Add 3.12 to action, but without cython support

.github/workflows/build.yml

@@ -104,11 +104,11 @@ jobs:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
     env:
-      # Set up wheels matrix.  This is CPython 3.6--3.11 for all OS targets.
-      CIBW_BUILD: "cp3{6,7,8,9,10,11}-*"
+      # Set up wheels matrix.  This is CPython 3.6--3.12 for all OS targets.
+      CIBW_BUILD: "cp3{6,7,8,9,10,11,12}-*"
       # Numpy and SciPy do not supply wheels for i686 or win32 for
       # Python 3.10+, so we skip those:
-      CIBW_SKIP: "*-musllinux* cp3{8,9,10,11}-manylinux_i686 cp3{8,9,10,11}-win32"
+      CIBW_SKIP: "*-musllinux* cp3{8,9,10,11,12}-manylinux_i686 cp3{8,9,10,11,12}-win32"
       OVERRIDE_VERSION: ${{ github.event.inputs.override_version }}
 
     steps:

.github/workflows/tests.yml

@@ -123,6 +123,13 @@ jobs:
             python-version: "3.10"
             pytest-extra-options: "-W ignore::ImportWarning -k 'not (test_correlation or test_interpolate or test_mcsolve)'"
 
+          # Cython 0.29 (pyximport) and python 3.12 do not play well together.
+          # Qutip will ignore cython in this case.
+          - case-name: Python 3.12
+            os: ubuntu-latest
+            python-version: "3.12"
+            pytest-extra-options: "-W ignore:Runtime:UserWarning -W ignore:datetime:DeprecationWarning"
+
     steps:
       - uses: actions/checkout@v3
 

qutip/__init__.py

@@ -54,24 +54,30 @@
     pass
 else:
     from qutip.utilities import _version2int
+    import sys
     _cy_require = "0.29.20"
     _cy_unsupported = "3.0.0"
     if _version2int(_Cython.__version__) < _version2int(_cy_require):
         warnings.warn(
             "Old version of Cython detected: needed {}, got {}."
             .format(_cy_require, _Cython.__version__)
         )
-    if _version2int(_Cython.__version__) >= _version2int(_cy_unsupported):
+    elif _version2int(_Cython.__version__) >= _version2int(_cy_unsupported):
         warnings.warn(
             "The new version of Cython, (>= 3.0.0) is not supported."
             .format(_Cython.__version__)
         )
+    elif _version2int(sys.version.split()[0]) >= _version2int("3.12.0"):
+        warnings.warn(
+            "Runtime cython compilation does not work on Python 3.12."
+        )
     else:
         # Setup pyximport
         import qutip.cy.pyxbuilder as _pyxbuilder
         _pyxbuilder.install()
         del _pyxbuilder, _Cython, _version2int
         qutip.settings.has_cython = True
+    del sys
 
 
 # -----------------------------------------------------------------------------

qutip/tests/conftest.py

@@ -1,6 +1,7 @@
 import pytest
 import functools
 import os
+import sys
 import tempfile
 import numpy as np
 from qutip.utilities import _version2int
@@ -32,6 +33,10 @@ def _skip_cython_tests_if_unavailable(item):
         # importorskip does not have maxversion
         if _version2int(_Cython.__version__) >= _version2int("3.0.0"):
             pytest.skip("cython 3.0.0 not supported")
+            return
+        import qutip
+        if _version2int(sys.version.split()[0]) >= _version2int("3.12.0"):
+            pytest.skip("Cython not available at runtime with python >=3.12.")
 
 
 @pytest.hookimpl(trylast=True)