python312Packages.sphinx: re-enable cython test

[implr]

6cad926 updated cython, which fixes the test failure here.

Extracted from #341644.
Didn't test dependent packages, as the set is huge.

Things done

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 25.05 Release Notes (or backporting 24.11 and 25.05 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

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[lukegb]

OOI does this have to be cython_0? The 7.4.7 pyproject.toml claims cython>=3.0, which would be normal cython, I think?

[lukegb]

OK, this also doesn't work properly under Python 3.12 because cython needs distutils for pyximport (which is used in the test), and this isn't available in stdlib anymore. You can't depend on distutils here because it causes a dependency loop.

My (awful) suggestion is that we instead introduce a dependency on setuptools, which will stub out distutils with its own implementation:

--- a/pkgs/development/python-modules/sphinx/default.nix
+++ b/pkgs/development/python-modules/sphinx/default.nix
@@ -31,7 +31,8 @@
   typing-extensions,
 
   # check phase
-  cython_0,
+  cython,
+  setuptools,
   defusedxml,
   filelock,
   html5lib,
@@ -60,6 +61,12 @@ buildPythonPackage rec {
     hash = "sha256-/5zH9IdLmTGnn5MY4FFSuZOIeF/x1L9Ga/wp57XrAQo=";
   };
 
+  prePatch = ''
+    # Import setuptools before distutils to use setuptools' distutils.
+    # This avoids a dependency loop on Python >=3.12, where distutils was removed from the stdlib.
+    sed -i '/import pyximport/i\    import setuptools' tests/test_extensions/test_ext_autodoc.py
+  '';
+
   build-system = [ flit-core ];
 
   dependencies =
@@ -88,7 +95,8 @@ buildPythonPackage rec {
   __darwinAllowLocalNetworking = true;
 
   nativeCheckInputs = [
-    cython_0
+    cython
+    setuptools
     defusedxml
     filelock
     html5lib

WDYT?

[implr]

OOI does this have to be cython_0? The 7.4.7 pyproject.toml claims cython>=3.0, which would be normal cython, I think?

Hm, you're right. I was going off the state as it was when it was disabled in nixpkgs, which was a long while ago.

It'd maybe be better if we could break the cycle and depend on distutils somehow, but I don't see an obvious way. The setuptools hack it is then.