fix: free threaded Python

.github/workflows/ci.yml

@@ -175,6 +175,25 @@ jobs:
       - name: Test min package
         run: pytest -ra --showlocals -Wdefault
 
+  manylinux:
+    name: Manylinux on 🐍 3.13 • Free-threaded
+    runs-on: ubuntu-latest
+    timeout-minutes: 40
+    container: quay.io/pypa/musllinux_1_2_x86_64:latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Prepare venv
+        run: python3.13t -m venv /venv
+
+      - name: Install deps
+        run: /venv/bin/pip install -e .[test] ninja
+
+      - name: Test package
+        run: /venv/bin/pytest
+
   cygwin:
     name: Tests on 🐍 3.9 • cygwin
     runs-on: windows-latest

.pre-commit-config.yaml

@@ -119,3 +119,17 @@ repos:
         language: pygrep
         entry: tool\.cmake
         exclude: .pre-commit-config.yaml
+
+  - repo: https://github.com/henryiii/validate-pyproject-schema-store
+    rev: 2024.04.29
+    hooks:
+      - id: validate-pyproject
+
+  - repo: https://github.com/python-jsonschema/check-jsonschema
+    rev: 0.28.3
+    hooks:
+      - id: check-dependabot
+      - id: check-github-workflows
+      - id: check-readthedocs
+      - id: check-metaschema
+        files: \.schema\.json

docs/cmakelists.md

@@ -132,14 +132,17 @@ When defining your module, if you only support the Stable ABI after some point,
 you should use (for example for 3.11):
 
 ```cmake
-if(Python_VERSION VERSION_GREATER_EQUAL 3.11 AND Python_INTERPRETER_ID STREQUAL Python)
-  python_add_library(some_ext MODULE USE_SABI 3.11 ...)
+if(NOT "${SKBUILD_SABI_COMPONENT}" STREQUAL "")
+  python_add_library(some_ext MODULE WITH_SOABI USE_SABI 3.11 ...)
 else()
   python_add_library(some_ext MODULE WITH_SOABI ...)
 endif()
 ```
 
-This will define `Py_LIMITED_API` for you.
+This will define `Py_LIMITED_API` for you. If you want to support building
+directly from CMake, you need to protect this for Python version,
+`Python_INTERPRETER_ID STREQUAL Python`, and free-threading Python 3.13+ doesn't
+support ABI3 either.
 
 If you are using `nanobind`'s `nanobind_add_module`, the `STABLE_ABI` flag does
 this automatically for you for 3.12+.

pyproject.toml

@@ -26,6 +26,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
     "Development Status :: 4 - Beta",
     "Typing :: Typed",
 ]
@@ -51,7 +52,8 @@ pyproject = [
 test = [
     "build >=0.8",
     "cattrs >=22.2.0",
-    "pip >=22",
+    "pip >=22; python_version<'3.13'",
+    "pip >=24.1b1; python_version>='3.13'",
     "pybind11 >=2.11",
     "pytest >=7.0",  # 7.2+ recommended for better tracebacks with ExceptionGroup
     "pytest-subprocess >=1.5",

src/scikit_build_core/builder/builder.py

@@ -114,7 +114,7 @@
         cache_entries: Mapping[str, str | Path] | None = None,
         name: str | None = None,
         version: Version | None = None,
-        limited_abi: bool | None = None,
+        limited_api: bool | None = None,
         configure_args: Iterable[str] = (),
     ) -> None:
         cmake_defines = {
@@ -162,16 +162,26 @@
             cache_config["SKBUILD_PROJECT_VERSION"] = version.base_version
             cache_config["SKBUILD_PROJECT_VERSION_FULL"] = str(version)
 
