chore: un-pin virtualenv update

virtualenv has been pinned to 20.21.1 in order to be
able to create python 3.6 venvs.

This commit allows to pin virtualenv for given versions
of pythons which in turns re-allows updates as a default.

bin/update_virtualenv.py

@@ -53,10 +53,6 @@ def git_ls_remote_versions(url) -> list[VersionTuple]:
             if version.is_prerelease:
                 log.info("Ignoring pre-release %r", str(version))
                 continue
-            # Do not upgrade past 20.22.0 to keep python 3.6 compat
-            if version >= Version("20.22.0"):
-                log.info("Ignoring %r which is not compatible with python 3.6", str(version))
-                continue
             versions.append(VersionTuple(version, version_string))
         except InvalidVersion:
             log.warning("Ignoring ref %r", ref)
@@ -82,15 +78,20 @@ def update_virtualenv(force: bool, level: str) -> None:
 
     original_toml = toml_file_path.read_text()
     with toml_file_path.open("rb") as f:
-        loaded_file = tomllib.load(f)
-    version = str(loaded_file["version"])
+        configurations = tomllib.load(f)
+    default = configurations.pop("default")
+    version = str(default["version"])
     versions = git_ls_remote_versions(GET_VIRTUALENV_GITHUB)
     if versions[0].version > Version(version):
         version = versions[0].version_string
 
-    result_toml = (
-        f'version = "{version}"\n'
-        f'url = "{GET_VIRTUALENV_URL_TEMPLATE.format(version=version)}"\n'
+    configurations["default"] = {
+        "version": version,
+        "url": GET_VIRTUALENV_URL_TEMPLATE.format(version=version),
+    }
+    result_toml = "".join(
+        f'{key} = {{ version = "{value["version"]}", url = "{value["url"]}" }}\n'
+        for key, value in configurations.items()
     )
 
     rich.print()  # spacer

cibuildwheel/macos.py

@@ -181,7 +181,9 @@ def setup_python(
 
     log.step("Setting up build environment...")
     venv_path = tmp / "venv"
-    env = virtualenv(base_python, venv_path, dependency_constraint_flags)
+    env = virtualenv(
+        python_configuration.version, base_python, venv_path, dependency_constraint_flags
+    )
     venv_bin_path = venv_path / "bin"
     assert venv_bin_path.exists()
     # Fix issue with site.py setting the wrong `sys.prefix`, `sys.exec_prefix`,

cibuildwheel/resources/virtualenv.toml

@@ -1,2 +1,2 @@
-version = "20.21.1"
-url = "https://github.com/pypa/get-virtualenv/blob/20.21.1/public/virtualenv.pyz?raw=true"
+py36 = { version = "20.21.1", url = "https://github.com/pypa/get-virtualenv/blob/20.21.1/public/virtualenv.pyz?raw=true" }
+default = { version = "20.26.2", url = "https://github.com/pypa/get-virtualenv/blob/20.26.2/public/virtualenv.pyz?raw=true" }

cibuildwheel/util.py

@@ -526,12 +526,15 @@ def get_pip_version(env: Mapping[str, str]) -> str:
 
 
 @lru_cache(maxsize=None)
-def _ensure_virtualenv() -> Path:
+def _ensure_virtualenv(version: str) -> Path:
+    version_parts = version.split(".")
+    key = f"py{version_parts[0]}{version_parts[1]}"
     input_file = resources_dir / "virtualenv.toml"
     with input_file.open("rb") as f:
         loaded_file = tomllib.load(f)
-    version = str(loaded_file["version"])
-    url = str(loaded_file["url"])
+    configuration = loaded_file.get(key, loaded_file["default"])
+    version = str(configuration["version"])
+    url = str(configuration["url"])
     path = CIBW_CACHE_PATH / f"virtualenv-{version}.pyz"
     with FileLock(str(path) + ".lock"):
         if not path.exists():
@@ -587,10 +590,10 @@ def _parse_constraints_for_virtualenv(
 
 
 def virtualenv(
-    python: Path, venv_path: Path, dependency_constraint_flags: Sequence[PathOrStr]
+    version: str, python: Path, venv_path: Path, dependency_constraint_flags: Sequence[PathOrStr]
 ) -> dict[str, str]:
     assert python.exists()
-    virtualenv_app = _ensure_virtualenv()
+    virtualenv_app = _ensure_virtualenv(version)
     allowed_seed_packages = ["pip", "setuptools", "wheel"]
     constraints = _parse_constraints_for_virtualenv(
         allowed_seed_packages, dependency_constraint_flags

cibuildwheel/windows.py

@@ -246,7 +246,9 @@ def setup_python(
 
     log.step("Setting up build environment...")
     venv_path = tmp / "venv"
-    env = virtualenv(base_python, venv_path, dependency_constraint_flags)
+    env = virtualenv(
+        python_configuration.version, base_python, venv_path, dependency_constraint_flags
+    )
 
     # set up environment variables for run_with_env
     env["PYTHON_VERSION"] = python_configuration.version

test/test_dependency_versions.py

@@ -111,7 +111,6 @@ def test_dependency_constraints_file(tmp_path, build_frontend_env):
             """
             pip=={pip}
             delocate=={delocate}
-            importlib-metadata<3,>=0.12; python_version < "3.8"
             """.format(**tool_versions)
         )
     )