feat: requires-python

cibuildwheel/__main__.py

@@ -7,6 +7,9 @@
 from pathlib import Path
 from typing import Any, Dict, List, Optional, Set, overload
 
+import toml
+from packaging.specifiers import SpecifierSet
+
 import cibuildwheel
 import cibuildwheel.linux
 import cibuildwheel.macos
@@ -25,10 +28,10 @@
 
 
 @overload
-def get_option_from_environment(option_name: str, platform: Optional[str], default: str) -> str: ...  # noqa: E704
+def get_option_from_environment(option_name: str, *, platform: Optional[str] = None, default: str) -> str: ...  # noqa: E704
 @overload
-def get_option_from_environment(option_name: str, platform: Optional[str] = None, default: None = None) -> Optional[str]: ...  # noqa: E704 E302
-def get_option_from_environment(option_name: str, platform: Optional[str] = None, default: Optional[str] = None) -> Optional[str]:  # noqa: E302
+def get_option_from_environment(option_name: str, *, platform: Optional[str] = None, default: None = None) -> Optional[str]: ...  # noqa: E704 E302
+def get_option_from_environment(option_name: str, *, platform: Optional[str] = None, default: Optional[str] = None) -> Optional[str]:  # noqa: E302
     '''
     Returns an option from the environment, optionally scoped by the platform.
 
@@ -151,7 +154,23 @@ def main() -> None:
     test_extras = get_option_from_environment('CIBW_TEST_EXTRAS', platform=platform, default='')
     build_verbosity_str = get_option_from_environment('CIBW_BUILD_VERBOSITY', platform=platform, default='')
 
-    build_selector = BuildSelector(build_config, skip_config)
+    # Default if not specified (may be increased in a later version)
+    requires_python = '>=2.7'
+
+    # Read in from metadata.requires-python if it exists
+    pyproject_toml = package_dir / 'pyproject.toml'
+    try:
+        info = toml.load(pyproject_toml)
+        requires_python = info["metadata"]["requires-python"]
+    except FileNotFoundError:
+        pass
+    except KeyError:
+        pass
+
+    # Passing this in as an environment variable will override default or pyproject.toml
+    requires_python = get_option_from_environment('CIBW_REQUIRES_PYTHON', platform=platform, default=requires_python)
+
+    build_selector = BuildSelector(build_config, skip_config, requires_python=SpecifierSet(requires_python))
 
     try:
         environment = parse_environment(environment_config)
@@ -181,14 +200,15 @@ def main() -> None:
     os.environ['CIBUILDWHEEL'] = '1'
 
     if not any((package_dir / name).exists()
-               for name in ["setup.py", "setup.cfg", "pyproject.toml"]):
+               for name in ['setup.py', 'setup.cfg', 'pyproject.toml']):
         print('cibuildwheel: Could not find setup.py, setup.cfg or pyproject.toml at root of package', file=sys.stderr)
         exit(2)
 
     if args.archs is not None:
         archs_config_str = args.archs
     else:
         archs_config_str = get_option_from_environment('CIBW_ARCHS', platform=platform, default='auto')
+
     archs = Architecture.parse_config(archs_config_str, platform=platform)
 
     if args.print_build_identifiers:
@@ -308,7 +328,7 @@ def print_preamble(platform: str, build_options: BuildOptions) -> None:
 
 
 def print_build_identifiers(
-    platform: str, build_selector: BuildSelector, architectures: Set[Architecture]
+        platform: str, build_selector: BuildSelector, architectures: Set[Architecture]
 ) -> None:
 
     python_configurations: List[Any] = []

cibuildwheel/util.py

@@ -14,6 +14,8 @@
 
 import certifi
 import toml
+from packaging.specifiers import SpecifierSet
+from packaging.version import Version
 
 from .environment import ParsedEnvironment
 from .typing import PathOrStr, PlatformName, assert_never
@@ -56,11 +58,25 @@ def read_python_configs(config: PlatformName) -> List[Dict[str, str]]:
 
