[runtime] Implement mono_class_get_nullable_param for CoreCLR. (#11531)

runtime/coreclr-bridge.m

@@ -533,6 +533,14 @@ mono_class_get_element_class (MonoClass *klass)
 	return rv;
 }
 
+MonoClass *
+mono_class_get_nullable_param (MonoClass * klass)
+{
+	MonoClass *rv = xamarin_bridge_get_nullable_element_type (klass);
+	LOG_CORECLR (stderr, "%s (%p) => %p\n", __func__, klass, rv);
+	return rv;
+}
+
 bool
 xamarin_is_class_nsobject (MonoClass *cls)
 {

runtime/delegates.t4

@@ -519,6 +519,14 @@
 			OnlyCoreCLR = true,
 		},
 
+		new XDelegate ("MonoObject *", "MonoObject *", "xamarin_bridge_get_nullable_element_type",
+			"MonoObject *", "MonoObject *", "typeobj"
+		) {
+			WrappedManagedFunction = "GetNullableElementType",
+			OnlyDynamicUsage = false,
+			OnlyCoreCLR = true,
+		},
+
 		new XDelegate ("bool", "bool", "xamarin_bridge_is_delegate",
 			"MonoObject *", "MonoObject *", "typeobj"
 		) {

runtime/exports.t4

@@ -96,7 +96,9 @@
 
 		new Export (true, "MonoClass *", "mono_class_get_nullable_param",
 			"MonoClass *", "klass"
-		),
+		) {
+			HasCoreCLRBridgeFunction = true,
+		},
 		#endregion
 
 		#region metadata/debug-helpers.h

runtime/trampolines.m

@@ -931,6 +931,7 @@ exception_handling:
 	xamarin_mono_object_release (&nativeType);
 	xamarin_mono_object_release (&nativeElementType);
 	xamarin_mono_object_release (&managedElementType);
+	xamarin_mono_object_release (&nullableManagedType);
 
 	return convertedValue;
 }
@@ -1019,6 +1020,7 @@ exception_handling:
 	xamarin_mono_object_release (&nativeType);
 	xamarin_mono_object_release (&nativeElementType);
 	xamarin_mono_object_release (&managedElementType);
+	xamarin_mono_object_release (&nullableManagedType);
 
 	return convertedValue;
 }

src/ObjCRuntime/Runtime.CoreCLR.cs

@@ -151,6 +151,13 @@ namespace ObjCRuntime {
 			return (MonoObject*) GetMonoObject (type.GetElementType ());
 		}
 
+		static unsafe MonoObject* GetNullableElementType (MonoObject* typeobj)
+		{
+			var type = (Type) GetMonoObjectTarget (typeobj);
+			var elementType = type.GetGenericArguments () [0];
+			return (MonoObject*) GetMonoObject (elementType);
+		}
+
 		static IntPtr CreateGCHandle (IntPtr gchandle, GCHandleType type)
 		{
 			// It's valid to create a GCHandle to a null value.

tools/common/StaticRegistrar.cs

@@ -4474,6 +4474,7 @@ namespace Registrar {
 				underlyingManagedType = GetNullableType (managedType);
 				sb.AppendLine ($"{classVariableName} = xamarin_get_nullable_type ({managedClassExpression}, &exception_gchandle);");
 				sb.AppendLine ($"if (exception_gchandle != INVALID_GCHANDLE) goto exception_handling;");
+				cleanup.AppendLine ($"xamarin_mono_object_release (&{classVariableName});");
 			} else {
 				sb.AppendLine ($"{classVariableName} = {managedClassExpression};");
 			}
@@ -4565,6 +4566,7 @@ namespace Registrar {
 				underlyingManagedType = GetNullableType (managedType);
 				sb.AppendLine ($"{classVariableName} = xamarin_get_nullable_type ({managedClassExpression}, &exception_gchandle);");
 				sb.AppendLine ($"if (exception_gchandle != INVALID_GCHANDLE) goto exception_handling;");
+				cleanup.AppendLine ($"xamarin_mono_object_release (&{classVariableName});");
 			} else {
 				sb.AppendLine ($"{classVariableName} = {managedClassExpression};");
 			}