Fix Open3D import crash when pybind stub directories exist (#7481)

[Iyanuoluwa007]

Type

Fixes #7481

Related issue:
#7481

• Bug fix (non-breaking change which fixes an issue): Fixes #
• New feature (non-breaking change which adds functionality). Resolves #
• Breaking change (fix or feature that would cause existing functionality to not work as expected) Resolves #

Motivation and Context

Checklist:

• I have run python util/check_style.py --apply to apply Open3D code style
  to my code.
• This PR changes Open3D behavior or adds new functionality.
  • Both C++ (Doxygen) and Python (Sphinx / Google style) documentation is
    updated accordingly.
  • I have added or updated C++ and / or Python unit tests OR included test
    results (e.g. screenshots or numbers) here.
• I will follow up and update the code if CI fails.
• For fork PRs, I have selected Allow edits from maintainers.

Description

Problem

When generating Python stubs using pybind11-stubgen, a pybind/ directory is created inside the Open3D package (e.g. open3d/cpu/pybind/ or open3d/cuda/pybind/).

The current implementation in open3d/__init__.py locates the compiled Python extension using:

CDLL(str(next(Path(...).glob("pybind*"))))

However, glob("pybind*") may return both:

• a directory (pybind/)
• a compiled shared library (pybind*.so, pybind*.dll, etc.)

Because next() does not filter by type, the directory may be selected first.

This leads to a runtime crash when ctypes attempts to load a directory:

OSError: ... pybind: Is a directory

Root Cause

• Path.glob("pybind*") matches both files and directories
• No filtering is applied before passing the result to CDLL
• Directory entries can be returned before the actual shared library depending on filesystem ordering

Fix

Filter glob results to ensure only valid shared library files are used:

p for p in Path(...).glob("pybind*") if p.is_file()

## Testing

Reproduced the issue described in #7481 by simulating the directory layout
created by `pybind11-stubgen`.

Created:

cpu/
├── pybind/      (directory)
└── pybind.so    (shared library)

Test script:

```python
from pathlib import Path

paths = list(Path("cpu").glob("pybind*"))
print("ALL MATCHES:", paths)

filtered = [p for p in paths if p.is_file()]
print("FILES ONLY:", filtered)

selected = next(
    p for p in Path("cpu").glob("pybind*")
    if p.is_file()
)
print("SELECTED FILE:", selected)

[update-docs]

Thanks for submitting this pull request! The maintainers of this repository would appreciate if you could update the CHANGELOG.md based on your changes.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Fixes a runtime crash in Open3D’s Python import path when pybind11-stubgen (or similar tooling) leaves pybind/ stub directories alongside the compiled extension, causing ctypes.CDLL to attempt to load a directory.

Changes:

• Filter Path.glob("pybind*") results to files-only before passing to ctypes.CDLL (CPU path).
• Apply the same files-only filtering for the CUDA ctypes.CDLL load used during CUDA availability checks.