Hmm, looks like it's failing here with pycparser not being installed. Somehow adding it to setup_requires here is too late.

I'm not sure how to explicitly add this for this project - because I don't see why it's only failing for 3.8?

If one of the interop*.cs files doesn't exist, it is generated on build. Generate it manually once and commit the resulting file, then pycparser will not be invoked.

Looks good, not quite sure what is going on on AppVeyor, though.

The error seems to be that System.EntryPointNotFoundException : Unable to find an entry point named 'Py_CompileString' in DLL 'python38'.. I traced it down to this bug in python: Py_CompileString and PyParser_SimpleParseString not exported in python38.dll.

Seems this will be fixed for the next release though, which will be in mid December. Not sure what to do about this PR in the meantime though.

Add the Windows/Python 3.8 builds as allow_failures in the appveyor.yaml (https://www.appveyor.com/docs/build-configuration/#allow-failing-jobs), a note to the README and we'll merge. No need to wait until December for this.

Ok, added a note to the readme and allow_failures. Apologies, but you may want to squash the PR as I was doing it in the browser so there's a commit for each change in a file.

Would it be possible to make a wheel of the last release for 3.8 and upload to pypi (e.g. by backporting this PR)? I'm not sure how you generate the wheels for the release - I can't find it happening on the CI. In my projects, we have a branch for each release called stable-x.y.z so we can backport and have the CI run again generating the wheels etc. But here it is only a tag so I'm not sure that is possible?

Codecov Report

Merging #988 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #988   +/-   ##
=======================================
  Coverage   86.71%   86.71%           
=======================================
  Files           1        1           
  Lines         301      301           
=======================================
  Hits          261      261           
  Misses         40       40

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It's probably easier to just do a 2.4.1 now, I'll see to it next weekend.

Thank you very much for this, in particular also for hunting down the bug! :)

The CI pipelines at conda-forge just started the Python 3.8 migration for the pythonnet-feedstock and failed: conda-forge/pythonnet-feedstock#3
So am I right we need a new version of pythonnet or Python 3.8.1 to get it working on Python 3.8?

pythonnet from current master should work fine for a lot of things, it will just fail on functions that run python code as a string from .net on Windows until 3.8.1.

conda-forge uses pypi uploads, so I will disable builds for Python 3.8 for now.