Hi everybody, I'd like to revive this thread as I feel like we have to do something here but some consensus is needed first.
To recap, the current state of things is as follows: - in March 2000 (d724b23420f) Christian Tismer contributed the "trashcan" patch that added Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END macros which allow destroying nested objects non-recursively. - in May 2019 (GH-11841 of BPO-35983) Antoine Pitrou merged a change by Jeroen Demeyer which made Py_TRASHCAN_SAFE_BEGIN/END (unintentionally?) backwards incompatible; this was released in Python 3.8.0. - by the way, GH-11841 introduced a new pair of macros (because they have different signatures) called simply Py_TRASHCAN_BEGIN and Py_TRASHCAN_END. - by that time there was already a follow-up PR open (GH-12607) to improve backwards compatibility of the macros, as well as introduce tests for them; this was never merged. - in Feb 2020 (0fa4f43db08) Victor Stinner removed the trashcan mechanism from the limited C API (note: not ABI, those are macros) since it accesses fields of structs not exposed in the limited C API; this was released in Python 3.9.0. - in May 2020 Irit noticed that the backwards incompatibility (BPO-40608) causes segfaults for C API code that worked fine with Python 3.7. Using the new macros requires code changes but doesn't crash. Now, there are a couple of things we can do here: Option 1: Finish GH-12607 to fix the old macros, keeping in mind this will restore compatibility lost with Python 3.8 - 3.10 only for users of 3.11+ Option 2: Review and merge GH-20104 that reverts the macro changes that make old client code segfault -- unclear what else this needs and again, that would only fix it for users of 3.11+ Option 3: Abandon GH-12607 and GH-20104, instead declaring the old macros deprecated for 3.11 and remove them in 3.13 I personally agree with Irit, voting +1 for Option 3 since the old macros were soft-deprecated already by introducing new macros in 3.8, and more importantly made incompatible with pre-3.8 usage. Let's talk on how to proceed. - Ł > On 26 Apr 2021, at 23:55, Irit Katriel via Python-Dev <python-dev@python.org> > wrote: > > > Re https://bugs.python.org/issue40608 <https://bugs.python.org/issue40608>. > > I think it will be an act of kindness to deprecate Py_TRASHCAN_SAFE_BEGIN/END > in 3.10 and tell people to use Py_TRASHCAN_BEGIN/END instead. > > TL;DR: There was a change in 3.8 that introduced the latter while leaving > the former for backwards compatibility, but also inadvertently breaking them. > This is not an easy bug to deal with in the wild, we found it because we have > a unit test in our codebase referencing https://bugs.python.org/issue16602 > <http://bugs.python.org/issue16602>. A deprecation note pointing to the new > macros would have made it easier. > > Is there any reason not to deprecate the old macros? > > Irit > _______________________________________________ > Python-Dev mailing list -- python-dev@python.org > To unsubscribe send an email to python-dev-le...@python.org > https://mail.python.org/mailman3/lists/python-dev.python.org/ > Message archived at > https://mail.python.org/archives/list/python-dev@python.org/message/LWP6MOLP5UW2TH3MROZQK4N64SX35N2B/ > Code of Conduct: http://python.org/psf/codeofconduct/
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