Install multiple extra dependencies using the square brackets method in one pip install command.

[hongyi-zhao]

Hi,

The following codes are the content of extras_require section of setup.py for pymatgen.

    extras_require={
        "provenance": ["pybtex"],
        "ase": ["ase>=3.3"],
        "vis": ["vtk>=6.0.0"],
        "abinit": ["netcdf4"],
        ':python_version < "3.7"': [
            "dataclasses>=0.6",
        ]},

So, if I want to install all of these extra dependencies with one run of pip, can I use the following command to do the trick:

$ pip install .[provenance,ase,vis,abinit] 

Regards,
HY

[uranusjr]

yes

[karlicoss]

Not sure if I should create a separate issue for that, but: before the new resolver it was possible to run something like pip install .[extra1] .[extra2]. Not it seems to fail, e.g.

$ pip3 install --user -e '.[testing]' '.[optional]'
Processing /adhoc-project
...
INFO: pip is looking at multiple versions of hpi[optional] to determine which version is compatible with other requirements. This could take a while.
ERROR: Cannot install hpi[optional]==0.2.20201126.dev4 and hpi[testing]==0.2.20201126.dev4 because these package versions have conflicting dependencies.

The conflict is caused by:
    hpi[optional] 0.2.20201126.dev4 depends on hpi 0.2.20201126.dev4 (from /adhoc-project)
    hpi[testing] 0.2.20201126.dev4 depends on hpi 0.2.20201126.dev4 (from /adhoc-project)

To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict

, whereas pip3 install --user -e '.[testing,optional]' works. Is this expected? The error message is a bit obscure, no way I would have guessed how to fix it without running into this issue :) Maybe worth adding a note about extras_require to the migration guide?
If necessary, happy to file a proper bugreport with a minimal reproducing example.

[uranusjr]

This is known, see #8785.