Mypy

for improved performance. You can ensure the presence of `orjson` using the `faster-cache` extra:

python3 -m pip install -U mypy[faster-cache]

Mypy may depend on `orjson` by default in the future.

These improvements were contributed by Shantanu.

List of changes:
* Significantly speed up file handling error paths (Shantanu, PR [17920](https://github.com/python/mypy/pull/17920))
* Use fast path in modulefinder more often (Shantanu, PR [17950](https://github.com/python/mypy/pull/17950))
* Let mypyc optimise os.path.join (Shantanu, PR [17949](https://github.com/python/mypy/pull/17949))
* Make is_sub_path faster (Shantanu, PR [17962](https://github.com/python/mypy/pull/17962))
* Speed up stubs suggestions (Shantanu, PR [17965](https://github.com/python/mypy/pull/17965))
* Use sha1 for hashing (Shantanu, PR [17953](https://github.com/python/mypy/pull/17953))
* Use orjson instead of json, when available (Shantanu, PR [17955](https://github.com/python/mypy/pull/17955))
* Add faster-cache extra, test in CI (Shantanu, PR [17978](https://github.com/python/mypy/pull/17978))

Acknowledgements
Thanks to all mypy contributors who contributed to this release:

- Shantanu Jain
- Jukka Lehtosalo

* Fix crash when showing partially analyzed type in error message (Ivan Levkivskyi, PR [17961](https://github.com/python/mypy/pull/17961))
* Fix iteration over union (when self type is involved) (Shantanu, PR [17976](https://github.com/python/mypy/pull/17976))
* Fix type object with type var default in union context (Jukka Lehtosalo, PR [17991](https://github.com/python/mypy/pull/17991))
* Revert change to `os.path` stubs affecting use of `os.PathLike[Any]` (Shantanu, PR [17995](https://github.com/python/mypy/pull/17995))

Acknowledgements
Thanks to all mypy contributors who contributed to this release:

- Ali Hamdan
- Anders Kaseorg
- Bénédikt Tran
- Brian Schubert
- bzoracler
- Chelsea Durazo
- Danny Yang
- Edgar Ramírez Mondragón
- Eric Mark Martin
- InSync
- Ivan Levkivskyi
- Jordandev678
- Katrina Connors
- Kirill Podoprigora
- Marc Mueller
- Max Muoto
- Max Murin
- Michael Carlstrom
- Michael I Chen
- Pradyun Gedam
- quinn-sasha
- Raphael Krupinski
- Sebastian Rittau
- Shantanu
- sobolevn
- Soubhik Kumar Mitra
- Stanislav Terliakov
- wyattscarpenter

I’d also like to thank my employer, Dropbox, for supporting mypy development.

We’ve just uploaded mypy 1.12 to the Python Package Index ([PyPI](https://pypi.org/project/mypy/)). Mypy is a static type
checker for Python. This release includes new features, performance improvements and bug fixes.
You can install it as follows:

python3 -m pip install -U mypy

You can read the full documentation for this release on [Read the Docs](http://mypy.readthedocs.io).

Support Python 3.12 Syntax for Generics (PEP 695)

Support for the new type parameter syntax introduced in Python 3.12 is now enabled by default,
documented, and no longer experimental. It was available through a feature flag in
mypy 1.11 as an experimental feature.

This example demonstrates the new syntax:

python
Generic function
def f[T](x: T) -> T: ...

reveal_type(f(1)) Revealed type is 'int'

Generic class
class C[T]:
def __init__(self, x: T) -> None:
self.x = x

c = C('a')
reveal_type(c.x) Revealed type is 'str'

Type alias
type A[T] = C[list[T]]


For more information, refer to the [documentation](https://mypy.readthedocs.io/en/latest/generics.html).

