Cython compilation error with const variable assignments in datetime.pyx (commit a29a6f6a)

Start in asyncpg/pgproto/codecs/datetime.pyx at lines 30-33 and review the Cython declarations named in the compilation error. Re-run the Python 3.12 build or metadata-generation command to confirm compilation succeeds without the const-assignment errors; done means the package builds successfully.

When building from a29a6f6aaa09013cb33ffadb8dd57e21d671ab55 there are compilation errors on 3.12. On relatively newer versions of cython declaring a const at module initialization has been deprecated.

Error compiling Cython file:
  ------------------------------------------------------------
  ...
  pg_epoch_date = datetime.date(2000, 1, 1)
  cdef int32_t pg_date_offset_ord = \
      <int32_t>cpython.PyLong_AsLong(pg_epoch_date.toordinal())

  # Binary representations of infinity for datetimes.
  cdef const int64_t pg_time64_infinity = 0x7fffffffffffffff
       ^
  ------------------------------------------------------------

  asyncpg/pgproto/./codecs/datetime.pyx:30:5: Assignment to const 'pg_time64_infinity'

  Error compiling Cython file:
  ------------------------------------------------------------
  ...
  cdef int32_t pg_date_offset_ord = \
      <int32_t>cpython.PyLong_AsLong(pg_epoch_date.toordinal())

  # Binary representations of infinity for datetimes.
  cdef const int64_t pg_time64_infinity = 0x7fffffffffffffff
  cdef const int64_t pg_time64_negative_infinity = <int64_t>0x8000000000000000
       ^
  ------------------------------------------------------------

  asyncpg/pgproto/./codecs/datetime.pyx:31:5: Assignment to const 'pg_time64_negative_infinity'

  Error compiling Cython file:
  ------------------------------------------------------------
  ...
      <int32_t>cpython.PyLong_AsLong(pg_epoch_date.toordinal())

  # Binary representations of infinity for datetimes.
  cdef const int64_t pg_time64_infinity = 0x7fffffffffffffff
  cdef const int64_t pg_time64_negative_infinity = <int64_t>0x8000000000000000
  cdef const int32_t pg_date_infinity = 0x7fffffff
       ^
  ------------------------------------------------------------

  asyncpg/pgproto/./codecs/datetime.pyx:32:5: Assignment to const 'pg_date_infinity'

  Error compiling Cython file:
  ------------------------------------------------------------
  ...

  # Binary representations of infinity for datetimes.
  cdef const int64_t pg_time64_infinity = 0x7fffffffffffffff
  cdef const int64_t pg_time64_negative_infinity = <int64_t>0x8000000000000000
  cdef const int32_t pg_date_infinity = 0x7fffffff
  cdef const int32_t pg_date_negative_infinity = <int32_t>0x80000000
       ^
  ------------------------------------------------------------

  asyncpg/pgproto/./codecs/datetime.pyx:33:5: Assignment to const 'pg_date_negative_infinity'
  Compiling asyncpg/pgproto/pgproto.pyx because it changed.
  Compiling asyncpg/protocol/protocol.pyx because it changed.
  [1/2] Cythonizing asyncpg/pgproto/pgproto.pyx
  Traceback (most recent call last):
    File "/usr/local/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 389, in <module>
      main()
    File "/usr/local/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 373, in main
      json_out["return_val"] = hook(**hook_input["kwargs"])
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/local/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 175, in prepare_metadata_for_build_wheel
      return hook(metadata_directory, config_settings)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/local/lib/python3.12/site-packages/setuptools/build_meta.py", line 374, in prepare_metadata_for_build_wheel
      self.run_setup()
    File "/usr/local/lib/python3.12/site-packages/setuptools/build_meta.py", line 317, in run_setup
      exec(code, locals())
    File "<string>", line 234, in <module>
    File "/usr/local/lib/python3.12/site-packages/setuptools/__init__.py", line 115, in setup
      return distutils.core.setup(**attrs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 186, in setup
      return run_commands(dist)
             ^^^^^^^^^^^^^^^^^^
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 202, in run_commands
      dist.run_commands()
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 1002, in run_commands
      self.run_command(cmd)
    File "/usr/local/lib/python3.12/site-packages/setuptools/dist.py", line 1102, in run_command
      super().run_command(command)
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 1021, in run_command
      cmd_obj.run()
    File "/usr/local/lib/python3.12/site-packages/setuptools/command/dist_info.py", line 94, in run
      self.egg_info.run()
    File "/usr/local/lib/python3.12/site-packages/setuptools/command/egg_info.py", line 312, in run
      self.find_sources()
    File "/usr/local/lib/python3.12/site-packages/setuptools/command/egg_info.py", line 320, in find_sources
      mm.run()
    File "/usr/local/lib/python3.12/site-packages/setuptools/command/egg_info.py", line 543, in run
      self.add_defaults()
    File "/usr/local/lib/python3.12/site-packages/setuptools/command/egg_info.py", line 581, in add_defaults
      sdist.add_defaults(self)
    File "/usr/local/lib/python3.12/site-packages/setuptools/command/sdist.py", line 109, in add_defaults
      super().add_defaults()
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/command/sdist.py", line 245, in add_defaults
      self._add_defaults_ext()
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/command/sdist.py", line 329, in _add_defaults_ext
      build_ext = self.get_finalized_command('build_ext')
                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/cmd.py", line 334, in get_finalized_command
      cmd_obj.ensure_finalized()
    File "/usr/local/lib/python3.12/site-packages/setuptools/_distutils/cmd.py", line 135, in ensure_finalized
      self.finalize_options()
    File "<string>", line 216, in finalize_options
    File "/usr/local/lib/python3.12/site-packages/Cython/Build/Dependencies.py", line 1154, in cythonize
      cythonize_one(*args)
    File "/usr/local/lib/python3.12/site-packages/Cython/Build/Dependencies.py", line 1321, in cythonize_one
      raise CompileError(None, pyx_file)
  Cython.Compiler.Errors.CompileError: asyncpg/pgproto/pgproto.pyx
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> No available output.
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
  full command: /usr/local/bin/python3.12 /usr/local/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py prepare_metadata_for_build_wheel /tmp/tmpk5opk_pk
  cwd: /tmp/eugo/asyncpg
  Preparing metadata (pyproject.toml) ... error
error: metadata-generation-failed

Fix

Remove the const keyword from lines 30-33 in codecs/datetime.pyx:

# Change from:
cdef const int64_t pg_time64_infinity = 0x7fffffffffffffff
cdef const int64_t pg_time64_negative_infinity = 0x8000000000000000
cdef const int32_t pg_date_infinity = 0x7fffffff
cdef const int32_t pg_date_negative_infinity = 0x80000000

# To:
cdef int64_t pg_time64_infinity = 0x7fffffffffffffff
cdef int64_t pg_time64_negative_infinity = 0x8000000000000000
cdef int32_t pg_date_infinity = 0x7fffffff
cdef int32_t pg_date_negative_infinity = 0x80000000