getting rid of a few minor warnings and compile errors

src/runtime/Codecs/EnumPyIntCodec.cs

@@ -10,7 +10,7 @@ namespace Python.Runtime.Codecs
         public bool CanDecode(PyType objectType, Type targetType)
         {
             return targetType.IsEnum
-                && objectType.IsSubclass(new BorrowedReference(Runtime.PyLongType));
+                && objectType.IsSubclass(Runtime.PyLongType);
         }
 
         public bool CanEncode(Type type)
@@ -18,7 +18,7 @@ namespace Python.Runtime.Codecs
             return type == typeof(object) || type == typeof(ValueType) || type.IsEnum;
         }
 
-        public bool TryDecode<T>(PyObject pyObj, out T value)
+        public bool TryDecode<T>(PyObject pyObj, out T? value)
         {
             value = default;
             if (!typeof(T).IsEnum) return false;
@@ -27,7 +27,7 @@ namespace Python.Runtime.Codecs
 
             if (!PyInt.IsIntType(pyObj)) return false;
 
-            object result;
+            object? result;
             try
             {
                 result = pyObj.AsManagedObject(etype);
@@ -46,7 +46,7 @@ namespace Python.Runtime.Codecs
             return false;
         }
 
-        public PyObject TryEncode(object value)
+        public PyObject? TryEncode(object value)
         {
             if (value is null) return null;
 

src/runtime/DefaultBaseTypeProvider.cs

@@ -21,11 +21,11 @@ namespace Python.Runtime
         static BorrowedReference GetBaseType(Type type)
         {
             if (type == typeof(Exception))
-                return new BorrowedReference(Exceptions.Exception);
+                return Exceptions.Exception;
 
             return type.BaseType is not null
                 ? ClassManager.GetClass(type.BaseType).ObjectReference
-                : new BorrowedReference(Runtime.PyBaseObjectType);
+                : Runtime.PyBaseObjectType;
         }
 
         DefaultBaseTypeProvider(){}

src/runtime/Mixins/CollectionMixinsProvider.cs

@@ -70,7 +70,7 @@ namespace Python.Runtime.Mixins
 
             if (type.IsInterface && type.BaseType is null)
             {
-                newBases.RemoveAll(@base => @base.Handle == Runtime.PyBaseObjectType);
+                newBases.RemoveAll(@base => PythonReferenceComparer.Instance.Equals(@base, Runtime.PyBaseObjectType));
             }
 
             return newBases;

src/runtime/ReferenceExtensions.cs

@@ -9,12 +9,12 @@ namespace Python.Runtime
         /// </summary>
         [Pure]
         public static bool IsNone(this in NewReference reference)
-            => reference.DangerousGetAddress() == Runtime.PyNone;
+            => reference.BorrowNullable() == Runtime.PyNone;
         /// <summary>
         /// Checks if the reference points to Python object <c>None</c>.
         /// </summary>
         [Pure]
         public static bool IsNone(this BorrowedReference reference)
-            => reference.DangerousGetAddress() == Runtime.PyNone;
+            => reference == Runtime.PyNone;
     }
 }

src/runtime/classderived.cs

@@ -349,7 +349,7 @@ namespace Python.Runtime
             Type[] parameterTypes = (from param in parameters select param.ParameterType).ToArray();
 
             // If the method isn't abstract create a method for calling the original method
-            string baseMethodName = null;
+            string? baseMethodName = null;
             if (!method.IsAbstract)
             {
                 baseMethodName = "_" + baseType.Name + "__" + method.Name;
@@ -678,7 +678,7 @@ namespace Python.Runtime
 
