hello! I've inherited a codebase that uses Pants 1.26.0, Python 3.6.12, and Cython 0.28.2 (yeah, I know...) I'm trying to chip away at getting all of this upgraded, but my first priority is getting to Python 3.7 because 3.6 is EOL and no longer receiving security updates the Cython part of the build happens using a plugin that a former coworker wrote, apparently with help from someone in the Pants community. this was originally in May 2018 and the mailing list archives don't seem to stretch back that far. if I just upgrade to 3.7 (changing interpreter_constraints in pants.toml, and running Pants inside a Py3.7-based Docker container instead of the 3.6-based one we use now), with no other changes, the build fails with:

Traceback (most recent call last):
  File "/srv/submodules/obscura-plugins/plugins/setup.py", line 4, in <module>
    from Cython.Build import cythonize
ModuleNotFoundError: No module named 'Cython'

Exception message: Command '['/usr/bin/python3.7', '/srv/submodules/obscura-plugins/plugins/setup.py', 'build_ext', '--inplace', '--verbose']' returned non-zero exit status 1.

is there a "simple" fix to get this working under 3.7? if I have to upgrade Pants and/or Cython to get it to work I will, but my goal in the short term is to do the minimum necessary to get upgraded to 3.7, and then tackle the rest of the tech debt separately pants.toml: http://ix.io/3PIe register.py of the plugin: http://ix.io/3PIi compile_cython.py: http://ix.io/3PIj BUILD containing the Cython target: http://ix.io/3PIk the setup.py living next to that BUILD file, where the exception above is being thrown from: http://ix.io/3PIm

@fast-notebook-4005 does

/srv/submodules/obscura-plugins/plugins/setup.py

represent your code or third party code?

that is my code, it's the last of those ix.io links...it doesn't seem to have

setup_requires

anywhere

Well, there are two paths: 1. You use setup_requires and lazify everything you need. If there is an import, hide it in function calls. 2. Use pyproject.toml / PEP-517 / PEP-518