Allow bdist_wheel working without ctypes (#613)

Co-authored-by: Alex Grönholm <[email protected]>

src/wheel/bdist_wheel.py

@@ -25,7 +25,6 @@
 from setuptools import Command
 
 from . import __version__ as wheel_version
-from .macosx_libfile import calculate_macosx_platform_tag
 from .metadata import pkginfo_to_metadata
 from .util import log
 from .vendored.packaging import tags
@@ -72,6 +71,8 @@ def get_platform(archive_root: str | None) -> str:
     """Return our platform name 'win32', 'linux_x86_64'"""
     result = sysconfig.get_platform()
     if result.startswith("macosx") and archive_root is not None:
+        from .macosx_libfile import calculate_macosx_platform_tag
+
         result = calculate_macosx_platform_tag(archive_root, result)
     elif _is_32bit_interpreter():
         if result == "linux-x86_64":

tests/test_bdist_wheel.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+import builtins
+import importlib
 import os.path
 import platform
 import shutil
@@ -421,3 +423,23 @@ def test_platform_linux32(reported, expected, monkeypatch):
     cmd.root_is_pure = False
     _, _, actual = cmd.get_tag()
     assert actual == expected
+
+
+def test_no_ctypes(monkeypatch) -> None:
+    def _fake_import(name: str, *args, **kwargs):
+        if name == "ctypes":
+            raise ModuleNotFoundError("No module named %s" % name)
+
+        return importlib.__import__(name, *args, **kwargs)
+
+    # Install an importer shim that refuses to load ctypes
+    monkeypatch.setattr(builtins, "__import__", _fake_import)
+
+    # Unload all wheel modules
+    for module in list(sys.modules):
+        if module.startswith("wheel"):
+            monkeypatch.delitem(sys.modules, module)
+
+    from wheel import bdist_wheel
+
+    assert bdist_wheel