                             PyObject py_result = method.Invoke(pyargs);
                             disposeList.Add(py_result);
-                            return (T)py_result.AsManagedObject(typeof(T));
+                            return py_result.As<T>();
                         }
                     }
                 }
@@ -781,7 +781,7 @@ namespace Python.Runtime
                 using var pyself = new PyObject(self.ObjectReference);
                 using (PyObject pyvalue = pyself.GetAttr(propertyName))
                 {
-                    return (T)pyvalue.AsManagedObject(typeof(T));
+                    return pyvalue.As<T>();
                 }
             }
             finally

src/runtime/constructorbinder.cs

@@ -53,7 +53,8 @@ namespace Python.Runtime
         {
             if (!_containingType.Valid)
             {
-                return Exceptions.RaiseTypeError(_containingType.DeletedMessage);
+                Exceptions.RaiseTypeError(_containingType.DeletedMessage);
+                return null;
             }
             object result;
             Type tp = _containingType.Value;
@@ -83,7 +84,7 @@ namespace Python.Runtime
                 return result;
             }
 
-            Binding binding = Bind(inst, args, kw, info);
+            Binding? binding = Bind(inst, args, kw, info);
 
             if (binding == null)
             {
@@ -94,9 +95,8 @@ namespace Python.Runtime
                 // if there is a default constructor and, if so, assume that
                 // any extra args are intended for the subclass' __init__.
 
-                IntPtr eargs = Runtime.PyTuple_New(0);
-                binding = Bind(inst, eargs, IntPtr.Zero);
-                Runtime.XDecref(eargs);
+                using var eargs = Runtime.PyTuple_New(0);
+                binding = Bind(inst, eargs.BorrowOrThrow(), kw: null);
 
                 if (binding == null)
                 {

src/runtime/loader.cs

@@ -1,8 +1,5 @@
-using System.Diagnostics;
 using System;
-using System.Runtime.InteropServices;
 using System.Text;
-using System.Threading;
 
 namespace Python.Runtime
 {
@@ -13,7 +10,6 @@ namespace Python.Runtime
     {
         public unsafe static int Initialize(IntPtr data, int size)
         {
-            IntPtr gs = IntPtr.Zero;
             try
             {
                 var dllPath = Encoding.UTF8.GetString((byte*)data.ToPointer(), size);
@@ -27,11 +23,18 @@ namespace Python.Runtime
                     PythonDLL = null;
                 }
 
-                gs = PyGILState_Ensure();
+                var gs = PyGILState_Ensure();
 
-                // Console.WriteLine("Startup thread");
-                PythonEngine.InitExt();
-                // Console.WriteLine("Startup finished");
+                try
+                {
+                    // Console.WriteLine("Startup thread");
+                    PythonEngine.InitExt();
+                    // Console.WriteLine("Startup finished");
+                }
+                finally
+                {
+                    PyGILState_Release(gs);
+                }
             }
             catch (Exception exc)
             {
@@ -40,27 +43,27 @@ namespace Python.Runtime
                 );
                 return 1;
             }
-            finally
-            {
-                if (gs != IntPtr.Zero)
-                {
-                    PyGILState_Release(gs);
-                }
-            }
+            
             return 0;
         }
 
         public unsafe static int Shutdown(IntPtr data, int size)
         {
-            IntPtr gs = IntPtr.Zero;
             try
             {
                 var command = Encoding.UTF8.GetString((byte*)data.ToPointer(), size);
 
                 if (command == "full_shutdown")
                 {
-                    gs = PyGILState_Ensure();
-                    PythonEngine.Shutdown();
+                    var gs = PyGILState_Ensure();
+                    try
+                    {
+                        PythonEngine.Shutdown();
+                    }
+                    finally
+                    {
+                        PyGILState_Release(gs);
+                    }
                 }
             }
             catch (Exception exc)
@@ -70,13 +73,7 @@ namespace Python.Runtime
                 );
                 return 1;
             }
-            finally
-            {
-                if (gs != IntPtr.Zero)
-                {
-                    PyGILState_Release(gs);
-                }
-            }
+
             return 0;
         }
     }

src/runtime/pythonexception.cs

@@ -174,7 +174,7 @@ namespace Python.Runtime
                 return pyErr;
             }
 
