Python 3.12 copy error

[amunra]

Problem

On Python 3.12 (not earlier versions) I encounter the following issue:

error: can't copy 'build/lib.macosx-14.3-arm64-cpython-312/questdb/egress.cpython-312-darwin.so': doesn't exist or not a regular file

In earlier versions of Python this works:

copying build/lib.macosx-12.6-arm64-cpython-311/questdb/egress.cpython-311-darwin.so -> src/questdb

In both cases, I'm running against the latest setuptools:

>>> setuptools.__version__
'65.5.0'

Context

I am building a Python extension in Rust and calling the rust build tooling explicitly.

https://github.com/questdb/py-questdb-client/compare/4ea8800..e8b39a7

My setup function defines a custom build_ext and defines a Cython and a pure Rust extension module.

setup(
    name='questdb',
    version='2.0.2',
    platforms=['any'],
    python_requires='>=3.8',
    install_requires=[],
    ext_modules=ext_modules(),                  # <--- see below
    cmdclass={'build_ext': questdb_build_ext},  # <--- see below
    zip_safe=False,
    package_dir={'': 'src'},
    test_suite="tests",
    packages=find_packages('src', exclude=['test']))

The Cython one works fine, so I'll focus on the other one.
These are my ext modules:

def ext_modules():
    ext_modules = []
    ext_modules.extend(cythonize([
        ingress_extension()], annotate=True))
    ext_modules.append(egress_extension())         # <--- see below
    return ext_modules

def egress_extension():
    if PLATFORM == 'darwin':
        lib_prefix, lib_suffix = 'lib', '.dylib'
    elif PLATFORM == 'win32':
        lib_prefix, lib_suffix = '', '.dll'
    else:    
        lib_prefix, lib_suffix = 'lib', '.so'
    lib_name = f'{lib_prefix}questdb_egress{lib_suffix}'
    lib_dir = PROJ_ROOT / 'target' / 'release'
    lib_path = lib_dir / lib_name
    extra_objects = [str(lib_dir / lib_name)]

    return Extension(
        "questdb.egress",
        sources=[],                    # <-- Is this an issue?
        include_dirs=[],
        extra_objects=extra_objects)   # Path to built lib passed in here.

My custom build_ext calls a function which invokes the Rust build system a bunch of times:

class questdb_build_ext(build_ext):
    """
    Build the extension, but first compile the pre-requisite
    library by invoking `cargo build --release --features ffi`.
    """
    def run(self):
        cargo_build()    # <-- generates `libquestdb_egress.dylib`, see above.
        super().run()

Current line of debugging

I've wrapped the setup() call with a try / except SystemError and I got the following traceback:

Traceback (most recent call last):
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 200, in run_commands
    dist.run_commands()
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 969, in run_commands
    self.run_command(cmd)
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/dist.py", line 967, in run_command
    super().run_command(command)
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/dist.py", line 988, in run_command
    cmd_obj.run()
  File "/Users/adam/questdb/repos/py-questdb-client/setup.py", line 169, in run
    super().run()
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/command/build_ext.py", line 94, in run
    self.copy_extensions_to_source()
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/command/build_ext.py", line 115, in copy_extensions_to_source
    self.copy_file(regular_file, inplace_file, level=self.verbose)
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/cmd.py", line 348, in copy_file
    return file_util.copy_file(
           ^^^^^^^^^^^^^^^^^^^^
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/file_util.py", line 108, in copy_file
    raise DistutilsFileError(
distutils.errors.DistutilsFileError: can't copy 'build/lib.macosx-14.3-arm64-cpython-312/questdb/egress.cpython-312-darwin.so': doesn't exist or not a regular file

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/adam/questdb/repos/py-questdb-client/setup.py", line 184, in <module>
    setup(
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/__init__.py", line 104, in setup
    return distutils.core.setup(**attrs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 184, in setup
    return run_commands(dist)
           ^^^^^^^^^^^^^^^^^^
  File "/Users/adam/.pyenv/versions/3.12.2/lib/python3.12/site-packages/setuptools/_distutils/core.py", line 214, in run_commands
    raise SystemExit("error: " + str(msg))
SystemExit: error: can't copy 'build/lib.macosx-14.3-arm64-cpython-312/questdb/egress.cpython-312-darwin.so': doesn't exist or not a regular file
error: can't copy 'build/lib.macosx-14.3-arm64-cpython-312/questdb/egress.cpython-312-darwin.so': doesn't exist or not a regular file

Looking for help

It looks like the extra object is not copied from the path where it's generated to the build/{pattern} directory.

I would appreciate any pointers to sanity-check my approach and things to try to fix the issue.

Thank you!