requirement with extra not installed

[adamchainz]

s## Issue

Minimized from daphne, which I just tried upgrading to tox 4.

Take this project setup in 4 files:

pyproject.toml:

[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"

setup.cfg:

[metadata]
name = example

[options]
py_modules = example
install_requires =
    twisted[tls]>=22.4

example.py:

import twisted

tox.ini:

[tox]
envlist = 311

[testenv]
commands =
    python -m example

On tox 3, this passes. On tox 4.0.0rc2+, it fails by not installing twisted:

tox
.pkg: install_requires> python -I -m pip install setuptools
.pkg: _optional_hooks> python /.../python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta
.pkg: get_requires_for_build_sdist> python /.../python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta
.pkg: prepare_metadata_for_build_wheel> python /.../python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta
.pkg: build_sdist> python /.../python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta
311: install_package> python -I -m pip install --force-reinstall --no-deps /Users/chainz/tmp/toxfail/.tox/.pkg/dist/example-0.0.0.tar.gz
311: commands[0]> python -m example
Traceback (most recent call last):
  File "<frozen runpy>", line 198, in _run_module_as_main
  File "<frozen runpy>", line 88, in _run_code
  File "/Users/chainz/tmp/toxfail/example.py", line 1, in <module>
    import twisted
ModuleNotFoundError: No module named 'twisted'
311: exit 1 (0.01 seconds) /Users/chainz/tmp/toxfail> python -m example pid=735
.pkg: _exit> python /.../python3.11/site-packages/pyproject_api/_backend.py True setuptools.build_meta
  311: FAIL code 1 (3.01=setup[3.00]+cmd[0.01] seconds)
  evaluation failed :( (3.03 seconds)

This succeeds on tox 4.0.0rc1.

Removing the [tls] extra from twisted in setup.cfg also makes this pass on tox 4.0.0rc2+.

I suspect it has the same cause as #2603.

[adamchainz]

Bisected to #2579.

[gaborbernat]

Can you try with #2605 ?

[gaborbernat]

Duplicate of #2603.

[adamchainz]

That’s fixed it! Thanks.