These improvements are included:

* Document Python 3.12 type parameter syntax (Jukka Lehtosalo, PR [17816](https://github.com/python/mypy/pull/17816))
* Further documentation updates (Jukka Lehtosalo, PR [17826](https://github.com/python/mypy/pull/17826))
* Allow Self return types with contravariance (Jukka Lehtosalo, PR [17786](https://github.com/python/mypy/pull/17786))
* Enable new type parameter syntax by default (Jukka Lehtosalo, PR [17798](https://github.com/python/mypy/pull/17798))
* Generate error if new-style type alias used as base class (Jukka Lehtosalo, PR [17789](https://github.com/python/mypy/pull/17789))
* Inherit variance if base class has explicit variance (Jukka Lehtosalo, PR [17787](https://github.com/python/mypy/pull/17787))
* Fix crash on invalid type var reference (Jukka Lehtosalo, PR [17788](https://github.com/python/mypy/pull/17788))
* Fix covariance of frozen dataclasses (Jukka Lehtosalo, PR [17783](https://github.com/python/mypy/pull/17783))
* Allow covariance with attribute that has "`_`" name prefix (Jukka Lehtosalo, PR [17782](https://github.com/python/mypy/pull/17782))
* Support `Annotated[...]` in new-style type aliases (Jukka Lehtosalo, PR [17777](https://github.com/python/mypy/pull/17777))
* Fix nested generic classes (Jukka Lehtosalo, PR [17776](https://github.com/python/mypy/pull/17776))
* Add detection and error reporting for the use of incorrect expressions within the scope of a type parameter and a type alias (Kirill Podoprigora, PR [17560](https://github.com/python/mypy/pull/17560))

Basic Support for Python 3.13

This release adds partial support for Python 3.13 features and compiled binaries for
Python 3.13. Mypyc now also supports Python 3.13.

In particular, these features are supported:
* Various new stdlib features and changes (through typeshed stub improvements)
* `typing.ReadOnly` (see below for more)
* `typing.TypeIs` (added in mypy 1.10, [PEP 742](https://peps.python.org/pep-0742/))
* Type parameter defaults when using the legacy syntax ([PEP 696](https://peps.python.org/pep-0696/))

These features are not supported yet:
* `warnings.deprecated` ([PEP 702](https://peps.python.org/pep-0702/))
* Type parameter defaults when using Python 3.12 type parameter syntax

Mypyc Support for Python 3.13

Mypyc now supports Python 3.13. This was contributed by Marc Mueller, with additional
fixes by Jukka Lehtosalo. Free threaded Python 3.13 builds are not supported yet.

List of changes:

* Add additional includes for Python 3.13 (Marc Mueller, PR [17506](https://github.com/python/mypy/pull/17506))
* Add another include for Python 3.13 (Marc Mueller, PR [17509](https://github.com/python/mypy/pull/17509))
* Fix ManagedDict functions for Python 3.13 (Marc Mueller, PR [17507](https://github.com/python/mypy/pull/17507))
* Update mypyc test output for Python 3.13 (Marc Mueller, PR [17508](https://github.com/python/mypy/pull/17508))
* Fix `PyUnicode` functions for Python 3.13 (Marc Mueller, PR [17504](https://github.com/python/mypy/pull/17504))
* Fix `_PyObject_LookupAttrId` for Python 3.13 (Marc Mueller, PR [17505](https://github.com/python/mypy/pull/17505))
* Fix `_PyList_Extend` for Python 3.13 (Marc Mueller, PR [17503](https://github.com/python/mypy/pull/17503))
* Fix `gen_is_coroutine` for Python 3.13 (Marc Mueller, PR [17501](https://github.com/python/mypy/pull/17501))
* Fix `_PyObject_FastCall` for Python 3.13 (Marc Mueller, PR [17502](https://github.com/python/mypy/pull/17502))
* Avoid uses of `_PyObject_CallMethodOneArg` on 3.13 (Jukka Lehtosalo, PR [17526](https://github.com/python/mypy/pull/17526))
* Don't rely on `_PyType_CalculateMetaclass` on 3.13 (Jukka Lehtosalo, PR [17525](https://github.com/python/mypy/pull/17525))
* Don't use `_PyUnicode_FastCopyCharacters` on 3.13 (Jukka Lehtosalo, PR [17524](https://github.com/python/mypy/pull/17524))
* Don't use `_PyUnicode_EQ` on 3.13, as it's no longer exported (Jukka Lehtosalo, PR [17523](https://github.com/python/mypy/pull/17523))

