jpype fails to build with Python 3.9.0a2:

running build_thunk
Building thunks
  including thunk build/lib/org/jpype/classloader/JPypeClassLoader.class
Traceback (most recent call last):
  File "/builddir/build/BUILD/jpype-0.7.1/setup.py", line 10, in <module>
    setup(
  File "/usr/lib/python3.9/site-packages/setuptools/__init__.py", line 145, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib64/python3.9/distutils/core.py", line 148, in setup
    dist.run_commands()
  File "/usr/lib64/python3.9/distutils/dist.py", line 966, in run_commands
    self.run_command(cmd)
  File "/usr/lib64/python3.9/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/usr/lib64/python3.9/distutils/command/build.py", line 135, in run
    self.run_command(cmd_name)
  File "/usr/lib64/python3.9/distutils/cmd.py", line 313, in run_command
    self.distribution.run_command(command)
  File "/usr/lib64/python3.9/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/usr/lib/python3.9/site-packages/setuptools/command/build_ext.py", line 84, in run
    _build_ext.run(self)
  File "/usr/lib64/python3.9/distutils/command/build_ext.py", line 340, in run
    self.build_extensions()
  File "/builddir/build/BUILD/jpype-0.7.1/setupext/build_ext.py", line 74, in build_extensions
    self.run_command("build_thunk")
  File "/usr/lib64/python3.9/distutils/cmd.py", line 313, in run_command
    self.distribution.run_command(command)
  File "/usr/lib64/python3.9/distutils/dist.py", line 985, in run_command
    cmd_obj.run()
  File "/builddir/build/BUILD/jpype-0.7.1/setupext/build_thunk.py", line 149, in run
    createThunks(
  File "/builddir/build/BUILD/jpype-0.7.1/setupext/build_thunk.py", line 103, in createThunks
    outputClass(filename, name, fimpl)
  File "/builddir/build/BUILD/jpype-0.7.1/setupext/build_thunk.py", line 53, in outputClass
    output(fout, l)
  File "/builddir/build/BUILD/jpype-0.7.1/setupext/build_thunk.py", line 36, in output
    buffer.fromstring(l)
AttributeError: 'array.array' object has no attribute 'fromstring'


See https://docs.python.org/3.9/whatsnew/3.9.html#removed

"array.array: tostring() and fromstring() methods have been removed. They were aliases to tobytes() and frombytes(), deprecated since Python 3.2.


For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.9/fedora-rawhide-x86_64/01148474-jpype/

For all our attempts to build jpype with Python 3.9, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/package/jpype/

Testing and mass rebuild of packages is happening in copr. You can follow these instructions to test locally in mock if your package builds with Python 3.9:
https://copr.fedorainfracloud.org/coprs/g/python/python3.9/

Let us know here if you have any questions.

Python 3.9 will be included in Fedora 33. To make that update smoother, we're building Fedora packages with early pre-releases of Python 3.9.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires), so if this package is required a lot, it's important for us to get it fixed soon.
We'd appreciate help from the people who know this package best, but if you don't want to work on this now, let us know so we can try to work around it on our side.