# Release 4.12.2 (June 7, 2024)

- Fix regression in v4.12.0 where specialization of certain
  generics with an overridden `__eq__` method would raise errors.
  Patch by Jelle Zijlstra.
- Fix tests so they pass on 3.13.0b2

# Release 4.12.1 (June 1, 2024)

- Preliminary changes for compatibility with the draft implementation
  of PEP 649 in Python 3.14. Patch by Jelle Zijlstra.
- Fix regression in v4.12.0 where nested `Annotated` types would cause
  `TypeError` to be raised if the nested `Annotated` type had unhashable
  metadata. Patch by Alex Waygood.

# Release 4.12.0 (May 23, 2024)

This release is mostly the same as 4.12.0rc1 but fixes one more
longstanding bug.

- Fix incorrect behaviour of `typing_extensions.ParamSpec` on Python 3.8 and
  3.9 that meant that
  `isinstance(typing_extensions.ParamSpec("P"), typing.TypeVar)` would have a
  different result in some situations depending on whether or not a profiling
  function had been set using `sys.setprofile`. Patch by Alex Waygood.

# Release 4.12.0rc1 (May 16, 2024)

This release focuses on compatibility with the upcoming release of
Python 3.13. Most changes are related to the implementation of type
parameter defaults (PEP 696).

Thanks to all of the people who contributed patches, especially Alex
Waygood, who did most of the work adapting typing-extensions to the
CPython PEP 696 implementation.

Full changelog:

- Improve the implementation of type parameter defaults (PEP 696)
  - Backport the `typing.NoDefault` sentinel object from Python 3.13.
    TypeVars, ParamSpecs and TypeVarTuples without default values now have
    their `__default__` attribute set to this sentinel value.
  - TypeVars, ParamSpecs and TypeVarTuples now have a `has_default()`
    method, matching `typing.TypeVar`, `typing.ParamSpec` and
    `typing.TypeVarTuple` on Python 3.13+.
  - TypeVars, ParamSpecs and TypeVarTuples with `default=None` passed to
    their constructors now have their `__default__` attribute set to `None`
    at runtime rather than `types.NoneType`.
  - Fix most tests for `TypeVar`, `ParamSpec` and `TypeVarTuple` on Python
    3.13.0b1 and newer.
  - Backport CPython PR [#118774](https://github.com/python/cpython/pull/118774),
    allowing type parameters without default values to follow those with
    default values in some type parameter lists. Patch by Alex Waygood,
    backporting a CPython PR by Jelle Zijlstra.
  - It is now disallowed to use a `TypeVar` with a default value after a
    `TypeVarTuple` in a type parameter list. This matches the CPython
    implementation of PEP 696 on Python 3.13+.
  - Fix bug in PEP-696 implementation where a default value for a `ParamSpec`
    would be cast to a tuple if a list was provided.
    Patch by Alex Waygood.
- Fix `Protocol` tests on Python 3.13.0a6 and newer. 3.13.0a6 adds a new
  `__static_attributes__` attribute to all classes in Python,
  which broke some assumptions made by the implementation of
  `typing_extensions.Protocol`. Similarly, 3.13.0b1 adds the new
  `__firstlineno__` attribute to all classes.
- Fix `AttributeError` when using `typing_extensions.runtime_checkable`
  in combination with `typing.Protocol` on Python 3.12.2 or newer.
  Patch by Alex Waygood.
- At runtime, `assert_never` now includes the repr of the argument
  in the `AssertionError`. Patch by Hashem, backporting of the original
  fix https://github.com/python/cpython/pull/91720 by Jelle Zijlstra.
- The second and third parameters of `typing_extensions.Generator`,
  and the second parameter of `typing_extensions.AsyncGenerator`,
  now default to `None`. This matches the behaviour of `typing.Generator`
  and `typing.AsyncGenerator` on Python 3.13+.
- `typing_extensions.ContextManager` and
  `typing_extensions.AsyncContextManager` now have an optional second
  parameter, which defaults to `Optional[bool]`. The new parameter
  signifies the return type of the `__(a)exit__` method, matching
  `typing.ContextManager` and `typing.AsyncContextManager` on Python
  3.13+.
- Backport `types.CapsuleType` from Python 3.13.
- Releases are now made using [Trusted Publishers](https://docs.pypi.org/trusted-publishers/)
  improving the security of the release process. Patch by Jelle Zijlstra.

