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Update mypy to 1.7.1 #257

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This PR updates mypy from 1.0.0 to 1.7.1.

Changelog

1.7

We’ve just uploaded mypy 1.7 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).

Using TypedDict for `**kwargs` Typing

Mypy now has support for using `Unpack[...]` with a TypedDict type to annotate `**kwargs` arguments enabled by default. Example:

python
Or 'from typing_extensions import ...'
from typing import TypedDict, Unpack

class Person(TypedDict):
 name: str
 age: int

def foo(**kwargs: Unpack[Person]) -> None:
 ...

foo(name="x", age=1)   Ok
foo(name=1)   Error


The definition of `foo` above is equivalent to the one below, with keyword-only arguments `name` and `age`:

python
def foo(*, name: str, age: int) -> None:
 ...


Refer to [PEP 692](https://peps.python.org/pep-0692/) for more information. Note that unlike in the current version of the PEP, mypy always treats signatures with `Unpack[SomeTypedDict]` as equivalent to their expanded forms with explicit keyword arguments, and there aren't special type checking rules for TypedDict arguments.

This was contributed by Ivan Levkivskyi back in 2022 (PR [13471](https://github.com/python/mypy/pull/13471)).

TypeVarTuple Support Enabled (Experimental)

Mypy now has support for variadic generics (TypeVarTuple) enabled by default, as an experimental feature. Refer to [PEP 646](https://peps.python.org/pep-0646/) for the details.

TypeVarTuple was implemented by Jared Hance and Ivan Levkivskyi over several mypy releases, with help from Jukka Lehtosalo.

Changes included in this release:

* Fix handling of tuple type context with unpacks (Ivan Levkivskyi, PR [16444](https://github.com/python/mypy/pull/16444))
* Handle TypeVarTuples when checking overload constraints (robjhornby, PR [16428](https://github.com/python/mypy/pull/16428))
* Enable Unpack/TypeVarTuple support (Ivan Levkivskyi, PR [16354](https://github.com/python/mypy/pull/16354))
* Fix crash on unpack call special-casing (Ivan Levkivskyi, PR [16381](https://github.com/python/mypy/pull/16381))
* Some final touches for variadic types support (Ivan Levkivskyi, PR [16334](https://github.com/python/mypy/pull/16334))
* Support PEP-646 and PEP-692 in the same callable (Ivan Levkivskyi, PR [16294](https://github.com/python/mypy/pull/16294))
* Support new `*` syntax for variadic types (Ivan Levkivskyi, PR [16242](https://github.com/python/mypy/pull/16242))
* Correctly handle variadic instances with empty arguments (Ivan Levkivskyi, PR [16238](https://github.com/python/mypy/pull/16238))
* Correctly handle runtime type applications of variadic types (Ivan Levkivskyi, PR [16240](https://github.com/python/mypy/pull/16240))
* Support variadic tuple packing/unpacking (Ivan Levkivskyi, PR [16205](https://github.com/python/mypy/pull/16205))
* Better support for variadic calls and indexing (Ivan Levkivskyi, PR [16131](https://github.com/python/mypy/pull/16131))
* Subtyping and inference of user-defined variadic types (Ivan Levkivskyi, PR [16076](https://github.com/python/mypy/pull/16076))
* Complete type analysis of variadic types (Ivan Levkivskyi, PR [15991](https://github.com/python/mypy/pull/15991))

New Way of Installing Mypyc Dependencies

If you want to install package dependencies needed by mypyc (not just mypy), you should now install `mypy[mypyc]` instead of just `mypy`:


python3 -m pip install -U 'mypy[mypyc]'


Mypy has many more users than mypyc, so always installing mypyc dependencies would often bring unnecessary dependencies.

This change was contributed by Shantanu (PR [16229](https://github.com/python/mypy/pull/16229)).

New Rules for Re-exports

Mypy no longer considers an import such as `import a.b as b` as an explicit re-export. The old behavior was arguably inconsistent and surprising. This may impact some stub packages, such as older versions of `types-six`. You can change the import to `from a import b as b`, if treating the import as a re-export was intentional.

This change was contributed by Anders Kaseorg (PR [14086](https://github.com/python/mypy/pull/14086)).

