Generated the proper return statements in the abstract implementations.

Signed-off-by: Dimitar Dobrev <dpldobrev@yahoo.com>

src/Generator/Generators/CSharp/CSharpTextTemplate.cs

@@ -1557,7 +1557,7 @@ namespace CppSharp.Generators.CSharp
             PopBlock(NewLineKind.BeforeNextBlock);
         }
 
-        private void GenerateVirtualTableMethodCall(ITypedDecl method, Class @class)
+        private void GenerateVirtualTableMethodCall(Method method, Class @class)
         {
             WriteLine("void* vtable = *((void**) __Instance.ToPointer());");
             int i;
@@ -1570,6 +1570,14 @@ namespace CppSharp.Generators.CSharp
                     break;
             }
             WriteLine("void* slot = *((void**) vtable + {0} * sizeof(IntPtr));", i);
+            string @delegate = method.Name + "Delegate";
+            string delegateId = GeneratedIdentifier(@delegate);
+            WriteLine("{0} {1} = ({0}) Marshal.GetDelegateForFunctionPointer(new IntPtr(slot), typeof({0}));",
+                @delegate, delegateId);
+            if (!method.OriginalReturnType.Type.IsPrimitiveType(PrimitiveType.Void))
+                Write("return ");
+            WriteLine("{0}({1});", delegateId, string.Join(", ", method.Parameters.Where(
+                p => p.Kind != ParameterKind.IndirectReturnType).Select(p => Helpers.SafeIdentifier(p.Name))));
         }
 
         private void GenerateOperator(Method method, Class @class)

src/Generator/Passes/AbstractImplementationsPass.cs

@@ -52,8 +52,21 @@ namespace CppSharp.Passes
                     abstractMethods.RemoveAt(i);
                 }
             }
-            internalImplementation.Methods.AddRange(from abstractMethod in abstractMethods
-                                                    select new Method(abstractMethod));
+            foreach (Method abstractMethod in abstractMethods)
+            {
+                internalImplementation.Methods.Add(new Method(abstractMethod));
+                var @delegate = new TypedefDecl { Name = abstractMethod.Name + "Delegate" };
+                var pointerType = new PointerType();
+                var functionType = new FunctionType();
+                functionType.CallingConvention = abstractMethod.CallingConvention;
+                functionType.ReturnType = abstractMethod.OriginalReturnType;
+                functionType.Parameters.AddRange(abstractMethod.Parameters.Where(
+                    p => p.Kind != ParameterKind.IndirectReturnType));
+                pointerType.QualifiedPointee = new QualifiedType(functionType);
+                @delegate.QualifiedType = new QualifiedType(pointerType);
+                @delegate.IgnoreFlags = abstractMethod.IgnoreFlags;
+                internalImplementation.Typedefs.Add(@delegate);
+            }
             internalImplementation.Layout = new ClassLayout(@class.Layout);
             var vTableComponents = GetVTableComponents(@class);
             for (int i = 0; i < abstractMethods.Count; i++)