Support proxies of classes with init properties

.config/dotnet-tools.json

@@ -3,7 +3,7 @@
   "isRoot": true,
   "tools": {
     "csharpasyncgenerator.tool": {
-      "version": "0.20.1",
+      "version": "0.21.1",
       "commands": [
         "async-generator"
       ]
@@ -15,4 +15,4 @@
       ]
     }
   }
-}
+}

src/NHibernate.Test/StaticProxyTest/IsExternalInit.cs

@@ -0,0 +1,16 @@
+#if !NET5_0_OR_GREATER
+using System.ComponentModel;
+
+// ReSharper disable once CheckNamespace
+namespace System.Runtime.CompilerServices
+{
+	/// <summary>
+	/// Reserved to be used by the compiler for tracking metadata.
+	/// This class should not be used by developers in source code.
+	/// </summary>
+	[EditorBrowsable(EditorBrowsableState.Never)]
+	internal static class IsExternalInit
+	{
+	}
+}
+#endif

src/NHibernate.Test/StaticProxyTest/StaticProxyFactoryFixture.cs

@@ -225,6 +225,13 @@ public interface IWithGenericMethod
 			T CopyTo<T>() where T : class, IWithGenericMethod;
 		}
 
+		[Serializable]
+		public class ClassWithInitProperties
+		{
+			public virtual int Id { get; init; }
+			public virtual string Name { get; init; }
+		}
+
 		[Test]
 		public void VerifyProxyForClassWithInternalInterface()
 		{
@@ -592,6 +599,32 @@ public void VerifyProxyForClassWithGenericNonVirtualMethod()
 
 					Assert.That(factory.GetFieldInterceptionProxy(), Is.InstanceOf<ClassWithGenericNonVirtualMethod>());
 
+#if NETFX
+				});
+#endif
+		}
+
+		[Test]
+		public void VerifyProxyForClassWithInitProperties()
+		{
+			var factory = new StaticProxyFactory();
+			factory.PostInstantiate(
+				typeof(ClassWithInitProperties).FullName,
+				typeof(ClassWithInitProperties),
+				new HashSet<System.Type> { typeof(INHibernateProxy) },
+				null, null, null, true);
+
+#if NETFX
+			VerifyGeneratedAssembly(
+				() =>
+				{
+#endif
+					var proxy = factory.GetProxy(1, null);
+					Assert.That(proxy, Is.Not.Null);
+					Assert.That(proxy, Is.InstanceOf<ClassWithInitProperties>());
+
+					Assert.That(factory.GetFieldInterceptionProxy(), Is.InstanceOf<ClassWithInitProperties>());
+
 #if NETFX
 				});
 #endif

src/NHibernate/Proxy/ProxyBuilderHelper.cs

@@ -171,13 +171,18 @@ internal static MethodBuilder GenerateMethodSignature(string name, MethodInfo me
 			var implementationName = explicitImplementation
 				? $"{method.DeclaringType.FullName}.{name}"
 				: name;
+
 			var methodBuilder =
 				typeBuilder.DefineMethod(
 					implementationName,
 					methodAttributes,
 					CallingConventions.HasThis,
 					method.ReturnType,
-					parameters.ToArray(param => param.ParameterType));
+					method.ReturnParameter?.GetRequiredCustomModifiers(),
+					method.ReturnParameter?.GetOptionalCustomModifiers(),
+					parameters.ToArray(p => p.ParameterType),
+					parameters.ToArray(p => p.GetRequiredCustomModifiers()),
+					parameters.ToArray(p => p.GetOptionalCustomModifiers()));
 
 			var typeArgs = method.GetGenericArguments();
 			if (typeArgs.Length > 0)