Fix #363: AttributeError: module 'cupy' has no attribute '_cupyx'

[JiwaniZakir]

Closes #363

Motivation

cupy._cupyx is a private internal attribute that was removed in CuPy 14.x, causing an AttributeError on initialization when CupyFunctions.__init__ called cp._cupyx.get_runtime_info() at kernel_tuner/backends/cupy.py:71.

Changes

kernel_tuner/backends/cupy.py

• Added import cupyx alongside import cupy as cp in the guarded try/except ImportError block (with cupyx = None as the fallback), making cupyx a proper top-level dependency rather than accessing it through CuPy's private namespace.
• Replaced cp._cupyx.get_runtime_info() with cupyx.get_runtime_info() on line 71.

test/test_cupy_functions.py

• Added test_cupy_init_uses_cupyx_not_private_attr: patches both kernel_tuner.backends.cupy.cp and kernel_tuner.backends.cupy.cupyx, constructs a CupyFunctions(device=0) instance, and asserts that cupyx.get_runtime_info() was called exactly once and that dev.name is correctly parsed from the mocked runtime info string. This serves as a regression test to prevent re-introduction of the _cupyx private attribute access.

Testing

The new unit test runs without a physical GPU by mocking both cp.cuda.Device and cupyx.get_runtime_info. Run it with:

pytest test/test_cupy_functions.py::test_cupy_init_uses_cupyx_not_private_attr -v

Manually verified on Google Colab with CuPy 14.0.1: CupyFunctions initializes without error and dev.env is populated correctly.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud