Cannot "poetry add matplotlib", possible bug in dependency resolution

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Ubuntu 18.04
• Poetry version: 0.12.4
• Contents of your pyproject.toml file: [tool.poetry] name = “test” version = “0.1.0” description = “” authors = [“mbello [e-mail]”]

[tool.poetry.dependencies] python = “*”

[tool.poetry.dev-dependencies] pytest = “^3.0”

[build-system] requires = [“poetry>=0.12”] build-backend = “poetry.masonry.api”

Issue

Matplotlib requires python >=3.5 I am on python 3.6.6 and poetry does not allow me to install matplotlib. The command poetry run pip install matplotlib did work as a workaround.

Steps to reproduce

$ rm -Rf test $ poetry new test Created package test in test $ cd test $ poetry --version Poetry 0.12.4 $ python --version Python 3.6.6 $ poetry run python --version Creating virtualenv test-py3.6 in /home/mbello/PycharmProjects/test/.venv Python 3.6.6 $ poetry -vvv add matplotlib Using virtualenv: /home/mbello/PycharmProjects/test/.venv PyPI: No release information found for matplotlib-0.63.0, skipping PyPI: No release information found for matplotlib-0.64, skipping PyPI: No release information found for matplotlib-0.65, skipping PyPI: No release information found for matplotlib-0.70, skipping PyPI: No release information found for matplotlib-0.71, skipping PyPI: No release information found for matplotlib-0.83.2, skipping PyPI: No release information found for matplotlib-0.85, skipping PyPI: No release information found for matplotlib-0.87.1, skipping PyPI: No release information found for matplotlib-0.87.2, skipping PyPI: No release information found for matplotlib-0.87.3, skipping PyPI: No release information found for matplotlib-0.87.4, skipping PyPI: No release information found for matplotlib-0.87.5, skipping PyPI: No release information found for matplotlib-0.87.6, skipping PyPI: No release information found for matplotlib-0.87.7, skipping PyPI: No release information found for matplotlib-0.90.0, skipping PyPI: No release information found for matplotlib-0.90.1, skipping PyPI: No release information found for matplotlib-0.91.2, skipping PyPI: No release information found for matplotlib-0.91.3, skipping PyPI: No release information found for matplotlib-0.91.4, skipping PyPI: No release information found for matplotlib-0.98.0, skipping PyPI: No release information found for matplotlib-0.98.1, skipping PyPI: No release information found for matplotlib-0.98.3, skipping PyPI: No release information found for matplotlib-0.98.5.1, skipping PyPI: No release information found for matplotlib-0.98.5.3, skipping PyPI: No release information found for matplotlib-0.99.0, skipping PyPI: No release information found for matplotlib-0.99.1, skipping PyPI: No release information found for matplotlib-0.99.3, skipping PyPI: No release information found for matplotlib-1.0.0, skipping PyPI: 41 packages found for matplotlib * Using version ^3.0 for matplotlib

Updating dependencies Resolving dependencies… 1: fact: test is 0.1.0 1: derived: test 1: fact: test depends on matplotlib (^3.0) 1: fact: test depends on pytest (^3.0) 1: selecting test (0.1.0) 1: derived: pytest (^3.0) 1: derived: matplotlib (^3.0) PyPI: 42 packages found for pytest >=3.0,<4.0 PyPI: No release information found for matplotlib-0.63.0, skipping PyPI: No release information found for matplotlib-0.64, skipping PyPI: No release information found for matplotlib-0.65, skipping PyPI: No release information found for matplotlib-0.70, skipping PyPI: No release information found for matplotlib-0.71, skipping PyPI: No release information found for matplotlib-0.83.2, skipping PyPI: No release information found for matplotlib-0.85, skipping PyPI: No release information found for matplotlib-0.87.1, skipping PyPI: No release information found for matplotlib-0.87.2, skipping PyPI: No release information found for matplotlib-0.87.3, skipping PyPI: No release information found for matplotlib-0.87.4, skipping PyPI: No release information found for matplotlib-0.87.5, skipping PyPI: No release information found for matplotlib-0.87.6, skipping PyPI: No release information found for matplotlib-0.87.7, skipping PyPI: No release information found for matplotlib-0.90.0, skipping PyPI: No release information found for matplotlib-0.90.1, skipping PyPI: No release information found for matplotlib-0.91.2, skipping PyPI: No release information found for matplotlib-0.91.3, skipping PyPI: No release information found for matplotlib-0.91.4, skipping PyPI: No release information found for matplotlib-0.98.0, skipping PyPI: No release information found for matplotlib-0.98.1, skipping PyPI: No release information found for matplotlib-0.98.3, skipping PyPI: No release information found for matplotlib-0.98.5.1, skipping PyPI: No release information found for matplotlib-0.98.5.3, skipping PyPI: No release information found for matplotlib-0.99.0, skipping PyPI: No release information found for matplotlib-0.99.1, skipping PyPI: No release information found for matplotlib-0.99.3, skipping PyPI: No release information found for matplotlib-1.0.0, skipping PyPI: 2 packages found for matplotlib >=3.0,<4.0 1: fact: matplotlib (3.0.1) requires Python >=3.5 1: derived: not matplotlib (3.0.1) 1: fact: matplotlib (3.0.0) requires Python >=3.5 1: derived: not matplotlib (3.0.0) 1: fact: no versions of matplotlib match >3.0,❤️.0.1 || >3.0.1,<4.0 1: conflict: no versions of matplotlib match >3.0,❤️.0.1 || >3.0.1,<4.0 1: ! matplotlib (>3.0,❤️.0.1 || >3.0.1,<4.0) is partially satisfied by not matplotlib (3.0.0) 1: ! which is caused by “matplotlib (3.0.0) requires Python >=3.5” 1: ! thus: matplotlib is forbidden 1: ! matplotlib (>=3.0,❤️.0.1 || >3.0.1,<4.0) is partially satisfied by not matplotlib (3.0.1) 1: ! which is caused by “matplotlib (3.0.1) requires Python >=3.5” 1: ! thus: matplotlib is forbidden 1: ! matplotlib (>=3.0,<4.0) is satisfied by matplotlib (^3.0) 1: ! which is caused by “test depends on matplotlib (^3.0)” 1: ! thus: version solving failed 1: Version solving took 0.247 seconds. 1: Tried 1 solutions.

