Thanks! This needs a NEWS entry, preferrably with a reference to when the bug was introduced. I think this should be backported through to 3.10.

Also, please add tests. There's a dedicated test.support helper for this. Grep through the code base to find it and see how it's used.

@erlend-aasland, are you talking about assert_python_ok? Can't we just check if TypeError with proper message is raised on attempt to create instance/subtype?

There's a disallow_instantiation helper in test.support.

Thanks! This needs a NEWS entry, preferrably with a reference to when the bug was introduced. I think this should be backported through to 3.10.

Ah, 3.10 is in security fix mode, so we can only backport to 3.11.

Some history, the original issue for applying PEP-384 to the _csv extension module:

• PEP 384 Refactoring applied to _csv module #59140 (bpo-14935)
• bpo-14935: Remove static state from the _csv module #23224

A later (duplicate issue); the linked PRs were closed and incorporated into gh-23224

• Apply PEP384 to _csv module #78714 (bpo-34533)
• bpo-34533: Apply PEP384 to _csv module #8977
• bpo-34533: Remove all static state from _csv module #16078

As you can see, both the Writer and the Reader class had Py_TPFLAGS_BASETYPE when they were converted from static to heap types. Removing that flag is a backwards incompatible change, as third-party software may depend on that behaviour. Please revert that particular change.

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

Looks like 6a02b38 from #23224 introduced this issue. How can I reflect this in NEWS entry text? Should I specify an issue number?

Looks like 6a02b38 from #23224 introduced this issue. How can I reflect this in NEWS entry text? Should I specify an issue number?

Indeed it did.

You can reference GitHub issues/PRs with the :gh: Sphinx directive. Here's a suggestion to a NEWS entry:

Prevent possible crash by disallow instantiation of the :class:`!_csv.Reader`
and :class:`!_csv.Writer` types. The regression was introduced by :gh:`23224`
in Python 3.10. Patch by <your-name-here>.

I have made the requested changes; please review again

Thanks for making the requested changes!

@erlend-aasland: please review the changes made to this pull request.

Thank you so much for the report and bugfix, Radislav; good job!

Thanks @chgnrdv for the PR, and @erlend-aasland for merging it 🌮🎉.. I'm working now to backport this PR to: 3.11.
🐍🍒⛏🤖

GH-104278 is a backport of this pull request to the 3.11 branch.

@erlend-aasland, thank you for your patient review :)