Message402738
This behavior is covered by the standard. The following C translation unit is valid according to C99:
struct PyTypeObject;
extern struct PyTypeObject Foo_Type;
struct PyTypeObject *ptr = &Foo_Type;
Specifically, &Foo_Type is an "address constant" per the standard because it is a pointer to an object of static storage duration (6.6p9).
The Python docs contradict this with the following incorrect statement:
> However, the unary ‘&’ operator applied to a non-static variable like PyBaseObject_Type() is not required to produce an address constant.
This statement is incorrect:
1. PyBaseObject_Type is an object of static storage duration. (Note, this is true even though it does not use the "static" keyword -- the "static" storage-class specifier and "static storage duration" are separate concepts).
2. It follows that &PyBaseObject_Type is required to produce an address constant. because it is a pointer to an object of static storage duration.
MSVC rejects this standard-conforming TU when __declspec(dllimport) is added: https://godbolt.org/z/GYrfTqaGn I am pretty sure this is out of compliance with C99. |
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2021-09-27 20:38:34 | haberman2 | set | recipients:
+ haberman2, loewis, jcea, amaury.forgeotdarc, belopolsky, pitrou, Arfrever, petr.viktorin, lekma, Alexander.Belopolsky, mattip, Robin.Schreiber, steve.dower, seberg, Christian.Tismer, jhaberman |
2021-09-27 20:38:34 | haberman2 | set | messageid: <1632775114.1.0.979208858986.issue15870@roundup.psfhosted.org> |
2021-09-27 20:38:34 | haberman2 | link | issue15870 messages |
2021-09-27 20:38:33 | haberman2 | create | |
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