Add DiagnosticSource.Write<T> API to assist with trimming

src/libraries/Microsoft.Extensions.Hosting/src/HostBuilder.cs

@@ -190,7 +190,7 @@ internal static DiagnosticListener LogHostBuilding(HostApplicationBuilder hostAp
 
         [UnconditionalSuppressMessage("ReflectionAnalysis", "IL2026:UnrecognizedReflectionPattern",
             Justification = "The values being passed into Write are being consumed by the application already.")]
-        private static void Write<T>(
+        private static void Write<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] T>(
             DiagnosticSource diagnosticSource,
             string name,
             T value)

src/libraries/System.Diagnostics.DiagnosticSource/ref/System.Diagnostics.DiagnosticSource.cs

@@ -29,5 +29,7 @@ protected DiagnosticSource() { }
         public virtual bool IsEnabled(string name, object? arg1, object? arg2 = null) { throw null; }
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("The type of object being written to DiagnosticSource cannot be discovered statically.")]
         public abstract void Write(string name, object? value);
+        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCodeAttribute("The type of object being written to DiagnosticSource cannot be discovered statically.")]
+        public void Write<[System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembers(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicProperties)] T>(string name, T? value) { }
     }
 }

src/libraries/System.Diagnostics.DiagnosticSource/ref/System.Diagnostics.DiagnosticSource.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <TargetFrameworks>$(NetCoreAppCurrent);$(NetCoreAppMinimum);netstandard2.0;$(NetFrameworkMinimum)</TargetFrameworks>
     <CLSCompliant>false</CLSCompliant>
@@ -11,6 +11,8 @@
   </ItemGroup>
 
   <ItemGroup Condition="'$(TargetFrameworkIdentifier)' != '.NETCoreApp'">
+    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicallyAccessedMemberTypes.cs" />
+    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicallyAccessedMembersAttribute.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\RequiresUnreferencedCodeAttribute.cs"  />
     <Compile Include="$(CoreLibSharedDir)System\Runtime\CompilerServices\IsExternalInit.cs" />
   </ItemGroup>

src/libraries/System.Diagnostics.DiagnosticSource/ref/System.Diagnostics.DiagnosticSourceActivity.cs

@@ -199,7 +199,11 @@ public virtual void OnActivityImport(System.Diagnostics.Activity activity, objec
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("The type of object being written to DiagnosticSource cannot be discovered statically.")]
         public System.Diagnostics.Activity StartActivity(System.Diagnostics.Activity activity, object? args) { throw null; }
         [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("The type of object being written to DiagnosticSource cannot be discovered statically.")]
+        public System.Diagnostics.Activity StartActivity<[System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembers(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicProperties)] T>(Activity activity, T? args) { throw null; }
+        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("The type of object being written to DiagnosticSource cannot be discovered statically.")]
         public void StopActivity(System.Diagnostics.Activity activity, object? args) { }
+        [System.Diagnostics.CodeAnalysis.RequiresUnreferencedCode("The type of object being written to DiagnosticSource cannot be discovered statically.")]
+        public void StopActivity<[System.Diagnostics.CodeAnalysis.DynamicallyAccessedMembers(System.Diagnostics.CodeAnalysis.DynamicallyAccessedMemberTypes.PublicProperties)] T>(Activity activity, T? args) { throw null; }
     }
     public enum ActivitySamplingResult
     {

src/libraries/System.Diagnostics.DiagnosticSource/src/System.Diagnostics.DiagnosticSource.csproj

@@ -99,6 +99,7 @@ System.Diagnostics.DiagnosticSource</PackageDescription>
 
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicDependencyAttribute.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicallyAccessedMemberTypes.cs" />
+    <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\DynamicallyAccessedMembersAttribute.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\RequiresUnreferencedCodeAttribute.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Diagnostics\CodeAnalysis\UnconditionalSuppressMessageAttribute.cs" />
     <Compile Include="$(CoreLibSharedDir)System\Runtime\CompilerServices\IsExternalInit.cs" />

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/DiagnosticSource.cs

@@ -37,6 +37,12 @@ public abstract partial class DiagnosticSource
         [RequiresUnreferencedCode(WriteRequiresUnreferencedCode)]
         public abstract void Write(string name, object? value);
 
+        /// <inheritdoc cref="Write"/>
+        /// <typeparam name="T">The type of the value being passed as a payload for the event.</typeparam>
+        [RequiresUnreferencedCode(WriteRequiresUnreferencedCode)]
+        public void Write<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] T>(string name, T? value) =>
+            Write(name, (object?)value);
+
         /// <summary>
         /// Optional: if there is expensive setup for the notification, you can call IsEnabled
         /// before doing this setup.   Consumers should not be assuming that they only get notifications

src/libraries/System.Diagnostics.DiagnosticSource/src/System/Diagnostics/DiagnosticSourceActivity.cs

