Installing private package (=package not published on pypi) is possible with pip using pip install -e .[dev]. It respects extra dependencies and the extra dependencies can even reference themselves (see the example bellow). However compiling such a project to get requirements.txt fails.

Environment Versions

1. OS Type: ubuntu 18.04
2. Python version: $ python -V: Python 3.8.0
3. pip version: $ pip --version: pip 22.2.2
4. pip-tools version: $ pip-compile --version: version 6.8.0

Steps to replicate

Minimal pyproject.toml:

[project]
name = "privateproject"
version = "0.0.1"
dependencies = [
    "tomli",
]

[project.optional-dependencies]
test = [
    "pep517",
]
dev = [
    "privateproject[test]",
]

1. save minimal pyproject.toml
2. run python -m piptools compile --extra dev pyproject.toml

Expected result

The requirements.txt is generated containing tomli and pep517.

Actual result

Could not find a version that matches privateproject[test] (from privateproject (pyproject.toml))
No versions found
Was https://pypi.org/simple reachable?