Add PreserveDependency to workaround linker limitation

Both cases have type references to a different assembly and linker currently can't add a new assembly to the closure when analyzing Type.GetType - so PreserveDepenency attribute is necessary in this case.

diff --git a/src/coreclr/src/System.Private.CoreLib/src/System/Threading/SynchronizationContext.Uap.cs b/src/coreclr/src/System.Private.CoreLib/src/System/Threading/SynchronizationContext.Uap.cs
index 7cdf7fc..b644b28 100644 (file)
--- a/src/coreclr/src/System.Private.CoreLib/src/System/Threading/SynchronizationContext.Uap.cs
+++ b/src/coreclr/src/System.Private.CoreLib/src/System/Threading/SynchronizationContext.Uap.cs
@@ -48,6 +48,10 @@ namespace System.Threading
 
         private static Func<object, SynchronizationContext>? s_createSynchronizationContextDelegate;
 
+        // This is necessary because linker can't add new assemblies to the closure when recognizing Type.GetType
+        // so even though the GetType call below is analyzable, the PreserveDependency is still necessary to actually include
+        // the assembly in the trimmed closure.
+        [PreserveDependency(".ctor()", "System.Threading.WinRTSynchronizationContextFactory", "System.Runtime.WindowsRuntime")]
         private static SynchronizationContext GetWinRTSynchronizationContext(object dispatcher)
         {
             //

diff --git a/src/libraries/System.Private.CoreLib/src/System/Resources/ResourceManager.Uap.cs b/src/libraries/System.Private.CoreLib/src/System/Resources/ResourceManager.Uap.cs
index 27ed243..2fa9e0d 100644 (file)
--- a/src/libraries/System.Private.CoreLib/src/System/Resources/ResourceManager.Uap.cs
+++ b/src/libraries/System.Private.CoreLib/src/System/Resources/ResourceManager.Uap.cs
@@ -6,6 +6,7 @@ using System.IO;
 using System.Globalization;
 using System.Reflection;
 using System.Diagnostics;
+using System.Runtime.CompilerServices;
 using Internal.Resources;
 
 namespace System.Resources
@@ -57,6 +58,10 @@ namespace System.Resources
         // Since we can't directly reference System.Runtime.WindowsRuntime from System.Private.CoreLib, we have to get the type via reflection.
         // It would be better if we could just implement WindowsRuntimeResourceManager in System.Private.CoreLib, but we can't, because
         // we can do very little with WinRT in System.Private.CoreLib.
+        // The attribute is necessary because linker can't add new assemblies to the closure when recognizing Type.GetType
+        // so even though the GetType call below is analyzable, the PreserveDependency is still necessary to actually include
+        // the assembly in the trimmed closure.
+        [PreserveDependency(".ctor()", "System.Resources.WindowsRuntimeResourceManager", "System.Runtime.WindowsRuntime")]
         internal static WindowsRuntimeResourceManagerBase GetWinRTResourceManager()
         {
             Type WinRTResourceManagerType = Type.GetType("System.Resources.WindowsRuntimeResourceManager, System.Runtime.WindowsRuntime", throwOnError: true)!;