Inferring Unions for Conditional Expressions

Mypy now always tries to infer a union type for a conditional expression if left and right
operand types are different. This results in more precise inferred types and lets mypy detect
more issues. Example:

python
s = "foo" if cond() else 1
Type of "s" is now "str | int" (it used to be "object")


Notably, if one of the operands has type `Any`, the type of a conditional expression is
now `<type> | Any`. Previously the inferred type was just `Any`. The new type essentially
indicates that the value can be of type `<type>`, and potentially of some (unknown) type.
Most operations performed on the result must also be valid for `<type>`.
Example where this is relevant:

python
from typing import Any

def func(a: Any, b: bool) -> None:
x = a if b else None
Type of x is "Any | None"
print(x.y) Error: None has no attribute "y"


This feature was contributed by Ivan Levkivskyi (PR [17427](https://github.com/python/mypy/pull/17427)).

ReadOnly Support for TypedDict (PEP 705)

You can now use `typing.ReadOnly` to specity TypedDict items as
read-only ([PEP 705](https://peps.python.org/pep-0705/)):

python
from typing import TypedDict

Or "from typing ..." on Python 3.13
from typing_extensions import ReadOnly

class TD(TypedDict):
a: int
b: ReadOnly[int]

d: TD = {"a": 1, "b": 2}
d["a"] = 3 OK
d["b"] = 5 Error: "b" is ReadOnly


This feature was contributed by Nikita Sobolev (PR [17644](https://github.com/python/mypy/pull/17644)).

Python 3.8 End of Life Approaching

We are planning to drop support for Python 3.8 in the next mypy feature release or the
one after that. Python 3.8 reaches end of life in October 2024.

Planned Changes to Defaults

We are planning to enable `--local-partial-types` by default in mypy 2.0. This will
often require at least minor code changes. This option is implicitly enabled by mypy
daemon, so this makes the behavior of daemon and non-daemon modes consistent.

We recommend that mypy users start using local partial types soon (or to explicitly disable
them) to prepare for the change.

This can also be configured in a mypy configuration file:


local_partial_types = True


For more information, refer to the
[documentation](https://mypy.readthedocs.io/en/stable/command_line.html#cmdoption-mypy-local-partial-types).

Documentation Updates

Mypy documentation now uses modern syntax variants and imports in many examples. Some
examples no longer work on Python 3.8, which is the earliest Python version that mypy supports.

Notably, `Iterable` and other protocols/ABCs are imported from `collections.abc` instead of
`typing`:
python
from collections.abc import Iterable, Callable


Examples also avoid the upper-case aliases to built-in types: `list[str]` is used instead
of `List[str]`. The `X | Y` union type syntax introduced in Python 3.10 is also now prevalent.

List of documentation updates:

* Document `--output=json` CLI option (Edgar Ramírez Mondragón, PR [17611](https://github.com/python/mypy/pull/17611))
* Update various references to deprecated type aliases in docs (Jukka Lehtosalo, PR [17829](https://github.com/python/mypy/pull/17829))
* Make "X | Y" union syntax more prominent in documentation (Jukka Lehtosalo, PR [17835](https://github.com/python/mypy/pull/17835))
* Discuss upper bounds before self types in documentation (Jukka Lehtosalo, PR [17827](https://github.com/python/mypy/pull/17827))
* Make changelog visible in mypy documentation (quinn-sasha, PR [17742](https://github.com/python/mypy/pull/17742))
* List all incomplete features in `--enable-incomplete-feature` docs (sobolevn, PR [17633](https://github.com/python/mypy/pull/17633))
* Remove the explicit setting of a pygments theme (Pradyun Gedam, PR [17571](https://github.com/python/mypy/pull/17571))
* Document ReadOnly with TypedDict (Jukka Lehtosalo, PR [17905](https://github.com/python/mypy/pull/17905))
* Document TypeIs (Chelsea Durazo, PR [17821](https://github.com/python/mypy/pull/17821))

Experimental Inline TypedDict Syntax

Mypy now supports a non-standard, experimental syntax for defining anonymous TypedDicts.
Example:

python
def func(n: str, y: int) -> {"name": str, "year": int}:
return {"name": n, "year": y}


The feature is disabled by default. Use `--enable-incomplete-feature=InlineTypedDict` to
enable it. *We might remove this feature in a future release.*

This feature was contributed by Ivan Levkivskyi (PR [17457](https://github.com/python/mypy/pull/17457)).

