Add support for out/ref Nullable parameters of proxied methods (#1389)

Author: Pirmin Mattmann

src/NHibernate.Test/DynamicProxyTests/ProxiedMembers/Fixture.cs

@@ -14,6 +14,16 @@ public virtual void Method2(ref int x)
 		{
 			x++;
 		}
+		
+		public virtual void Method3(out int? y)
+		{
+			y = 4;
+		}
+
+		public virtual void Method4(ref int? y)
+		{
+			y++;
+		}
 	}
 
 	[TestFixture]
@@ -32,6 +42,13 @@ public void Proxy()
 			x = 4;
 			c.Method2(ref x);
 			Assert.AreEqual(5, x);
+			
+			int? y;
+			c.Method3(out y);
+			Assert.AreEqual(4, y);
+			
+			c.Method4(ref y);
+			Assert.AreEqual(5, y);
 		}
 	}
 }

src/NHibernate/Proxy/DynamicProxy/DefaultArgumentHandler.cs

@@ -6,6 +6,7 @@
 
 #endregion
 
+using System;
 using System.Reflection;
 using System.Reflection.Emit;
 
@@ -55,12 +56,19 @@ public void PushArguments(ParameterInfo[] methodParameters, ILGenerator IL, bool
 
 				if (param.ParameterType.IsByRef)
 				{
-					OpCode ldindInstruction;
-					if(!OpCodesMap.TryGetLdindOpCode(param.ParameterType.GetElementType(), out ldindInstruction))
+					var unboxedType = param.ParameterType.GetElementType();
+					if (Nullable.GetUnderlyingType(unboxedType) != null)
 					{
-						ldindInstruction = OpCodes.Ldind_Ref;
+						IL.Emit(OpCodes.Ldobj, unboxedType);
+					}
+					else if (OpCodesMap.TryGetLdindOpCode(unboxedType, out var ldind))
+					{
+						IL.Emit(ldind);
+					}
+					else
+					{
+						IL.Emit(OpCodes.Ldind_Ref);
 					}
-					IL.Emit(ldindInstruction);
 				}
 
 				if (parameterType.IsValueType || param.ParameterType.IsByRef || parameterType.IsGenericParameter)
@@ -78,4 +86,4 @@ public void PushArguments(ParameterInfo[] methodParameters, ILGenerator IL, bool
 
 		#endregion
 	}
-}
+}

src/NHibernate/Proxy/DynamicProxy/DefaultMethodEmitter.cs

@@ -142,23 +142,19 @@ private static void SaveRefArguments(ILGenerator IL, ParameterInfo[] parameters)
 
 				IL.Emit(OpCodes.Unbox_Any, unboxedType);
 
-				OpCode stind = GetStindInstruction(param.ParameterType);
-				IL.Emit(stind);
-			}
-		}
-
-		private static OpCode GetStindInstruction(System.Type parameterType)
-		{
-			if (parameterType.IsByRef)
-			{
-				OpCode stindOpCode;
-				if(OpCodesMap.TryGetStindOpCode(parameterType.GetElementType(), out stindOpCode))
+				if (Nullable.GetUnderlyingType(unboxedType) != null)
 				{
-					return stindOpCode;
+					IL.Emit(OpCodes.Stobj, unboxedType);
+				}
+				else if (OpCodesMap.TryGetStindOpCode(param.ParameterType.GetElementType(), out var stind))
+				{
+					IL.Emit(stind);
+				}
+				else
+				{
+					IL.Emit(OpCodes.Stind_Ref);
 				}
 			}
-
-			return OpCodes.Stind_Ref;
 		}
 
 		private static void PushTargetMethodInfo(ILGenerator IL, MethodBuilder generatedMethod, MethodInfo method)
@@ -247,4 +243,4 @@ private void PackageReturnType(MethodInfo method, ILGenerator IL)
 			IL.Emit(OpCodes.Unbox_Any, returnType);
 		}
 	}
-}
+}