[vstinner]

Change also PyType_GetFlags() return type to uint64_t. Add _PyType_GetFlags64() and expose it as PyType_GetFlags() with a macro. Keep the existing PyType_GetFlags() function unchanged (return unsigned long) for the stable ABI.

PyType_HasFeature() now calls _PyType_GetFlags64() on the limited C API 3.16 or newer, or calls PyType_GetFlags() on the limited C API 3.15 and older.

PyType_Spec.flags type stays as unsigned long, since the structure is part of the stable ABI. Use PyType_FromSlots() if you need 64-bit flags.

• Issue: [C API] Change PyTypeObject.tp_flags type to uint64_t #161562

[vstinner]

cc @encukou

[read-the-docs-community]

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• c-api/type.html
• c-api/typeobj.html
• extending/newtypes.html
• library/ssl.html
• whatsnew/changelog.html

[vstinner]

I'm not sure how debuggers/profilers are supposed to deal with PyTypeObject.tp_flags type change. I had to update _remote_debugging to change the member type (size):

-    if ((GET_MEMBER(unsigned long, type_obj, unwinder->debug_offsets.type_object.tp_flags) & Py_TPFLAGS_LONG_SUBCLASS)) {
+    if ((GET_MEMBER(uint64_t, type_obj, unwinder->debug_offsets.type_object.tp_flags) & Py_TPFLAGS_LONG_SUBCLASS)) {

[ronaldoussoren]

This function is in the stable ABI, this change is an ABI change on 32-bit platforms and 64-bit windows.

[vstinner]

Ah, I should maybe elaborate the documentation. The unsigned long PyType_GetFlags(PyTypeObject* type) function remains unchanged with my change, it still returns unsigned long. What changes is the PyType_GetFlags "API": when you write PyType_GetFlags() in your code, in fact, _PyType_GetFlags64() will be called at the ABI level, and _PyType_GetFlags64() return value is uint64_t.

This replacement trick is only done if you don't use use the limited C API or if you target the limited C API 3.16 or newer.

In practice:

PyAPI_FUNC(unsigned long) PyType_GetFlags(PyTypeObject*);
PyAPI_FUNC(uint64_t) _PyType_GetFlags64(PyTypeObject*);

#if !defined(Py_LIMITED_API) || Py_LIMITED_API >= _Py_PACK_VERSION(3, 16)
#  define PyType_GetFlags _PyType_GetFlags64
#endif

[vstinner]

I updated the doc. Does it make sense to you?