Stubgen Improvements

* Fix crash on literal class-level keywords (sobolevn, PR [17663](https://github.com/python/mypy/pull/17663))
* Stubgen add `--version` (sobolevn, PR [17662](https://github.com/python/mypy/pull/17662))
* Fix `stubgen --no-analysis/--parse-only` docs (sobolevn, PR [17632](https://github.com/python/mypy/pull/17632))
* Include keyword only args when generating signatures in stubgenc (Eric Mark Martin, PR [17448](https://github.com/python/mypy/pull/17448))
* Add support for detecting `Literal` types when extracting types from docstrings (Michael Carlstrom, PR [17441](https://github.com/python/mypy/pull/17441))
* Use `Generator` type var defaults (Sebastian Rittau, PR [17670](https://github.com/python/mypy/pull/17670))

Stubtest Improvements
* Add support for `cached_property` (Ali Hamdan, PR [17626](https://github.com/python/mypy/pull/17626))
* Add `enable_incomplete_feature` validation to `stubtest` (sobolevn, PR [17635](https://github.com/python/mypy/pull/17635))
* Fix error code handling in `stubtest` with `--mypy-config-file` (sobolevn, PR [17629](https://github.com/python/mypy/pull/17629))

Other Notables Fixes and Improvements

* Report error if using unsupported type parameter defaults (Jukka Lehtosalo, PR [17876](https://github.com/python/mypy/pull/17876))
* Fix re-processing cross-reference in mypy daemon when node kind changes (Ivan Levkivskyi, PR [17883](https://github.com/python/mypy/pull/17883))
* Don't use equality to narrow when value is IntEnum/StrEnum (Jukka Lehtosalo, PR [17866](https://github.com/python/mypy/pull/17866))
* Don't consider None vs IntEnum comparison ambiguous (Jukka Lehtosalo, PR [17877](https://github.com/python/mypy/pull/17877))
* Fix narrowing of IntEnum and StrEnum types (Jukka Lehtosalo, PR [17874](https://github.com/python/mypy/pull/17874))
* Filter overload items based on self type during type inference (Jukka Lehtosalo, PR [17873](https://github.com/python/mypy/pull/17873))
* Enable negative narrowing of union TypeVar upper bounds (Brian Schubert, PR [17850](https://github.com/python/mypy/pull/17850))
* Fix issue with member expression formatting (Brian Schubert, PR [17848](https://github.com/python/mypy/pull/17848))
* Avoid type size explosion when expanding types (Jukka Lehtosalo, PR [17842](https://github.com/python/mypy/pull/17842))
* Fix negative narrowing of tuples in match statement (Brian Schubert, PR [17817](https://github.com/python/mypy/pull/17817))
* Narrow falsey str/bytes/int to literal type (Brian Schubert, PR [17818](https://github.com/python/mypy/pull/17818))
* Test against latest Python 3.13, make testing 3.14 easy (Shantanu, PR [17812](https://github.com/python/mypy/pull/17812))
* Reject ParamSpec-typed callables calls with insufficient arguments (Stanislav Terliakov, PR [17323](https://github.com/python/mypy/pull/17323))
* Fix crash when passing too many type arguments to generic base class accepting single ParamSpec (Brian Schubert, PR [17770](https://github.com/python/mypy/pull/17770))
* Fix TypeVar upper bounds sometimes not being displayed in pretty callables (Brian Schubert, PR [17802](https://github.com/python/mypy/pull/17802))
* Added error code for overlapping function signatures (Katrina Connors, PR [17597](https://github.com/python/mypy/pull/17597))
* Check for `truthy-bool` in `not ...` unary expressions (sobolevn, PR [17773](https://github.com/python/mypy/pull/17773))
* Add missing lines-covered and lines-valid attributes (Soubhik Kumar Mitra, PR [17738](https://github.com/python/mypy/pull/17738))
* Fix another crash scenario with recursive tuple types (Ivan Levkivskyi, PR [17708](https://github.com/python/mypy/pull/17708))
* Resolve TypeVar upper bounds in `functools.partial` (Shantanu, PR [17660](https://github.com/python/mypy/pull/17660))
* Always reset binder when checking deferred nodes (Ivan Levkivskyi, PR [17643](https://github.com/python/mypy/pull/17643))
* Fix crash on a callable attribute with single unpack (Ivan Levkivskyi, PR [17641](https://github.com/python/mypy/pull/17641))
* Fix mismatched signature between checker plugin API and implementation (bzoracler, PR [17343](https://github.com/python/mypy/pull/17343))
* Indexing a type also produces a GenericAlias (Shantanu, PR [17546](https://github.com/python/mypy/pull/17546))
* Fix crash on self-type in callable protocol (Ivan Levkivskyi, PR [17499](https://github.com/python/mypy/pull/17499))
* Fix crash on NamedTuple with method and error in function (Ivan Levkivskyi, PR [17498](https://github.com/python/mypy/pull/17498))
* Add `__replace__` for dataclasses in 3.13 (Max Muoto, PR [17469](https://github.com/python/mypy/pull/17469))
* Fix help message for `--no-namespace-packages` (Raphael Krupinski, PR [17472](https://github.com/python/mypy/pull/17472))
* Fix typechecking for async generators (Danny Yang, PR [17452](https://github.com/python/mypy/pull/17452))
* Fix strict optional handling in attrs plugin (Ivan Levkivskyi, PR [17451](https://github.com/python/mypy/pull/17451))
* Allow mixing ParamSpec and TypeVarTuple in Generic (Ivan Levkivskyi, PR [17450](https://github.com/python/mypy/pull/17450))
* Improvements to `functools.partial` of types (Shantanu, PR [17898](https://github.com/python/mypy/pull/17898))
* Make ReadOnly TypedDict items covariant (Jukka Lehtosalo, PR [17904](https://github.com/python/mypy/pull/17904))
* Fix union callees with `functools.partial` (Jukka Lehtosalo, PR [17903](https://github.com/python/mypy/pull/17903))
* Improve handling of generic functions with `functools.partial` (Ivan Levkivskyi, PR [17925](https://github.com/python/mypy/pull/17925))

