Example project demonstrating failure of poetry to correctly install packages with compiled dependencies.

When you have configured poetry to generate a setup file, for example by using:

[tool.poetry.build]
script = "build.py"
generate-setup-file = true

and then attempt an editable install, poetry will include the module in the generated wheel, which leads to it being added to the site-packages folder, breaking the whole point of the editable installation. Moreover, compiled modules are not built in-place, meaning that the module cannot be used "editably" even if that issue were resolved.

See poetry-core#335 for more details, and a potential fix.

Reproduction

To reproduce the issue, run pip install -e . in the root folder of a checked out copy of this repository. You will note:

1. editable_failure is installed into the site-packages folder of the appropriate Python installation. (PEP 660 indicates that only the files necessary to create an editable installation should be included; see https://peps.python.org/pep-0660/#what-to-put-in-the-wheel ).
2. cpp_module is not built inplace in the local checked out copy of the module, which is necessary if you actually wanted to use the Python code in an editable manner. (This is an optional feature suggested by PEP 660; see https://peps.python.org/pep-0660/#build-editable).

If you comment out the poetry-core build requirement in the pyproject.toml file, uncomment the "poetry-core @ git+https://github.com/matthewwardrop/poetry-core.git@fix_editable_installs" requirement, and then rerun pip install -e ., things work as they should.

Other notes

Using poetry instead of poetry-core does not fix anything.