Fix type instance conversion

Author: jhonabreul

src/embed_tests/TestConverter.cs

@@ -450,6 +450,27 @@ public void PrimitiveIntConversion()
             var testInt = pyValue.As<int>();
             Assert.AreEqual(testInt , 10);
         }
+
+        [TestCase(typeof(Type), true)]
+        [TestCase(typeof(string), false)]
+        [TestCase(typeof(TestCSharpModel), false)]
+        public void NoErrorSetWhenFailingToConvertClassType(Type type, bool shouldConvert)
+        {
+            using var _ = Py.GIL();
+
+            var module = PyModule.FromString("CallsCorrectOverloadWithoutErrors", @"
+from clr import AddReference
+AddReference(""System"")
+AddReference(""Python.EmbeddingTest"")
+from Python.EmbeddingTest import *
+
+class TestPythonModel(TestCSharpModel):
+    pass
+");
+            var testPythonModelClass = module.GetAttr("TestPythonModel");
+            Assert.AreEqual(shouldConvert, Converter.ToManaged(testPythonModelClass, type, out var result, setError: false));
+            Assert.IsFalse(Exceptions.ErrorOccurred());
+        }
     }
 
     public interface IGetList
@@ -461,4 +482,8 @@ public class GetListImpl : IGetList
     {
         public List<string> GetList() => new() { "testing" };
     }
+
+    public class TestCSharpModel
+    {
+    }
 }

src/embed_tests/TestMethodBinder.cs

@@ -740,6 +740,57 @@ from Python.EmbeddingTest import *
 "));
         }
 
+        public class CSharpClass
+        {
+            public string CalledMethodMessage { get; private set; }
+
+            public void Method()
+            {
+                CalledMethodMessage = "Overload 1";
+            }
+
+            public void Method(string stringArgument, decimal decimalArgument = 1.2m)
+            {
+                CalledMethodMessage = "Overload 2";
+            }
+
+            public void Method(PyObject typeArgument, decimal decimalArgument = 1.2m)
+            {
+                CalledMethodMessage = "Overload 3";
+            }
+        }
+
+        [Test]
+        public void CallsCorrectOverloadWithoutErrors()
+        {
+            using var _ = Py.GIL();
+
+            var module = PyModule.FromString("CallsCorrectOverloadWithoutErrors", @"
+from clr import AddReference
+AddReference(""System"")
+AddReference(""Python.EmbeddingTest"")
+from Python.EmbeddingTest import *
+
+class PythonModel(TestMethodBinder.CSharpModel):
+    pass
+
+def call_method(instance):
+    instance.Method(PythonModel, decimalArgument=1.234)
+");
+
+            var instance = new CSharpClass();
+            using var pyInstance = instance.ToPython();
+
+            Assert.DoesNotThrow(() =>
+            {
+                module.GetAttr("call_method").Invoke(pyInstance);
+            });
+
+            Assert.AreEqual("Overload 3", instance.CalledMethodMessage);
+
+            Assert.IsFalse(Exceptions.ErrorOccurred());
+        }
+
 
         // Used to test that we match this function with Py DateTime & Date Objects
         public static int GetMonth(DateTime test)

src/runtime/Converter.cs

@@ -473,7 +473,13 @@ internal static bool ToManagedValue(BorrowedReference value, Type obType,
                 }
                 if (mt is ClassBase cb)
                 {
-                    if (!cb.type.Valid || !obType.IsInstanceOfType(cb.type.Value))
+                    // The value being converted is a class type, so it will only succeed if it's being converted into a Type
+                    if (obType != typeof(Type))
+                    {
+                        return false;
+                    }
+
+                    if (!cb.type.Valid)
                     {
                         Exceptions.SetError(Exceptions.TypeError, cb.type.DeletedMessage);
                         return false;