From c65b813f458cec66f20663ec1b72c6911fcde7c2 Mon Sep 17 00:00:00 2001
From: Rolf Bjarne Kvinge <rolf@xamarin.com>
Date: Mon, 6 May 2024 16:05:25 +0200
Subject: [PATCH] [dotnet] Throw an exception if the developer tries to use
 server garbage collection. Fixes #16853.

Our runtime doesn't support server garbage collection:

https://github.com/xamarin/xamarin-macios/blob/main/runtime/coreclr-bridge.m#L203-L210

Fixes https://github.com/xamarin/xamarin-macios/issues/16853.
---
 dotnet/targets/Xamarin.Shared.Sdk.targets |  6 ++++++
 src/ObjCRuntime/Runtime.cs                | 22 ++++++++++++++++++++++
 tools/mtouch/Errors.designer.cs           |  9 +++++++++
 tools/mtouch/Errors.resx                  |  5 +++++
 4 files changed, 42 insertions(+)

diff --git a/dotnet/targets/Xamarin.Shared.Sdk.targets b/dotnet/targets/Xamarin.Shared.Sdk.targets
index 2cae73aa144a..513f7b2357c7 100644
--- a/dotnet/targets/Xamarin.Shared.Sdk.targets
+++ b/dotnet/targets/Xamarin.Shared.Sdk.targets
@@ -2124,6 +2124,12 @@
 		<Error Condition="'$(_IsValidRuntimeIdentifier)' != 'true'" Text="The RuntimeIdentifier '$(RuntimeIdentifier)' is invalid." />
 	</Target>
 
+	<Target Name="_ValidateGarbageCollector"
+		Condition="'$(ServerGarbageCollection)' == 'true'"
+		BeforeTargets="Build;ResolvedFrameworkReference;ResolveRuntimePackAssets">
+		<Error Text=".NET for $(_PlatformName) does not support server garbage collection. Please don't set the 'ServerGarbageCollection' property." />
+	</Target>
+
 	<!-- This target can be removed in .NET 9 (when we stop supporting the compat logic to make the invalid TPV just a warning instead of an error) -->
 	<Target Name="_XamarinValidateTargetPlatformVersion"
 		BeforeTargets="Build;ResolvedFrameworkReference;ResolveRuntimePackAssets"
diff --git a/src/ObjCRuntime/Runtime.cs b/src/ObjCRuntime/Runtime.cs
index d942aa4925b5..a95371782f68 100644
--- a/src/ObjCRuntime/Runtime.cs
+++ b/src/ObjCRuntime/Runtime.cs
@@ -83,6 +83,20 @@ internal unsafe struct MTRegistrationMap {
 		}
 #pragma warning restore 649
 
+#if __TVOS__
+		internal const string PlatformName = "tvOS";
+#elif __WATCHOS__
+		internal const string PlatformName = "watchOS";
+#elif __MACCATALYST__
+		internal const string PlatformName = "Mac Catalyst";
+#elif __IOS__
+		internal const string PlatformName = "iOS";
+#elif __MACOS__
+		internal const string PlatformName = "macOS";
+#else
+#error Undetermined platform name
+#endif
+
 		[Flags]
 		internal enum MTTypeFlags : uint {
 			None = 0,
@@ -359,6 +373,14 @@ unsafe static void Initialize (InitializationOptions* options)
 				throw ErrorHelper.CreateError (8010, msg);
 			}
 
+#if NET
+			if (System.Runtime.GCSettings.IsServerGC) {
+				var msg = $".NET for {PlatformName} does not support server garbage collection.";
+				NSLog (msg);
+				throw ErrorHelper.CreateError (8057, msg);
+			}
+#endif
+
 #if NET
 			if (options->RegistrationMap is not null && options->RegistrationMap->classHandles is not null) {
 				ClassHandles.InitializeClassHandles (options->RegistrationMap->classHandles);
diff --git a/tools/mtouch/Errors.designer.cs b/tools/mtouch/Errors.designer.cs
index bf2075c8616a..15b3ed749e75 100644
--- a/tools/mtouch/Errors.designer.cs
+++ b/tools/mtouch/Errors.designer.cs
@@ -4257,5 +4257,14 @@ public static string MX8056 {
                 return ResourceManager.GetString("MX8056", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to .NET for {0} does not support server garbage collection..
+        /// </summary>
+        public static string MX8057 {
+            get {
+                return ResourceManager.GetString("MX8057", resourceCulture);
+            }
+        }
     }
 }
diff --git a/tools/mtouch/Errors.resx b/tools/mtouch/Errors.resx
index 77718d85f59d..c059da1cbffa 100644
--- a/tools/mtouch/Errors.resx
+++ b/tools/mtouch/Errors.resx
@@ -2266,4 +2266,9 @@
 	<data name="MX8056" xml:space="preserve">
 		<value>Failed to marshal the Objective-C object 0x{0} (type: {1}). Could not find an existing managed instance for this object, nor was it possible to create a new managed instance of generic type {2}.</value>
 	</data>
+
+	<data name="MX8057" xml:space="preserve">
+		<value>.NET for {0} does not support server garbage collection.</value>
+		<comment>{0}: the platform (iOS, macOS, etc.)</comment>
+	</data>
 </root>