[DuckTyping] Generate proxies in target AssemblyLoadContext

Datadog.Trace.Build.g.sln

@@ -175,6 +175,10 @@ Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Benchmarks.Trace", "tracer\
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Datadog.Trace.DuckTyping.Tests", "tracer\test\Datadog.Trace.DuckTyping.Tests\Datadog.Trace.DuckTyping.Tests.csproj", "{91E50134-0E55-4D22-B180-6967174FCE0B}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Datadog.Trace.DuckTyping.Tests.Fixtures.Shared", "tracer\test\Datadog.Trace.DuckTyping.Tests.Fixtures\Shared\Datadog.Trace.DuckTyping.Tests.Fixtures.Shared.csproj", "{AF81B51B-C799-468D-9488-2D30C7A435B6}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Datadog.Trace.DuckTyping.Tests.Fixtures.Target", "tracer\test\Datadog.Trace.DuckTyping.Tests.Fixtures\Target\Datadog.Trace.DuckTyping.Tests.Fixtures.Target.csproj", "{DE30EF39-4373-4485-8DC2-8CC08233CEA1}"
+EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "CallTargetNativeTest", "tracer\test\test-applications\instrumentation\CallTargetNativeTest\CallTargetNativeTest.csproj", "{021EFBA6-C4BA-4DE5-BF3F-C263EE9E20DB}"
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Samples.AspNet472.LoaderOptimizationRegKey", "tracer\test\test-applications\aspnet\Samples.AspNet472.LoaderOptimizationRegKey\Samples.AspNet472.LoaderOptimizationRegKey.csproj", "{BBB60B0F-BF01-4499-936A-4A299A9ACFD4}"
@@ -369,6 +373,14 @@ Global
 		{91E50134-0E55-4D22-B180-6967174FCE0B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{91E50134-0E55-4D22-B180-6967174FCE0B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{91E50134-0E55-4D22-B180-6967174FCE0B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Release|Any CPU.Build.0 = Release|Any CPU
 		{021EFBA6-C4BA-4DE5-BF3F-C263EE9E20DB}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{021EFBA6-C4BA-4DE5-BF3F-C263EE9E20DB}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{021EFBA6-C4BA-4DE5-BF3F-C263EE9E20DB}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -602,6 +614,8 @@ Global
 		{C00D8070-A38A-4267-9730-E9985CAE77DF} = {9E5F0022-0A50-40BF-AC6A-C3078585ECAB}
 		{B8D132F6-43E3-44D9-902C-78051DBAD01C} = {E5439139-6F94-44FA-9590-C32FCC1C7A93}
 		{91E50134-0E55-4D22-B180-6967174FCE0B} = {8CEC2042-F11C-49F5-A674-2355793B600A}
+		{AF81B51B-C799-468D-9488-2D30C7A435B6} = {8CEC2042-F11C-49F5-A674-2355793B600A}
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1} = {8CEC2042-F11C-49F5-A674-2355793B600A}
 		{021EFBA6-C4BA-4DE5-BF3F-C263EE9E20DB} = {933F1D4B-1216-4BC1-956E-8C30818BAA0F}
 		{BBB60B0F-BF01-4499-936A-4A299A9ACFD4} = {AFA0AB23-64F0-4AC1-9050-6CE8FE06F580}
 		{78004AA7-26DD-44DB-A2C7-C287A5BBE5D6} = {A0C5FBBB-CFB2-4FB9-B8F0-55676E9DCF06}