-            if (PyObjectConversions.TryDecode(valRef, typeRef, typeof(Exception), out object decoded)
+            if (PyObjectConversions.TryDecode(valRef, typeRef, typeof(Exception), out object? decoded)
                 && decoded is Exception decodedException)
             {
                 return decodedException;
@@ -199,7 +199,7 @@ namespace Python.Runtime
             using var pyErrType = Runtime.InteropModule.GetAttr("PyErr");
             using var pyErrInfo = pyErrType.Invoke(new PyTuple(), errorDict);
             if (PyObjectConversions.TryDecode(pyErrInfo.Reference, pyErrType.Reference,
-                typeof(Exception), out object decoded) && decoded is Exception decodedPyErrInfo)
+                typeof(Exception), out object? decoded) && decoded is Exception decodedPyErrInfo)
             {
                 return decodedPyErrInfo;
             }
@@ -394,11 +394,11 @@ namespace Python.Runtime
             => new PythonException(type: Type, value: Value, traceback: Traceback,
                                    Message, InnerException);
 
-        internal bool Is(IntPtr type)
+        internal bool Is(BorrowedReference type)
         {
             return Runtime.PyErr_GivenExceptionMatches(
                 given: (Value ?? Type).Reference,
-                typeOrTypes: new BorrowedReference(type)) != 0;
+                typeOrTypes: type) != 0;
         }
 
         private static void CheckRuntimeIsRunning()

src/runtime/runtime.cs

@@ -176,7 +176,7 @@ namespace Python.Runtime
 
         private static void InitPyMembers()
         {
-            using (var builtinsOwned = PyImport_Import(new BorrowedReference(PyIdentifier.builtins)))
+            using (var builtinsOwned = PyImport_Import(PyIdentifier.builtins))
             {
                 var builtins = builtinsOwned.Borrow();
                 SetPyMember(out PyNotImplemented, PyObject_GetAttrString(builtins, "NotImplemented").StealNullable());
@@ -403,10 +403,11 @@ namespace Python.Runtime
             _pyRefs.Add(obj);
         }
 
-        private static void SetPyMemberTypeOf(out PyObject obj, PyObject value)
+        private static void SetPyMemberTypeOf(out PyType obj, PyObject value)
         {
             var type = PyObject_Type(value);
-            SetPyMember(out obj, type.StealNullable());
+            obj = new PyType(type.StealOrThrow(), prevalidated: true);
+            _pyRefs.Add(obj);
         }
 
         private static void SetPyMemberTypeOf(out PyObject obj, StolenReference value)
@@ -513,8 +514,8 @@ namespace Python.Runtime
         internal static PyObject PyDictType;
         internal static PyObject PyLongType;
         internal static PyObject PyFloatType;
-        internal static PyObject PyBoolType;
-        internal static PyObject PyNoneType;
+        internal static PyType PyBoolType;
+        internal static PyType PyNoneType;
         internal static PyType PyTypeType;
 
         internal static int* Py_NoSiteFlag;

src/runtime/slots/mp_length.cs

@@ -9,7 +9,7 @@ namespace Python.Runtime.Slots
 {
     internal static class mp_length_slot
     {
-        private static MethodInfo _lengthMethod;
+        private static MethodInfo? _lengthMethod;
         public static MethodInfo Method
         {
             get
@@ -22,7 +22,7 @@ namespace Python.Runtime.Slots
                     nameof(mp_length_slot.mp_length),
                     BindingFlags.Static | BindingFlags.NonPublic);
                 Debug.Assert(_lengthMethod != null);
-                return _lengthMethod;
+                return _lengthMethod!;
             }
         }
 
@@ -47,12 +47,13 @@ namespace Python.Runtime.Slots
         /// Implements __len__ for classes that implement ICollection
         /// (this includes any IList implementer or Array subclass)
         /// </summary>
-        private static int mp_length(IntPtr ob)
+        private static nint mp_length(BorrowedReference ob)
         {
             var co = ManagedType.GetManagedObject(ob) as CLRObject;
             if (co == null)
             {
                 Exceptions.RaiseTypeError("invalid object");
+                return -1;
             }
 
             // first look for ICollection implementation directly