Confusing message when the wheel package is not installed

[mcclurem]

Environment

• pip version: 20.1
• Python version: 3.6
• OS: CentOS 6.9

Description
I happen to have a script that myself and my coworkers I run frequently to create a virtualenv, update to the latest version of pip, then install a pinned requirements.txt as part of my daily workflow. Suddenly when I ran it today I got a whole lot of:
Could not build wheels for <pkgname>, since package 'wheel' is not installed.
I got this message even though all my requirements were actually up to date so it shouldn't have even been trying to build wheels.

The wording of this is extremely jarring and especially since theres no coloration of the output or a prefix saying "INFO" or something, the first assumption that myself and my coworkers made was that our package installation wasn't happening correctly.

This pull request should be reverted or at the very least the language changed a lot because it will cause a lot of panic. I would argue that it should only launch a single log line at the top that says something like "Info: the package wheel isn't installed, so we won't try building any wheels" instead of printing one line for each package

[sbidoul]

Linking #7768

[sbidoul]

Example output when reinstalling packaging from a local directory in a venv without the wheel package:

$ pip install ./packaging                                                                                                                                                    Processing ./packaging
Requirement already satisfied: pyparsing>=2.0.2 in /tmp/venv/lib/python3.7/site-packages (from packaging==20.1) (2.4.7)
Requirement already satisfied: six in /tmp/venv/lib/python3.7/site-packages (from packaging==20.1) (1.14.0)
Could not build wheels for packaging, since package 'wheel' is not installed.
Could not build wheels for pyparsing, since package 'wheel' is not installed.
Could not build wheels for six, since package 'wheel' is not installed.
Installing collected packages: packaging
  Attempting uninstall: packaging
    Found existing installation: packaging 20.1
    Uninstalling packaging-20.1:
      Successfully uninstalled packaging-20.1
    Running setup.py install for packaging ... done
Successfully installed packaging-20.1

[sbidoul]

Improved output with #8180 :

$ pip install ./packaging
Processing ./packaging
Requirement already satisfied: pyparsing>=2.0.2 in /tmp/venv/lib/python3.7/site-packages (from packaging==20.1) (2.4.7)
Requirement already satisfied: six in /tmp/venv/lib/python3.7/site-packages (from packaging==20.1) (1.14.0)
Using legacy setup.py install for packaging, since package 'wheel' is not installed.
Installing collected packages: packaging
  Attempting uninstall: packaging
    Found existing installation: packaging 20.1
    Uninstalling packaging-20.1:
      Successfully uninstalled packaging-20.1
    Running setup.py install for packaging ... done
Successfully installed packaging-20.1

[sbidoul]

@mcclurem Thanks for reporting. Could you test #8180?

[mcclurem]

I'd be happy to test it, is there an easy trick for testing/installing pip from a git hash or do I need to check it out and then do a "python setup.py install"?

[xavfernandez]

pip install https://github.com/sbidoul/pip/archive/wheel-absent-warning-sbi.zip should work.

[mcclurem]

Looks good!

[rahitashpaul]

pip install . wheel

problem solve