
 {
-    // Test cases for DuplicateAndClose, Socket(socketInformation), Socket.UseOnlyOverlappedIO,
+    // Test cases for DuplicateAndClose, Socket(socketInformation), Socket(socketInformation),
     // and asynchronous IO behavior for duplicate sockets.
     // Since the constructor Socket(socketInformation) is strongly coupled
     // with the rest of the duplication logic, it's being tested here instead of CreateSocketTests.
@@ -32,9 +32,11 @@ public void UseOnlyOverlappedIO_AlwaysFalse()
         {
             using Socket s = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
 
+#pragma warning disable 0618
             Assert.False(s.UseOnlyOverlappedIO);
             s.UseOnlyOverlappedIO = true;
             Assert.False(s.UseOnlyOverlappedIO);
+#pragma warning restore 0618
         }
 
         [PlatformSpecific(TestPlatforms.Windows)]