-        if limited_abi is None:
+        if limited_api is None:
             if self.settings.wheel.py_api.startswith("cp3"):
                 target_minor_version = int(self.settings.wheel.py_api[3:])
-                limited_abi = target_minor_version <= sys.version_info.minor
+                limited_api = target_minor_version <= sys.version_info.minor
             else:
-                limited_abi = False
+                limited_api = False
+
+        if limited_api and sys.implementation.name != "cpython":
+            limited_api = False
+            logger.info("PyPy doesn't support the Limited API, ignoring")
+
+        if limited_api and sysconfig.get_config_var("Py_GIL_DISABLED"):
+            limited_api = False
+            logger.info(
+                "Free-threaded Python doesn't support the Limited API currently, ignoring"
+            )
 
         python_library = get_python_library(self.config.env, abi3=False)
         python_sabi_library = (
-            get_python_library(self.config.env, abi3=True) if limited_abi else None
+            get_python_library(self.config.env, abi3=True) if limited_api else None
         )
         python_include_dir = get_python_include_dir()
         numpy_include_dir = get_numpy_include_dir()
@@ -196,11 +206,11 @@
             if numpy_include_dir:
                 cache_config[f"{prefix}_NumPy_INCLUDE_DIR"] = numpy_include_dir
 
-        cache_config["SKBUILD_SOABI"] = get_soabi(self.config.env, abi3=limited_abi)
+        cache_config["SKBUILD_SOABI"] = get_soabi(self.config.env, abi3=limited_api)
 
         # Allow CMakeLists to detect this is supposed to be a limited ABI build
         cache_config["SKBUILD_SABI_COMPONENT"] = (
-            "Development.SABIModule" if limited_abi else ""
+            "Development.SABIModule" if limited_api else ""
         )
 
         if cache_entries:

src/scikit_build_core/builder/wheel_tag.py

@@ -3,6 +3,7 @@
 import dataclasses
 import itertools
 import sys
+import sysconfig
 from typing import TYPE_CHECKING
 
 import packaging.tags
@@ -104,11 +105,12 @@ def compute_best(
                 if (
                     sys.implementation.name == "cpython"
                     and minor <= sys.version_info.minor
+                    and not sysconfig.get_config_var("Py_GIL_DISABLED")
                 ):
                     pyvers = pyvers_new
                     abi = "abi3"
                 else:
-                    msg = "Ignoring py-api, not a CPython interpreter ({}) or version (3.{}) is too high"
+                    msg = "Ignoring py-api, not a CPython interpreter ({}) or version (3.{}) is too high or free-threaded"
                     logger.debug(msg, sys.implementation.name, minor)
             elif all(x.startswith("py") and x[2:].isdecimal() for x in pyvers_new):
                 pyvers = pyvers_new

src/scikit_build_core/setuptools/build_cmake.py

@@ -141,7 +141,7 @@ def run(self) -> None:
             name=dist.get_name(),
             version=Version(dist.get_version()),
             defines={},
-            limited_abi=limited_api,
+            limited_api=limited_api,
             configure_args=configure_args,
         )
 

tests/conftest.py

@@ -52,7 +52,8 @@ def pep518_wheelhouse(tmp_path_factory: pytest.TempPathFactory) -> Path:
         "build",
         "cython",
         "hatchling",
-        "pip>=23",
+        "pip>=23; python_version<'3.13'",
+        "pip>=24.1b1; python_version>='3.13'",
         "pybind11",
         "setuptools",
         "virtualenv",
@@ -94,6 +95,8 @@ def __init__(self, env_dir: Path, *, wheelhouse: Path | None = None) -> None:
         self.purelib = Path(
             self.execute("import sysconfig; print(sysconfig.get_path('purelib'))")
         )
+        if sys.version_info >= (3, 13):
+            self.run("pip", "install", "-U", "pip>=24.1b1")
 
     @overload
     def run(self, *args: str, capture: Literal[True]) -> str: ...

tests/packages/abi3_pyproject_ext/CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.15...3.26)
+cmake_minimum_required(VERSION 3.15...3.29)
 
 project(
   ${SKBUILD_PROJECT_NAME}
@@ -7,9 +7,13 @@ project(
 
 find_package(
   Python
-  COMPONENTS Interpreter Development.SABIModule
+  COMPONENTS Interpreter Development.Module ${SKBUILD_SABI_COMPONENT}
   REQUIRED)
 