@@ -33,6 +33,12 @@ public Activity StartActivity(Activity activity, object? args)
             return activity;
         }
 
+        /// <inheritdoc cref="StartActivity"/>
+        /// <typeparam name="T">The type of the value being passed as a payload for the event.</typeparam>
+        [RequiresUnreferencedCode(WriteRequiresUnreferencedCode)]
+        public Activity StartActivity<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] T>(Activity activity, T? args)
+            => StartActivity(activity, (object?)args);
+
         /// <summary>
         /// Stops given Activity: maintains global Current Activity and notifies consumers
         /// that Activity was stopped. Consumers could access <see cref="Activity.Current"/>
@@ -54,6 +60,12 @@ public void StopActivity(Activity activity, object? args)
             activity.Stop();    // Resets Activity.Current (we want this after the Write)
         }
 
+        /// <inheritdoc cref="StartActivity"/>
+        /// <typeparam name="T">The type of the value being passed as a payload for the event.</typeparam>
+        [RequiresUnreferencedCode(WriteRequiresUnreferencedCode)]
+        public void StopActivity<[DynamicallyAccessedMembers(DynamicallyAccessedMemberTypes.PublicProperties)] T>(Activity activity, T? args)
+            => StopActivity(activity, (object?)args);
+
         /// <summary>
         /// Optional: If an instrumentation site creating an new activity that was caused
         /// by something outside the process (e.g. an incoming HTTP request), then that site

src/libraries/System.Diagnostics.DiagnosticSource/tests/DiagnosticSourceTests.cs

@@ -41,6 +41,34 @@ public void IntPayload()
             }
         }
 
+        /// <summary>
+        /// Trivial example of passing an object
+        /// </summary>
+        [Fact]
+        public void ObjectPayload()
+        {
+            using (DiagnosticListener listener = new DiagnosticListener("TestingObjectPayload"))
+            {
+                DiagnosticSource source = listener;
+                var result = new List<KeyValuePair<string, object>>();
+                var observer = new ObserverToList<TelemData>(result);
+
+                using (listener.Subscribe(new ObserverToList<TelemData>(result)))
+                {
+                    object o = new object();
+
+                    listener.Write("ObjectPayload", o);
+                    Assert.Equal(1, result.Count);
+                    Assert.Equal("ObjectPayload", result[0].Key);
+                    Assert.Same(o, result[0].Value);
+                }   // unsubscribe
+
+                // Make sure that after unsubscribing, we don't get more events.
+                source.Write("ObjectPayload", new object());
+                Assert.Equal(1, result.Count);
+            }
+        }
+
         /// <summary>
         /// slightly less trivial of passing a structure with a couple of fields
         /// </summary>

src/libraries/System.Diagnostics.DiagnosticSource/tests/NativeAotTests/DiagnosticSourceEventSourceTests.cs

@@ -9,7 +9,7 @@
 using System.Diagnostics.Tracing;
 
 /// <summary>
-/// Tests that using writing to a DiagnosticSource writes the correct payloads
+/// Tests that writing to a DiagnosticSource writes the correct payloads
 /// to the DiagnosticSourceEventSource.
 /// </summary>
 internal class Program

src/libraries/System.Diagnostics.DiagnosticSource/tests/TrimmingTests/System.Diagnostics.DiagnosticSource.proj

@@ -0,0 +1,9 @@
+<Project DefaultTargets="Build">
+  <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.props))" />
+
+  <ItemGroup>
+    <TestConsoleAppSourceFiles Include="WritePreservesAnonymousProperties.cs" />
+  </ItemGroup>
+
+  <Import Project="$([MSBuild]::GetPathOfFileAbove(Directory.Build.targets))" />
+</Project>

src/libraries/System.Diagnostics.DiagnosticSource/tests/TrimmingTests/WritePreservesAnonymousProperties.cs

