Remove deprecated rmm.pylibrmm.cuda_stream module

[bdice]

Summary

• Remove the deprecated rmm.pylibrmm.cuda_stream backwards-compatibility shim module (.pyx, .pxd, .pyi)
• Remove the associated deprecation test (test_cuda_stream_module_deprecation)
• Remove cuda_stream.pyx from the Cython build sources in CMakeLists.txt

The module was deprecated in #2256 (closing #1782) when stream objects were moved to rmm.pylibrmm.stream. Users should use rmm.pylibrmm.stream.Stream and rmm.pylibrmm.stream.CudaStreamFlags instead.

Checklist

• I am familiar with the Contributing Guidelines.
• New or existing tests cover these changes.
• The documentation is up to date with these changes.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 5e7034b and 8124760.

📒 Files selected for processing (1)

• docs/python/pylibrmm.md

💤 Files with no reviewable changes (1)

• docs/python/pylibrmm.md

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📝 Walkthrough

Summary by CodeRabbit

• Chores
  • Removed the cuda_stream module and associated CudaStream and CudaStreamFlags type definitions.
  • Removed related test coverage.
  • Updated copyright year to 2026.

Walkthrough

This PR removes the deprecated cuda_stream compatibility module and its type stubs, updates the CMake cython sources to omit cuda_stream.pyx and reorders remaining sources, removes the deprecation-focused test, and updates the SPDX copyright year to 2026.

Changes

Cohort / File(s)	Summary
Build configuration python/rmm/rmm/pylibrmm/CMakeLists.txt	Removed cuda_stream.pyx from the cython_sources list, reordered remaining .pyx entries, and updated SPDX copyright year to 2026.
Deprecated compatibility module python/rmm/rmm/pylibrmm/cuda_stream.pyx, python/rmm/rmm/pylibrmm/cuda_stream.pxd, python/rmm/rmm/pylibrmm/cuda_stream.pyi	Deleted the deprecated shim that re-exported CudaStream/CudaStreamFlags (and its import-time deprecation warning); removed related pxd and pyi declarations.
Tests python/rmm/rmm/tests/test_stream.py	Removed test_cuda_stream_module_deprecation which asserted the import emitted a DeprecationWarning.
Docs docs/python/pylibrmm.md	Removed Sphinx automodule:: rmm.pylibrmm.cuda_stream block from CUDA Stream documentation.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• Forward-merge release/26.04 into main #2334: Switches usages away from rmm.pylibrmm.cuda_stream to rmm.pylibrmm.stream for stream flags/types.
• Fix flags type annotation in CudaStreamPool #2331: Updates typing/imports to stop referencing the deprecated cuda_stream stub and use stream instead.
• Move stream objects from cuda_stream cython to stream cython #2256: Previously added the deprecated re-export shim (the module that this PR removes).

Suggested labels

3 - Ready for review

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Remove deprecated rmm.pylibrmm.cuda_stream module' directly and clearly summarizes the main change: removing the deprecated cuda_stream module and related components.
Description check	✅ Passed	The description clearly explains the removal of the deprecated cuda_stream module, associated test, and CMakeLists.txt update, providing context about the prior deprecation and migration guidance for users.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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🧪 Generate unit tests (beta)

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[TomAugspurger]

Docs failure:

WARNING: autodoc: failed to import module 'cuda_stream' from module 'rmm.pylibrmm'; the following exception was raised:

['Traceback (most recent call last):\n', '  File "/opt/conda/envs/docs/lib/python3.14/site-packages/sphinx/ext/autodoc/importer.py", line 269, in import_object\n    module = import_module(modname, try_reload=True)\n', '  File "/opt/conda/envs/docs/lib/python3.14/site-packages/sphinx/ext/autodoc/importer.py", line 172, in import_module\n    raise ModuleNotFoundError(msg, name=modname)  # NoQA: TRY301\n    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n', "ModuleNotFoundError: No module named 'rmm.pylibrmm.cuda_stream'\n"] [autodoc.import_object]

I think this section can be removed:

rmm/docs/python/pylibrmm.md

Lines 27 to 34 in b325755

	### rmm.pylibrmm.cuda_stream
	```{eval-rst}
	.. automodule:: rmm.pylibrmm.cuda_stream
	:members:
	:undoc-members:
	:show-inheritance:
	```

[TomAugspurger]

LGTM once the docs section is removed.