New submission from Josh Haberman <jhaber...@gmail.com>: I believe the following excerpt from the docs is incorrect (https://docs.python.org/3/c-api/typeobj.html#c.PyTypeObject.tp_base):
> Slot initialization is subject to the rules of initializing > globals. C99 requires the initializers to be “address > constants”. Function designators like PyType_GenericNew(), > with implicit conversion to a pointer, are valid C99 address > constants. > > However, the unary ‘&’ operator applied to a non-static > variable like PyBaseObject_Type() is not required to produce > an address constant. Compilers may support this (gcc does), > MSVC does not. Both compilers are strictly standard > conforming in this particular behavior. > > Consequently, tp_base should be set in the extension module’s init function. I explained why in https://mail.python.org/archives/list/python-...@python.org/thread/2WUFTVQA7SLEDEDYSRJ75XFIR3EUTKKO/ and on https://bugs.python.org/msg402738. The short version: &foo is an "address constant" according to the standard whenever "foo" has static storage duration. Variables declared "extern" have static storage duration. Therefore strictly conforming implementations should accept &PyBaseObject_Type as a valid constant initializer. I believe the text above could be replaced by something like: > MSVC does not support constant initialization of of an address > that comes from another DLL, so extensions should be set in the > extension module's init function. ---------- assignee: docs@python components: Documentation messages: 402752 nosy: docs@python, jhaberman priority: normal severity: normal status: open title: Docs are incorrect re: constant initialization in the C99 standard _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue45306> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