# Release 4.12.0a1 and 4.12.0a2 (May 16, 2024)

These releases primarily test a revised release workflow. If all goes
well, release 4.12.0rc1 will follow soon.

# Release 4.11.0 (April 5, 2024)

This feature release provides improvements to various recently
added features, most importantly type parameter defaults (PEP 696).

There are no changes since 4.11.0rc1.

# Release 4.11.0rc1 (March 24, 2024)

- Fix tests on Python 3.13.0a5. Patch by Jelle Zijlstra.
- Fix the runtime behavior of type parameters with defaults (PEP 696).
  Patch by Nadir Chowdhury.
- Fix minor discrepancy between error messages produced by `typing`
  and `typing_extensions` on Python 3.10. Patch by Jelle Zijlstra.
- When `include_extra=False`, `get_type_hints()` now strips `ReadOnly` from the annotation.

# Release 4.10.0 (February 24, 2024)

This feature release adds support for PEP 728 (TypedDict with extra
items) and PEP 742 (``TypeIs``).

There are no changes since 4.10.0rc1.

# Release 4.10.0rc1 (February 17, 2024)

- Add support for PEP 728, supporting the `closed` keyword argument and the
  special `__extra_items__` key for TypedDict. Patch by Zixuan James Li.
- Add support for PEP 742, adding `typing_extensions.TypeIs`. Patch
  by Jelle Zijlstra.
- Drop runtime error when a read-only `TypedDict` item overrides a mutable
  one. Type checkers should still flag this as an error. Patch by Jelle
  Zijlstra.
- Speedup `issubclass()` checks against simple runtime-checkable protocols by
  around 6% (backporting https://github.com/python/cpython/pull/112717, by Alex
  Waygood).
- Fix a regression in the implementation of protocols where `typing.Protocol`
  classes that were not marked as `@runtime_checkable` would be unnecessarily
  introspected, potentially causing exceptions to be raised if the protocol had
  problematic members. Patch by Alex Waygood, backporting
  https://github.com/python/cpython/pull/113401.

# Release 4.9.0 (December 9, 2023)

This feature release adds `typing_extensions.ReadOnly`, as specified
by PEP 705, and makes various other improvements, especially to
`@typing_extensions.deprecated()`.

There are no changes since 4.9.0rc1.

# Release 4.9.0rc1 (November 29, 2023)

- Add support for PEP 705, adding `typing_extensions.ReadOnly`. Patch
  by Jelle Zijlstra.
- All parameters on `NewType.__call__` are now positional-only. This means that
  the signature of `typing_extensions.NewType.__call__` now exactly matches the
  signature of `typing.NewType.__call__`. Patch by Alex Waygood.
- Fix bug with using `@deprecated` on a mixin class. Inheriting from a
  deprecated class now raises a `DeprecationWarning`. Patch by Jelle Zijlstra.
- `@deprecated` now gives a better error message if you pass a non-`str`
  argument to the `msg` parameter. Patch by Alex Waygood.
- `@deprecated` is now implemented as a class for better introspectability.
  Patch by Jelle Zijlstra.
- Exclude `__match_args__` from `Protocol` members.
  Backport of https://github.com/python/cpython/pull/110683 by Nikita Sobolev.
- When creating a `typing_extensions.NamedTuple` class, ensure `__set_name__`
  is called on all objects that define `__set_name__` and exist in the values
  of the `NamedTuple` class's class dictionary. Patch by Alex Waygood,
  backporting https://github.com/python/cpython/pull/111876.
- Improve the error message when trying to call `issubclass()` against a
  `Protocol` that has non-method members. Patch by Alex Waygood (backporting
  https://github.com/python/cpython/pull/112344, by Randolph Scholz).

# Release 4.8.0 (September 17, 2023)

No changes since 4.8.0rc1.

