Extras dependencies listed in groups do not raise error.

Description

Buried in the documentation is a single line:

Dependencies listed in dependency groups cannot be specified as extras.

Strictly speaking, you'd never know it, since doing so works fine in your project itself (call it mylibrary). It's only when you go to depend on mylibrary[myextra] in a downstream repo does it become clear that the extra's dependencies are missing.

At least one of poetry lock, poetry build, or poetry publish ought to complain in this case.

Workarounds

Yes, but it is time-consuming to diagnose why dependencies are missing without a careful reading of the documentation.

Poetry Installation Method

other

Operating System

Ubuntu

Poetry Version

Poetry (version 1.8.2)

Poetry Configuration

cache-dir = "/home/REDACTED/.cache/pypoetry"
experimental.system-git-client = false
installer.max-workers = null
installer.modern-installation = true
installer.no-binary = null
installer.parallel = true
keyring.enabled = true
repositories.REDACTED.url = "REDACTED"
solver.lazy-wheel = true
virtualenvs.create = true
virtualenvs.in-project = null
virtualenvs.options.always-copy = false
virtualenvs.options.no-pip = false
virtualenvs.options.no-setuptools = false
virtualenvs.options.system-site-packages = false
virtualenvs.path = "{cache-dir}/virtualenvs"  # /home/REDACTED/.cache/pypoetry/virtualenvs
virtualenvs.prefer-active-python = true
virtualenvs.prompt = "{project_name}-py{python_version}"
warnings.export = false

Python Sysconfig

No response

Example pyproject.toml

mylibrary:

[tool.poetry.dependencies]
dep = "1.0.0"

[tool.poetry.group.downstream.dependencies]
# With or without optional = true:
otherdep = "2.0.0"

[tool.poetry.extras]
myextra = ["otherdep"]

downstream repo:

[tool.poetry.dependencies]
mylibrary = { version = "*", extras = ["myextra"] }
dep = "*"  # GOOD: Detects `dep` in `mylibrary`, pegged to 1.0.0 as expected.
otherdep = "*"  # BAD: Does not detect `dep` in `mylibrary[myextra]`, gets 3.0.0.

### Poetry Runtime Logs

```bash session
N/A

Reproduce the example from the issue in pyproject.toml, then run poetry lock, poetry build, and poetry publish to identify which entry points accept the invalid extra. Trace dependency-group and extras validation from the failing command; done means at least one command reports that group dependencies cannot be specified as extras.