Deprecate call to 'setup.py install' when 'wheel' is absent for source distributions without pyproject.toml

This is one of a series of deprecations meant to collect feedback on the ultimate goal of always installing source distributions by first building a wheel and then installing from it.

This specific issue is about the case when pip has to call setup.py bdist_wheel because the wheel package is not installed. In that case, pip currently displays deprecation warning and continues installation by attempting a setup.py install.

In a future version, pip will ~either (to be decided)~:

• ~fail right away~
• ~attempt setup.py bdist_wheel and let that fail (the error message might be unclear in that case)~
• attempt an isolated build in PEP 517 mode with the default build system

The recommended way to silence this warning is to enable the --use-pep517 flag, which will in turn install setuptools and wheel in an isolated environment where it will attempt to build a wheel and install it.

Towards #8102

[melaukik]

ok no the building wheels issue is legit that astephan023 posted. I am getting the same error while installing grpcio, typedb client etc multiple files. Idk what the problem is the error is Building wheel for grpcio (pyproject.toml) did not run successfully. and then the last message is the same as what astephan says

[pradyunsg]

Will pip install http://example.com/some_source_tarball.zip run the build in an isolated or not isolated environment, if wheel is present in the current (virtual) environment?

It’ll behave the same as today, if wheel is installed – i.e. without isolation if there’s no pyproject.toml. That will not change due to this issue, but as @uranusjr alluded to, it will be changing with a similar message in a future pip release.