Use Py_TYPE() and Py_REFCNT() macros (GH-3932)

Don't access directly PyObject.ob_type and PyObject.ob_refcnt members.

Cython/Utility/Builtins.c

@@ -333,7 +333,7 @@ static long __Pyx__PyObject_Ord(PyObject* c) {
     } else {
         // FIXME: support character buffers - but CPython doesn't support them either
         PyErr_Format(PyExc_TypeError,
-            "ord() expected string of length 1, but %.200s found", c->ob_type->tp_name);
+            "ord() expected string of length 1, but %.200s found", Py_TYPE(c)->tp_name);
         return (long)(Py_UCS4)-1;
     }
     PyErr_Format(PyExc_TypeError,

Cython/Utility/Coroutine.c

@@ -1159,7 +1159,7 @@ static void __Pyx_Coroutine_dealloc(PyObject *self) {
         if (PyObject_CallFinalizerFromDealloc(self))
 #else
         Py_TYPE(gen)->tp_del(self);
-        if (self->ob_refcnt > 0)
+        if (Py_REFCNT(self) > 0)
 #endif
         {
             // resurrected.  :(
@@ -1274,7 +1274,7 @@ static void __Pyx_Coroutine_del(PyObject *self) {
 #if !CYTHON_USE_TP_FINALIZE
     // Undo the temporary resurrection; can't use DECREF here, it would
     // cause a recursive call.
-    assert(self->ob_refcnt > 0);
+    assert(Py_REFCNT(self) > 0);
     if (--self->ob_refcnt == 0) {
         // this is the normal path out
         return;
@@ -1283,12 +1283,12 @@ static void __Pyx_Coroutine_del(PyObject *self) {
     // close() resurrected it!  Make it look like the original Py_DECREF
     // never happened.
     {
-        Py_ssize_t refcnt = self->ob_refcnt;
+        Py_ssize_t refcnt = Py_REFCNT(self);
         _Py_NewReference(self);
         __Pyx_SET_REFCNT(self, refcnt);
     }
 #if CYTHON_COMPILING_IN_CPYTHON
-    assert(PyType_IS_GC(self->ob_type) &&
+    assert(PyType_IS_GC(Py_TYPE(self)) &&
            _Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);
 
     // If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so

Cython/Utility/CythonFunction.c

@@ -1136,7 +1136,7 @@ __pyx_FusedFunction_call(PyObject *func, PyObject *args, PyObject *kw)
             PyErr_Format(PyExc_TypeError,
                          "First argument should be of type %.200s, got %.200s.",
                          ((PyTypeObject *) binding_func->type)->tp_name,
-                         self->ob_type->tp_name);
+                         Py_TYPE(self)->tp_name);
             goto bad;
         } else if (unlikely(is_instance == -1)) {
             goto bad;

Cython/Utility/ObjectHandling.c

@@ -1040,7 +1040,7 @@ static CYTHON_INLINE int __Pyx_TypeTest(PyObject *obj, PyTypeObject *type) {
 /////////////// CallableCheck.proto ///////////////
 
 #if CYTHON_USE_TYPE_SLOTS && PY_MAJOR_VERSION >= 3
-#define __Pyx_PyCallable_Check(obj)   ((obj)->ob_type->tp_call != NULL)
+#define __Pyx_PyCallable_Check(obj)   (Py_TYPE(obj)->tp_call != NULL)
 #else
 #define __Pyx_PyCallable_Check(obj)   PyCallable_Check(obj)
 #endif
@@ -1913,7 +1913,7 @@ static CYTHON_INLINE PyObject* __Pyx_PyObject_Call(PyObject *func, PyObject *arg
 #if CYTHON_COMPILING_IN_CPYTHON
 static CYTHON_INLINE PyObject* __Pyx_PyObject_Call(PyObject *func, PyObject *arg, PyObject *kw) {
     PyObject *result;
-    ternaryfunc call = func->ob_type->tp_call;
+    ternaryfunc call = Py_TYPE(func)->tp_call;
 
     if (unlikely(!call))
         return PyObject_Call(func, arg, kw);