Add RpcTargetMetadata.FromShape<T> overloads that work on .NET Framework

Author: AArnott

src/StreamJsonRpc/JsonMessageFormatter.cs

@@ -1050,6 +1050,7 @@ public override void WriteJson(JsonWriter writer, object? value, JsonSerializer
     /// Converts an enumeration token to an <see cref="IAsyncEnumerable{T}"/>.
     /// </summary>
     [RequiresDynamicCode(RuntimeReasons.CloseGenerics)]
+    [RequiresUnreferencedCode(RuntimeReasons.CloseGenerics)]
     private class AsyncEnumerableConsumerConverter : JsonConverter
     {
         private static readonly MethodInfo ReadJsonOpenGenericMethod = typeof(AsyncEnumerableConsumerConverter).GetMethods(BindingFlags.Instance | BindingFlags.NonPublic).Single(m => m.Name == nameof(ReadJson) && m.IsGenericMethod);
@@ -1109,6 +1110,7 @@ private IAsyncEnumerable<T> ReadJson<T>(JsonReader reader, JsonSerializer serial
     /// Converts an instance of <see cref="IAsyncEnumerable{T}"/> to an enumeration token.
     /// </summary>
     [RequiresDynamicCode(RuntimeReasons.CloseGenerics)]
+    [RequiresUnreferencedCode(RuntimeReasons.CloseGenerics)]
     private class AsyncEnumerableGeneratorConverter : JsonConverter
     {
         private static readonly MethodInfo WriteJsonOpenGenericMethod = typeof(AsyncEnumerableGeneratorConverter).GetMethods(BindingFlags.NonPublic | BindingFlags.Instance).Single(m => m.Name == nameof(WriteJson) && m.IsGenericMethod);

src/StreamJsonRpc/RpcTargetMetadataExtensions.cs

@@ -0,0 +1,56 @@
+using System.ComponentModel;
+using System.Diagnostics.CodeAnalysis;
+using PolyType.Abstractions;
+
+namespace StreamJsonRpc;
+
+/// <summary>
+/// Extension methods for the <see cref="RpcTargetMetadata"/> class.
+/// </summary>
+public static class RpcTargetMetadataExtensions
+{
+#if NET8_0
+    /// <summary>
+    /// A message to use as the argument to <see cref="RequiresDynamicCodeAttribute"/>
+    /// for methods that call into <see cref="TypeShapeResolver.ResolveDynamicOrThrow{T}"/>.
+    /// </summary>
+    /// <seealso href="https://github.com/dotnet/runtime/issues/119440#issuecomment-3269894751"/>
+    internal const string ResolveDynamicMessage =
+        "Dynamic resolution of IShapeable<T> interface may require dynamic code generation in .NET 8 Native AOT. " +
+        "It is recommended to switch to statically resolved IShapeable<T> APIs or upgrade your app to .NET 9 or later.";
+#endif
+
+    extension(RpcTargetMetadata)
+    {
+        /// <summary>
+        /// Creates an <see cref="RpcTargetMetadata"/> instance from the specified shape.
+        /// </summary>
+        /// <typeparam name="T">The type for which a shape should be obtained and <see cref="RpcTargetMetadata"/> generated for.</typeparam>
+        /// <returns>An <see cref="RpcTargetMetadata"/> instance initialized from the shape of the <typeparamref name="T"/>.</returns>
+#if NET8_0
+        [RequiresDynamicCode(ResolveDynamicMessage)]
+#endif
+#if NET
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        [Obsolete("Use the RpcTargetMetadata.FromShape<T>() method instead. If using the extension method syntax, check that your type argument actually has a [GenerateShape] attribute or otherwise implements IShapeable<T> to avoid a runtime failure.", error: true)]
+#endif
+        public static RpcTargetMetadata FromShape<T>()
+            => RpcTargetMetadata.FromShape(TypeShapeResolver.ResolveDynamicOrThrow<T>());
+
+        /// <summary>
+        /// Creates an <see cref="RpcTargetMetadata"/> instance from the specified shape.
+        /// </summary>
+        /// <typeparam name="T">The type for which a shape should be obtained and <see cref="RpcTargetMetadata"/> generated for.</typeparam>
+        /// <typeparam name="TProvider">The provider of type shapes from which to obtain the shape.</typeparam>
+        /// <returns>An <see cref="RpcTargetMetadata"/> instance initialized from the shape of the <typeparamref name="T"/>.</returns>
+#if NET8_0
+        [RequiresDynamicCode(ResolveDynamicMessage)]
+#endif
+#if NET
+        [EditorBrowsable(EditorBrowsableState.Never)]
+        [Obsolete("Use the RpcTargetMetadata.FromShape<T, TProvider>() method instead. If using the extension method syntax, check that your type argument actually has a [GenerateShape] attribute or otherwise implements IShapeable<T> to avoid a runtime failure.", error: true)]
+#endif
+        public static RpcTargetMetadata FromShape<T, TProvider>()
+            => RpcTargetMetadata.FromShape(TypeShapeResolver.ResolveDynamicOrThrow<TProvider>());
+    }
+}

src/StreamJsonRpc/StreamJsonRpc.csproj

@@ -1,6 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0;netstandard2.1;net8.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netstandard2.1;net8.0;net9.0</TargetFrameworks>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
@@ -13,6 +13,8 @@
     <IsAotCompatible Condition="$([MSBuild]::IsTargetFrameworkCompatible('$(TargetFramework)', 'net8.0'))">true</IsAotCompatible>
     <EnableStreamJsonRpcInterceptors>false</EnableStreamJsonRpcInterceptors>
     <PackageValidationBaselineVersion>2.22.11</PackageValidationBaselineVersion>
+    <!-- StyleCop.Analyzers cannot handle the new C# 14 extension syntax we use in RpcTargetMetadataExtensions. -->
+    <NoWarn>$(NoWarn);SA1201</NoWarn>
   </PropertyGroup>
   <ItemGroup>
     <EmbeddedResource Update="Resources.resx" EmitFormatMethods="true" />

test/StreamJsonRpc.Tests/RpcTargetMetadataTests.cs

@@ -1,8 +1,6 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-using PolyType;
-
 public partial class RpcTargetMetadataTests
 {
     internal interface IRpcContractBase
@@ -45,7 +43,7 @@ internal partial interface IShapedContract
     [Fact]
     public void FromShape()
     {
-        RpcTargetMetadata metadata = RpcTargetMetadata.FromShape<IShapedContract>(Witness.GeneratedTypeShapeProvider);
+        RpcTargetMetadata metadata = RpcTargetMetadata.FromShape<IShapedContract>();
 
         var addAsync = Assert.Single(metadata.Methods["AddAsync"]);
         var add = Assert.Single(metadata.AliasedMethods["Add"]);

test/StreamJsonRpc.Tests/StreamJsonRpc.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFrameworks>net8.0</TargetFrameworks>
+    <TargetFrameworks>net8.0;net9.0</TargetFrameworks>
     <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('Windows'))">$(TargetFrameworks);net472</TargetFrameworks>
     <OutputType>exe</OutputType>
     <RootNamespace />