build: enable free-threading compatibility (#1103)

* build: enable free-threading compatibility

* chore: add ftcompat flag to cython tests

* build: enable ft compat for all cython tests

Author: cpcloud

cuda_bindings/setup.py

@@ -329,7 +329,7 @@ def do_cythonize(extensions):
     return cythonize(
         extensions,
         nthreads=nthreads,
-        compiler_directives=dict(language_level=3, embedsignature=True, binding=True),
+        compiler_directives=dict(language_level=3, embedsignature=True, binding=True, freethreading_compatible=True),
         **extra_cythonize_kwargs,
     )
 

cuda_bindings/tests/cython/build_tests.bat

@@ -5,5 +5,5 @@ REM SPDX-License-Identifier: LicenseRef-NVIDIA-SOFTWARE-LICENSE
 
 setlocal
 	set CL=%CL% /I"%CUDA_HOME%\include"
-	cythonize -3 -i %~dp0test_*.pyx
+	cythonize -3 -i -Xfreethreading_compatible=True %~dp0test_*.pyx
 endlocal

cuda_bindings/tests/cython/build_tests.sh

@@ -14,4 +14,4 @@ else
   exit 1
 fi
 
-cythonize -3 -i ${SCRIPTPATH}/test_*.pyx
+cythonize -3 -i -Xfreethreading_compatible=True ${SCRIPTPATH}/test_*.pyx

cuda_core/build_hooks.py

@@ -101,7 +101,7 @@ def get_cuda_paths():
         verbose=True,
         language_level=3,
         nthreads=nthreads,
-        compiler_directives={"embedsignature": True, "warn.deprecated.IF": False},
+        compiler_directives={"embedsignature": True, "warn.deprecated.IF": False, "freethreading_compatible": True},
         compile_time_env=compile_time_env,
     )
 

cuda_core/pyproject.toml

@@ -51,7 +51,7 @@ cu12 = ["cuda-bindings[all]==12.*"]
 cu13 = ["cuda-bindings[all]==13.*"]
 
 [dependency-groups]
-test = ["cython>=3.0", "setuptools", "pytest>=6.2.4"]
+test = ["cython>=3.1", "setuptools", "pytest>=6.2.4"]
 test-cu12 = ["cuda-core[test]", "cupy-cuda12x; python_version < '3.14'", "cuda-toolkit[cudart]==12.*"]  # runtime headers needed by CuPy
 test-cu13 = ["cuda-core[test]", "cupy-cuda13x; python_version < '3.14'", "cuda-toolkit[cudart]==13.*"]  # runtime headers needed by CuPy
 # free threaded build, cupy doesn't support free-threaded builds yet, so avoid installing it for now

cuda_core/tests/cython/build_tests.sh

@@ -15,4 +15,4 @@ else
   exit 1
 fi
 
-cythonize -3 -i ${SCRIPTPATH}/test_*.pyx
+cythonize -3 -i -Xfreethreading_compatible=True ${SCRIPTPATH}/test_*.pyx