-python_add_library(abi3_example MODULE abi3_example.c WITH_SOABI USE_SABI 3.7)
+if(NOT "${SKBUILD_SABI_COMPONENT}" STREQUAL "")
+  python_add_library(abi3_example MODULE abi3_example.c WITH_SOABI USE_SABI 3.7)
+else()
+  python_add_library(abi3_example MODULE abi3_example.c WITH_SOABI)
+endif()
 
 install(TARGETS abi3_example DESTINATION .)

tests/packages/cython_pxd_editable/pkg1/CMakeLists.txt

@@ -7,8 +7,8 @@ find_package(
   REQUIRED)
 
 add_custom_command(
-  OUTPUT src/pkg1/one.c
-  DEPENDS src/pkg1/one.pyx
+  OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/src/pkg1/one.c"
+  DEPENDS "${CMAKE_CURRENT_SOURCE_DIR}/src/pkg1/one.pyx"
   VERBATIM
   COMMAND
     Python::Interpreter -m cython

tests/packages/cython_pxd_editable/pkg1/pyproject.toml

@@ -10,4 +10,4 @@ name = "pkg1"
 version = "1.0.0"
 
 [tool.scikit-build]
-wheel.packages = ["src/pkg1"]
+ninja.make-fallback = false

tests/packages/cython_pxd_editable/pkg2/pyproject.toml

@@ -10,4 +10,4 @@ name = "pkg2"
 version = "1.0.0"
 
 [tool.scikit-build]
-wheel.packages = ["src/pkg2"]
+ninja.make-fallback = false

tests/test_builder.py

@@ -139,6 +139,12 @@ def test_builder_get_cmake_args(monkeypatch, cmake_args, answer):
     ],
 )
 def test_wheel_tag(monkeypatch, minver, archs, answer):
+    get_config_var = sysconfig.get_config_var
+    monkeypatch.setattr(
+        sysconfig,
+        "get_config_var",
+        lambda x: None if x == "Py_GIL_DISABLED" else get_config_var(x),
+    )
     monkeypatch.setattr(sys, "platform", "darwin")
     monkeypatch.setenv("MACOSX_DEPLOYMENT_TARGET", minver)
     monkeypatch.setattr(platform, "mac_ver", lambda: ("10.9.2", "", ""))
@@ -150,6 +156,12 @@ def test_wheel_tag(monkeypatch, minver, archs, answer):
 
 @pytest.mark.parametrize("archs", ["x86_64" "arm64" "universal2"])
 def test_wheel_build_tag(monkeypatch, archs):
+    get_config_var = sysconfig.get_config_var
+    monkeypatch.setattr(
+        sysconfig,
+        "get_config_var",
+        lambda x: None if x == "Py_GIL_DISABLED" else get_config_var(x),
+    )
     monkeypatch.setattr(sys, "platform", "darwin")
     monkeypatch.setenv("MACOSX_DEPLOYMENT_TARGET", "10.12")
     monkeypatch.setattr(platform, "mac_ver", lambda: ("10.9.2", "", ""))
@@ -160,6 +172,12 @@ def test_wheel_build_tag(monkeypatch, archs):
 
 
 def test_wheel_tag_expand(monkeypatch):
+    get_config_var = sysconfig.get_config_var
+    monkeypatch.setattr(
+        sysconfig,
+        "get_config_var",
+        lambda x: None if x == "Py_GIL_DISABLED" else get_config_var(x),
+    )
     monkeypatch.setattr(sys, "platform", "darwin")
     monkeypatch.setenv("MACOSX_DEPLOYMENT_TARGET", "10.10")
     monkeypatch.setattr(platform, "mac_ver", lambda: ("10.9.2", "", ""))
@@ -177,6 +195,12 @@ def test_wheel_tag_expand(monkeypatch):
 
 
 def test_wheel_tag_expand_11(monkeypatch):
+    get_config_var = sysconfig.get_config_var
+    monkeypatch.setattr(
+        sysconfig,
+        "get_config_var",
+        lambda x: None if x == "Py_GIL_DISABLED" else get_config_var(x),
+    )
     monkeypatch.setattr(sys, "platform", "darwin")
     monkeypatch.setenv("MACOSX_DEPLOYMENT_TARGET", "11.2")
     monkeypatch.setattr(platform, "mac_ver", lambda: ("10.9.2", "", ""))
@@ -191,6 +215,12 @@ def test_wheel_tag_expand_11(monkeypatch):
 
