Add PlatformNeutralAssembly property for targeted builds of cross platform assembly (#53626)

eng/Versions.props

@@ -45,7 +45,7 @@
     <MicrosoftCodeAnalysisVersion>3.8.0</MicrosoftCodeAnalysisVersion>
   </PropertyGroup>
   <PropertyGroup>
-    <MicrosoftCodeAnalysisNetAnalyzersVersion>6.0.0-preview6.21274.2</MicrosoftCodeAnalysisNetAnalyzersVersion>
+    <MicrosoftCodeAnalysisNetAnalyzersVersion>6.0.0-preview6.21281.1</MicrosoftCodeAnalysisNetAnalyzersVersion>
     <MicrosoftCodeAnalysisCSharpCodeStyleVersion>3.10.0-2.final</MicrosoftCodeAnalysisCSharpCodeStyleVersion>
     <MicrosoftCodeAnalysisCSharpVersion>3.10.0-2.final</MicrosoftCodeAnalysisCSharpVersion>
     <!-- Arcade dependencies -->

eng/versioning.targets

@@ -84,6 +84,11 @@
     </ItemGroup>
   </Target>
 
+  <!-- Add PlatformNeutralAssembly property for targeted builds of cross platform assemblies -->
+  <ItemGroup Condition="'$(TargetsAnyOS)' != 'true' and '$(IsTestProject)' != 'true' and '@(SupportedOSPlatforms)' == ''">
+    <CompilerVisibleProperty Include="PlatformNeutralAssembly" />
+  </ItemGroup>
+
   <PropertyGroup>
     <!-- corefx has never generated these attributes so don't let the SDK generate them -->
     <GenerateAssemblyConfigurationAttribute>false</GenerateAssemblyConfigurationAttribute>

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/ConnectHelper.cs

@@ -101,7 +101,6 @@ private static async ValueTask<SslStream> EstablishSslConnectionAsyncCore(bool a
             return sslStream;
         }
 
-        // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
         [SupportedOSPlatform("windows")]
         [SupportedOSPlatform("linux")]
         [SupportedOSPlatform("macos")]

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http3Connection.cs

@@ -14,7 +14,6 @@
 
 namespace System.Net.Http
 {
-    // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
     [SupportedOSPlatform("windows")]
     [SupportedOSPlatform("linux")]
     [SupportedOSPlatform("macos")]

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http3ConnectionException.cs

@@ -7,7 +7,6 @@
 namespace System.Net.Http
 {
     [Serializable]
-    // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
     [SupportedOSPlatform("windows")]
     [SupportedOSPlatform("linux")]
     [SupportedOSPlatform("macos")]

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http3ProtocolException.cs

@@ -7,7 +7,6 @@
 namespace System.Net.Http
 {
     [Serializable]
-    // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
     [SupportedOSPlatform("windows")]
     [SupportedOSPlatform("linux")]
     [SupportedOSPlatform("macos")]

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/Http3RequestStream.cs

@@ -16,7 +16,6 @@
 
 namespace System.Net.Http
 {
-    // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
     [SupportedOSPlatform("windows")]
     [SupportedOSPlatform("linux")]
     [SupportedOSPlatform("macos")]

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionPool.cs

@@ -664,7 +664,6 @@ private void AddHttp2Connection(Http2Connection newConnection)
             }
         }
 
-        // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
         [SupportedOSPlatform("windows")]
         [SupportedOSPlatform("linux")]
         [SupportedOSPlatform("macos")]
@@ -764,7 +763,6 @@ private async ValueTask<Http3Connection> GetHttp3ConnectionAsync(HttpRequestMess
         }
 
         // Returns null if HTTP3 cannot be used.
-        // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
         [SupportedOSPlatform("windows")]
         [SupportedOSPlatform("linux")]
         [SupportedOSPlatform("macos")]

src/libraries/System.Net.Http/src/System/Net/Http/SocketsHttpHandler/HttpConnectionSettings.cs

@@ -187,7 +187,6 @@ private static bool AllowDraftHttp3
 
         private byte[]? _http3SettingsFrame;
 
-        // TODO: SupportedOSPlatform doesn't work for internal APIs https://github.com/dotnet/runtime/issues/51305
         [SupportedOSPlatform("windows")]
         [SupportedOSPlatform("linux")]
         [SupportedOSPlatform("macos")]