Improved Type Inference

The new type inference algorithm that was recently introduced to mypy (but was not enabled by default) is now enabled by default. It improves type inference of calls to generic callables where an argument is also a generic callable, in particular. You can use `--old-type-inference` to disable the new behavior.

The new algorithm can (rarely) produce different error messages, different error codes, or errors reported on different lines. This is more likely in cases where generic types were used incorrectly.

The new type inference algorithm was contributed by Ivan Levkivskyi. PR [16345](https://github.com/python/mypy/pull/16345) enabled it by default.

Narrowing Tuple Types Using len()

Mypy now can narrow tuple types using `len()` checks. Example:

python
def f(t: tuple[int, int] | tuple[int, int, int]) -> None:
 if len(t) == 2:
     a, b = t    Ok
 ...


This feature was contributed by Ivan Levkivskyi (PR [16237](https://github.com/python/mypy/pull/16237)).

More Precise Tuple Lengths (Experimental)

Mypy supports experimental, more precise checking of tuple type lengths through `--enable-incomplete-feature=PreciseTupleTypes`. Refer to the [documentation](https://mypy.readthedocs.io/en/latest/command_line.html#enabling-incomplete-experimental-features) for more information.

More generally, we are planning to use `--enable-incomplete-feature` to introduce experimental features that would benefit from community feedback.

This feature was contributed by Ivan Levkivskyi (PR [16237](https://github.com/python/mypy/pull/16237)).

Mypy Changelog

We now maintain a [changelog](https://github.com/python/mypy/blob/master/CHANGELOG.md) in the mypy Git repository. It mirrors the contents of [mypy release blog posts](https://mypy-lang.blogspot.com/). We will continue to also publish release blog posts. In the future, release blog posts will be created based on the changelog near a release date.

This was contributed by Shantanu (PR [16280](https://github.com/python/mypy/pull/16280)).

Mypy Daemon Improvements

* Fix daemon crash caused by deleted submodule (Jukka Lehtosalo, PR [16370](https://github.com/python/mypy/pull/16370))
* Fix file reloading in dmypy with --export-types (Ivan Levkivskyi, PR [16359](https://github.com/python/mypy/pull/16359))
* Fix dmypy inspect on Windows (Ivan Levkivskyi, PR [16355](https://github.com/python/mypy/pull/16355))
* Fix dmypy inspect for namespace packages (Ivan Levkivskyi, PR [16357](https://github.com/python/mypy/pull/16357))
* Fix return type change to optional in generic function (Jukka Lehtosalo, PR [16342](https://github.com/python/mypy/pull/16342))
* Fix daemon false positives related to module-level `__getattr__` (Jukka Lehtosalo, PR [16292](https://github.com/python/mypy/pull/16292))
* Fix daemon crash related to ABCs (Jukka Lehtosalo, PR [16275](https://github.com/python/mypy/pull/16275))
* Stream dmypy output instead of dumping everything at the end (Valentin Stanciu, PR [16252](https://github.com/python/mypy/pull/16252))
* Make sure all dmypy errors are shown (Valentin Stanciu, PR [16250](https://github.com/python/mypy/pull/16250))

Mypyc Improvements

* Generate error on duplicate function definitions (Jukka Lehtosalo, PR [16309](https://github.com/python/mypy/pull/16309))
* Don't crash on unreachable statements (Jukka Lehtosalo, PR [16311](https://github.com/python/mypy/pull/16311))
* Avoid cyclic reference in nested functions (Jukka Lehtosalo, PR [16268](https://github.com/python/mypy/pull/16268))
* Fix direct `__dict__` access on inner functions in new Python (Shantanu, PR [16084](https://github.com/python/mypy/pull/16084))
* Make tuple packing and unpacking more efficient (Jukka Lehtosalo, PR [16022](https://github.com/python/mypy/pull/16022))