Datadog.Trace.sln

@@ -227,6 +227,10 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "dependency-libs", "dependen
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Datadog.Trace.DuckTyping.Tests", "tracer\test\Datadog.Trace.DuckTyping.Tests\Datadog.Trace.DuckTyping.Tests.csproj", "{91E50134-0E55-4D22-B180-6967174FCE0B}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Datadog.Trace.DuckTyping.Tests.Fixtures.Shared", "tracer\test\Datadog.Trace.DuckTyping.Tests.Fixtures\Shared\Datadog.Trace.DuckTyping.Tests.Fixtures.Shared.csproj", "{AF81B51B-C799-468D-9488-2D30C7A435B6}"
+EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Datadog.Trace.DuckTyping.Tests.Fixtures.Target", "tracer\test\Datadog.Trace.DuckTyping.Tests.Fixtures\Target\Datadog.Trace.DuckTyping.Tests.Fixtures.Target.csproj", "{DE30EF39-4373-4485-8DC2-8CC08233CEA1}"
+EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "build", "build", "{A0C5FBBB-CFB2-4FB9-B8F0-55676E9DCF06}"
 	ProjectSection(SolutionItems) = preProject
 		tracer\build\PackageVersionsGeneratorDefinitions.json = tracer\build\PackageVersionsGeneratorDefinitions.json
@@ -871,6 +875,14 @@ Global
 		{91E50134-0E55-4D22-B180-6967174FCE0B}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{91E50134-0E55-4D22-B180-6967174FCE0B}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{91E50134-0E55-4D22-B180-6967174FCE0B}.Release|Any CPU.Build.0 = Release|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{AF81B51B-C799-468D-9488-2D30C7A435B6}.Release|Any CPU.Build.0 = Release|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1}.Release|Any CPU.Build.0 = Release|Any CPU
 		{D79491F0-CA92-439B-98CE-7AF9F57EBEB0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{D79491F0-CA92-439B-98CE-7AF9F57EBEB0}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{D79491F0-CA92-439B-98CE-7AF9F57EBEB0}.Release|Any CPU.ActiveCfg = Release|Any CPU
@@ -1661,6 +1673,8 @@ Global
 		{AFA0AB23-64F0-4AC1-9050-6CE8FE06F580} = {9518425A-36A5-4B8F-B0B8-6137DB88441D}
 		{8683D82A-2BBE-4199-9C36-C59F48804F90} = {BAF8F246-3645-42AD-B1D0-0F7EAFBAB34A}
 		{91E50134-0E55-4D22-B180-6967174FCE0B} = {8CEC2042-F11C-49F5-A674-2355793B600A}
+		{AF81B51B-C799-468D-9488-2D30C7A435B6} = {8CEC2042-F11C-49F5-A674-2355793B600A}
+		{DE30EF39-4373-4485-8DC2-8CC08233CEA1} = {8CEC2042-F11C-49F5-A674-2355793B600A}
 		{CC53E5C5-9D3E-4AD9-A9CA-D2190463EB5B} = {A0C5FBBB-CFB2-4FB9-B8F0-55676E9DCF06}
 		{E5439139-6F94-44FA-9590-C32FCC1C7A93} = {8CEC2042-F11C-49F5-A674-2355793B600A}
 		{D79491F0-CA92-439B-98CE-7AF9F57EBEB0} = {498A300E-D036-49B7-A43D-821D1CAF11A5}

tracer/build/_build/Build.Steps.cs

@@ -1427,6 +1427,8 @@ void PrepareMonitoringHomeLinuxForPackaging(AbsolutePath assetsDirectory, string
         .Executes(() =>
         {
             //we need to build in this exact order
+            DotnetBuild(TracerDirectory.GlobFiles("test/Datadog.Trace.DuckTyping.Tests.Fixtures/Shared/*.csproj"));
+            DotnetBuild(TracerDirectory.GlobFiles("test/Datadog.Trace.DuckTyping.Tests.Fixtures/Target/*.csproj"));
             DotnetBuild(TracerDirectory.GlobFiles("test/**/*TestHelpers.csproj"));
             DotnetBuild(TracerDirectory.GlobFiles("test/**/*TestHelpers.AutoInstrumentation.csproj"));
         });

tracer/src/Datadog.Trace.Trimming/build/Datadog.Trace.Trimming.xml

@@ -1107,6 +1107,7 @@
    </assembly>
    <assembly fullname="System.Runtime.Loader">
       <type fullname="System.Runtime.Loader.AssemblyLoadContext" />
+      <type fullname="System.Runtime.Loader.AssemblyLoadContext/ContextualReflectionScope" />
    </assembly>
    <assembly fullname="System.Runtime.Numerics">
       <type fullname="System.Numerics.BigInteger" />

tracer/src/Datadog.Trace/DuckTyping/DuckType.Statics.cs

@@ -12,6 +12,9 @@
 using System.Reflection;
 using System.Reflection.Emit;
 using System.Runtime.CompilerServices;
+#if NETCOREAPP3_1 || NET6_0_OR_GREATER
+using System.Runtime.Loader;
+#endif
 // ReSharper disable InconsistentNaming
 
 namespace Datadog.Trace.DuckTyping
@@ -40,6 +43,18 @@ public static partial class DuckType
         private static readonly MethodInfo? _methodBuilderGetToken;
         [DebuggerBrowsable(DebuggerBrowsableState.Never)]
         private static readonly ConstructorInfo? _ignoresAccessChecksToAttributeCtor;
+#if NETSTANDARD2_0 || NETCOREAPP3_1
+        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+        private static readonly MethodInfo? _defineDynamicAssemblyMethodInfo;
+#endif
+#if NETSTANDARD2_0
+        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+        private static readonly MethodInfo? _getAssemblyLoadContextMethodInfo;
+        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+        private static readonly object? _duckTypeAssemblyLoadContext;
+        [DebuggerBrowsable(DebuggerBrowsableState.Never)]
+        private static readonly Dictionary<Assembly, bool> AssembliesInDuckTypeLoadContext;
+#endif
 
