gh-92898: Enhance _testcppext test on cast to PyObject* by vstinner · Pull Request #93111 · python/cpython · GitHub
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gh-92898: Enhance _testcppext test on cast to PyObject* #93111

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vstinner merged 2 commits into from
May 26, 2022
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gh-92898: Enhance _testcppext test on cast to PyObject* #93111

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gh-92898: Enhance _testcppext test on cast to PyObject*
vstinner May 23, 2022
84a18b4
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vstinner May 23, 2022
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48 changes: 23 additions & 25 deletions Include/pyport.h
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42 changes: 31 additions & 11 deletions Lib/test/_testcppext.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -23,13 +23,35 @@ _testcppext_add(PyObject *Py_UNUSED(module), PyObject *args)
}


// Class to test operator casting an object to PyObject*
class StrongRef
{
public:
StrongRef(PyObject *obj) : m_obj(obj) {
Py_INCREF(this->m_obj);
}

~StrongRef() {
Py_DECREF(this->m_obj);
}

// Cast to PyObject*: get a borrowed reference
inline operator PyObject*() const { return this->m_obj; }

private:
PyObject *m_obj; // Strong reference
};


static PyObject *
test_api_casts(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
{
PyObject *obj = Py_BuildValue("(ii)", 1, 2);
if (obj == nullptr) {
return nullptr;
}
Py_ssize_t refcnt = Py_REFCNT(obj);
assert(refcnt >= 1);

// gh-92138: For backward compatibility, functions of Python C API accepts
// "const PyObject*". Check that using it does not emit C++ compiler
Expand All @@ -38,22 +60,20 @@ test_api_casts(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
Py_INCREF(const_obj);
Py_DECREF(const_obj);
PyTypeObject *type = Py_TYPE(const_obj);
assert(Py_REFCNT(const_obj) >= 1);

struct PyObjectProxy {
PyObject* obj;
operator PyObject *() { return obj; }
} proxy_obj = { obj };
Py_INCREF(proxy_obj);
Py_DECREF(proxy_obj);
assert(Py_REFCNT(proxy_obj) >= 1);


assert(Py_REFCNT(const_obj) == refcnt);
assert(type == &PyTuple_Type);
assert(PyTuple_GET_SIZE(const_obj) == 2);
PyObject *one = PyTuple_GET_ITEM(const_obj, 0);
assert(PyLong_AsLong(one) == 1);

// gh-92898: StrongRef doesn't inherit from PyObject but has an operator to
// cast to PyObject*.
StrongRef strong_ref(obj);
assert(Py_TYPE(strong_ref) == &PyTuple_Type);
assert(Py_REFCNT(strong_ref) == (refcnt + 1));
Py_INCREF(strong_ref);
Py_DECREF(strong_ref);

Py_DECREF(obj);
Py_RETURN_NONE;
}
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/C API/2022-05-23-15-22-18.gh-issue-92898.Qjc9d3.rst
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