feat: add option to opt-in free-threaded builds

cibuildwheel/options.py

@@ -117,7 +117,7 @@ class BuildOptions:
         return self.globals.architectures
 
 
-Setting = Union[Mapping[str, str], Sequence[str], str, int]
+Setting = Union[Mapping[str, str], Sequence[str], str, int, bool]
 
 
 @dataclasses.dataclass(frozen=True)
@@ -196,7 +196,7 @@ def _resolve_cascade(
         if value is None:
             continue
 
-        if ignore_empty and not value:
+        if ignore_empty and not value and value is not False:
             continue
 
         value_string = _stringify_setting(value, list_sep, table_format)
@@ -258,7 +258,7 @@ def _stringify_setting(
             raise ConfigOptionError(msg)
         return list_sep.join(setting)
 
-    if isinstance(setting, int):
+    if isinstance(setting, (bool, int)):
         return str(setting)
 
     return setting
@@ -516,6 +516,10 @@ class Options:
         skip_config = self.reader.get("skip", env_plat=False, list_sep=" ")
         test_skip = self.reader.get("test-skip", env_plat=False, list_sep=" ")
 
+        free_threaded_support = strtobool(
+            self.reader.get("free-threaded-support", env_plat=False, ignore_empty=True)
+        )
+
         prerelease_pythons = args.prerelease_pythons or strtobool(
             self.env.get("CIBW_PRERELEASE_PYTHONS", "0")
         )
@@ -536,12 +540,14 @@ class Options:
             skip_config = ""
             architectures = Architecture.all_archs(self.platform)
             prerelease_pythons = True
+            free_threaded_support = True
 
         build_selector = BuildSelector(
             build_config=build_config,
             skip_config=skip_config,
             requires_python=requires_python,
             prerelease_pythons=prerelease_pythons,
+            free_threaded_support=free_threaded_support,
         )
         test_selector = TestSelector(skip_config=test_skip)
 

cibuildwheel/resources/cibuildwheel.schema.json

@@ -255,6 +255,12 @@
       ],
       "title": "CIBW_ENVIRONMENT_PASS"
     },
+    "free-threaded-support": {
+      "type": "boolean",
+      "default": false,
+      "description": "The project supports free-threaded builds of Python (PEP703)",
+      "title": "CIBW_FREE_THREADED_SUPPORT"
+    },
     "manylinux-aarch64-image": {
       "type": "string",
       "description": "Specify alternative manylinux / musllinux container images",

cibuildwheel/resources/defaults.toml

@@ -2,6 +2,7 @@
 build = "*"
 skip = ""
 test-skip = ""
+free-threaded-support = false
 
 archs = ["auto"]
 build-frontend = "default"

cibuildwheel/util.py

@@ -241,6 +241,8 @@ class BuildSelector:
     PRERELEASE_SKIP: ClassVar[str] = "cp313-* cp313t-*"
     prerelease_pythons: bool = False
 
+    free_threaded_support: bool = False
+
     def __call__(self, build_id: str) -> bool:
         # Filter build selectors by python_requires if set
         if self.requires_python is not None:
@@ -257,6 +259,10 @@ class BuildSelector:
         if not self.prerelease_pythons and selector_matches(self.PRERELEASE_SKIP, build_id):
             return False
 
+        # filter out free threaded pythons if self.free_threaded_support is False
+        if not self.free_threaded_support and selector_matches("*t-*", build_id):
+            return False
+
         should_build = selector_matches(self.build_config, build_id)
         should_skip = selector_matches(self.skip_config, build_id)
 
@@ -268,6 +274,7 @@ class BuildSelector:
             "skip_config": self.skip_config,
             "requires_python": str(self.requires_python),
             "prerelease_pythons": self.prerelease_pythons,
+            "free_threaded_support": self.free_threaded_support,
         }