AttributeError: can't set attribute on v1.2.0a1 during lock or install

• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: Debian Linux (slim-buster docker image, python 3.8.2)
• Poetry version: 1.2.0a1

Issue

I am seeing the following issue when a new project is created with the following minimal pyproject.toml file:

[build-system]
requires = ["poetry-core>=1.0.0"]
build-backend = "poetry.core.masonry.api"

[tool.poetry]
name = "example"
version = "0.1.0-alpha.0"
description = "An example"
authors = ["First Last <[e-mail]>"]

Running poetry install or poetry lock gives the following error:

Skipping virtualenv creation, as specified in config file.
Updating dependencies
Resolving dependencies... (0.0s)

  AttributeError

  can't set attribute

  at /opt/poetry/venv/lib/python3.8/site-packages/poetry/packages/dependency_package.py:38 in __setattr__
       34│     def __setattr__(self, key: str, value: Any) -> None:
       35│         if key in {"_dependency", "_package"}:
       36│             return super().__setattr__(key, value)
       37│ 
    →  38│         setattr(self._package, key, value)
       39│ 
       40│     def __str__(self) -> str:
       41│         return str(self._package)

Note there are no dependencies in the pyproject.toml file. In addition to standard install of python, the only other package installed is poetry-dotenv-plugin and it’s dependencies. Here is a pip list if needed:

appdirs              1.4.4
CacheControl         0.12.6
cachy                0.3.0
certifi              2021.5.30
cffi                 1.14.6
charset-normalizer   2.0.4
cleo                 1.0.0a4
crashtest            0.3.1
cryptography         3.4.7
distlib              0.3.2
entrypoints          0.3
filelock             3.0.12
html5lib             1.1
idna                 3.2
importlib-metadata   4.6.3
jeepney              0.7.1
keyring              23.0.1
lockfile             0.12.2
msgpack              1.0.2
packaging            20.9
pexpect              4.8.0
pip                  21.1.3
pkginfo              1.7.1
poetry               1.2.0a1
poetry-core          1.1.0a6
poetry-dotenv-plugin 0.1.0a2
ptyprocess           0.7.0
pycparser            2.20
pylev                1.4.0
pyparsing            2.4.7
python-dotenv        0.19.0
requests             2.26.0
requests-toolbelt    0.9.1
SecretStorage        3.3.1
setuptools           41.2.0
shellingham          1.4.0
six                  1.16.0
tomlkit              0.7.2
urllib3              1.26.6
virtualenv           20.4.4
webencodings         0.5.1
zipp                 3.5.0

This issue may be related to issue 4085.

[covuworie]

Thanks @KCC13 and @paulmelnikow. I tested today with v1.2.0a2 and it fixed the problem. The maintainers can close this issue when they are ready.

[dimbleby]

indeed this code doesn’t exist any more, should be safe to close