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

Fix dotnet#50454

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