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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"test/upcast.cpp does not compile since python 3.10","articleBody":"revision: 3e7be69e1e405e1d5ddd232c69c024ee441592c5\n\nSince Python 3.10, compilation of test/upcast.cpp fails.\n\nhttps://github.com/boostorg/python/blob/3e7be69e1e405e1d5ddd232c69c024ee441592c5/test/upcast.cpp#L16-L17\n\n```console\n$ g++ -Iinclude -I/opt/miniconda3/envs/py310/include/python3.10 test/upcast.cpp\nIn file included from /usr/include/boost/detail/lightweight_test.hpp:15,\n                 from ./test/upcast.cpp:7:\n./test/upcast.cpp: In function 'int main()':\n/opt/miniconda3/envs/py310/include/python3.10/object.h:133:33: error: lvalue required as unary '\u0026' operand\n  133 | #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))\n      |                       ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~\n./test/upcast.cpp:16:17: note: in expansion of macro 'Py_REFCNT'\n   16 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026o)) == \u0026Py_REFCNT(\u0026o));\n      |                 ^~~~~~~~~\n/opt/miniconda3/envs/py310/include/python3.10/object.h:133:33: error: lvalue required as unary '\u0026' operand\n  133 | #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))\n      |                       ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~\n./test/upcast.cpp:16:68: note: in expansion of macro 'Py_REFCNT'\n   16 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026o)) == \u0026Py_REFCNT(\u0026o));\n      |                                                                    ^~~~~~~~~\n/opt/miniconda3/envs/py310/include/python3.10/object.h:133:33: error: lvalue required as unary '\u0026' operand\n  133 | #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))\n      |                       ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~\n./test/upcast.cpp:17:17: note: in expansion of macro 'Py_REFCNT'\n   17 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026y)) == \u0026Py_REFCNT(\u0026y));\n      |                 ^~~~~~~~~\n/opt/miniconda3/envs/py310/include/python3.10/object.h:133:33: error: lvalue required as unary '\u0026' operand\n  133 | #define Py_REFCNT(ob) _Py_REFCNT(_PyObject_CAST_CONST(ob))\n      |                       ~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~\n./test/upcast.cpp:17:68: note: in expansion of macro 'Py_REFCNT'\n   17 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026y)) == \u0026Py_REFCNT(\u0026y));\n      |                                                                    ^~~~~~~~~\n```\n\n```console\n$ g++ -Iinclude -I/usr/include/python3.13 test/upcast.cpp\nIn file included from /usr/include/boost/detail/lightweight_test.hpp:15,\n                 from test/upcast.cpp:7:\ntest/upcast.cpp: In function 'int main()':\n/usr/include/python3.13/object.h:330:34: error: lvalue required as unary '\u0026' operand\n  330 | #  define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))\n      |                         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~\ntest/upcast.cpp:16:17: note: in expansion of macro 'Py_REFCNT'\n   16 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026o)) == \u0026Py_REFCNT(\u0026o));\n      |                 ^~~~~~~~~\n/usr/include/python3.13/object.h:330:34: error: lvalue required as unary '\u0026' operand\n  330 | #  define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))\n      |                         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~\ntest/upcast.cpp:16:68: note: in expansion of macro 'Py_REFCNT'\n   16 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026o)) == \u0026Py_REFCNT(\u0026o));\n      |                                                                    ^~~~~~~~~\n/usr/include/python3.13/object.h:330:34: error: lvalue required as unary '\u0026' operand\n  330 | #  define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))\n      |                         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~\ntest/upcast.cpp:17:17: note: in expansion of macro 'Py_REFCNT'\n   17 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026y)) == \u0026Py_REFCNT(\u0026y));\n      |                 ^~~~~~~~~\n/usr/include/python3.13/object.h:330:34: error: lvalue required as unary '\u0026' operand\n  330 | #  define Py_REFCNT(ob) Py_REFCNT(_PyObject_CAST(ob))\n      |                         ~~~~~~~~~^~~~~~~~~~~~~~~~~~~~\ntest/upcast.cpp:17:68: note: in expansion of macro 'Py_REFCNT'\n   17 |     BOOST_TEST(\u0026Py_REFCNT(boost::python::upcast\u003cPyObject\u003e(\u0026y)) == \u0026Py_REFCNT(\u0026y));\n      |                                                                    ^~~~~~~~~\n```\n\nThis is because [`Py_REFCNT()` is changed to the inline static function](https://docs.python.org/3.10/c-api/structures.html#c.Py_REFCNT).\n\nUnfortunately, the CI images use python upto 3.8, so the issue has not been found.","author":{"url":"https://github.com/e-kwsm","@type":"Person","name":"e-kwsm"},"datePublished":"2025-03-28T19:38:13.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":0},"url":"https://github.com/479/python/issues/479"}