 
 def test_wheel_tag_with_abi_darwin(monkeypatch):
+    get_config_var = sysconfig.get_config_var
+    monkeypatch.setattr(
+        sysconfig,
+        "get_config_var",
+        lambda x: None if x == "Py_GIL_DISABLED" else get_config_var(x),
+    )
     monkeypatch.setattr(sys, "platform", "darwin")
     monkeypatch.setenv("MACOSX_DEPLOYMENT_TARGET", "10.10")
     monkeypatch.setattr(platform, "mac_ver", lambda: ("10.9.2", "", ""))

tests/test_editable.py

@@ -73,7 +73,14 @@ def test_cython_pxd(monkeypatch, tmp_path, editable, editable_mode, isolated):
     tmp_path1.mkdir()
     process_package(package1, tmp_path1, monkeypatch)
 
-    isolated.install("pip>23", "cython", "scikit-build-core")
+    ninja = [
+        "ninja" for f in isolated.wheelhouse.iterdir() if f.name.startswith("ninja-")
+    ]
+    cmake = [
+        "cmake" for f in isolated.wheelhouse.iterdir() if f.name.startswith("cmake-")
+    ]
+
+    isolated.install("pip>23", "cython", "scikit-build-core", *ninja, *cmake)
 
     isolated.install(
         "-v",

tests/test_pyproject_abi3.py

@@ -15,9 +15,6 @@
 
 @pytest.mark.compile()
 @pytest.mark.configure()
-@pytest.mark.skipif(
-    sys.implementation.name == "pypy", reason="pypy does not support abi3"
-)
 @pytest.mark.skipif(
     sysconfig.get_platform().startswith(("msys", "mingw")),
     reason="abi3 FindPython on MSYS/MinGW reports not found",
@@ -34,7 +31,14 @@ def test_abi3_wheel(tmp_path, monkeypatch, virtualenv):
     out = build_wheel(str(dist))
     (wheel,) = dist.glob("abi3_example-0.0.1-*.whl")
     assert wheel == dist / out
-    assert "-cp37-abi3-" in out
+    abi3 = sys.implementation.name == "cpython" and not sysconfig.get_config_var(
+        "Py_GIL_DISABLED"
+    )
+
+    if abi3:
+        assert "-cp37-abi3-" in out
+    else:
+        assert "-cp37-abi3-" not in out
 
     if sys.version_info >= (3, 8):
         with wheel.open("rb") as f:
@@ -47,11 +51,19 @@ def test_abi3_wheel(tmp_path, monkeypatch, virtualenv):
         (so_file,) = file_names
 
         if sysconfig.get_platform().startswith("win"):
-            assert so_file == "abi3_example.pyd"
+            if sys.implementation.name == "cpython":
+                assert so_file == "abi3_example.pyd"
+            else:
+                assert so_file.endswith(".pyd")
         elif sys.platform.startswith("cygwin"):
-            assert so_file == "abi3_example.abi3.dll"
-        else:
+            if abi3:
+                assert so_file == "abi3_example.abi3.dll"
+            else:
+                assert so_file != "abi3_example.abi3.dll"
+        elif abi3:
             assert so_file == "abi3_example.abi3.so"
+        else:
+            assert so_file != "abi3_example.abi3.so"
 
     virtualenv.install(wheel)
 

tests/test_setuptools_abi3.py

@@ -20,6 +20,10 @@
 @pytest.mark.skipif(
     sys.implementation.name == "pypy", reason="pypy does not support abi3"
 )
+@pytest.mark.skipif(
+    sysconfig.get_config_var("Py_GIL_DISABLED"),
+    reason="Free-threaded Python does not support abi3",
+)
 @pytest.mark.skipif(
     SYSCONFIGPLAT.startswith(("msys", "mingw")),
     reason="abi3 FindPython on MSYS/MinGW reports not found",