         [DebuggerBrowsable(DebuggerBrowsableState.Never)]
         private static long _assemblyCount;
@@ -59,6 +74,15 @@ static DuckType()
             _methodBuilderGetToken = typeof(MethodBuilder).GetMethod("GetToken", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)
                                   ?? typeof(MethodBuilder).GetProperty("MetadataToken", BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance)?.GetMethod;
             _ignoresAccessChecksToAttributeCtor = typeof(IgnoresAccessChecksToAttribute).GetConstructor(new[] { typeof(string) });
+#if NETSTANDARD2_0 || NETCOREAPP3_1
+            _defineDynamicAssemblyMethodInfo = typeof(AssemblyBuilder).GetMethod(nameof(AssemblyBuilder.DefineDynamicAssembly), new[] { typeof(AssemblyName), typeof(AssemblyBuilderAccess) });
+#endif
+#if NETSTANDARD2_0
+            var assemblyLoadContextType = Type.GetType("System.Runtime.Loader.AssemblyLoadContext, System.Runtime.Loader", throwOnError: false);
+            _getAssemblyLoadContextMethodInfo = assemblyLoadContextType?.GetMethod("GetLoadContext", BindingFlags.Public | BindingFlags.Static, binder: null, [typeof(Assembly)], modifiers: null);
+            _duckTypeAssemblyLoadContext = _getAssemblyLoadContextMethodInfo?.Invoke(obj: null, [typeof(DuckType).Assembly]);
+            AssembliesInDuckTypeLoadContext = new();
+#endif
 
             _assemblyCount = 0;
             _typeCount = 0;
@@ -139,6 +163,21 @@ private static ConstructorInfo IgnoresAccessChecksToAttributeCtor
             }
         }
 
+#if NETSTANDARD2_0 || NETCOREAPP3_1
+        private static MethodInfo DefineDynamicAssemblyMethodInfo
+        {
+            get
+            {
+                if (_defineDynamicAssemblyMethodInfo is null)
+                {
+                    DuckTypeException.Throw($"{nameof(AssemblyBuilder)}.{nameof(AssemblyBuilder.DefineDynamicAssembly)}() cannot be found.");
+                }
+
+                return _defineDynamicAssemblyMethodInfo;
+            }
+        }
+#endif
+
         /// <summary>
         /// Gets the ModuleBuilder instance from a target type.  (.NET Framework / Non AssemblyLoadContext version)
         /// </summary>
@@ -180,9 +219,81 @@ static ModuleBuilder CreateModuleBuilder(string name, Assembly targetAssembly)
             {
                 var assemblyName = new AssemblyName(name + $"_{++_assemblyCount}");
                 assemblyName.Version = targetAssembly.GetName().Version;
+
+#if NET6_0_OR_GREATER
+                AssemblyBuilder assemblyBuilder;
+                if (IsAssemblyInCurrentLoadContext(targetAssembly))
+                {
+                    assemblyBuilder = AssemblyBuilder.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
+                }
+                else
+                {
+                    using var contextualReflectionScope = AssemblyLoadContext.EnterContextualReflection(targetAssembly);
+                    assemblyBuilder = AssemblyBuilder.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
+                }
+#elif NETSTANDARD2_0 || NETCOREAPP3_1
+                var assemblyBuilder = IsAssemblyInCurrentLoadContext(targetAssembly)
+                                          ? AssemblyBuilder.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run)
+                                          : DefineDynamicAssemblyInTargetLoadContext(assemblyName, targetAssembly.ManifestModule);
+#else
                 var assemblyBuilder = AssemblyBuilder.DefineDynamicAssembly(assemblyName, AssemblyBuilderAccess.Run);
+#endif
                 return assemblyBuilder.DefineDynamicModule("MainModule");
             }
+
+#if NETCOREAPP3_1 || NET6_0_OR_GREATER
+            static bool IsAssemblyInCurrentLoadContext(Assembly targetAssembly)
+            {
+#if NET6_0_OR_GREATER
+                var currentLoadContext = AssemblyLoadContext.CurrentContextualReflectionContext
+                                      ?? AssemblyLoadContext.GetLoadContext(typeof(DuckType).Assembly);
+#else
+                var currentLoadContext = AssemblyLoadContext.GetLoadContext(typeof(DuckType).Assembly);
+#endif
+                return ReferenceEquals(AssemblyLoadContext.GetLoadContext(targetAssembly), currentLoadContext);
+            }
+#elif NETSTANDARD2_0
+            static bool IsAssemblyInCurrentLoadContext(Assembly targetAssembly)
+            {
+                // AssemblyLoadContext is not part of the .NET Standard 2.0 contract. Resolve it at runtime
+                // so the fast path does not add a System.Runtime.Loader dependency to Datadog.Trace.
+                if (_getAssemblyLoadContextMethodInfo is null)
+                {
+                    return true;
+                }
+
+                if (!AssembliesInDuckTypeLoadContext.TryGetValue(targetAssembly, out var isInDuckTypeLoadContext))
+                {
+                    var targetAssemblyLoadContext = _getAssemblyLoadContextMethodInfo.Invoke(obj: null, [targetAssembly]);
+                    isInDuckTypeLoadContext = ReferenceEquals(targetAssemblyLoadContext, _duckTypeAssemblyLoadContext);
+                    AssembliesInDuckTypeLoadContext.Add(targetAssembly, isInDuckTypeLoadContext);
+                }
+
+                return isInDuckTypeLoadContext;
+            }
+#endif
+
+#if NETSTANDARD2_0 || NETCOREAPP3_1
+            static AssemblyBuilder DefineDynamicAssemblyInTargetLoadContext(AssemblyName assemblyName, Module targetModule)
+            {
+                // Before .NET 6, DefineDynamicAssembly does not honor contextual reflection. Associating the
+                // call site with the target module makes the runtime create the proxy in the target load context.
+                var createAssemblyMethod = new DynamicMethod(
+                    "CreateDuckTypeAssembly",
+                    typeof(AssemblyBuilder),
+                    [typeof(AssemblyName)],
+                    targetModule,
+                    skipVisibility: false);
+                var il = createAssemblyMethod.GetILGenerator();
+                il.Emit(OpCodes.Ldarg_0);
+                il.Emit(OpCodes.Ldc_I4, (int)AssemblyBuilderAccess.Run);
+                il.Emit(OpCodes.Call, DefineDynamicAssemblyMethodInfo);
+                il.Emit(OpCodes.Ret);
+
+                var createAssembly = (Func<AssemblyName, AssemblyBuilder>)createAssemblyMethod.CreateDelegate(typeof(Func<AssemblyName, AssemblyBuilder>));
+                return createAssembly(assemblyName);
+            }
+#endif
         }
 