Typeshed Updates

Please see [git log](https://github.com/python/typeshed/commits/main?after=91a58b07cdd807b1d965e04ba85af2adab8bf924+0&branch=main&path=stdlib) for full list of standard library typeshed stub changes.

* Alternative fix for a union-like literal string (Ivan Levkivskyi, PR [17639](https://github.com/python/mypy/pull/17639))
* Unwrap `TypedDict` item types before storing (Ivan Levkivskyi, PR [17640](https://github.com/python/mypy/pull/17640))

Acknowledgements
Thanks to all mypy contributors who contributed to this release:

- Alex Waygood
- Alexander Leopold Shon
- Ali Hamdan
- Anders Kaseorg
- Ben Brown
- Bénédikt Tran
- bzoracler
- Christoph Tyralla
- Christopher Barber
- dexterkennedy
- gilesgc
- GiorgosPapoutsakis
- Ivan Levkivskyi
- Jelle Zijlstra
- Jukka Lehtosalo
- Marc Mueller
- Matthieu Devlin
- Michael R. Crusoe
- Nikita Sobolev
- Seo Sanghyeon
- Shantanu
- sobolevn
- Steven Troxler
- Tadeu Manoel
- Tamir Duberstein
- Tushar Sadhwani
- urnest
- Valentin Stanciu

I’d also like to thank my employer, Dropbox, for supporting mypy development.

* Fix `RawExpressionType.accept` crash with `--cache-fine-grained` (Anders Kaseorg, PR [17588](https://github.com/python/mypy/pull/17588))
* Fix PEP 604 isinstance caching (Shantanu, PR [17563](https://github.com/python/mypy/pull/17563))
* Fix `typing.TypeAliasType` being undefined on python < 3.12 (Nikita Sobolev, PR [17558](https://github.com/python/mypy/pull/17558))
* Fix `types.GenericAlias` lookup crash (Shantanu, PR [17543](https://github.com/python/mypy/pull/17543))

We’ve just uploaded mypy 1.11 to the Python Package Index ([PyPI](https://pypi.org/project/mypy/)). Mypy is a static type checker for Python. This release includes new features, performance improvements and bug fixes. You can install it as follows:

python3 -m pip install -U mypy

You can read the full documentation for this release on [Read the Docs](http://mypy.readthedocs.io).

