feat: configure FindPython backport (#103)

Exposing this (largely so users can disable it if they want to).

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

README.md

@@ -165,6 +165,11 @@ wheel.expand-macos-universal-tags = false
 # available)
 wheel.install-dir = "."
 
+# This will backport an internal copy of FindPython if CMake is less than this
+# value. Set to 0 or the empty string to disable. The default will be kept in
+# sync with the version of FindPython stored in scikit-build-core.
+backport.find-python = "3.24"
+
 # Enable experimental features if any are available
 experimental = false
 

src/scikit_build_core/builder/builder.py

@@ -78,7 +78,8 @@ def configure(
         if site_packages != DIR.parent.parent:
             self.config.prefix_dirs.append(DIR.parent.parent)
 
-        if self.config.cmake.version < Version("3.24"):
+        fp_backport = self.settings.backport.find_python
+        if fp_backport and self.config.cmake.version < Version(fp_backport):
             self.config.module_dirs.append(Path(find_python.__file__).parent.resolve())
 
         if sys.platform.startswith("win32"):

src/scikit_build_core/settings/skbuild_model.py

@@ -94,13 +94,21 @@ class WheelSettings:
     install_dir: str = ""
 
 
+@dataclasses.dataclass
+class BackportSettings:
+    #: If CMake is less than this value, backport a copy of FindPython. Set
+    #: to 0 disable this, or the empty string.
+    find_python: str = "3.24"
+
+
 @dataclasses.dataclass
 class ScikitBuildSettings:
     cmake: CMakeSettings = dataclasses.field(default_factory=CMakeSettings)
     ninja: NinjaSettings = dataclasses.field(default_factory=NinjaSettings)
     logging: LoggingSettings = dataclasses.field(default_factory=LoggingSettings)
     sdist: SDistSettings = dataclasses.field(default_factory=SDistSettings)
     wheel: WheelSettings = dataclasses.field(default_factory=WheelSettings)
+    backport: BackportSettings = dataclasses.field(default_factory=BackportSettings)
 
     #: Strictly check all config options. If False, warnings will be
     #: printed for unknown options. If True, an error will be raised.

tests/test_skbuild_settings.py

@@ -32,6 +32,7 @@ def test_skbuild_settings_default(tmp_path):
     assert settings.wheel.packages is None
     assert settings.wheel.py_api == ""
     assert not settings.wheel.expand_macos_universal_tags
+    assert settings.backport.find_python == "3.24"
     assert settings.strict_config
     assert not settings.experimental
     assert settings.minimum_version is None
@@ -55,6 +56,7 @@ def test_skbuild_settings_envvar(tmp_path, monkeypatch):
     monkeypatch.setenv("SKBUILD_WHEEL_PACKAGES", "j; k; l")
     monkeypatch.setenv("SKBUILD_WHEEL_PY_API", "cp39")
     monkeypatch.setenv("SKBUILD_WHEEL_EXPAND_MACOS_UNIVERSAL_TAGS", "True")
+    monkeypatch.setenv("SKBUILD_BACKPORT_FIND_PYTHON", "0")
     monkeypatch.setenv("SKBUILD_STRICT_CONFIG", "0")
     monkeypatch.setenv("SKBUILD_EXPERIMENTAL", "1")
     monkeypatch.setenv("SKBUILD_MINIMUM_VERSION", "0.1")
@@ -83,6 +85,7 @@ def test_skbuild_settings_envvar(tmp_path, monkeypatch):
     assert settings.wheel.packages == ["j", "k", "l"]
     assert settings.wheel.py_api == "cp39"
     assert settings.wheel.expand_macos_universal_tags
+    assert settings.backport.find_python == "0"
     assert not settings.strict_config
     assert settings.experimental
     assert settings.minimum_version == "0.1"
@@ -112,6 +115,7 @@ def test_skbuild_settings_config_settings(tmp_path, monkeypatch):
         "wheel.packages": ["j", "k", "l"],
         "wheel.py-api": "cp39",
         "wheel.expand-macos-universal-tags": "True",
+        "backport.find-python": "",
         "strict-config": "false",
         "experimental": "1",
         "minimum-version": "0.1",
@@ -135,6 +139,7 @@ def test_skbuild_settings_config_settings(tmp_path, monkeypatch):
     assert settings.wheel.packages == ["j", "k", "l"]
     assert settings.wheel.py_api == "cp39"
     assert settings.wheel.expand_macos_universal_tags
+    assert settings.backport.find_python == ""
     assert not settings.strict_config
     assert settings.experimental
     assert settings.minimum_version == "0.1"
@@ -163,6 +168,7 @@ def test_skbuild_settings_pyproject_toml(tmp_path, monkeypatch):
             wheel.packages = ["j", "k", "l"]
             wheel.py-api = "cp39"
             wheel.expand-macos-universal-tags = true
+            backport.find-python = "3.18"
             strict-config = false
             experimental = true
             minimum-version = "0.1"
@@ -191,6 +197,7 @@ def test_skbuild_settings_pyproject_toml(tmp_path, monkeypatch):
     assert settings.wheel.packages == ["j", "k", "l"]
     assert settings.wheel.py_api == "cp39"
     assert settings.wheel.expand_macos_universal_tags
+    assert settings.backport.find_python == "3.18"
     assert not settings.strict_config
     assert settings.experimental
     assert settings.minimum_version == "0.1"