pip: 2020 resolver: get_topological_weights AssertionError

What did you want to do?

pip install --use-feature 2020-resolver sphinx==1.8.5
pip install --use-feature 2020-resolver sphinx sphinxcontrib-bibtex

After installing sphinx 1.8.5, pip freeze gives this:

alabaster==0.7.12
Babel==2.8.0
certifi==2020.6.20
chardet==3.0.4
docutils==0.16
idna==2.10
imagesize==1.2.0
Jinja2==2.11.2
MarkupSafe==1.1.1
packaging==20.4
Pygments==2.7.1
pyparsing==2.4.7
pytz==2020.1
requests==2.24.0
six==1.15.0
snowballstemmer==2.0.0
Sphinx==1.8.5
sphinxcontrib-serializinghtml==1.1.4
sphinxcontrib-websupport==1.2.4
urllib3==1.25.11

Output

ERROR: Exception:
Traceback (most recent call last):
  File "/home/jahn/usr/src/pipmaster/src/pip/_internal/cli/base_command.py", line 222, in _main
    status = self.run(options, args)
  File "/home/jahn/usr/src/pipmaster/src/pip/_internal/cli/req_command.py", line 178, in wrapper
    return func(self, options, args)
  File "/home/jahn/usr/src/pipmaster/src/pip/_internal/commands/install.py", line 378, in run
    requirement_set
  File "/home/jahn/usr/src/pipmaster/src/pip/_internal/resolution/resolvelib/resolver.py", line 183, in get_installation_order
    weights = get_topological_weights(graph)
  File "/home/jahn/usr/src/pipmaster/src/pip/_internal/resolution/resolvelib/resolver.py", line 242, in get_topological_weights
    assert len(weights) == len(graph)
AssertionError

Additional information

Dependency tree (before error):

pipdeptree==1.0.0
  - pip [required: >=6.0.0, installed: 20.3.dev0]
Sphinx==1.8.5
  - alabaster [required: >=0.7,<0.8, installed: 0.7.12]
  - babel [required: >=1.3,!=2.0, installed: 2.8.0]
    - pytz [required: >=2015.7, installed: 2020.1]
  - docutils [required: >=0.11, installed: 0.16]
  - imagesize [required: Any, installed: 1.2.0]
  - Jinja2 [required: >=2.3, installed: 2.11.2]
    - MarkupSafe [required: >=0.23, installed: 1.1.1]
  - packaging [required: Any, installed: 20.4]
    - pyparsing [required: >=2.0.2, installed: 2.4.7]
    - six [required: Any, installed: 1.15.0]
  - Pygments [required: >=2.0, installed: 2.7.1]
  - requests [required: >=2.0.0, installed: 2.24.0]
    - certifi [required: >=2017.4.17, installed: 2020.6.20]
    - chardet [required: >=3.0.2,<4, installed: 3.0.4]
    - idna [required: >=2.5,<3, installed: 2.10]
    - urllib3 [required: >=1.21.1,<1.26,!=1.25.1,!=1.25.0, installed: 1.25.11]
  - setuptools [required: Any, installed: 41.6.0]
  - six [required: >=1.5, installed: 1.15.0]
  - snowballstemmer [required: >=1.1, installed: 2.0.0]
  - sphinxcontrib-websupport [required: Any, installed: 1.2.4]
    - sphinxcontrib-serializinghtml [required: Any, installed: 1.1.4]

When installing sphinx and sphixcontrib-bibtex, sphinx is set to upgrade to 3.2.1. The error only appears when sphinx is given on the command line. When only sphinxcontrib-bibtex is installed, it works fine and sphinx is upgraded. The error appears both in 20.2.4 and master.

This is the value of weights in get_topological_weights:

{'six': 5, '<Python from Requires-Python>': 5, 'latexcodec': 4, 'pyyaml': 4, 'pybtex': 3, 'setuptools': 3, 'oset': 2, 'docutils': 3, 'pybtex-docutils': 2, 'pyparsing': 4, 'packaging': 3, 'pygments': 3, 'alabaster': 3, 'sphinxcontrib-devhelp': 3, 'sphinxcontrib-jsmath': 3, 'sphinxcontrib-serializinghtml': 3, 'markupsafe': 4, 'jinja2': 3, 'snowballstemmer': 3, 'sphinxcontrib-applehelp': 3, 'sphinxcontrib-htmlhelp': 3, 'idna': 4, 'chardet': 4, 'urllib3': 4, 'certifi': 4, 'requests': 3, 'pytz': 4, 'babel': 3, 'imagesize': 3, 'sphinxcontrib-qthelp': 3, 'sphinx': 2, 'sphinxcontrib-bibtex': 1, None: 0}

This is graph:

<pip._vendor.resolvelib.structs.DirectedGraph object at 0x7f99ccef19d0>

This is graph._vertices:

{'<Python from Requires-Python>', 'oset', None, 'idna', 'sphinxcontrib-devhelp', 'sphinxcontrib-jsmath', 'urllib3', 'sphinxcontrib-htmlhelp', 'six', 'imagesize', 'pyyaml', 'snowballstemmer', 'certifi', 'sphinxcontrib-qthelp', 'markupsafe', 'docutils', 'packaging', 'sphinxcontrib-bibtex', 'sphinx', 'pytz', 'alabaster', 'pyparsing', 'jinja2', 'sphinxcontrib-applehelp', 'babel', 'pygments', 'pybtex-docutils', 'setuptools', 'sphinxcontrib-websupport', 'sphinxcontrib-serializinghtml', 'pybtex', 'requests', 'latexcodec', 'chardet'}

sphinxcontrib-websupport is missing from weights.

