Fix up compiler warnings

src/StreamJsonRpc/Exceptions/BadRpcHeaderException.cs

@@ -34,6 +34,9 @@ public class BadRpcHeaderException : RemoteRpcException
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected BadRpcHeaderException(
       System.Runtime.Serialization.SerializationInfo info,
       System.Runtime.Serialization.StreamingContext context)

src/StreamJsonRpc/Exceptions/ConnectionLostException.cs

@@ -42,6 +42,9 @@ public class ConnectionLostException : RemoteRpcException
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected ConnectionLostException(
       System.Runtime.Serialization.SerializationInfo info,
       System.Runtime.Serialization.StreamingContext context)

src/StreamJsonRpc/Exceptions/RemoteInvocationException.cs

@@ -64,6 +64,9 @@ public class RemoteInvocationException : RemoteRpcException
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected RemoteInvocationException(SerializationInfo info, StreamingContext context)
         : base(info, context)
     {

src/StreamJsonRpc/Exceptions/RemoteMethodNotFoundException.cs

@@ -41,6 +41,9 @@ public class RemoteMethodNotFoundException : RemoteRpcException
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected RemoteMethodNotFoundException(SerializationInfo info, StreamingContext context)
         : base(info, context)
     {
@@ -67,6 +70,9 @@ public class RemoteMethodNotFoundException : RemoteRpcException
     public new object? DeserializedErrorData => base.DeserializedErrorData;
 
     /// <inheritdoc/>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     public override void GetObjectData(SerializationInfo info, StreamingContext context)
     {
         base.GetObjectData(info, context);

src/StreamJsonRpc/Exceptions/RemoteRpcException.cs

@@ -37,6 +37,9 @@ public abstract class RemoteRpcException : Exception
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected RemoteRpcException(SerializationInfo info, StreamingContext context)
         : base(info, context)
     {
@@ -69,6 +72,9 @@ public abstract class RemoteRpcException : Exception
     public object? DeserializedErrorData { get; protected set; }
 
     /// <inheritdoc/>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     public override void GetObjectData(SerializationInfo info, StreamingContext context)
     {
         base.GetObjectData(info, context);

src/StreamJsonRpc/Exceptions/RemoteSerializationException.cs

@@ -31,6 +31,9 @@ public class RemoteSerializationException : RemoteRpcException
     /// </summary>
     /// <param name="serializationInfo">Serialization info.</param>
     /// <param name="streamingContext">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected RemoteSerializationException(System.Runtime.Serialization.SerializationInfo serializationInfo, System.Runtime.Serialization.StreamingContext streamingContext)
         : base(serializationInfo, streamingContext)
     {

src/StreamJsonRpc/Exceptions/RpcArgumentDeserializationException.cs

@@ -52,6 +52,9 @@ public class RpcArgumentDeserializationException : RemoteRpcException
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Serialization context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected RpcArgumentDeserializationException(SerializationInfo info, StreamingContext context)
         : base(info, context)
     {
@@ -85,6 +88,9 @@ public class RpcArgumentDeserializationException : RemoteRpcException
     public Type? DeserializedType { get; private set; }
 
     /// <inheritdoc/>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     public override void GetObjectData(SerializationInfo info, StreamingContext context)
     {
         base.GetObjectData(info, context);

src/StreamJsonRpc/Exceptions/UnrecognizedJsonRpcMessageException.cs

@@ -43,6 +43,9 @@ public class UnrecognizedJsonRpcMessageException : RemoteRpcException
     /// </summary>
     /// <param name="info">Serialization info.</param>
     /// <param name="context">Streaming context.</param>
+#if NET8_0_OR_GREATER
+    [Obsolete]
+#endif
     protected UnrecognizedJsonRpcMessageException(SerializationInfo info, StreamingContext context)
         : base(info, context)
     {

src/StreamJsonRpc/JsonMessageFormatter.cs

@@ -1288,7 +1288,10 @@ public class JsonMessageFormatter : FormatterBase, IJsonRpcAsyncMessageTextForma
             this.serializer = serializer;
         }
 
-        public object Convert(object value, Type type) => ((JToken)value).ToObject(type, this.serializer)!;
+#pragma warning disable CS8766 // This method may in fact return null, and no one cares.
+        public object? Convert(object value, Type type)
+#pragma warning restore CS8766
+            => ((JToken)value).ToObject(type, this.serializer);
 
         public object Convert(object value, TypeCode typeCode)
         {

src/StreamJsonRpc/JsonRpc.cs

@@ -2219,7 +2219,7 @@ public class JsonRpc : IDisposableObservable, IJsonRpcFormatterCallbacks, IJsonR
 
