* ``gc.collect(1)``: Performs an increment of GC,

* An :exc:`OSError` is now raised by :func:`getpass.getuser` for any failure to

retrieve a username, instead of :exc:`ImportError` on non-Unix platforms or

:exc:`KeyError` on Unix platforms where the password database is empty.

* The :mod:`threading` module now expects the :mod:`!_thread` module to have

an ``_is_main_interpreter`` attribute. It is a function with no

arguments that returns ``True`` if the current interpreter is the

main interpreter.

Any library or application that provides a custom ``_thread`` module

must provide :func:`!_is_main_interpreter`, just like the module's

other "private" attributes.

(See :gh:`112826`.)

* :class:`mailbox.Maildir` now ignores files with a leading dot.

(Contributed by Zackery Spytz in :gh:`65559`.)

* :meth:`pathlib.Path.glob` and :meth:`~pathlib.Path.rglob` now return both

files and directories if a pattern that ends with "``**``" is given, rather

than directories only. Users may add a trailing slash to match only

directories.

* The value of the :attr:`!mode` attribute of :class:`gzip.GzipFile` was

changed from integer (``1`` or ``2``) to string (``'rb'`` or ``'wb'``).

returned by :meth:`zipfile.ZipFile.open` was changed from ``'r'`` to ``'rb'``.

* :class:`functools.partial` now emits a :exc:`FutureWarning` when it is

used as a method.

Its behavior will be changed in future Python versions.

Wrap it in :func:`staticmethod` if you want to preserve the old behavior.

(Contributed by Serhiy Storchaka in :gh:`121027`.)

.. _pep667-porting-notes-py:

* Calling :func:`locals` in an :term:`optimized scope` now produces an

independent snapshot on each call, and hence no longer implicitly updates

previously returned references. Obtaining the legacy CPython behaviour now

requires explicit calls to update the initially returned dictionary with the

results of subsequent calls to :func:`!locals`. Code execution functions that

implicitly target :func:`!locals` (such as ``exec`` and ``eval``) must be

passed an explicit namespace to access their results in an optimized scope.

(Changed as part of :pep:`667`.)

* Calling :func:`locals` from a comprehension at module or class scope

(including via ``exec`` or ``eval``) once more behaves as if the comprehension

were running as an independent nested function (i.e. the local variables from

the containing scope are not included). In Python 3.12, this had changed

to include the local variables from the containing scope when implementing

:pep:`709`. (Changed as part of :pep:`667`.)

* Accessing :attr:`FrameType.f_locals <frame.f_locals>` in an

:term:`optimized scope` now returns a write-through proxy rather than a

snapshot that gets updated at ill-specified times. If a snapshot is desired,

it must be created explicitly with ``dict`` or the proxy's ``.copy()`` method.

(Changed as part of :pep:`667`.)

* Functions :c:func:`PyDict_GetItem`, :c:func:`PyDict_GetItemString`,

:c:func:`PyMapping_HasKey`, :c:func:`PyMapping_HasKeyString`,

:c:func:`PyObject_HasAttr`, :c:func:`PyObject_HasAttrString`, and

:c:func:`PySys_GetObject`, which clear all errors which occurred when calling

them, now report them using :func:`sys.unraisablehook`.

You may replace them with other functions as

recommended in the documentation.

(Contributed by Serhiy Storchaka in :gh:`106672`.)

* :c:func:`!PyCode_GetFirstFree` is an unstable API now and has been renamed

to :c:func:`PyUnstable_Code_GetFirstFree`.

(Contributed by Bogdan Romanyuk in :gh:`115781`.)

* The effects of mutating the dictionary returned from :c:func:`PyEval_GetLocals` in an

:term:`optimized scope` have changed. New dict entries added this way will now *only* be

visible to subsequent :c:func:`PyEval_GetLocals` calls in that frame, as

:c:func:`PyFrame_GetLocals`, :func:`locals`, and

:attr:`FrameType.f_locals <frame.f_locals>` no longer access the same underlying cached

dictionary. Changes made to entries for actual variable names and names added via the

write-through proxy interfaces will be overwritten on subsequent calls to

:c:func:`PyEval_GetLocals` in that frame. The recommended code update depends on how the

function was being used, so refer to the deprecation notice on the function for details.

(Changed as part of :pep:`667`.)

* Calling :c:func:`PyFrame_GetLocals` in an :term:`optimized scope` now returns a

write-through proxy rather than a snapshot that gets updated at ill-specified times.

If a snapshot is desired, it must be created explicitly (e.g. with :c:func:`PyDict_Copy`)

or by calling the new :c:func:`PyEval_GetFrameLocals` API. (Changed as part of :pep:`667`.)

* :c:func:`!PyFrame_FastToLocals` and :c:func:`!PyFrame_FastToLocalsWithError`

no longer have any effect. Calling these functions has been redundant since

Python 3.11, when :c:func:`PyFrame_GetLocals` was first introduced.

(Changed as part of :pep:`667`.)

* :c:func:`!PyFrame_LocalsToFast` no longer has any effect. Calling this function

is redundant now that :c:func:`PyFrame_GetLocals` returns a write-through proxy

for :term:`optimized scopes <optimized scope>`. (Changed as part of :pep:`667`.)