# Release 4.8.0rc1 (September 7, 2023)

- Add `typing_extensions.Doc`, as proposed by PEP 727. Patch by
  Sebastián Ramírez.
- Drop support for Python 3.7 (including PyPy-3.7). Patch by Alex Waygood.
- Fix bug where `get_original_bases()` would return incorrect results when
  called on a concrete subclass of a generic class. Patch by Alex Waygood
  (backporting https://github.com/python/cpython/pull/107584, by James
  Hilton-Balfe).
- Fix bug where `ParamSpec(default=...)` would raise a `TypeError` on Python
  versions <3.11. Patch by James Hilton-Balfe

# Release 4.7.1 (July 2, 2023)

- Fix support for `TypedDict`, `NamedTuple` and `is_protocol` on PyPy-3.7 and
  PyPy-3.8. Patch by Alex Waygood. Note that PyPy-3.7 and PyPy-3.8 are unsupported
  by the PyPy project. The next feature release of typing-extensions will
  drop support for PyPy-3.7 and may also drop support for PyPy-3.8.

# Release 4.7.0 (June 28, 2023)

- This is expected to be the last feature release supporting Python 3.7,
  which reaches its end of life on June 27, 2023. Version 4.8.0 will support
  only Python 3.8.0 and up.
- Fix bug where a `typing_extensions.Protocol` class that had one or more
  non-callable members would raise `TypeError` when `issubclass()`
  was called against it, even if it defined a custom `__subclasshook__`
  method. The correct behaviour -- which has now been restored -- is not to
  raise `TypeError` in these situations if a custom `__subclasshook__` method
  is defined. Patch by Alex Waygood (backporting
  https://github.com/python/cpython/pull/105976).

# Release 4.7.0rc1 (June 21, 2023)

- Add `typing_extensions.get_protocol_members` and
  `typing_extensions.is_protocol` (backport of CPython PR #104878).
  Patch by Jelle Zijlstra.
- `typing_extensions` now re-exports all names in the standard library's
  `typing` module, except the deprecated `ByteString`. Patch by Jelle
  Zijlstra.
- Due to changes in the implementation of `typing_extensions.Protocol`,
  `typing.runtime_checkable` can now be used on `typing_extensions.Protocol`
  (previously, users had to use `typing_extensions.runtime_checkable` if they
  were using `typing_extensions.Protocol`).
- Align the implementation of `TypedDict` with the implementation in the
  standard library on Python 3.9 and higher.
  `typing_extensions.TypedDict` is now a function instead of a class. The
  private functions `_check_fails`, `_dict_new`, and `_typeddict_new`
  have been removed. `is_typeddict` now returns `False` when called with
  `TypedDict` itself as the argument. Patch by Jelle Zijlstra.
- Declare support for Python 3.12. Patch by Jelle Zijlstra.
- Fix tests on Python 3.13, which removes support for creating
  `TypedDict` classes through the keyword-argument syntax. Patch by
  Jelle Zijlstra.
- Fix a regression introduced in v4.6.3 that meant that
  ``issubclass(object, typing_extensions.Protocol)`` would erroneously raise
  ``TypeError``. Patch by Alex Waygood (backporting the CPython PR
  https://github.com/python/cpython/pull/105239).
- Allow `Protocol` classes to inherit from `typing_extensions.Buffer` or
  `collections.abc.Buffer`. Patch by Alex Waygood (backporting
  https://github.com/python/cpython/pull/104827, by Jelle Zijlstra).
- Allow classes to inherit from both `typing.Protocol` and `typing_extensions.Protocol`
  simultaneously. Since v4.6.0, this caused `TypeError` to be raised due to a
  metaclass conflict. Patch by Alex Waygood.
- Backport several deprecations from CPython relating to unusual ways to
  create `TypedDict`s and `NamedTuple`s. CPython PRs #105609 and #105780
  by Alex Waygood; `typing_extensions` backport by Jelle Zijlstra.
  - Creating a `NamedTuple` using the functional syntax with keyword arguments
    (`NT = NamedTuple("NT", a=int)`) is now deprecated.
  - Creating a `NamedTuple` with zero fields using the syntax `NT = NamedTuple("NT")`
    or `NT = NamedTuple("NT", None)` is now deprecated.
  - Creating a `TypedDict` with zero fields using the syntax `TD = TypedDict("TD")`
    or `TD = TypedDict("TD", None)` is now deprecated.
- Fix bug on Python 3.7 where a protocol `X` that had a member `a` would not be
  considered an implicit subclass of an unrelated protocol `Y` that only has a
  member `a`. Where the members of `X` are a superset of the members of `Y`,
  `X` should always be considered a subclass of `Y` iff `Y` is a
  runtime-checkable protocol that only has callable members. Patch by Alex
  Waygood (backporting CPython PR
  https://github.com/python/cpython/pull/105835).