@@ -0,0 +1,83 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Collections.ObjectModel;
+using System.Diagnostics;
+using System.Diagnostics.Tracing;
+
+/// <summary>
+/// Tests that writing an anonymous type to a DiagnosticSource preserves the anonymous type's properties
+/// correctly, so they are written to the EventSource correctly.
+/// </summary>
+internal class Program
+{
+    private class TestEventListener : EventListener
+    {
+        public ReadOnlyCollection<object> LogDataPayload { get; set; }
+
+        protected override void OnEventSourceCreated(EventSource eventSource)
+        {
+            if (eventSource.Name == "Microsoft-Diagnostics-DiagnosticSource")
+            {
+                EnableEvents(eventSource, EventLevel.Verbose, EventKeywords.All, new Dictionary<string, string>
+                {
+                    { "FilterAndPayloadSpecs", "TestDiagnosticListener/Test.Start@Activity2Start:-Id;Name"}
+                });
+            }
+
+            base.OnEventSourceCreated(eventSource);
+        }
+
+        protected override void OnEventWritten(EventWrittenEventArgs eventData)
+        {
+            if (eventData.EventName == "Activity2Start")
+            {
+                LogDataPayload = eventData.Payload;
+            }
+
+            base.OnEventWritten(eventData);
+        }
+    }
+
+    public static int Main()
+    {
+        DiagnosticSource diagnosticSource = new DiagnosticListener("TestDiagnosticListener");
+        using (var listener = new TestEventListener())
+        {
+            var data = new 
+            {
+                Id = Guid.NewGuid(),
+                Name = "EventName"
+            };
+
+            diagnosticSource.Write("Test.Start", data);
+
+            if (!(listener.LogDataPayload?.Count == 3 &&
+                (string)listener.LogDataPayload[0] == "TestDiagnosticListener" &&
+                (string)listener.LogDataPayload[1] == "Test.Start"))
+            {
+                return -1;
+            }
+
+            object[] args = (object[])listener.LogDataPayload[2];
+            if (args.Length != 2)
+            {
+                return -2;
+            }
+
+            IDictionary<string, object> arg = (IDictionary<string, object>)args[0];
+            if (!((string)arg["Key"] == "Id" && (string)arg["Value"] == data.Id.ToString()))
+            {
+                return -3;
+            }
+
+            arg = (IDictionary<string, object>)args[1];
+            if (!((string)arg["Key"] == "Name" && (string)arg["Value"] == "EventName"))
+            {
+                return -4;
+            }
+
+            return 100;
+        }
+    }
+}

src/libraries/System.Net.Http/src/System/Net/Http/DiagnosticsHandler.cs

@@ -217,7 +217,6 @@ private sealed class ActivityStartData
             // matches the properties selected in https://github.com/dotnet/diagnostics/blob/ffd0254da3bcc47847b1183fa5453c0877020abd/src/Microsoft.Diagnostics.Monitoring.EventPipe/Configuration/HttpRequestSourceConfiguration.cs#L36-L40
             [DynamicDependency(nameof(HttpRequestMessage.RequestUri), typeof(HttpRequestMessage))]
             [DynamicDependency(nameof(HttpRequestMessage.Method), typeof(HttpRequestMessage))]
-            [DynamicDependency(nameof(HttpRequestMessage.RequestUri), typeof(HttpRequestMessage))]
             [DynamicDependency(nameof(Uri.Host), typeof(Uri))]
             [DynamicDependency(nameof(Uri.Port), typeof(Uri))]
             internal ActivityStartData(HttpRequestMessage request)
@@ -251,7 +250,6 @@ private sealed class ExceptionData
             // preserve the same properties as ActivityStartData above + common Exception properties
             [DynamicDependency(nameof(HttpRequestMessage.RequestUri), typeof(HttpRequestMessage))]
             [DynamicDependency(nameof(HttpRequestMessage.Method), typeof(HttpRequestMessage))]
-            [DynamicDependency(nameof(HttpRequestMessage.RequestUri), typeof(HttpRequestMessage))]
             [DynamicDependency(nameof(Uri.Host), typeof(Uri))]
             [DynamicDependency(nameof(Uri.Port), typeof(Uri))]
             [DynamicDependency(nameof(System.Exception.Message), typeof(Exception))]
@@ -273,7 +271,6 @@ private sealed class RequestData
             // preserve the same properties as ActivityStartData above
             [DynamicDependency(nameof(HttpRequestMessage.RequestUri), typeof(HttpRequestMessage))]
             [DynamicDependency(nameof(HttpRequestMessage.Method), typeof(HttpRequestMessage))]
-            [DynamicDependency(nameof(HttpRequestMessage.RequestUri), typeof(HttpRequestMessage))]
             [DynamicDependency(nameof(Uri.Host), typeof(Uri))]
             [DynamicDependency(nameof(Uri.Port), typeof(Uri))]
             internal RequestData(HttpRequestMessage request, Guid loggingRequestId, long timestamp)