GH-1881 - Fix interface method attributes when generating proxies

Author: PleasantD

src/NHibernate.Test/NHSpecificTest/GH1881/TestFixture.cs

@@ -0,0 +1,33 @@
+using System;
+using System.Linq;
+using System.Reflection;
+using NHibernate.Collection;
+using NHibernate.Collection.Generic;
+using NHibernate.Proxy.DynamicProxy;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.GH1881
+{
+	[TestFixture]
+	[Obsolete]
+	public class TestFixture
+	{
+		[Test]
+		public void InterfacesShouldBeImplementedExplicitlyOnProxies()
+		{
+			var proxy = new ProxyFactory().CreateProxy(typeof(PersistentGenericBag<object>), null, typeof(ILazyInitializedCollection));
+			Assert.That(proxy, Is.Not.Null);
+
+			foreach (var method in proxy.GetType().GetMethods().Where(m => m.DeclaringType == typeof(ILazyInitializedCollection)))
+			{
+				// These attributes are what .NET uses for explicitly implemented interface methods
+				Assert.That(method.Attributes, Is.EqualTo(MethodAttributes.Private |
+				                                          MethodAttributes.Final |
+				                                          MethodAttributes.Virtual |
+				                                          MethodAttributes.HideBySig |
+				                                          MethodAttributes.NewSlot |
+				                                          MethodAttributes.SpecialName));
+			}
+		}
+	}
+}

src/NHibernate/Proxy/DynamicProxy/ProxyFactory.cs

@@ -68,6 +68,13 @@ public System.Type CreateProxyType(System.Type baseType, params System.Type[] in
 		{
 			if (baseType == null) throw new ArgumentNullException(nameof(baseType));
 
+			// Also proxy the methods of [object] if creating a proxy for an interface
+			if (baseType.IsInterface)
+			{
+				interfaces = new [] { baseType }.Concat(interfaces ?? new System.Type[0]).ToArray();
+				baseType = typeof(object);
+			}
+
 			var typeFactory = _cache.GetOrAdd(
 				new ProxyCacheEntry(baseType, interfaces),
 				k => CreateUncachedProxyType(k.BaseType, k.Interfaces));

src/NHibernate/Proxy/NHibernateProxyBuilder.cs

@@ -394,7 +394,7 @@ private static void EmitCallBaseIfLazyInitializerIsNull(
 			IL.Emit(OpCodes.Bne_Un, skipBaseCall);
 
 			IL.Emit(OpCodes.Ldarg_0);
-			EmitCallMethod(IL, OpCodes.Call, method);
+			EmitCallMethod(IL, method.DeclaringType.IsInterface ? OpCodes.Callvirt : OpCodes.Call, method);
 			IL.Emit(OpCodes.Ret);
 
 			IL.MarkLabel(skipBaseCall);

src/NHibernate/Proxy/ProxyBuilderHelper.cs

@@ -137,7 +137,24 @@ internal static MethodBuilder GetObjectDataMethodBuilder(TypeBuilder typeBuilder
 		internal static MethodBuilder GenerateMethodSignature(string name, MethodInfo method, TypeBuilder typeBuilder)
 		{
 			//TODO: Should we use attributes of base method?
-			var methodAttributes = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual;
+			MethodAttributes methodAttributes;
+			if (method.DeclaringType.IsInterface)
+			{
+				// These are the attributes used for an explicit interface method implementation in .NET.
+				methodAttributes =
+					MethodAttributes.Private |
+					MethodAttributes.Final |
+					MethodAttributes.Virtual |
+					MethodAttributes.HideBySig |
+					MethodAttributes.NewSlot |
+					MethodAttributes.SpecialName;
+				// .NET uses an expanded name for explicit interface implementation methods.
+				name = typeBuilder.FullName + "." + method.DeclaringType.FullName + "." + name;
+			}
+			else
+			{
+				methodAttributes = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual;
+			}
 
 			if (method.IsSpecialName)
 				methodAttributes |= MethodAttributes.SpecialName;