Support Python 3.12 Syntax for Generics (PEP 695)

Mypy now supports the new type parameter syntax introduced in Python 3.12 ([PEP 695](https://peps.python.org/pep-0695/)).
This feature is still experimental and must be enabled with the `--enable-incomplete-feature=NewGenericSyntax` flag, or with `enable_incomplete_feature = NewGenericSyntax` in the mypy configuration file.
We plan to enable this by default in the next mypy feature release.

This example demonstrates the new syntax:

python
Generic function
def f[T](x: T) -> T: ...

reveal_type(f(1)) Revealed type is 'int'

Generic class
class C[T]:
def __init__(self, x: T) -> None:
self.x = x

c = C('a')
reveal_type(c.x) Revealed type is 'str'

Type alias
type A[T] = C[list[T]]


This feature was contributed by Jukka Lehtosalo.


Support for `functools.partial`

Mypy now type checks uses of `functools.partial`. Previously mypy would accept arbitrary arguments.

This example will now produce an error:

python
from functools import partial

def f(a: int, b: str) -> None: ...

g = partial(f, 1)

Argument has incompatible type "int"; expected "str"
g(11)


This feature was contributed by Shantanu (PR [16939](https://github.com/python/mypy/pull/16939)).


Stricter Checks for Untyped Overrides

Past mypy versions didn't check if untyped methods were compatible with overridden methods. This would result in false negatives. Now mypy performs these checks when using `--check-untyped-defs`.

For example, this now generates an error if using `--check-untyped-defs`:

python
class Base:
def f(self, x: int = 0) -> None: ...

class Derived(Base):
Signature incompatible with "Base"
def f(self): ...


This feature was contributed by Steven Troxler (PR [17276](https://github.com/python/mypy/pull/17276)).


Type Inference Improvements

The new polymorphic inference algorithm introduced in mypy 1.5 is now used in more situations. This improves type inference involving generic higher-order functions, in particular.

This feature was contributed by Ivan Levkivskyi (PR [17348](https://github.com/python/mypy/pull/17348)).

Mypy now uses unions of tuple item types in certain contexts to enable more precise inferred types. Example:

python
for x in (1, 'x'):
Previously inferred as 'object'
reveal_type(x) Revealed type is 'int | str'


This was also contributed by Ivan Levkivskyi (PR [17408](https://github.com/python/mypy/pull/17408)).


Improvements to Detection of Overlapping Overloads

The details of how mypy checks if two `overload` signatures are unsafely overlapping were overhauled. This both fixes some false positives, and allows mypy to detect additional unsafe signatures.

This feature was contributed by Ivan Levkivskyi (PR [17392](https://github.com/python/mypy/pull/17392)).


Better Support for Type Hints in Expressions

Mypy now allows more expressions that evaluate to valid type annotations in all expression contexts. The inferred types of these expressions are also sometimes more precise. Previously they were often `object`.

This example uses a union type that includes a callable type as an expression, and it no longer generates an error:

python
from typing import Callable

print(Callable[[], int] | None) No error


This feature was contributed by Jukka Lehtosalo (PR [17404](https://github.com/python/mypy/pull/17404)).


Mypyc Improvements

Mypyc now supports the new syntax for generics introduced in Python 3.12 (see above). Another notable improvement is signficantly faster basic operations on `int` values.