Improvements to Error Reporting

* Update starred expression error message to match CPython (Cibin Mathew, PR [16304](https://github.com/python/mypy/pull/16304))
* Fix error code of "Maybe you forgot to use await" note (Jelle Zijlstra, PR [16203](https://github.com/python/mypy/pull/16203))
* Use error code `[unsafe-overload]` for unsafe overloads, instead of `[misc]` (Randolf Scholz, PR [16061](https://github.com/python/mypy/pull/16061))
* Reword the error message related to void functions (Albert Tugushev, PR [15876](https://github.com/python/mypy/pull/15876))
* Represent bottom type as Never in messages (Shantanu, PR [15996](https://github.com/python/mypy/pull/15996))
* Add hint for AsyncIterator incompatible return type (Ilya Priven, PR [15883](https://github.com/python/mypy/pull/15883))
* Don't suggest stubs packages where the runtime package now ships with types (Alex Waygood, PR [16226](https://github.com/python/mypy/pull/16226))

Performance Improvements

* Speed up type argument checking (Jukka Lehtosalo, PR [16353](https://github.com/python/mypy/pull/16353))
* Add fast path for checking self types (Jukka Lehtosalo, PR [16352](https://github.com/python/mypy/pull/16352))
* Cache information about whether file is typeshed file (Jukka Lehtosalo, PR [16351](https://github.com/python/mypy/pull/16351))
* Skip expensive `repr()` in logging call when not needed (Jukka Lehtosalo, PR [16350](https://github.com/python/mypy/pull/16350))

Attrs and Dataclass Improvements

* `dataclass.replace`: Allow transformed classes (Ilya Priven, PR [15915](https://github.com/python/mypy/pull/15915))
* `dataclass.replace`: Fall through to typeshed signature (Ilya Priven, PR [15962](https://github.com/python/mypy/pull/15962))
* Document `dataclass_transform` behavior (Ilya Priven, PR [16017](https://github.com/python/mypy/pull/16017))
* `attrs`: Remove fields type check (Ilya Priven, PR [15983](https://github.com/python/mypy/pull/15983))
* `attrs`, `dataclasses`: Don't enforce slots when base class doesn't (Ilya Priven, PR [15976](https://github.com/python/mypy/pull/15976))
* Fix crash on dataclass field / property collision (Nikita Sobolev, PR [16147](https://github.com/python/mypy/pull/16147))

Stubgen Improvements

* Write stubs with utf-8 encoding (Jørgen Lind, PR [16329](https://github.com/python/mypy/pull/16329))
* Fix missing property setter in semantic analysis mode (Ali Hamdan, PR [16303](https://github.com/python/mypy/pull/16303))
* Unify C extension and pure python stub generators with object oriented design (Chad Dombrova, PR [15770](https://github.com/python/mypy/pull/15770))
* Multiple fixes to the generated imports (Ali Hamdan, PR [15624](https://github.com/python/mypy/pull/15624))
* Generate valid dataclass stubs (Ali Hamdan, PR [15625](https://github.com/python/mypy/pull/15625))

Fixes to Crashes

* Fix incremental mode crash on TypedDict in method (Ivan Levkivskyi, PR [16364](https://github.com/python/mypy/pull/16364))
* Fix crash on star unpack in TypedDict (Ivan Levkivskyi, PR [16116](https://github.com/python/mypy/pull/16116))
* Fix crash on malformed TypedDict in incremental mode (Ivan Levkivskyi, PR [16115](https://github.com/python/mypy/pull/16115))
* Fix crash with report generation on namespace packages (Shantanu, PR [16019](https://github.com/python/mypy/pull/16019))
* Fix crash when parsing error code config with typo (Shantanu, PR [16005](https://github.com/python/mypy/pull/16005))
* Fix `__post_init__()` internal error (Ilya Priven, PR [16080](https://github.com/python/mypy/pull/16080))

Documentation Updates

* Make it easier to copy commands from README (Hamir Mahal, PR [16133](https://github.com/python/mypy/pull/16133))
* Document and rename `[overload-overlap]` error code (Shantanu, PR [16074](https://github.com/python/mypy/pull/16074))
* Document `--force-uppercase-builtins` and `--force-union-syntax` (Nikita Sobolev, PR [16049](https://github.com/python/mypy/pull/16049))
* Document `force_union_syntax` and `force_uppercase_builtins` (Nikita Sobolev, PR [16048](https://github.com/python/mypy/pull/16048))
* Document we're not tracking relationships between symbols (Ilya Priven, PR [16018](https://github.com/python/mypy/pull/16018))

