Merging and releasing this would fix #601

Would it be possible to backport this fix to 5.x & release a hotfix as well? We're currently blocked on upgrading to pyyaml v6 (which we're hoping to resolve this week), but it'd be helpful for a few reasons to be able to pick this up in 5.4.2

Hi @nitzmahone, the AWS CLI is also currently impacted by this (aws/aws-cli#8036). If we can get this PR merged and released as 6.0.1, it will resolve the issues faced by the AWS CLI and other impacted packages.

This is just a stopgap measure to ensure the libyaml extension build continues to function whenever Cython 3.0 is released (date TBD).

Cython just released 3.0 so everything that has any kind of transitive dependency on PyYAML will now fail to install. This is now a necessary change.

This is causing a number of products in our organization to be unbuildable. Please consider this another plea for a quick merge and release of this now critical PR.

We've also been wrestling with this dependency issue this morning during our builds.

@ingydotnet, @xitology, and @perlpunk thanks for your quick review on this

Yep, I'll be doing a 6.0.1 release imminently to cover this (grumblesmurf that I somehow missed the Cython 3.0 release was actually happening since they've been in beta for so long).

No commitment to a 5.x backport/release, but if I can easily resurrect all the necessary wheel builds for it, I might consider it.

For anyone that needs a quick fix for this do the following instead of installing PyYAML directly

git clone https://github.com/yaml/pyyaml.git && \
cd pyyaml && \
git checkout release/5.4.1 && \
sed -i.bak 's/Cython/Cython<3.0/g' pyproject.toml && \
python setup.py sdist && \
pip install --pre dist/PyYAML-5.4.1.tar.gz 

For anyone that needs a quick fix for this do the following instead of installing PyYAML directly

git clone https://github.com/yaml/pyyaml.git && \
cd pyyaml && \
git checkout release/5.4.1 && \
sed -i.bak 's/Cython/Cython<3.0/g' pyproject.toml && \
python setup.py sdist && \
pip install --pre dist/PyYAML-5.4.1.tar.gz 

For this should we install cython before hand?