python · vstinner · Jul 8, 2020 · Jul 8, 2020
diff --git a/Include/object.h b/Include/object.h
@@ -637,8 +637,16 @@ times.


 static inline int
-PyType_HasFeature(PyTypeObject *type, unsigned long feature) {
-    return ((PyType_GetFlags(type) & feature) != 0);
+PyType_HasFeature(PyTypeObject *type, unsigned long feature)
+{
+    unsigned long flags;
+#ifdef Py_LIMITED_API
+    // PyTypeObject is opaque in the limited C API
+    flags = PyType_GetFlags(type);
+#else
+    flags = type->tp_flags;
+#endif
+    return ((flags & feature) != 0);
 }

 #define PyType_FastSubclass(type, flag) PyType_HasFeature(type, flag)

diff --git a/Misc/NEWS.d/next/C API/2020-07-08-10-14-52.bpo-40170.N6Qx1i.rst b/Misc/NEWS.d/next/C API/2020-07-08-10-14-52.bpo-40170.N6Qx1i.rst
@@ -0,0 +1,4 @@
+Revert :c:func:`PyType_HasFeature` change: it reads again directly the
+:c:member:`PyTypeObject.tp_flags` member when the limited C API is not used,
+rather than always calling :c:func:`PyType_GetFlags` which hides implementation
+details.