'wheel' not detected when building wheel for legacy setup.py project

Description

Context including links to CI job logs: https://github.com/dependabot/dependabot-core/issues/5478

The pipfile package doesn’t publish a wheel: https://pypi.org/project/pipfile/#files

However, when installing the package, I got the following error message:

Using legacy 'setup.py install' for pipfile, since package 'wheel' is not installed.

This implies that I need to install the wheel package, which is extremely confusing, because I had installed wheel, and other packages were successfully installing wheel.

It took some digging before I realized the problem was that the target package had never published their wheel.

Expected behavior

Please reword the error message to make it clear that the problem is the target package hasn’t published a wheel… maybe:

Using legacy 'setup.py install' for pipfile, since pipfile has not published a wheel.

pip version

22.0.4

Python version

3.10.5

OS

Ubuntu 20.04

How to Reproduce

pip install pipfile

Output

No response

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[pradyunsg]

That’s a valid solution as well, yes.

That might interact weirdly with certain redistributions of Python, such as the one that Debian ships (but IIUC, dependabot doesn’t use the Debian-provided Python, so it should be fine). +

[uranusjr]

The main misunderstanding here was that wheel is not for installing wheels, but for building wheels. So if a project starts publishing wheels, pip can install those directly without needing to build anything, so yes, you wouldn’t see the message in that case.