distutils removed in Python3.12

[Jacobfaib]

Python 3.12 removes distutils, and this is causing some grief with the cmake utilities shipped with scikit-build, which result in the following cmake errors:

Traceback (most recent call last):
  File "<string>", line 2, in <module>
  ModuleNotFoundError: No module named 'distutils'
  CMake Error at
  /path/toskbuild/resources/cmake/FindPythonExtensions.cmake:304
   (list):
  list GET given empty list

The following patch addresses this in a backwards compatible way:

--- FindPythonExtensions.old.cmake	2023-12-13 13:05:03
+++ FindPythonExtensions.cmake	2023-12-13 13:06:16
@@ -254,19 +254,23 @@
 include(targetLinkLibrariesWithDynamicLookup)

 set(_command "
-import distutils.sysconfig
+import sys
+
+if sys.version_info >= (3, 10):
+    import sysconfig
+else:
+    import distutils.sysconfig as sysconfig
 import itertools
 import os
 import os.path
 import site
-import sys

 result = None
 rel_result = None
 candidate_lists = []

 try:
-    candidate_lists.append((distutils.sysconfig.get_python_lib(),))
+    candidate_lists.append((sysconfig.get_python_lib(),))
 except AttributeError: pass

 try:
@@ -293,7 +297,7 @@
     sys.prefix,
     result,
     rel_result,
-    distutils.sysconfig.get_config_var('EXT_SUFFIX')
+    sysconfig.get_config_var('EXT_SUFFIX')
 )))
 ")

[henryiii]

This actually isn't quite this easy, since this value was broken before 3.8.7. So this is necessary:

https://github.com/scikit-build/scikit-build-core/blob/565bd6b67f730acc30f982059b507c04e98fa40f/src/scikit_build_core/builder/sysconfig.py#L153-L159

[henryiii]

Ahh, missed you already had a version-based if there, only saw the bottom part.