Support for free-threaded Python

[astrojuanlu]

Installing from source on Python 3.13 (M1 Mac) works fine:

$ python -VV
Python 3.13.0 (main, Oct 16 2024, 08:05:40) [Clang 18.1.8 ]
$ uv pip install "httptools==0.6.4" --no-binary :all:
Resolved 1 package in 1.31s
   Built httptools==0.6.4
Prepared 1 package in 5.47s
Installed 1 package in 8ms
 + httptools==0.6.4

But in free-threaded Python:

$ python -VV
Python 3.13.0 experimental free-threading build (main, Oct 16 2024, 08:24:33) [Clang 18.1.8 ]
$ uv pip install "httptools==0.6.4" --no-binary :all:
Resolved 1 package in 1.14s
error: Failed to prepare distributions
  Caused by: Failed to download and build `httptools==0.6.4`
  Caused by: Build backend failed to build wheel through `build_wheel` (exit status: 1)

[stdout]
running bdist_wheel
running build
running build_py
copying httptools/_version.py -> build/lib.macosx-11.0-arm64-cpython-313t/httptools
copying httptools/__init__.py -> build/lib.macosx-11.0-arm64-cpython-313t/httptools
copying httptools/parser/__init__.py -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
copying httptools/parser/errors.py -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
running egg_info
writing httptools.egg-info/PKG-INFO
writing dependency_links to httptools.egg-info/dependency_links.txt
writing requirements to httptools.egg-info/requires.txt
writing top-level names to httptools.egg-info/top_level.txt
reading manifest file 'httptools.egg-info/SOURCES.txt'
reading manifest template 'MANIFEST.in'
adding license file 'LICENSE'
writing manifest file 'httptools.egg-info/SOURCES.txt'
copying httptools/parser/cparser.pxd -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
copying httptools/parser/parser.pyx -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
copying httptools/parser/python.pxd -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
copying httptools/parser/url_cparser.pxd -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
copying httptools/parser/url_parser.pyx -> build/lib.macosx-11.0-arm64-cpython-313t/httptools/parser
running build_ext
building 'httptools.parser.parser' extension
clang -fno-strict-overflow -Wsign-compare -Wunreachable-code -DNDEBUG -g -O3 -Wall -arch arm64 -mmacosx-version-min=11.0 -Wno-nullability-completeness -Wno-expansion-to-defined -Wno-undef-prefix -fPIC -Werror=unguarded-availability-new -I/Users/juan_cano/.cache/uv/sdists-v5/index/d2e01f6a682f0b5c/httptools/0.6.4/uI2NjLIM8YFjwSjCP_QiN/httptools-0.6.4.tar.gz/vendor/llhttp/include -I/Users/juan_cano/.cache/uv/sdists-v5/index/d2e01f6a682f0b5c/httptools/0.6.4/uI2NjLIM8YFjwSjCP_QiN/httptools-0.6.4.tar.gz/vendor/llhttp/src -I/Users/juan_cano/.cache/uv/builds-v0/.tmpAVsfvs/include -I/Users/juan_cano/.local/share/uv/python/cpython-3.13.0+freethreaded-macos-aarch64-none/include/python3.13t -c httptools/parser/parser.c -o build/temp.macosx-11.0-arm64-cpython-313t/httptools/parser/parser.o -O2

