An anonymous union was added recently, making this header produce warnings/errors for C++ compilers that have not enabled the relevant extensions/standards.

https://github.com/python/cpython/blame/1668b41dc477bc9562e4c50ab36a232839b4621b/Include/object.h#L168-L173

This code looks like it's making a few too many assumptions anyway. I suspect we ought to be wrapping up accesses to ob_refcnt_split in a macro and masking, rather than using a union. Or at least setting up the union to not assume that SIZEOF_VOID_P > 4 implies SIZEOF_VOID_P == 8.

(Ping @eduardo-elizondo)

Linked PRs

• gh-105059: Remove anonymous union from PyObject #105275
• [DRAFT] gh-105059: In C++, Py_INCREF() uses a function call #105764
• [DRAFT] gh-105059: C99 avoids PyObject.ob_refcnt union #105767
• gh-105059: Use GCC/clang extension for PyObject union #107232
• [3.12] gh-105059: Use GCC/clang extension for PyObject union (GH-107232) #107236
• gh-105059: Fix MSCV compiler warning on PyObject union #107239
• [3.12] gh-105059: Fix MSCV compiler warning on PyObject union (GH-107239) #107248