fix: min version logic issue (#853)

Fixing an issue using `cmake.minimum-version`.

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

src/scikit_build_core/settings/skbuild_read_settings.py

@@ -58,7 +58,8 @@ def _handle_minimum_version(
 
     # Check for minimum_version < 0.8 and the modern version setting
     if (
-        dc.version != version_default
+        dc.version is not None
+        and dc.version != version_default
         and minimum_version is not None
         and minimum_version < Version("0.8")
     ):
@@ -74,13 +75,16 @@ def _handle_minimum_version(
         elif minimum_version >= Version("0.8"):
             rich_error(msg)
 
-        if dc.version != version_default:
+        if dc.version is not None and dc.version != version_default:
             rich_error(
                 f"Cannot set both {name}.minimum_version and {name}.version; use version only for scikit-build-core >= 0.8."
             )
 
         dc.version = SpecifierSet(f">={dc.minimum_version}")
 
+    if dc.version is None:
+        dc.version = SpecifierSet(f">={default}")
+
 
 def _handle_move(
     before_name: str,
@@ -226,16 +230,15 @@ def __init__(
         if self.settings.install.strip is None:
             self.settings.install.strip = install_policy
 
-        # Before 0.10, we hard-coded 3.15+ as the minimum CMake version
+        # If we noted earlier that auto-cmake was requested, handle it now
         if (
             self.settings.cmake.version is None
-            and self.settings.minimum_version is not None
-            and self.settings.minimum_version < Version("0.10")
+            and self.settings.cmake.minimum_version is None
+            and (
+                self.settings.minimum_version is None
+                or self.settings.minimum_version >= Version("0.10")
+            )
         ):
-            self.settings.cmake.version = SpecifierSet(">=3.15")
-
-        # If we noted earlier that auto-cmake was requested, handle it now
-        if self.settings.cmake.version is None:
             cmake_path = self.settings.cmake.source_dir / "CMakeLists.txt"
             try:
                 with cmake_path.open(encoding="utf-8-sig") as f:

tests/test_skbuild_settings.py

@@ -472,13 +472,19 @@ def test_skbuild_settings_min_version_versions(
     tmp_path: Path, monkeypatch: pytest.MonkeyPatch
 ):
     monkeypatch.setattr(
-        scikit_build_core.settings.skbuild_read_settings, "__version__", "0.8.0"
+        scikit_build_core.settings.skbuild_read_settings, "__version__", "0.10.0"
     )
 
     pyproject_toml = tmp_path / "pyproject.toml"
     pyproject_toml.write_text(
         "tool.scikit-build.cmake.minimum-version = '3.21'", encoding="utf-8"
     )
+    cmakelists = tmp_path / "CMakeLists.txt"
+    cmakelists.write_text("cmake_minimum_required(VERSION 3.20)", encoding="utf-8")
+
+    settings_reader = SettingsReader.from_file(pyproject_toml, {})
+    settings = settings_reader.settings
+    assert settings.cmake.version == SpecifierSet(">=3.21")
 
     settings_reader = SettingsReader.from_file(
         pyproject_toml, {"minimum-version": "0.7"}