[BUG] AttributeError: 'NoneType' object has no attribute 'cname'

[albireox]

Describe the bug

I'm receiving this error when trying to install sep on Ubuntu

  [1/1] Cythonizing sep.pyx
  Traceback (most recent call last):
    File "/opt/pyenv/versions/3.11.3/envs/gallegoj/lib/python3.11/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 353, in <module>
      main()
    File "/opt/pyenv/versions/3.11.3/envs/gallegoj/lib/python3.11/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 335, in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/opt/pyenv/versions/3.11.3/envs/gallegoj/lib/python3.11/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 149, in prepare_metadata_for_build_wheel
      return hook(metadata_directory, config_settings)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/setuptools/build_meta.py", line 396, in prepare_metadata_for_build_wheel
      self.run_setup()
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/setuptools/build_meta.py", line 341, in run_setup
      exec(code, locals())
    File "<string>", line 38, in <module>
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Build/Dependencies.py", line 1134, in cythonize
      cythonize_one(*args)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Build/Dependencies.py", line 1280, in cythonize_one
      result = compile_single(pyx_file, options, full_module_name=full_module_name)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Main.py", line 618, in compile_single
      return run_pipeline(source, options, full_module_name)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Main.py", line 542, in run_pipeline
      err, enddata = Pipeline.run_pipeline(pipeline, source)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Pipeline.py", line 398, in run_pipeline
      data = run(phase, data)
             ^^^^^^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Pipeline.py", line 375, in run
      return phase(data)
             ^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Pipeline.py", line 52, in generate_pyx_code_stage
      module_node.process_implementation(options, result)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ModuleNode.py", line 222, in process_implementation
      self.generate_c_code(env, options, result)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ModuleNode.py", line 516, in generate_c_code
      self.body.generate_function_definitions(env, code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 404, in generate_function_definitions
      stat.generate_function_definitions(env, code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 404, in generate_function_definitions
      stat.generate_function_definitions(env, code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 3499, in generate_function_definitions
      self.defaults_getter.generate_function_definitions(env.global_scope(), code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 3506, in generate_function_definitions
      FuncDefNode.generate_function_definitions(self, env, code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 2200, in generate_function_definitions
      self.generate_function_body(env, code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 1953, in generate_function_body
      self.body.generate_execution_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/Nodes.py", line 6856, in generate_execution_code
      value.generate_evaluation_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 831, in generate_evaluation_code
      self.generate_subexpr_evaluation_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 846, in generate_subexpr_evaluation_code
      node.generate_evaluation_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 837, in generate_evaluation_code
      self.generate_result_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 8017, in generate_result_code
      self.generate_operation_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 8576, in generate_operation_code
      self.generate_sequence_packing_code(code)
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 8084, in generate_sequence_packing_code
      code.put_incref(arg.result(), arg.ctype())
                      ^^^^^^^^^^^^
    File "/tmp/pip-build-env-gsjt32r2/overlay/lib/python3.11/site-packages/Cython/Compiler/ExprNodes.py", line 10113, in result
      self.defaults_struct.lookup(self.arg.name).cname)
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  AttributeError: 'NoneType' object has no attribute 'cname'

This seems to fail only with Python 3.11. The same install worked last night, so I assume that this was broken by the update to Cython 3.0.1, which seems to have modified this file.

Code to reproduce the behaviour:

No code, but I think it's quite reproducible by trying to install sep with Python 3.11 on Linux (Ubuntu, but probably other distros as well).

Expected behaviour

No response

OS

Linux

Python version

3.11.3

Cython version

3.0.1

Additional context

No response

[albireox]

Closing in favour of #5643 that was open while I typed this!