         /// <summary>

tracer/test/Datadog.Trace.DuckTyping.Tests.Fixtures/Directory.Build.props

@@ -0,0 +1,3 @@
+<Project>
+  <Import Project="..\..\Directory.Build.props" />
+</Project>

tracer/test/Datadog.Trace.DuckTyping.Tests.Fixtures/Shared/Datadog.Trace.DuckTyping.Tests.Fixtures.Shared.csproj

@@ -0,0 +1,9 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <IsTestProject>false</IsTestProject>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

tracer/test/Datadog.Trace.DuckTyping.Tests.Fixtures/Shared/FieldValue.cs

@@ -0,0 +1,13 @@
+// <copyright file="FieldValue.cs" company="Datadog">
+// Unless explicitly stated otherwise all files in this repository are licensed under the Apache 2 License.
+// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
+// </copyright>
+
+namespace Datadog.Trace.DuckTyping.Tests.Fixtures.Shared;
+
+public sealed class FieldValue
+{
+    public const int ExpectedValue = 42;
+
+    public int Value => ExpectedValue;
+}

tracer/test/Datadog.Trace.DuckTyping.Tests.Fixtures/Target/Datadog.Trace.DuckTyping.Tests.Fixtures.Target.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>netstandard2.0</TargetFramework>
+    <IsTestProject>false</IsTestProject>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Shared\Datadog.Trace.DuckTyping.Tests.Fixtures.Shared.csproj" />
+  </ItemGroup>
+
+</Project>

tracer/test/Datadog.Trace.DuckTyping.Tests.Fixtures/Target/DuckTypingTarget.cs

@@ -0,0 +1,15 @@
+// <copyright file="DuckTypingTarget.cs" company="Datadog">
+// Unless explicitly stated otherwise all files in this repository are licensed under the Apache 2 License.
+// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2017 Datadog, Inc.
+// </copyright>
+
+using Datadog.Trace.DuckTyping.Tests.Fixtures.Shared;
+
+namespace Datadog.Trace.DuckTyping.Tests.Fixtures.Target;
+
+public sealed class DuckTypingTarget
+{
+    private readonly FieldValue _field = new();
+
+    public object FieldValue => _field;
+}