* Support Python 3.12 syntax for generic functions and classes (Jukka Lehtosalo, PR [17357](https://github.com/python/mypy/pull/17357))
* Support Python 3.12 type alias syntax (Jukka Lehtosalo, PR [17384](https://github.com/python/mypy/pull/17384))
* Fix ParamSpec (Shantanu, PR [17309](https://github.com/python/mypy/pull/17309))
* Inline fast paths of integer unboxing operations (Jukka Lehtosalo, PR [17266](https://github.com/python/mypy/pull/17266))
* Inline tagged integer arithmetic and bitwise operations (Jukka Lehtosalo, PR [17265](https://github.com/python/mypy/pull/17265))
* Allow specifying primitives as pure (Jukka Lehtosalo, PR [17263](https://github.com/python/mypy/pull/17263))


Changes to Stubtest
* Ignore `_ios_support` (Alex Waygood, PR [17270](https://github.com/python/mypy/pull/17270))
* Improve support for Python 3.13 (Shantanu, PR [17261](https://github.com/python/mypy/pull/17261))


Changes to Stubgen
* Gracefully handle invalid `Optional` and recognize aliases to PEP 604 unions (Ali Hamdan, PR [17386](https://github.com/python/mypy/pull/17386))
* Fix for Python 3.13 (Jelle Zijlstra, PR [17290](https://github.com/python/mypy/pull/17290))
* Preserve enum value initialisers (Shantanu, PR [17125](https://github.com/python/mypy/pull/17125))


Miscellaneous New Features
* Add error format support and JSON output option via `--output json` (Tushar Sadhwani, PR [11396](https://github.com/python/mypy/pull/11396))
* Support `enum.member` in Python 3.11+ (Nikita Sobolev, PR [17382](https://github.com/python/mypy/pull/17382))
* Support `enum.nonmember` in Python 3.11+ (Nikita Sobolev, PR [17376](https://github.com/python/mypy/pull/17376))
* Support `namedtuple.__replace__` in Python 3.13 (Shantanu, PR [17259](https://github.com/python/mypy/pull/17259))
* Support `rename=True` in collections.namedtuple (Jelle Zijlstra, PR [17247](https://github.com/python/mypy/pull/17247))
* Add support for `__spec__` (Shantanu, PR [14739](https://github.com/python/mypy/pull/14739))


Changes to Error Reporting
* Mention `--enable-incomplete-feature=NewGenericSyntax` in messages (Shantanu, PR [17462](https://github.com/python/mypy/pull/17462))
* Do not report plugin-generated methods with `explicit-override` (sobolevn, PR [17433](https://github.com/python/mypy/pull/17433))
* Use and display namespaces for function type variables (Ivan Levkivskyi, PR [17311](https://github.com/python/mypy/pull/17311))
* Fix false positive for Final local scope variable in Protocol (GiorgosPapoutsakis, PR [17308](https://github.com/python/mypy/pull/17308))
* Use Never in more messages, use ambiguous in join (Shantanu, PR [17304](https://github.com/python/mypy/pull/17304))
* Log full path to config file in verbose output (dexterkennedy, PR [17180](https://github.com/python/mypy/pull/17180))
* Added `[prop-decorator]` code for unsupported property decorators (14461) (Christopher Barber, PR [16571](https://github.com/python/mypy/pull/16571))
* Suppress second error message with `:=` and `[truthy-bool]` (Nikita Sobolev, PR [15941](https://github.com/python/mypy/pull/15941))
* Generate error for assignment of functional Enum to variable of different name (Shantanu, PR [16805](https://github.com/python/mypy/pull/16805))
* Fix error reporting on cached run after uninstallation of third party library (Shantanu, PR [17420](https://github.com/python/mypy/pull/17420))


Fixes for Crashes
* Fix daemon crash on invalid type in TypedDict (Ivan Levkivskyi, PR [17495](https://github.com/python/mypy/pull/17495))
* Fix crash and bugs related to `partial()` (Ivan Levkivskyi, PR [17423](https://github.com/python/mypy/pull/17423))
* Fix crash when overriding with unpacked TypedDict (Ivan Levkivskyi, PR [17359](https://github.com/python/mypy/pull/17359))
* Fix crash on TypedDict unpacking for ParamSpec (Ivan Levkivskyi, PR [17358](https://github.com/python/mypy/pull/17358))
* Fix crash involving recursive union of tuples (Ivan Levkivskyi, PR [17353](https://github.com/python/mypy/pull/17353))
* Fix crash on invalid callable property override (Ivan Levkivskyi, PR [17352](https://github.com/python/mypy/pull/17352))
* Fix crash on unpacking self in NamedTuple (Ivan Levkivskyi, PR [17351](https://github.com/python/mypy/pull/17351))
* Fix crash on recursive alias with an optional type (Ivan Levkivskyi, PR [17350](https://github.com/python/mypy/pull/17350))
* Fix crash on type comment inside generic definitions (Bénédikt Tran, PR [16849](https://github.com/python/mypy/pull/16849))


