DLL loading fails when using pyenv and poetry on Windows

[daara-s]

When using pyenv for python versions, and poetry for virtual environments, the following bit of lib loading code for treelite breaks with the error:

ImportError while loading conftest 'C:\Users\daarashaw\windows-dev\my_repo\tests\conftest.py'.
...
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\tl2cgen\__init__.py:6: in <module>
    from .core import _dump_compiler_ast, _py_version, annotate_branch, generate_c_code
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\tl2cgen\core.py:8: in <module>
    import treelite
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\treelite\__init__.py:5: in <module>
    from . import frontend, gtil, model_builder, sklearn
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\treelite\frontend.py:10: in <module>
    from . import compat
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\treelite\compat.py:9: in <module>
    from .core import _LIB, TreeliteError, _check_call
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\treelite\core.py:58: in <module>
    _LIB = _load_lib()
..\..\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\lib\site-packages\treelite\core.py:36: in _load_lib
    os.add_dll_directory(
..\..\.pyenv\pyenv-win\versions\3.10.11\lib\os.py:1118: in add_dll_directory
    cookie = nt._add_dll_directory(path)
E   FileNotFoundError: [WinError 3] The system cannot find the path specified: 'C:\\Users\\daarashaw\\.pyenv\\pyenv-win\\versions\\3.10.11\\Library\\bin'

poetry env info

Virtualenv
Python:         3.10.11
Implementation: CPython
Path:           C:\Users\daarashaw\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10
Executable:     C:\Users\daarashaw\AppData\Local\pypoetry\Cache\virtualenvs\my-repo-py3.10\Scripts\python.exe
Valid:          True

Base
Platform:   win32
OS:         nt
Python:     3.10.11
Path:       C:\Users\daarashaw\.pyenv\pyenv-win\versions\3.10.11
Executable: C:\Users\daarashaw\.pyenv\pyenv-win\versions\3.10.11\python.exe

In here, it doesn't check whether the folder exists, causing it to break.

I've been able to manually solve it my making the Library/bin directory under my base virtualenv.

---

What's the purpose of this dll location check, is it for a specific python install method (eg via conda?)

I can make a quick PR fix to solve it later today. Should just need checking whether the folder exists before trying to add a dll from it.

[hcho3]

Yes, feel free to submit a pull request.