Check Python version when initializing xbuildenv [integration]

pyodide_build/build_env.py

@@ -83,6 +83,8 @@ def _init_xbuild_env(*, quiet: bool = False) -> Path:
         if manager.current_version is None:
             manager.install()
 
+        manager.check_version_marker()
+
         return manager.pyodide_root
 
 

pyodide_build/cli/xbuildenv.py

@@ -117,8 +117,8 @@ def _uninstall(
     """
     check_xbuildenv_root(path)
     manager = CrossBuildEnvManager(path)
-    manager.uninstall_version(version)
-    typer.echo(f"Pyodide cross-build environment {version} uninstalled")
+    v = manager.uninstall_version(version)
+    typer.echo(f"Pyodide cross-build environment {v} uninstalled")
 
 
 @app.command("use")

pyodide_build/tests/test_xbuildenv.py

@@ -1,3 +1,5 @@
+import sys
+
 import pytest
 
 from pyodide_build.xbuildenv import CrossBuildEnvManager, _url_to_version
@@ -156,6 +158,11 @@ def test_install_version(
         ).exists()
         assert (manager.symlink_dir / "xbuildenv" / "site-packages-extras").exists()
 
+        assert (manager.symlink_dir / ".build-python-version").exists()
+        assert (
+            manager.symlink_dir / ".build-python-version"
+        ).read_text() == f"{sys.version_info.major}.{sys.version_info.minor}"
+
         # installing the same version again should be a no-op
         manager.install(version)
 
@@ -180,6 +187,11 @@ def test_install_url(
         ).exists()
         assert (manager.symlink_dir / "xbuildenv" / "site-packages-extras").exists()
 
+        assert (manager.symlink_dir / ".build-python-version").exists()
+        assert (
+            manager.symlink_dir / ".build-python-version"
+        ).read_text() == f"{sys.version_info.major}.{sys.version_info.minor}"
+
     def test_install_force(
         self,
         tmp_path,
@@ -278,6 +290,37 @@ def test_uninstall_version(self, tmp_path):
 
         assert set(manager.list_versions()) == set(versions) - {"0.25.0", "0.25.1"}
 
+    def test_version_marker(
+        self,
+        tmp_path,
+        dummy_xbuildenv_url,
+        monkeypatch,
+        monkeypatch_subprocess_run_pip,
+        fake_xbuildenv_releases_compatible,
+    ):
+        manager = CrossBuildEnvManager(
+            tmp_path, str(fake_xbuildenv_releases_compatible)
+        )
+        version = "0.1.0"
+
+        manager.install(version)
+
+        assert (manager.symlink_dir / ".build-python-version").exists()
+        assert (
+            manager.symlink_dir / ".build-python-version"
+        ).read_text() == f"{sys.version_info.major}.{sys.version_info.minor}"
+
+        # No error
+        assert manager.check_version_marker() is None
+
+        (manager.symlink_dir / ".build-python-version").write_text("2.7.10")
+
+        with pytest.raises(
+            ValueError,
+            match="does not match the Python version",
+        ):
+            manager.check_version_marker()
+
 
 @pytest.mark.parametrize(
     "url, version",

pyodide_build/xbuildenv.py

@@ -18,6 +18,7 @@
 )
 
 CDN_BASE = "https://cdn.jsdelivr.net/pyodide/v{version}/full/"
+PYTHON_VERSION_MARKER_FILE = ".build-python-version"
 
 
 class CrossBuildEnvManager:
@@ -215,6 +216,7 @@ def install(
 
             install_marker.touch()
             self.use_version(version)
+            self._add_version_marker()
         except Exception as e:
             # if the installation failed, remove the downloaded directory
             shutil.rmtree(download_path)
@@ -366,7 +368,7 @@ def _create_package_index(self, xbuildenv_pyodide_root: Path, version: str) -> N
         lockfile = PyodideLockSpec(**json.loads(lockfile_path.read_bytes()))
         create_package_index(lockfile.packages, xbuildenv_pyodide_root, cdn_base)
 
-    def uninstall_version(self, version: str) -> None:
+    def uninstall_version(self, version: str | None) -> str:
         """
         Uninstall the installed xbuildenv version.
 
@@ -375,6 +377,12 @@ def uninstall_version(self, version: str) -> None:
         version
             The version of xbuildenv to uninstall.
         """
+        if version is None:
+            version = self.current_version
+
+        if version is None:
+            raise ValueError("No xbuildenv version is currently in use")
+
         version_path = self._path_for_version(version)
 
         # if the target version is the current version, remove the symlink
@@ -389,6 +397,35 @@ def uninstall_version(self, version: str) -> None:
                 f"Cannot find cross-build environment version {version}, available versions: {self.list_versions()}"
             )
 
+        return version
+
+    def _add_version_marker(self) -> None:
+        """
+        Store the Python version in the xbuildenv directory, so we can check compatibility later.
+        """
+        if not self.symlink_dir.is_dir():
+            raise ValueError("cross-build env directory does not exist")
+
+        version_file = self.symlink_dir / PYTHON_VERSION_MARKER_FILE
+        version_file.write_text(build_env.local_versions()["python"])
+
+    def check_version_marker(self):
+        if not self.symlink_dir.is_dir():
+            raise ValueError("cross-build env directory does not exist")
+
+        version_file = self.symlink_dir / PYTHON_VERSION_MARKER_FILE
+        if not version_file.exists():
+            raise ValueError("Python version marker file not found")
+
+        version_local = build_env.local_versions()["python"]
+        version_on_install = version_file.read_text().strip()
+        if version_on_install != version_local:
+            raise ValueError(
+                f"local Python version ({version_local}) does not match the Python version ({version_on_install}) "
+                "used to create the Pyodide cross-build environment. "
+                "Please reinstall the xbuildenv, by running `pyodide xbuildenv uninstall` and then `pyodide xbuildenv install`"
+            )
+
 
 def _url_to_version(url: str) -> str:
     return url.replace("://", "_").replace(".", "_").replace("/", "_")