Other Notable Changes and Fixes

* Propagate narrowed types to lambda expressions (Ivan Levkivskyi, PR [16407](https://github.com/python/mypy/pull/16407))
* Avoid importing from `setuptools._distutils` (Shantanu, PR [16348](https://github.com/python/mypy/pull/16348))
* Delete recursive aliases flags (Ivan Levkivskyi, PR [16346](https://github.com/python/mypy/pull/16346))
* Properly use proper subtyping for callables (Ivan Levkivskyi, PR [16343](https://github.com/python/mypy/pull/16343))
* Use upper bound as inference fallback more consistently (Ivan Levkivskyi, PR [16344](https://github.com/python/mypy/pull/16344))
* Add `[unimported-reveal]` error code (Nikita Sobolev, PR [16271](https://github.com/python/mypy/pull/16271))
* Add `|=` and `|` operators support for `TypedDict` (Nikita Sobolev, PR [16249](https://github.com/python/mypy/pull/16249))
* Clarify variance convention for Parameters (Ivan Levkivskyi, PR [16302](https://github.com/python/mypy/pull/16302))
* Correctly recognize `typing_extensions.NewType` (Ganden Schaffner, PR [16298](https://github.com/python/mypy/pull/16298))
* Fix partially defined in the case of missing type maps (Shantanu, PR [15995](https://github.com/python/mypy/pull/15995))
* Use SPDX license identifier (Nikita Sobolev, PR [16230](https://github.com/python/mypy/pull/16230))
* Make `__qualname__` and `__module__` available in class bodies (Anthony Sottile, PR [16215](https://github.com/python/mypy/pull/16215))
* stubtest: Hint when args in stub need to be keyword-only (Alex Waygood, PR [16210](https://github.com/python/mypy/pull/16210))
* Tuple slice should not propagate fallback (Thomas Grainger, PR [16154](https://github.com/python/mypy/pull/16154))
* Fix cases of type object handling for overloads (Shantanu, PR [16168](https://github.com/python/mypy/pull/16168))
* Fix walrus interaction with empty collections (Ivan Levkivskyi, PR [16197](https://github.com/python/mypy/pull/16197))
* Use type variable bound when it appears as actual during inference (Ivan Levkivskyi, PR [16178](https://github.com/python/mypy/pull/16178))
* Use upper bounds as fallback solutions for inference (Ivan Levkivskyi, PR [16184](https://github.com/python/mypy/pull/16184))
* Special-case type inference of empty collections (Ivan Levkivskyi, PR [16122](https://github.com/python/mypy/pull/16122))
* Allow TypedDict unpacking in Callable types (Ivan Levkivskyi, PR [16083](https://github.com/python/mypy/pull/16083))
* Fix inference for overloaded `__call__` with generic self (Shantanu, PR [16053](https://github.com/python/mypy/pull/16053))
* Call dynamic class hook on generic classes (Petter Friberg, PR [16052](https://github.com/python/mypy/pull/16052))
* Preserve implicitly exported types via attribute access (Shantanu, PR [16129](https://github.com/python/mypy/pull/16129))
* Fix a stubtest bug (Alex Waygood)
* Fix `tuple[Any, ...]` subtyping (Shantanu, PR [16108](https://github.com/python/mypy/pull/16108))
* Lenient handling of trivial Callable suffixes (Ivan Levkivskyi, PR [15913](https://github.com/python/mypy/pull/15913))
* Add `add_overloaded_method_to_class` helper for plugins (Nikita Sobolev, PR [16038](https://github.com/python/mypy/pull/16038))
* Bundle `misc/proper_plugin.py` as a part of `mypy` (Nikita Sobolev, PR [16036](https://github.com/python/mypy/pull/16036))
* Fix `case Any()` in match statement (DS/Charlie, PR [14479](https://github.com/python/mypy/pull/14479))
* Make iterable logic more consistent (Shantanu, PR [16006](https://github.com/python/mypy/pull/16006))
* Fix inference for properties with `__call__` (Shantanu, PR [15926](https://github.com/python/mypy/pull/15926))

Typeshed Updates

Please see [git log](https://github.com/python/typeshed/commits/main?after=4a854366e03dee700109f8e758a08b2457ea2f51+0&branch=main&path=stdlib) for full list of standard library typeshed stub changes.