 
 class BuildSelector:
-    def __init__(self, build_config: str, skip_config: str):
+    def __init__(self, build_config: str, skip_config: str, *, requires_python: Optional[SpecifierSet] = None):
         self.build_patterns = build_config.split()
         self.skip_patterns = skip_config.split()
+        self.requires_python = requires_python
 
     def __call__(self, build_id: str) -> bool:
+        # Filter build selectors by python_requires if set
+        if self.requires_python is not None and '-' in build_id:
+            py_ver_str = build_id.split('-')[0]
+            try:
+                major = int(py_ver_str[2])
+                minor = int(py_ver_str[3:])
+            except ValueError:
+                pass
+            else:
+                version = Version(f"{major}.{minor}")
+                if not self.requires_python.contains(version):
+                    return False
+
         def match_any(patterns: List[str]) -> bool:
             return any(fnmatch(build_id, pattern) for pattern in patterns)
         return match_any(self.build_patterns) and not match_any(self.skip_patterns)

docs/options.md

@@ -184,6 +184,31 @@ to limit builds for each job; this list could grow in the future.
 CIBW_ARCHS_LINUX: "auto aarch64"
 ```
 
+
+### `pyproject.toml:metadata.requires-python` / `CIBW_REQUIRES_PYTHON` {: #requires-python}
+> Limit the Python versions to build
+
+The provisionally accepted [PEP 621](https://www.python.org/dev/peps/pep-0621/)
+setting in `pyproject.toml` for `metadata.requires-python` is respected by
+cibuildwheel. You can override this if needed using an environment variable.
+You do not have to manually avoid versions that cibuildwheel does not support;
+`>=2.7` and `>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*,` are
+equivalent, as far as cibuildwheel is concerned.
+
+Default: `>=2.7`, all supported versions are built. In the future, this will match
+the EOL of Python, so setting this is recommended if you want to support past-EOL
+Python versions.
+
+Example `pyproject.toml`:
+
+```toml
+[metadata]
+requires-python: ">=3.6"
+```
+
+Remember to always set `build-system.requires` and `build-system.build-backend`
+if you add a `pyproject.toml` file.
+
 ## Build customization
 
 ### `CIBW_ENVIRONMENT` {: #environment}

setup.cfg

@@ -31,6 +31,7 @@ install_requires =
     bashlex!=0.13
     toml
     certifi
+    packaging
     typing_extensions; python_version < '3.8'
     importlib_resources>=1.4; python_version < '3.9'
 
@@ -51,7 +52,6 @@ dev =
     pyyaml
     requests
     typing-extensions
-    packaging>=20.8
     rich>=9.6
 
 [options.packages.find]

unit_test/build_ids_test.py

@@ -1,11 +1,8 @@
-import pytest
 import toml
-
-from cibuildwheel.util import resources_dir
-
-Version = pytest.importorskip("packaging.version").Version
+from packaging.version import Version
 
 from cibuildwheel.extra import InlineArrayDictEncoder  # noqa: E402
+from cibuildwheel.util import resources_dir
 
 
 def test_compare_configs():

unit_test/build_selector_test.py

@@ -1,3 +1,5 @@
+from packaging.specifiers import SpecifierSet
+
 from cibuildwheel.util import BuildSelector
 
 
@@ -59,3 +61,20 @@ def test_build_and_skip():
     assert not build_selector('cp27-win_amd64')
     assert build_selector('cp36-win_amd64')
     assert not build_selector('cp37-win_amd64')
+
+
+def test_build_limited_python():
+    build_selector = BuildSelector(build_config="*", skip_config="", requires_python=SpecifierSet(">=3.6"))
+
+    assert not build_selector('cp27-manylinux1_x86_64')
+    assert build_selector('cp36-manylinux1_x86_64')
+    assert build_selector('cp37-manylinux1_x86_64')
+    assert not build_selector('cp27-manylinux1_i686')
+    assert build_selector('cp36-manylinux1_i686')
+    assert build_selector('cp37-manylinux1_i686')
+    assert not build_selector('cp27-win32')
+    assert build_selector('cp36-win32')
+    assert build_selector('cp37-win32')
+    assert not build_selector('pp27-win32')
+    assert build_selector('pp36-win32')
+    assert build_selector('pp37-win32')