# Release 4.6.3 (June 1, 2023)

- Fix a regression introduced in v4.6.0 in the implementation of
  runtime-checkable protocols. The regression meant
  that doing `class Foo(X, typing_extensions.Protocol)`, where `X` was a class that
  had `abc.ABCMeta` as its metaclass, would then cause subsequent
  `isinstance(1, X)` calls to erroneously raise `TypeError`. Patch by
  Alex Waygood (backporting the CPython PR
  https://github.com/python/cpython/pull/105152).
- Sync the repository's LICENSE file with that of CPython.
  `typing_extensions` is distributed under the same license as
  CPython itself.
- Skip a problematic test on Python 3.12.0b1. The test fails on 3.12.0b1 due to
  a bug in CPython, which will be fixed in 3.12.0b2. The
  `typing_extensions` test suite now passes on 3.12.0b1.

# Release 4.6.2 (May 25, 2023)

- Fix use of `@deprecated` on classes with `__new__` but no `__init__`.
  Patch by Jelle Zijlstra.
- Fix regression in version 4.6.1 where comparing a generic class against a
  runtime-checkable protocol using `isinstance()` would cause `AttributeError`
  to be raised if using Python 3.7.

# Release 4.6.1 (May 23, 2023)

- Change deprecated `@runtime` to formal API `@runtime_checkable` in the error
  message. Patch by Xuehai Pan.
- Fix regression in 4.6.0 where attempting to define a `Protocol` that was
  generic over a `ParamSpec` or a `TypeVarTuple` would cause `TypeError` to be
  raised. Patch by Alex Waygood.

# Release 4.6.0 (May 22, 2023)

- `typing_extensions` is now documented at
  https://typing-extensions.readthedocs.io/en/latest/. Patch by Jelle Zijlstra.
- Add `typing_extensions.Buffer`, a marker class for buffer types, as proposed
  by PEP 688. Equivalent to `collections.abc.Buffer` in Python 3.12. Patch by
  Jelle Zijlstra.
- Backport two CPython PRs fixing various issues with `typing.Literal`:
  https://github.com/python/cpython/pull/23294 and
  https://github.com/python/cpython/pull/23383. Both CPython PRs were
  originally by Yurii Karabas, and both were backported to Python >=3.9.1, but
  no earlier. Patch by Alex Waygood.

  A side effect of one of the changes is that equality comparisons of `Literal`
  objects will now raise a `TypeError` if one of the `Literal` objects being
  compared has a mutable parameter. (Using mutable parameters with `Literal` is
  not supported by PEP 586 or by any major static type checkers.)
- `Literal` is now reimplemented on all Python versions <= 3.10.0. The
  `typing_extensions` version does not suffer from the bug that was fixed in
  https://github.com/python/cpython/pull/29334. (The CPython bugfix was
  backported to CPython 3.10.1 and 3.9.8, but no earlier.)
- Backport [CPython PR 26067](https://github.com/python/cpython/pull/26067)
  (originally by Yurii Karabas), ensuring that `isinstance()` calls on
  protocols raise `TypeError` when the protocol is not decorated with
  `@runtime_checkable`. Patch by Alex Waygood.
- Backport several significant performance improvements to runtime-checkable
  protocols that have been made in Python 3.12 (see
  https://github.com/python/cpython/issues/74690 for details). Patch by Alex
  Waygood.

