Fix marker parsing with pyparsing 3.0.5

[9999years]

Closes #486

Context in pyparsing: pyparsing/pyparsing#110 (comment)

Equivalent to #485

[brettcannon]

@9999years @layday we now have competing PRs for the same fix. What are the pro/cons of each?

[layday]

The end result is the same, this one's using the expanded callback signature, which isn't necessary since we're only manipulating the token, and item instead of attribute access, which is less transparent.

[layday]

Which is to say, feel free to merge either one ;)

[TimB87]

Just a note: having setuptools-scm installed will still break the build with this patch.

[ptmcg]

Just a note: having setuptools-scm installed will still break the build with this patch.

Please use pyparsing 3.0.6, as it restores compatibility with the previous parse action implementation.

[TimB87]

This is with pyparsing 3.0.6 and this patch against packaging version 21.2

With setuptools-scm installed, it looks like this

❯ doas prt-get update -fr python3-packaging
prt-get: updating /usr/ports/opt/python3-packaging
=======> Building '/home/pkgmk/packages_thor/python3-packaging#21.2-1.pkg.tar.xz'.
bsdtar -p -o -C /home/ramdisk/python3-packaging/src -xf /home/pkgmk/distfiles/packaging-21.2.tar.gz
cp 487.patch /home/ramdisk/python3-packaging/src
+ build
+ cd packaging-21.2
+ patch -Np1 -i /home/ramdisk/python3-packaging/src/487.patch
patching file packaging/requirements.py
+ /usr/bin/python3 setup.py build
Traceback (most recent call last):
  File "/home/ramdisk/python3-packaging/src/packaging-21.2/setup.py", line 40, in <module>
    setup(
  File "/usr/lib/python3.9/site-packages/setuptools/__init__.py", line 159, in setup
    return distutils.core.setup(**attrs)
  File "/usr/lib/python3.9/distutils/core.py", line 108, in setup
    _setup_distribution = dist = klass(attrs)
  File "/usr/lib/python3.9/site-packages/setuptools/dist.py", line 453, in __init__
    _Distribution.__init__(
  File "/usr/lib/python3.9/distutils/dist.py", line 292, in __init__
    self.finalize_options()
  File "/usr/lib/python3.9/site-packages/setuptools/dist.py", line 830, in finalize_options
    for ep in sorted(loaded, key=by_order):
  File "/usr/lib/python3.9/site-packages/setuptools/dist.py", line 829, in <lambda>
    loaded = map(lambda e: e.load(), filtered)
  File "/usr/lib/python3.9/site-packages/pkg_resources/__init__.py", line 2454, in load
    self.require(*args, **kwargs)
  File "/usr/lib/python3.9/site-packages/pkg_resources/__init__.py", line 2477, in require
    items = working_set.resolve(reqs, env, installer, extras=self.extras)
  File "/usr/lib/python3.9/site-packages/pkg_resources/__init__.py", line 782, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.ContextualVersionConflict: (pyparsing 3.0.6 (/usr/lib/python3.9/site-packages), Requirement.parse('pyparsing<3,>=2.0.2'), {'packaging'})
=======> ERROR: Building '/home/pkgmk/packages_thor/python3-packaging#21.2-1.pkg.tar.xz' failed.

-- Packages where update failed
python3-packaging

When I remove setuptools-scm temporarily it will build just fine, with or without the patch