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Update CHANGELOG for mypy 1.11 #17540

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188 changes: 131 additions & 57 deletions CHANGELOG.md
Original file line number Diff line number Diff line change
Expand Up @@ -11,125 +11,199 @@ We’ve just uploaded mypy 1.11 to the Python Package Index ([PyPI](https://pypi

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

#### Additional support for PEP 695
#### Support Python 3.12 Syntax for Generics (PEP 695)

Mypy now has experimental support for 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.
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

```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 (PR [17233](https://github.com/python/mypy/pull/17233)).
This feature was contributed by Jukka Lehtosalo.


#### Support for `functools.partial`

Mypy now typechecks uses of `functools.partial`, which previous mypy would always accept.
This example would previously pass:
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)
g(1) # error: Argument 1 to "f" has incompatible type "int"; expected "str" [arg-type]

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

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


#### Changes to stubtest
* Stubtest: ignore `_ios_support` (Alex Waygood, PR [17270](https://github.com/python/mypy/pull/17270))
* stubtest: changes for py313 (Shantanu, PR [17261](https://github.com/python/mypy/pull/17261))
#### 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

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

#### Changes to mypyc
* [mypyc] Sync pythoncapi_compat.h (Jukka Lehtosalo, PR [17390](https://github.com/python/mypy/pull/17390))
* [mypyc] Support Python 3.12 type alias syntax (PEP 695) (Jukka Lehtosalo, PR [17384](https://github.com/python/mypy/pull/17384))
* [mypyc] Support new syntax for generic functions and classes (PEP 695) (Jukka Lehtosalo, PR [17357](https://github.com/python/mypy/pull/17357))
* [mypyc] Fix ParamSpec (Shantanu, PR [17309](https://github.com/python/mypy/pull/17309))
* [mypyc] Inline fast paths of integer unboxing operations (Jukka Lehtosalo, PR [17266](https://github.com/python/mypy/pull/17266))
* [mypyc] Inline tagged integer arithmetic and bitwise operations (Jukka Lehtosalo, PR [17265](https://github.com/python/mypy/pull/17265))
* [mypyc] Allow specifying primitives as pure (Jukka Lehtosalo, PR [17263](https://github.com/python/mypy/pull/17263))

#### Better Support for Type Hints in Expressions

#### Changes to error reporting
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))
* Fix explicit type for partial (Ivan Levkivskyi, PR [17424](https://github.com/python/mypy/pull/17424))
* Re-work overload overlap logic (Ivan Levkivskyi, PR [17392](https://github.com/python/mypy/pull/17392))
* Use namespaces for function type variables (Ivan Levkivskyi, PR [17311](https://github.com/python/mypy/pull/17311))
* 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))
* 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))
* Error for assignment of functional Enum to variable of different name (Shantanu, PR [16805](https://github.com/python/mypy/pull/16805))
* Add Error format support, and JSON output option (Tushar Sadhwani, PR [11396](https://github.com/python/mypy/pull/11396))
* 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
#### Fixes for Crashes
* Fix daemon crash on invalid type in TypedDict (Ivan Levkivskyi, PR [17495](https://github.com/python/mypy/pull/17495))
* Some cleanup in partial plugin (Ivan Levkivskyi, PR [17423](https://github.com/python/mypy/pull/17423))
* 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 type comments crash inside generic definitions (Bénédikt Tran, PR [16849](https://github.com/python/mypy/pull/16849))
* Fix crash on type comment inside generic definitions (Bénédikt Tran, PR [16849](https://github.com/python/mypy/pull/16849))


#### Changes to documentation
* Mention --enable-incomplete-feature=NewGenericSyntax (Shantanu, PR [17462](https://github.com/python/mypy/pull/17462))
* Use inline config in the optional error codes docs (Shantanu, PR [17374](https://github.com/python/mypy/pull/17374))
* docs: Use lower-case generics (Seo Sanghyeon, PR [17176](https://github.com/python/mypy/pull/17176))
#### 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 contributions
#### 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 error reporting on cached run after uninstallation of third party library (Shantanu, PR [17420](https://github.com/python/mypy/pull/17420))
* Fix isinstance checks with PEP 604 unions containing None (Shantanu, PR [17415](https://github.com/python/mypy/pull/17415))
* Use (simplified) unions instead of joins for tuple fallbacks (Ivan Levkivskyi, PR [17408](https://github.com/python/mypy/pull/17408))
* 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))
* Support `enum.member` for python3.11+ (Nikita Sobolev, PR [17382](https://github.com/python/mypy/pull/17382))
* Allow new-style self-types in classmethods (Ivan Levkivskyi, PR [17381](https://github.com/python/mypy/pull/17381))
* Support `enum.nonmember` for python3.11+ (Nikita Sobolev, PR [17376](https://github.com/python/mypy/pull/17376))
* 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))
* Use polymorphic inference in unification (Ivan Levkivskyi, PR [17348](https://github.com/python/mypy/pull/17348))
* 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 for bug with descriptors in non-strict-optional (Max Murin, PR [17293](https://github.com/python/mypy/pull/17293))
* 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))
* Validate more about overrides on untyped methods (Steven Troxler, PR [17276](https://github.com/python/mypy/pull/17276))
* Fix case involving non-ASCII chars on Windows (Alexander Leopold Shon, PR [17275](https://github.com/python/mypy/pull/17275))
* Support namedtuple.__replace__ in Python 3.13 (Shantanu, PR [17259](https://github.com/python/mypy/pull/17259))
* 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))
* Support rename=True in collections.namedtuple (Jelle Zijlstra, PR [17247](https://github.com/python/mypy/pull/17247))
* [dmypy] sort list of files for update by extension (Valentin Stanciu, PR [17245](https://github.com/python/mypy/pull/17245))
* fix #16935 fix type of tuple[X,Y] expression (urnest, PR [17235](https://github.com/python/mypy/pull/17235))
* Do not 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))
* fix: annotated argument's `var` node type is explicit, not inferred (bzoracler, PR [17217](https://github.com/python/mypy/pull/17217))
* Enum private attributes are not enum members (Ali Hamdan, PR [17182](https://github.com/python/mypy/pull/17182))
* 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))
* Add support for __spec__ (Shantanu, PR [14739](https://github.com/python/mypy/pull/14739))


#### Typeshed Updates
Expand Down Expand Up @@ -331,7 +405,7 @@ This feature was contributed by Shantanu (PR [16756](https://github.com/python/m

#### Typeshed Updates

Please see [git log](https://github.com/python/typeshed/commits/main?after=7c8e82fe483a40ec4cb0a2505cfdb0f3e7cc81d9+0&branch=main&path=stdlib) for full list of standard library typeshed stub changes.
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.

#### Mypy 1.10.1

Expand Down