                 // Be sure to dispose the link to the local method token we created in case it is linked to our long-lived disposal token
                 // and otherwise cause a memory leak.
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
                 await disconnectedRegistration.DisposeAsync().ConfigureAwait(false);
 #else
                 disconnectedRegistration.Dispose();

src/StreamJsonRpc/MessageHandlerBase.cs

@@ -239,7 +239,11 @@ public abstract class MessageHandlerBase : IJsonRpcMessageHandler, IDisposableOb
     {
         if (!this.disposalTokenSource.IsCancellationRequested)
         {
+#if NET8_0_OR_GREATER
+            await this.disposalTokenSource.CancelAsync().ConfigureAwait(false);
+#else
             this.disposalTokenSource.Cancel();
+#endif
 
             // Kick off disposal of reading and/or writing resources based on whether they're active right now or not.
             // If they're active, they'll take care of themselves when they finish since we signaled disposal.

src/StreamJsonRpc/MessagePackFormatter.cs

@@ -405,7 +405,7 @@ public class MessagePackFormatter : FormatterBase, IJsonRpcMessageFormatter, IJs
     private static void ReadUnknownProperty(ref MessagePackReader reader, ref Dictionary<string, ReadOnlySequence<byte>>? topLevelProperties, ReadOnlySpan<byte> stringKey)
     {
         topLevelProperties ??= new Dictionary<string, ReadOnlySequence<byte>>(StringComparer.Ordinal);
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
         string name = Encoding.UTF8.GetString(stringKey);
 #else
         string name = Encoding.UTF8.GetString(stringKey.ToArray());
@@ -660,7 +660,10 @@ public class MessagePackFormatter : FormatterBase, IJsonRpcMessageFormatter, IJs
             this.options = options;
         }
 
-        public object? Convert(object value, Type type) => ((RawMessagePack)value).Deserialize(type, this.options);
+#pragma warning disable CS8766 // This method may in fact return null, and no one cares.
+        public object? Convert(object value, Type type)
+#pragma warning restore CS8766
+            => ((RawMessagePack)value).Deserialize(type, this.options);
 
         public object Convert(object value, TypeCode typeCode)
         {

src/StreamJsonRpc/ProxyGeneration.cs

@@ -302,7 +302,7 @@ internal static class ProxyGeneration
 
                     Label positionalArgsLabel = il.DefineLabel();
 
-                    ParameterInfo cancellationTokenParameter = methodParameters.FirstOrDefault(p => p.ParameterType == typeof(CancellationToken));
+                    ParameterInfo? cancellationTokenParameter = methodParameters.FirstOrDefault(p => p.ParameterType == typeof(CancellationToken));
                     int argumentCountExcludingCancellationToken = methodParameters.Length - (cancellationTokenParameter is not null ? 1 : 0);
                     VerifySupported(cancellationTokenParameter is null || cancellationTokenParameter.Position == methodParameters.Length - 1, Resources.CancellationTokenMustBeLastParameter, method);
 
@@ -913,11 +913,11 @@ internal static class ProxyGeneration
         public bool Equals(GeneratedProxiesByInterfaceKey other)
         {
             return this.baseInterfaceType == other.baseInterfaceType &&
-                   !(this.implementedOptionalInterfaces is not null ^ other.implementedOptionalInterfaces is not null) &&
-                   (this.implementedOptionalInterfaces?.SequenceEqual(other.implementedOptionalInterfaces) ?? true);
+                ((this.implementedOptionalInterfaces is null && other.implementedOptionalInterfaces is null) ||
+                (this.implementedOptionalInterfaces is not null && other.implementedOptionalInterfaces is not null && this.implementedOptionalInterfaces.SequenceEqual(other.implementedOptionalInterfaces)));
         }
 
-        public override bool Equals(object obj)
+        public override bool Equals(object? obj)
         {
             return obj is GeneratedProxiesByInterfaceKey other && this.Equals(other);
         }

src/StreamJsonRpc/Reflection/ExceptionSerializationHelpers.cs

@@ -88,7 +88,9 @@ internal static class ExceptionSerializationHelpers
     {
         Type exceptionType = exception.GetType();
         EnsureSerializableAttribute(exceptionType);
+#pragma warning disable SYSLIB0051 // Type or member is obsolete -- NOT so obsolete without the BinaryFormatter.
         exception.GetObjectData(info, Context);
+#pragma warning restore SYSLIB0051 // Type or member is obsolete
         info.AddValue(AssemblyNameKeyName, exception.GetType().Assembly.FullName);
     }
 

src/StreamJsonRpc/Reflection/MessageFormatterEnumerableTracker.cs

@@ -322,11 +322,15 @@ public class MessageFormatterEnumerableTracker
             }
         }
 