  A side effect of one of the performance improvements is that the members of
  a runtime-checkable protocol are now considered “frozen” at runtime as soon
  as the class has been created. Monkey-patching attributes onto a
  runtime-checkable protocol will still work, but will have no impact on
  `isinstance()` checks comparing objects to the protocol. See
  ["What's New in Python 3.12"](https://docs.python.org/3.12/whatsnew/3.12.html#typing)
  for more details.
- `isinstance()` checks against runtime-checkable protocols now use
  `inspect.getattr_static()` rather than `hasattr()` to lookup whether
  attributes exist (backporting https://github.com/python/cpython/pull/103034).
  This means that descriptors and `__getattr__` methods are no longer
  unexpectedly evaluated during `isinstance()` checks against runtime-checkable
  protocols. However, it may also mean that some objects which used to be
  considered instances of a runtime-checkable protocol on older versions of
  `typing_extensions` may no longer be considered instances of that protocol
  using the new release, and vice versa. Most users are unlikely to be affected
  by this change. Patch by Alex Waygood.
- Backport the ability to define `__init__` methods on Protocol classes, a
  change made in Python 3.11 (originally implemented in
  https://github.com/python/cpython/pull/31628 by Adrian Garcia Badaracco).
  Patch by Alex Waygood.
- Speedup `isinstance(3, typing_extensions.SupportsIndex)` by >10x on Python
  <3.12. Patch by Alex Waygood.
- Add `typing_extensions` versions of `SupportsInt`, `SupportsFloat`,
  `SupportsComplex`, `SupportsBytes`, `SupportsAbs` and `SupportsRound`. These
  have the same semantics as the versions from the `typing` module, but
  `isinstance()` checks against the `typing_extensions` versions are >10x faster
  at runtime on Python <3.12. Patch by Alex Waygood.
- Add `__orig_bases__` to non-generic TypedDicts, call-based TypedDicts, and
  call-based NamedTuples. Other TypedDicts and NamedTuples already had the attribute.
  Patch by Adrian Garcia Badaracco.
- Add `typing_extensions.get_original_bases`, a backport of
  [`types.get_original_bases`](https://docs.python.org/3.12/library/types.html#types.get_original_bases),
  introduced in Python 3.12 (CPython PR
  https://github.com/python/cpython/pull/101827, originally by James
  Hilton-Balfe). Patch by Alex Waygood.

  This function should always produce correct results when called on classes
  constructed using features from `typing_extensions`. However, it may
  produce incorrect results when called on some `NamedTuple` or `TypedDict`
  classes that use `typing.{NamedTuple,TypedDict}` on Python <=3.11.
- Constructing a call-based `TypedDict` using keyword arguments for the fields
  now causes a `DeprecationWarning` to be emitted. This matches the behaviour
  of `typing.TypedDict` on 3.11 and 3.12.
- Backport the implementation of `NewType` from 3.10 (where it is implemented
  as a class rather than a function). This allows user-defined `NewType`s to be
  pickled. Patch by Alex Waygood.
- Fix tests and import on Python 3.12, where `typing.TypeVar` can no longer be
  subclassed. Patch by Jelle Zijlstra.
- Add `typing_extensions.TypeAliasType`, a backport of `typing.TypeAliasType`
  from PEP 695. Patch by Jelle Zijlstra.
- Backport changes to the repr of `typing.Unpack` that were made in order to
  implement [PEP 692](https://peps.python.org/pep-0692/) (backport of
  https://github.com/python/cpython/pull/104048). Patch by Alex Waygood.

# Release 4.5.0 (February 14, 2023)

- Runtime support for PEP 702, adding `typing_extensions.deprecated`. Patch
  by Jelle Zijlstra.
- Add better default value for TypeVar `default` parameter, PEP 696. Enables
  runtime check if `None` was passed as default. Patch by Marc Mueller (@cdce8p).
- The `@typing_extensions.override` decorator now sets the `.__override__`
  attribute. Patch by Steven Troxler.
- Fix `get_type_hints()` on cross-module inherited `TypedDict` in 3.9 and 3.10.
  Patch by Carl Meyer.
- Add `frozen_default` parameter on `dataclass_transform`. Patch by Erik De Bonte.

# Release 4.4.0 (October 6, 2022)

- Add `typing_extensions.Any` a backport of python 3.11's Any class which is
  subclassable at runtime. (backport from python/cpython#31841, by Shantanu
  and Jelle Zijlstra). Patch by James Hilton-Balfe (@Gobot1234).
- Add initial support for TypeVarLike `default` parameter, PEP 696.
  Patch by Marc Mueller (@cdce8p).
- Runtime support for PEP 698, adding `typing_extensions.override`. Patch by
  Jelle Zijlstra.
- Add the `infer_variance` parameter to `TypeVar`, as specified in PEP 695.
  Patch by Jelle Zijlstra.

