[Cython] Ready for Cython 3.1 ?

[Stefan Behnel]

Hi all,

it looks like Cython 3.0.6 is going to be a "most things fixed" kind of 
release for the 3.0.x release series. Given the work that lies ahead of us 
for Cython 3.1, I think we're at a point to get started on that, making the 
future 3.0.x releases stable and "boring".

As a reminder, Cython 3.1 will remove support for Python 2.7 and Python 
3.[567], i.e. all Python versions that are now EOL. Python 3.8 will 
continue to receive security fixes for another year. Python 3.7 is EOL but 
still up for debate since it's probably not hard to support and still 
maintained in some Linux distributions for another couple of years. But I'm 
fine with considering it legacy. We'll probably notice if it gets in the 
way while preparing Cython 3.0, and can leave support in until there's a 
reason to remove it.

https://github.com/cython/cython/issues/2800

I'd like to ease our feature development by using more modern Python 
features in our code base and by targeting less Python versions in Cython 
3.1 compared to the "all things supported" Cython 3.0.

I also consider Cython 3.1 a prime target for better Limited API support. 
Users probably won't care both for that and for outdated Python versions at 
the same time. Or, they can use Cython 3.0.x for continued legacy support.

Since Cython 3.1 is mostly about ripping out old code, we can try to keep 
the development cycle short, so that new features don't have to wait that 
long. Certainly not as long as for Cython 3.0…

Is everyone and everything ready to start working on Cython 3.1?

Stefan