[stderr]
/Users/juan_cano/.cache/uv/builds-v0/.tmpAVsfvs/lib/python3.13t/site-packages/setuptools/_distutils/dist.py:261: UserWarning: Unknown distribution option: 'test_suite'
  warnings.warn(msg)
httptools/parser/parser.c:2189:80: error: unknown type name '__pyx_vectorcallfunc'; did you mean 'vectorcallfunc'?
 2189 | static CYTHON_INLINE PyObject *__Pyx_PyVectorcall_FastCallDict(PyObject *func, __pyx_vectorcallfunc vc, PyObject *const *args, size_t nargs, PyObject *kw);
      |                                                                                ^~~~~~~~~~~~~~~~~~~~
      |                                                                                vectorcallfunc
/Users/juan_cano/.local/share/uv/python/cpython-3.13.0+freethreaded-macos-aarch64-none/include/python3.13t/object.h:495:21: note: 'vectorcallfunc' declared here
  495 | typedef PyObject *(*vectorcallfunc)(PyObject *callable, PyObject *const *args,
      |                     ^
httptools/parser/parser.c:14183:69: error: unknown type name '__pyx_vectorcallfunc'; did you mean 'vectorcallfunc'?
 14183 | static PyObject *__Pyx_PyVectorcall_FastCallDict_kw(PyObject *func, __pyx_vectorcallfunc vc, PyObject *const *args, size_t nargs, PyObject *kw)
       |                                                                     ^~~~~~~~~~~~~~~~~~~~
       |                                                                     vectorcallfunc
/Users/juan_cano/.local/share/uv/python/cpython-3.13.0+freethreaded-macos-aarch64-none/include/python3.13t/object.h:495:21: note: 'vectorcallfunc' declared here
  495 | typedef PyObject *(*vectorcallfunc)(PyObject *callable, PyObject *const *args,
      |                     ^
httptools/parser/parser.c:14228:80: error: unknown type name '__pyx_vectorcallfunc'; did you mean 'vectorcallfunc'?
 14228 | static CYTHON_INLINE PyObject *__Pyx_PyVectorcall_FastCallDict(PyObject *func, __pyx_vectorcallfunc vc, PyObject *const *args, size_t nargs, PyObject *kw)
       |                                                                                ^~~~~~~~~~~~~~~~~~~~
       |                                                                                vectorcallfunc
/Users/juan_cano/.local/share/uv/python/cpython-3.13.0+freethreaded-macos-aarch64-none/include/python3.13t/object.h:495:21: note: 'vectorcallfunc' declared here
  495 | typedef PyObject *(*vectorcallfunc)(PyObject *callable, PyObject *const *args,
      |                     ^
httptools/parser/parser.c:14917:6: error: unknown type name '__pyx_vectorcallfunc'; did you mean 'vectorcallfunc'?
 14917 |      __pyx_vectorcallfunc vc = __Pyx_CyFunction_func_vectorcall(cyfunc);
       |      ^~~~~~~~~~~~~~~~~~~~
       |      vectorcallfunc
/Users/juan_cano/.local/share/uv/python/cpython-3.13.0+freethreaded-macos-aarch64-none/include/python3.13t/object.h:495:21: note: 'vectorcallfunc' declared here
  495 | typedef PyObject *(*vectorcallfunc)(PyObject *callable, PyObject *const *args,
      |                     ^
4 errors generated.
error: command '/usr/bin/clang' failed with exit code 1

[ngoldbaum]

Cython 3.1 is out now, and httptools builds on the free-threaded build:

goldbaum at Nathans-MacBook-Pro in ~/Documents/httptools on master
± pip install .
Processing /Users/goldbaum/Documents/httptools
  Preparing metadata (setup.py) ... done
Building wheels for collected packages: httptools
  Building wheel for httptools (setup.py) ... done
  Created wheel for httptools: filename=httptools-0.7.0.dev0-cp313-cp313t-macosx_15_0_arm64.whl size=109184 sha256=0c40984cc0b4ade3ddafa4e1951bf302b3dcad62bbb9264f702df9c7e1d3fb3e
  Stored in directory: /private/var/folders/nk/yds4mlh97kg9qdq745g715rw0000gn/T/pip-ephem-wheel-cache-eiyb5ne8/wheels/ea/f5/f8/2339ab0e4c1eb68b3e46381d04b922d0997650e9cdb84d0699
Successfully built httptools
Installing collected packages: httptools
Successfully installed httptools-0.7.0.dev0

[notice] A new release of pip is available: 25.0.1 -> 25.1.1
[notice] To update, run: pip install --upgrade pip

goldbaum at Nathans-MacBook-Pro in ~/Documents/httptools on master
± python -VV
Python 3.13.3 experimental free-threading build (main, May 14 2025, 08:53:19) [Clang 17.0.0 (clang-1700.0.13.3)]

I'm happy to help out if anyone has any questions about adding support for free-threading. Also take a look at https://cython.readthedocs.io/en/latest/src/userguide/freethreading.html and https://py-free-threading.github.io.