h5py fails to build with Python 3.14.0a4.

=================================== FAILURES ===================================
________________________ TestFileObj.test_TemporaryFile ________________________

cls = <class '_pytest.runner.CallInfo'>
func = <function call_and_report.<locals>.<lambda> at 0x7f09aee9eb90>
when = 'call'
reraise = (<class '_pytest.outcomes.Exit'>, <class 'KeyboardInterrupt'>)

    @classmethod
    def from_call(
        cls,
        func: Callable[[], TResult],
        when: Literal["collect", "setup", "call", "teardown"],
        reraise: type[BaseException] | tuple[type[BaseException], ...] | None = None,
    ) -> CallInfo[TResult]:
        """Call func, wrapping the result in a CallInfo.
    
        :param func:
            The function to call. Called without arguments.
        :type func: Callable[[], _pytest.runner.TResult]
        :param when:
            The phase in which the function is called.
        :param reraise:
            Exception or exceptions that shall propagate if raised by the
            function, instead of being wrapped in the CallInfo.
        """
        excinfo = None
        start = timing.time()
        precise_start = timing.perf_counter()
        try:
>           result: TResult | None = func()

/usr/lib/python3.14/site-packages/_pytest/runner.py:341: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib/python3.14/site-packages/_pytest/runner.py:242: in <lambda>
    lambda: runtest_hook(item=item, **kwds), when=when, reraise=reraise
/usr/lib/python3.14/site-packages/pluggy/_hooks.py:513: in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
/usr/lib/python3.14/site-packages/pluggy/_manager.py:120: in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
/usr/lib/python3.14/site-packages/_pytest/threadexception.py:92: in pytest_runtest_call
    yield from thread_exception_runtest_hook()
/usr/lib/python3.14/site-packages/_pytest/threadexception.py:68: in thread_exception_runtest_hook
    yield
/usr/lib/python3.14/site-packages/_pytest/unraisableexception.py:95: in pytest_runtest_call
    yield from unraisable_exception_runtest_hook()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

    def unraisable_exception_runtest_hook() -> Generator[None]:
        with catch_unraisable_exception() as cm:
            try:
                yield
            finally:
                if cm.unraisable:
                    if cm.unraisable.err_msg is not None:
                        err_msg = cm.unraisable.err_msg
                    else:
                        err_msg = "Exception ignored in"
                    msg = f"{err_msg}: {cm.unraisable.object!r}\n\n"
                    msg += "".join(
                        traceback.format_exception(
                            cm.unraisable.exc_type,
                            cm.unraisable.exc_value,
                            cm.unraisable.exc_traceback,
                        )
                    )
>                   warnings.warn(pytest.PytestUnraisableExceptionWarning(msg))
E                   pytest.PytestUnraisableExceptionWarning: Exception ignored in: <function _TemporaryFileCloser.__del__ at 0x7f09c4f8ceb0>
E                   
E                   Traceback (most recent call last):
E                     File "/usr/lib64/python3.14/tempfile.py", line 483, in __del__
E                       _warnings.warn(self.warn_message, ResourceWarning)
E                       ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
E                   ResourceWarning: Implicitly cleaning up <_TemporaryFileWrapper file=<_io.BufferedRandom name='/tmp/tmp8pqafmzv'>>

https://docs.python.org/3.14/whatsnew/3.14.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.14/fedora-rawhide-x86_64/08554796-h5py/

For all our attempts to build h5py with Python 3.14, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/package/h5py/

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 3.14:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/

Let us know here if you have any questions.

Python 3.14 is planned to be included in Fedora 43.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.14.
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.