refactor: optimize venv creation for nvidia and pkgutil style namespace packages (#3460)

When pkgutil style namespace packages are used, multiple distributions
provide
the same venv path (e.g. `foo/__init__.py`). The venv symlink logic then
tries to
symlink the `foo/` directory as it looks like the highest linkable
directory. When
conflict merging logic runs later, it then has to flatten a depset with
all the files
in the conflicting distributions.

To fix, have whl_library() try to guess when a file is a pkgutil
namespace package.
These are then pass onto py_library's venv building logic so it can
treat the
directories as not directly linkable. A conflict still occurs, but it
only
contains the single `__init__.py` file.

Along the way, special case the "nvidia" package name and always treat
it as a namespace
package. This is because nvidia packages aren't strictly correct: each
has a blank
`__init__.py` file (which marks it as a regular package, not namespace
package). Special
casing like this is undesirable, but it greatly reduces the number of
conflicts if
e.g. torch is installed, and I couldn't find any other metadata to
indicate it's a
namespace package.

Along the way, add some hints to AGENTS.md so they understand repository
rules better.

Fixes https://github.com/bazel-contrib/rules_python/issues/3401

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
28 files changed
tree: 4400f1af2962d26c675f2a7dbf113d662c7fa145
  1. .bazelci/
  2. .bcr/
  3. .ci/
  4. .github/
  5. docs/
  6. examples/
  7. gazelle/
  8. private/
  9. python/
  10. sphinxdocs/
  11. tests/
  12. tools/
  13. .bazelignore
  14. .bazelrc
  15. .bazelrc.deleted_packages
  16. .bazelversion
  17. .editorconfig
  18. .git-blame-ignore-revs
  19. .gitattributes
  20. .gitignore
  21. .pre-commit-config.yaml
  22. .python-version
  23. .readthedocs.yml
  24. addlicense.sh
  25. AGENTS.md
  26. AUTHORS
  27. BUILD.bazel
  28. BZLMOD_SUPPORT.md
  29. CHANGELOG.md
  30. CONTRIBUTING.md
  31. CONTRIBUTORS
  32. GEMINI.md
  33. internal_dev_deps.bzl
  34. internal_dev_setup.bzl
  35. LICENSE
  36. MODULE.bazel
  37. README.md
  38. RELEASING.md
  39. version.bzl
  40. WORKSPACE
  41. WORKSPACE.bzlmod
README.md

Python Rules for Bazel

Build status

Overview

This repository is the home of the core Python rules -- py_library, py_binary, py_test, py_proto_library, and related symbols that provide the basis for Python support in Bazel. It also contains package installation rules for integrating with PyPI and other indices.

Documentation for rules_python is at https://rules-python.readthedocs.io and in the Bazel Build Encyclopedia.

Examples live in the examples directory.

The core rules are stable. Their implementation is subject to Bazel's backward compatibility policy. This repository aims to follow semantic versioning.

The Bazel community maintains this repository. Neither Google nor the Bazel team provides support for the code. However, this repository is part of the test suite used to vet new Bazel releases. See How to contribute page for information on our development workflow.

Documentation

For detailed documentation, see https://rules-python.readthedocs.io

Bzlmod support

See Bzlmod support for more details.