This is graph._forwards:

{None: {'sphinxcontrib-bibtex', 'sphinx'}, 'sphinx': {'docutils', 'packaging', '<Python from Requires-Python>', 'pygments', 'setuptools', 'alabaster', 'sphinxcontrib-devhelp', 'sphinxcontrib-jsmath', 'sphinxcontrib-serializinghtml', 'jinja2', 'snowballstemmer', 'sphinxcontrib-applehelp', 'sphinxcontrib-htmlhelp', 'requests', 'babel', 'imagesize', 'sphinxcontrib-qthelp'}, 'sphinxcontrib-bibtex': {'pybtex', 'oset', 'pybtex-docutils', 'sphinx'}, 'alabaster': set(), 'babel': {'pytz'}, 'six': set(), 'packaging': {'six', 'pyparsing'}, 'pybtex': {'six', 'latexcodec', 'pyyaml', '<Python from Requires-Python>'}, 'pybtex-docutils': {'six', 'docutils', 'pybtex', '<Python from Requires-Python>'}, 'latexcodec': {'six', '<Python from Requires-Python>'}, 'docutils': set(), 'jinja2': {'markupsafe'}, 'imagesize': set(), 'requests': {'idna', 'chardet', 'urllib3', 'certifi'}, 'setuptools': set(), 'oset': {'setuptools'}, 'snowballstemmer': set(), 'pygments': set(), 'sphinxcontrib-jsmath': {'<Python from Requires-Python>'}, 'sphinxcontrib-applehelp': {'<Python from Requires-Python>'}, 'sphinxcontrib-htmlhelp': {'<Python from Requires-Python>'}, 'sphinxcontrib-qthelp': {'<Python from Requires-Python>'}, 'sphinxcontrib-devhelp': {'<Python from Requires-Python>'}, 'sphinxcontrib-serializinghtml': set(), 'sphinxcontrib-websupport': {'sphinxcontrib-serializinghtml'}, '<Python from Requires-Python>': set(), 'pyyaml': {'<Python from Requires-Python>'}, 'pytz': set(), 'markupsafe': set(), 'urllib3': set(), 'certifi': set(), 'chardet': set(), 'idna': set(), 'pyparsing': set()}

This is graph._backwards:

{None: set(), 'sphinx': {'sphinxcontrib-bibtex', None}, 'sphinxcontrib-bibtex': {None}, 'alabaster': {'sphinx'}, 'babel': {'sphinx'}, 'six': {'pybtex', 'packaging', 'latexcodec', 'pybtex-docutils'}, 'packaging': {'sphinx'}, 'pybtex': {'sphinxcontrib-bibtex', 'pybtex-docutils'}, 'pybtex-docutils': {'sphinxcontrib-bibtex'}, 'latexcodec': {'pybtex'}, 'docutils': {'pybtex-docutils', 'sphinx'}, 'jinja2': {'sphinx'}, 'imagesize': {'sphinx'}, 'requests': {'sphinx'}, 'setuptools': {'oset', 'sphinx'}, 'oset': {'sphinxcontrib-bibtex'}, 'snowballstemmer': {'sphinx'}, 'pygments': {'sphinx'}, 'sphinxcontrib-jsmath': {'sphinx'}, 'sphinxcontrib-applehelp': {'sphinx'}, 'sphinxcontrib-htmlhelp': {'sphinx'}, 'sphinxcontrib-qthelp': {'sphinx'}, 'sphinxcontrib-devhelp': {'sphinx'}, 'sphinxcontrib-serializinghtml': {'sphinxcontrib-websupport', 'sphinx'}, 'sphinxcontrib-websupport': set(), '<Python from Requires-Python>': {'pybtex-docutils', 'sphinx', 'sphinxcontrib-devhelp', 'sphinxcontrib-jsmath', 'sphinxcontrib-applehelp', 'pybtex', 'sphinxcontrib-htmlhelp', 'latexcodec', 'pyyaml', 'sphinxcontrib-qthelp'}, 'pyyaml': {'pybtex'}, 'pytz': {'babel'}, 'markupsafe': {'jinja2'}, 'urllib3': {'requests'}, 'certifi': {'requests'}, 'chardet': {'requests'}, 'idna': {'requests'}, 'pyparsing': {'packaging'}}