[SolverProblemError]
The current supported Python versions are *
Because no versions of matplotlib match >3.0,❤️.0.1 || >3.0.1,<4.0
and matplotlib (3.0.0) requires Python >=3.5, matplotlib is forbidden.
So, because matplotlib (3.0.1) requires Python >=3.5
and test depends on matplotlib (^3.0), version solving failed.

Exception trace: /home/mbello/.poetry/lib/poetry/vendor/py3.6/cleo/application.py in run() at line 94 status_code = self.do_run(input, output_) /home/mbello/.poetry/lib/poetry/console/application.py in do_run() at line 88 return super(Application, self).do_run(i, o) /home/mbello/.poetry/lib/poetry/vendor/py3.6/cleo/application.py in do_run() at line 197 status_code = command.run(input, output_) /home/mbello/.poetry/lib/poetry/console/commands/command.py in run() at line 77 return super(BaseCommand, self).run(i, o) /home/mbello/.poetry/lib/poetry/vendor/py3.6/cleo/commands/base_command.py in run() at line 146 status_code = self.execute(input, output_) /home/mbello/.poetry/lib/poetry/_vendor/py3.6/cleo/commands/command.py in execute() at line 107 return self.handle() /home/mbello/.poetry/lib/poetry/console/commands/add.py in handle() at line 139 status = installer.run() /home/mbello/.poetry/lib/poetry/installation/installer.py in run() at line 76 self._do_install(local_repo) /home/mbello/.poetry/lib/poetry/installation/installer.py in _do_install() at line 158 ops = solver.solve(use_latest=self._whitelist) /home/mbello/.poetry/lib/poetry/puzzle/solver.py in solve() at line 37 packages, depths = self._solve(use_latest=use_latest) /home/mbello/.poetry/lib/poetry/puzzle/solver.py in _solve() at line 154 raise SolverProblemError(e)

add [-D|–dev] [–git GIT] [–path PATH] [-E|–extras EXTRAS] [–optional] [–python PYTHON] [–platform PLATFORM] [–allow-prereleases] [–dry-run] [–] <name> (<name>)…

$ poetry run pip install matplotlib Collecting matplotlib Using cached https://files.pythonhosted.org/packages/1e/f8/4aba1144dad8c67db060049d1a8bc740ad9fa35288d21b82bb85de69ff15/matplotlib-3.0.1-cp36-cp36m-manylinux1_x86_64.whl Collecting python-dateutil>=2.1 (from matplotlib) Using cached https://files.pythonhosted.org/packages/74/68/d87d9b36af36f44254a8d512cbfc48369103a3b9e474be9bdfe536abfc45/python_dateutil-2.7.5-py2.py3-none-any.whl Collecting cycler>=0.10 (from matplotlib) Using cached https://files.pythonhosted.org/packages/f7/d2/e07d3ebb2bd7af696440ce7e754c59dd546ffe1bbe732c8ab68b9c834e61/cycler-0.10.0-py2.py3-none-any.whl Collecting pyparsing!=2.0.4,!=2.1.2,!=2.1.6,>=2.0.1 (from matplotlib) Using cached https://files.pythonhosted.org/packages/2b/4a/f06b45ab9690d4c37641ec776f7ad691974f4cf6943a73267475b05cbfca/pyparsing-2.2.2-py2.py3-none-any.whl Collecting kiwisolver>=1.0.1 (from matplotlib) Using cached https://files.pythonhosted.org/packages/69/a7/88719d132b18300b4369fbffa741841cfd36d1e637e1990f27929945b538/kiwisolver-1.0.1-cp36-cp36m-manylinux1_x86_64.whl Collecting numpy>=1.10.0 (from matplotlib) Using cached https://files.pythonhosted.org/packages/16/21/2e88568c134cc3c8d22af290865e2abbd86efa58a1358ffcb19b6c74f9a3/numpy-1.15.3-cp36-cp36m-manylinux1_x86_64.whl Collecting six>=1.5 (from python-dateutil>=2.1->matplotlib) Using cached https://files.pythonhosted.org/packages/67/4b/141a581104b1f6397bfa78ac9d43d8ad29a7ca43ea90a2d863fe3056e86a/six-1.11.0-py2.py3-none-any.whl Requirement already satisfied: setuptools in ./.venv/lib/python3.6/site-packages (from kiwisolver>=1.0.1->matplotlib) Installing collected packages: six, python-dateutil, cycler, pyparsing, kiwisolver, numpy, matplotlib Successfully installed cycler-0.10.0 kiwisolver-1.0.1 matplotlib-3.0.1 numpy-1.15.3 pyparsing-2.2.2 python-dateutil-2.7.5 six-1.11.0

[sdispater]

The default behavior will not change since I prefer people stumbling on the error when adding the package and make it clear for them what’s going on than locking a version of a package that is not compatible with the Python versions supported by the project and lead to the confusion of not understanding why the package does not appear in non-supported Python versions.

[sdispater]

If any version is supported and matplotlib requires a supported version why is this dependency not met?

This is the other way around. Poetry will always try to find a package version that is compatible with the all the versions supported by the project.

But I admit that the wording is not the clearest. I will see if I can improve it.