python-accelerate fails to build with Python 3.15.0a8.

3 tests fail with a similar issue:

____________ CPUOptimizerTester.test_accelerated_optimizer_pickling ____________

self = <test_optimizer.CPUOptimizerTester testMethod=test_accelerated_optimizer_pickling>

    def test_accelerated_optimizer_pickling(self):
        model = torch.nn.Linear(10, 10)
>       optimizer = torch.optim.SGD(model.parameters(), 0.1)
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

tests/test_optimizer.py:28: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.15/site-packages/torch/optim/sgd.py:65: in __init__
    super().__init__(params, defaults)
/usr/lib64/python3.15/site-packages/torch/optim/optimizer.py:408: in __init__
    self.add_param_group(cast(dict, param_group))
/usr/lib64/python3.15/site-packages/torch/_compile.py:47: in inner
    import torch._dynamo
/usr/lib64/python3.15/site-packages/torch/_dynamo/__init__.py:76: in <module>
    from .polyfills import loader as _  # usort: skip # noqa: F401
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/usr/lib64/python3.15/site-packages/torch/_dynamo/polyfills/loader.py:34: in <module>
    POLYFILLED_MODULES: tuple["ModuleType", ...] = tuple(
                                                   ^^^^^
/usr/lib64/python3.15/site-packages/torch/_dynamo/polyfills/loader.py:35: in <genexpr>
    importlib.import_module(f".{submodule}", package=polyfills.__name__)
/usr/lib64/python3.15/importlib/__init__.py:88: in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
/usr/lib64/python3.15/site-packages/torch/_dynamo/polyfills/struct.py:20: in <module>
    @substitute_in_graph(struct.pack, can_constant_fold_through=True)  # type: ignore[arg-type]
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

traceable_fn = <function pack at 0x7f50247c78a0>

    def wrapper(traceable_fn: Callable[_P, _R]) -> Callable[_P, _R]:
        if not is_function(traceable_fn):
            raise TypeError(
                f"@substitute_in_graph(...) expects a function but got {type(traceable_fn)!r}"
            )
    
        if not skip_signature_check:
            try:
                original_sig = inspect.signature(original_fn)
            except ValueError:
                pass
            else:
                traceable_sig = inspect.signature(traceable_fn)
    
                def sig_ident(
                    sig: inspect.Signature,
                ) -> tuple[tuple[str, ...], set[str], dict[str, Any]]:
                    # Ignore annotations for parameters and return type
                    return (
                        tuple(
                            p.name
                            for p in sig.parameters.values()
                            if (
                                p.kind
                                not in {
                                    p.KEYWORD_ONLY,
                                    # the name of *args and **kwargs is not important
                                    p.VAR_POSITIONAL,
                                    p.VAR_KEYWORD,
                                }
                            )
                        ),
                        {
                            p.name
                            for p in sig.parameters.values()
                            if p.kind == p.KEYWORD_ONLY
                        },
                        {
                            p.name: p.default
                            for p in sig.parameters.values()
                            # the name of *args and **kwargs is not important
                            if p.kind not in {p.VAR_POSITIONAL, p.VAR_KEYWORD}
                        },
                    )
    
                wildcard_sig = inspect.signature(lambda *args, **kwargs: None)
    
                if (
                    sig_ident(original_sig) != sig_ident(traceable_sig)
                    and sig_ident(original_sig) != sig_ident(wildcard_sig)
                    and sig_ident(traceable_sig) != sig_ident(wildcard_sig)
                ):
>                   raise TypeError(
                        f"Signature mismatch between {original_fn} and {traceable_fn}: "
                        f"{original_sig} != {traceable_sig}"
                    )
E                   TypeError: Signature mismatch between <built-in function pack> and <function pack at 0x7f50247c78a0>: (format, /, *values) != (fmt: 'bytes | str', /, *v: 'Any') -> 'bytes'

https://docs.python.org/3.15/whatsnew/3.15.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.15/fedora-rawhide-x86_64/10341837-python-accelerate/

For all our attempts to build python-accelerate with Python 3.15, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15/package/python-accelerate/

Testing and mass rebuild of packages is happening in copr.
You can follow these instructions to test locally in mock if your package builds with Python 3.15:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15/

Let us know here if you have any questions.

Python 3.15 is planned to be included in Fedora 45.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.15.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.