Changes to Documentation
* Use inline config in documentation for optional error codes (Shantanu, PR [17374](https://github.com/python/mypy/pull/17374))
* Use lower-case generics in documentation (Seo Sanghyeon, PR [17176](https://github.com/python/mypy/pull/17176))
* Add documentation for show-error-code-links (GiorgosPapoutsakis, PR [17144](https://github.com/python/mypy/pull/17144))
* Update CONTRIBUTING.md to include commands for Windows (GiorgosPapoutsakis, PR [17142](https://github.com/python/mypy/pull/17142))


Other Notable Improvements and Fixes
* Fix ParamSpec inference against TypeVarTuple (Ivan Levkivskyi, PR [17431](https://github.com/python/mypy/pull/17431))
* Fix explicit type for `partial` (Ivan Levkivskyi, PR [17424](https://github.com/python/mypy/pull/17424))
* Always allow lambda calls (Ivan Levkivskyi, PR [17430](https://github.com/python/mypy/pull/17430))
* Fix isinstance checks with PEP 604 unions containing None (Shantanu, PR [17415](https://github.com/python/mypy/pull/17415))
* Fix self-referential upper bound in new-style type variables (Ivan Levkivskyi, PR [17407](https://github.com/python/mypy/pull/17407))
* Consider overlap between instances and callables (Ivan Levkivskyi, PR [17389](https://github.com/python/mypy/pull/17389))
* Allow new-style self-types in classmethods (Ivan Levkivskyi, PR [17381](https://github.com/python/mypy/pull/17381))
* Fix isinstance with type aliases to PEP 604 unions (Shantanu, PR [17371](https://github.com/python/mypy/pull/17371))
* Properly handle unpacks in overlap checks (Ivan Levkivskyi, PR [17356](https://github.com/python/mypy/pull/17356))
* Fix type application for classes with generic constructors (Ivan Levkivskyi, PR [17354](https://github.com/python/mypy/pull/17354))
* Update `typing_extensions` to >=4.6.0 to fix Python 3.12 error (Ben Brown, PR [17312](https://github.com/python/mypy/pull/17312))
* Avoid "does not return" error in lambda (Shantanu, PR [17294](https://github.com/python/mypy/pull/17294))
* Fix bug with descriptors in non-strict-optional mode (Max Murin, PR [17293](https://github.com/python/mypy/pull/17293))
* Don’t leak unreachability from lambda body to surrounding scope (Anders Kaseorg, PR [17287](https://github.com/python/mypy/pull/17287))
* Fix issues with non-ASCII characters on Windows (Alexander Leopold Shon, PR [17275](https://github.com/python/mypy/pull/17275))
* Fix for type narrowing of negative integer literals (gilesgc, PR [17256](https://github.com/python/mypy/pull/17256))
* Fix confusion between .py and .pyi files in mypy daemon (Valentin Stanciu, PR [17245](https://github.com/python/mypy/pull/17245))
* Fix type of `tuple[X, Y]` expression (urnest, PR [17235](https://github.com/python/mypy/pull/17235))
* Don't forget that a `TypedDict` was wrapped in `Unpack` after a `name-defined` error occurred (Christoph Tyralla, PR [17226](https://github.com/python/mypy/pull/17226))
* Mark annotated argument as having an explicit, not inferred type (bzoracler, PR [17217](https://github.com/python/mypy/pull/17217))
* Don't consider Enum private attributes as enum members (Ali Hamdan, PR [17182](https://github.com/python/mypy/pull/17182))
* Fix Literal strings containing pipe characters (Jelle Zijlstra, PR [17148](https://github.com/python/mypy/pull/17148))


Typeshed Updates

Please see [git log](https://github.com/python/typeshed/commits/main?after=6dda799d8ad1d89e0f8aad7ac41d2d34bd838ace+0&branch=main&path=stdlib) for full list of standard library typeshed stub changes.