# Release 4.3.0 (July 1, 2022)

- Add `typing_extensions.NamedTuple`, allowing for generic `NamedTuple`s on
  Python <3.11 (backport from python/cpython#92027, by Serhiy Storchaka). Patch
  by Alex Waygood (@AlexWaygood).
- Adjust `typing_extensions.TypedDict` to allow for generic `TypedDict`s on
  Python <3.11 (backport from python/cpython#27663, by Samodya Abey). Patch by
  Alex Waygood (@AlexWaygood).

# Release 4.2.0 (April 17, 2022)

- Re-export `typing.Unpack` and `typing.TypeVarTuple` on Python 3.11.
- Add `ParamSpecArgs` and `ParamSpecKwargs` to `__all__`.
- Improve "accepts only single type" error messages.
- Improve the distributed package. Patch by Marc Mueller (@cdce8p).
- Update `typing_extensions.dataclass_transform` to rename the
  `field_descriptors` parameter to `field_specifiers` and accept
  arbitrary keyword arguments.
- Add `typing_extensions.get_overloads` and
  `typing_extensions.clear_overloads`, and add registry support to
  `typing_extensions.overload`. Backport from python/cpython#89263.
- Add `typing_extensions.assert_type`. Backport from bpo-46480.
- Drop support for Python 3.6. Original patch by Adam Turner (@AA-Turner).

# Release 4.1.1 (February 13, 2022)

- Fix importing `typing_extensions` on Python 3.7.0 and 3.7.1. Original
  patch by Nikita Sobolev (@sobolevn).

# Release 4.1.0 (February 12, 2022)

- Runtime support for PEP 646, adding `typing_extensions.TypeVarTuple`
  and `typing_extensions.Unpack`.
- Add interaction of `Required` and `NotRequired` with `__required_keys__`,
  `__optional_keys__` and `get_type_hints()`. Patch by David Cabot (@d-k-bo).
- Runtime support for PEP 675 and `typing_extensions.LiteralString`.
- Add `Never` and `assert_never`. Backport from bpo-46475.
- `ParamSpec` args and kwargs are now equal to themselves. Backport from
  bpo-46676. Patch by Gregory Beauregard (@GBeauregard).
- Add `reveal_type`. Backport from bpo-46414.
- Runtime support for PEP 681 and `typing_extensions.dataclass_transform`.
- `Annotated` can now wrap `ClassVar` and `Final`. Backport from
  bpo-46491. Patch by Gregory Beauregard (@GBeauregard).
- Add missed `Required` and `NotRequired` to `__all__`. Patch by
  Yuri Karabas (@uriyyo).
- The `@final` decorator now sets the `__final__` attribute on the
  decorated object to allow runtime introspection. Backport from
  bpo-46342.
- Add `is_typeddict`. Patch by Chris Moradi (@chrismoradi) and James
  Hilton-Balfe (@Gobot1234).

# Release 4.0.1 (November 30, 2021)

- Fix broken sdist in release 4.0.0. Patch by Adam Turner (@AA-Turner).
- Fix equality comparison for `Required` and `NotRequired`. Patch by
  Jelle Zijlstra (@jellezijlstra).
- Fix usage of `Self` as a type argument. Patch by Chris Wesseling
  (@CharString) and James Hilton-Balfe (@Gobot1234).

# Release 4.0.0 (November 14, 2021)

- Starting with version 4.0.0, typing_extensions uses Semantic Versioning.
  See the README for more information.
- Dropped support for Python versions 3.5 and older, including Python 2.7.
- Simplified backports for Python 3.6.0 and newer. Patch by Adam Turner (@AA-Turner).

## Added in version 4.0.0

- Runtime support for PEP 673 and `typing_extensions.Self`. Patch by
  James Hilton-Balfe (@Gobot1234).
- Runtime support for PEP 655 and `typing_extensions.Required` and `NotRequired`.
  Patch by David Foster (@davidfstr).

## Removed in version 4.0.0

The following non-exported but non-private names have been removed as they are
unneeded for supporting Python 3.6 and newer.

- TypingMeta
- OLD_GENERICS
- SUBS_TREE
- HAVE_ANNOTATED
- HAVE_PROTOCOLS
- V_co
- VT_co

# Previous releases

Prior to release 4.0.0 we did not provide a changelog. Please check
the Git history for details.