Greenlet

==================

- No changes from 3.0rc3 aside from the version number.

=====================

- Fix an intermittent error during process termination on some
platforms (GCC/Linux/libstdc++).

=====================

- Fix some potential bugs (assertion failures and memory leaks) in
previously-untested error handling code. In some cases, this means
that the process will execute a controlled ``abort()`` after severe
trouble when previously the process might have continued for some
time with a corrupt state. It is unlikely those errors occurred in
practice.
- Fix some assertion errors and potential bugs with re-entrant
switches.
- Fix a potential crash when certain compilers compile greenlet with
high levels of optimization. The symptom would be that switching to
a greenlet for the first time immediately crashes.
- Fix a potential crash when the callable object passed to the
greenlet constructor (or set as the ``greenlet.run`` attribute) has
a destructor attached to it that switches. Typically, triggering
this issue would require an unlikely subclass of
``greenlet.greenlet``.
- Python 3.11+: Fix rare switching errors that could occur when a
garbage collection was triggered during the middle of a switch, and
Python-level code in ``__del__`` or weakref callbacks switched to a
different greenlet and ultimately switched back to the original
greenlet. This often manifested as a ``SystemError``: "switch
returned NULL without an exception set."

For context on the fixes, see `gevent issue 1985
<https://github.com/gevent/gevent/issues/1985>`_.

=====================

- Windows wheels are linked statically to the C runtime in an effort
to prevent import errors on systems without the correct C runtime
installed. It's not clear if this will make the situation better or
worse, so please share your experiences in `issue 346
<https://github.com/python-greenlet/greenlet/issues/346>`_.

Note that this only applies to the binary wheels found on PyPI.
Building greenlet from source defaults to the shared library. Set
the environment variable ``GREENLET_STATIC_RUNTIME=1`` at build time
to change that.
- Build binary wheels for Python 3.12 on macOS.
- Fix compiling greenlet on a debug build of CPython 3.12. There is
`one known issue
<https://github.com/python-greenlet/greenlet/issues/368>`_ that
leads to an interpreter crash on debug builds.
- Python 3.12: Fix walking the frame stack of suspended greenlets.
Previously accessing ``glet.gr_frame.f_back`` would crash due to
`changes in CPython's undocumented internal frame handling <https://github.com/python/cpython/commit/1e197e63e21f77b102ff2601a549dda4b6439455>`_.

Platforms
---------
- Now, greenlet *may* compile and work on Windows ARM64 using
llvm-mingw, but this is untested and unsupported. See `PR
<https://github.com/python-greenlet/greenlet/pull/224>`_ by Adrian
Vladu.
- Now, greenlet *may* compile and work on LoongArch64 Linux systems,
but this is untested and unsupported. See `PR 257
<https://github.com/python-greenlet/greenlet/pull/257/files>`_ by merore.

Known Issues
------------

- There may be (very) subtle issues with tracing on Python 3.12, which
has redesigned the entire tracing infrastructure.

====================

- Build binary wheels for S390x Linux. See `PR 358
<https://github.com/python-greenlet/greenlet/pull/358>`_ from Steven
Silvester.
- Fix a rare crash on shutdown seen in uWSGI deployments. See `issue
330 <https://github.com/python-greenlet/greenlet/issues/330>`_ and `PR 356
<https://github.com/python-greenlet/greenlet/pull/356>`_ from Andrew
Wason.
- Make the platform-specific low-level C/assembly snippets stop using
the ``register`` storage class. Newer versions of standards remove
this storage class, and it has been generally ignored by many
compilers for some time. See `PR 347
<https://github.com/python-greenlet/greenlet/pull/347>`_ from Khem
Raj.
- Add initial support for Python 3.12. See `issue
<https://github.com/python-greenlet/greenlet/issues/323>`_ and `PR
<https://github.com/python-greenlet/greenlet/pull/327>`_; thanks go
to (at least) Michael Droettboom, Andreas Motl, Thomas A Caswell,
raphaelauv, Hugo van Kemenade, Mark Shannon, and Petr Viktorin.
- Remove support for end-of-life Python versions, including Python
2.7, Python 3.5 and Python 3.6.
- Require a compiler that supports ``noinline`` directives. See
`issue 271
<https://github.com/python-greenlet/greenlet/issues/266>`_.
- Require a compiler that supports C++11.

==================

- Fix calling ``greenlet.settrace()`` with the same tracer object that
was currently active. See `issue 332
<https://github.com/python-greenlet/greenlet/issues/332>`_.
- Various compilation and standards conformance fixes. See 335, 336,
300, 302, 334.