-        public ValueTask DisposeAsync()
+        public async ValueTask DisposeAsync()
         {
+#if NET8_0_OR_GREATER
+            await this.cancellationTokenSource.CancelAsync().ConfigureAwait(false);
+#else
             this.cancellationTokenSource.Cancel();
+#endif
             this.readAheadElements?.Complete();
-            return this.enumerator.DisposeAsync();
+            await this.enumerator.DisposeAsync().ConfigureAwait(false);
         }
 
         private async Task ReadAheadAsync()

src/StreamJsonRpc/Reflection/RpcTargetInfo.cs

@@ -530,7 +530,8 @@ internal class RpcTargetInfo : System.IAsyncDisposable
                 // Only add methods that do not have equivalent signatures to what we already have.
                 foreach (MethodSignature newMethod in item.Value)
                 {
-                    if (!alreadyExists || !existingList.Any(e => e.Equals(newMethod)))
+                    // Null forgiveness operator in use due to: https://github.com/dotnet/roslyn/issues/73274
+                    if (!alreadyExists || !existingList!.Any(e => e.Equals(newMethod)))
                     {
                         var signatureAndTarget = new MethodSignatureAndTarget(newMethod, target, null);
                         this.TraceLocalMethodAdded(rpcMethodName, signatureAndTarget);

src/StreamJsonRpc/Reflection/TrackerHelpers.cs

@@ -15,7 +15,7 @@ internal static class TrackerHelpers<TInterface>
     /// <summary>
     /// Dictionary to record the calculation made in <see cref="FindInterfaceImplementedBy(Type)"/> to obtain the <typeparamref name="TInterface"/> type from a given <see cref="Type"/>.
     /// </summary>
-    private static readonly Dictionary<Type, Type> TypeToImplementedInterfaceMap = new Dictionary<Type, Type>();
+    private static readonly Dictionary<Type, Type?> TypeToImplementedInterfaceMap = new();
 
     /// <summary>
     /// Gets the generic type definition for whatever type parameter was given by <typeparamref name="TInterface" />.

src/StreamJsonRpc/RequestId.cs

@@ -104,7 +104,7 @@ public struct RequestId : IEquatable<RequestId>
     public override bool Equals(object? obj) => obj is RequestId other && this.Equals(other);
 
     /// <inheritdoc/>
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
     public override int GetHashCode() => this.Number?.GetHashCode() ?? this.String?.GetHashCode(StringComparison.Ordinal) ?? 0;
 #else
     public override int GetHashCode() => this.Number?.GetHashCode() ?? this.String?.GetHashCode() ?? 0;

src/StreamJsonRpc/StreamJsonRpc.csproj

@@ -6,6 +6,8 @@
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <Description>A cross-platform .NETStandard library that implements the JSON-RPC wire protocol and can use System.IO.Stream, System.IO.Pipelines or WebSocket so you can use it with any transport.</Description>
     <PackageTags>visualstudio stream json rpc jsonrpc</PackageTags>
+    <!-- We use the ISerializable APIs *without* the BinaryFormatter. Not as obsolete as the .NET SDK would have us believe. -->
+    <NoWarn>$(NoWarn);SYSLIB0050</NoWarn>
   </PropertyGroup>
   <ItemGroup>
     <EmbeddedResource Update="Resources.resx" />

src/StreamJsonRpc/SystemTextJsonFormatter.cs

@@ -1104,16 +1104,15 @@ public class SystemTextJsonFormatter : FormatterBase, IJsonRpcMessageFormatter,
             this.serializerOptions = serializerOptions;
         }
 
+#pragma warning disable CS8766 // This method may in fact return null, and no one cares.
         public object? Convert(object value, Type type)
+#pragma warning restore CS8766
         {
-            var jsonValue = (JsonNode?)value;
-            if (jsonValue is null)
-            {
-                return null;
-            }
+            var jsonValue = (JsonNode)value;
 
             if (type == typeof(System.Collections.IDictionary))
             {
+                // In this world, we may in fact be returning a null value based on a non-null value.
                 return DeserializePrimitive(jsonValue);
             }
 

src/StreamJsonRpc/WebSocketMessageHandler.cs

@@ -82,14 +82,14 @@ public class WebSocketMessageHandler : MessageHandlerBase, IJsonRpcMessageBuffer
     /// <inheritdoc />
     protected override async ValueTask<JsonRpcMessage?> ReadCoreAsync(CancellationToken cancellationToken)
     {
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
         ValueWebSocketReceiveResult result;
 #else
         WebSocketReceiveResult result;
 #endif
         do
         {
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
             Memory<byte> memory = this.contentSequenceBuilder.GetMemory(this.sizeHint);
             result = await this.WebSocket.ReceiveAsync(memory, cancellationToken).ConfigureAwait(false);
             this.contentSequenceBuilder.Advance(result.Count);
@@ -155,7 +155,7 @@ public class WebSocketMessageHandler : MessageHandlerBase, IJsonRpcMessageBuffer
             foreach (ReadOnlyMemory<byte> memory in contentSequence)
             {
                 bool endOfMessage = bytesCopied + memory.Length == contentSequence.Length;
-#if NETSTANDARD2_1_OR_GREATER
+#if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
                 await this.WebSocket.SendAsync(memory, messageType, endOfMessage, cancellationToken).ConfigureAwait(false);
 #else
                 if (MemoryMarshal.TryGetArray(memory, out ArraySegment<byte> segment))