editable install breaks custom package_dir spec

I have a project with this directory structure:

- project_folder_name
  - lib
    - __init__.py
    - module.py
    - ...

So in my setup.py I followed the instructions in the docs and set the package_dir:

from setuptools import setup
setup(name='project-name',
      packages=['project'],
      package_dir={'project' : 'lib'},
)

If I install normally python setup.py install everything is fine and I can get the module like: import project. (Possibly another issue but pip install . seems to have issues though.)

However, in development mode python setup.py develop or pip install -e . I can’t import via the package name. Strangely, I can import from the folder name import lib.

Just as a reference and sanity check I also tried other organizations that work i.e. “lib/project” with package_dir={'' : 'lib'}. Would like for this directory structure though if possible.

[itcarroll]

thanks @abravalheri for offering to troubleshoot my pyproject.toml! I was copying the error here when I finally read it in eough detail to realize that package_dir is renamed package-dir for use in pyproject.toml. So this is my now working and equivalent pyproject.toml

[project]
name = "test-1801"
version = "0.1.0"

[tool.setuptools]
packages = ["issue_1801"]
package-dir = { issue_1801 = "src" }

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

[abravalheri]

Thank you for confirming @itcarroll !