Acknowledgements

Thanks to all mypy contributors who contributed to this release:

* Albert Tugushev
* Alex Waygood
* Ali Hamdan
* Anders Kaseorg
* Anthony Sottile
* Chad Dombrova
* Cibin Mathew
* dinaldoap
* DS/Charlie
* Eli Schwartz
* Ganden Schaffner
* Hamir Mahal
* Ihor
* Ikko Eltociear Ashimine
* Ilya Priven
* Ivan Levkivskyi
* Jelle Zijlstra
* Jukka Lehtosalo
* Jørgen Lind
* KotlinIsland
* Matt Bogosian
* Nikita Sobolev
* Petter Friberg
* Randolf Scholz
* Shantanu
* Thomas Grainger
* Valentin Stanciu

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

Posted by Jukka Lehtosalo

1.6

[Tuesday, 10 October 2023](https://mypy-lang.blogspot.com/2023/10/mypy-16-released.html)

We’ve just uploaded mypy 1.6 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).

Introduce Error Subcodes for Import Errors

Mypy now uses the error code import-untyped if an import targets an installed library that doesn’t support static type checking, and no stub files are available. Other invalid imports produce the import-not-found error code. They both are subcodes of the import error code, which was previously used for both kinds of import-related errors.

Use \--disable-error-code=import-untyped to only ignore import errors about installed libraries without stubs. This way mypy will still report errors about typos in import statements, for example.

If you use \--warn-unused-ignore or \--strict, mypy will complain if you use \ type: ignore\[import\] to ignore an import error. You are expected to use one of the more specific error codes instead. Otherwise, ignoring the import error code continues to silence both errors.

This feature was contributed by Shantanu (PR [15840](https://github.com/python/mypy/pull/15840), PR [14740](https://github.com/python/mypy/pull/14740)).

Remove Support for Targeting Python 3.6 and Earlier

Running mypy with \--python-version 3.6, for example, is no longer supported. Python 3.6 hasn’t been properly supported by mypy for some time now, and this makes it explicit. This was contributed by Nikita Sobolev (PR [15668](https://github.com/python/mypy/pull/15668)).

Selective Filtering of \--disallow-untyped-calls Targets

Using \--disallow-untyped-calls could be annoying when using libraries with missing type information, as mypy would generate many errors about code that uses the library. Now you can use \--untyped-calls-exclude=acme, for example, to disable these errors about calls targeting functions defined in the acme package. Refer to the [documentation](https://mypy.readthedocs.io/en/latest/command_line.html#cmdoption-mypy-untyped-calls-exclude) for more information.

This feature was contributed by Ivan Levkivskyi (PR [15845](https://github.com/python/mypy/pull/15845)).

Improved Type Inference between Callable Types

Mypy now does a better job inferring type variables inside arguments of callable types. For example, this code fragment now type checks correctly:

python
def f(c: Callable[[T, S], None]) -> Callable[[str, T, S], None]: ...
def g(*x: int) -> None: ...

reveal_type(f(g))   Callable[[str, int, int], None]


This was contributed by Ivan Levkivskyi (PR [15910](https://github.com/python/mypy/pull/15910)).

Don’t Consider None and TypeVar to Overlap in Overloads

Mypy now doesn’t consider an overload item with an argument type None to overlap with a type variable:

python
overload
def f(x: None) -> None: ..
overload
def f(x: T) -> Foo[T]: ...
...


Previously mypy would generate an error about the definition of f above. This is slightly unsafe if the upper bound of T is object, since the value of the type variable could be None. We relaxed the rules a little, since this solves a common issue.

This feature was contributed by Ivan Levkivskyi (PR [15846](https://github.com/python/mypy/pull/15846)).

Improvements to \--new-type-inference

The experimental new type inference algorithm (polymorphic inference) introduced as an opt-in feature in mypy 1.5 has several improvements:

*   Improve transitive closure computation during constraint solving (Ivan Levkivskyi, PR [15754](https://github.com/python/mypy/pull/15754))
*   Add support for upper bounds and values with \--new-type-inference (Ivan Levkivskyi, PR [15813](https://github.com/python/mypy/pull/15813))
*   Basic support for variadic types with \--new-type-inference (Ivan Levkivskyi, PR [15879](https://github.com/python/mypy/pull/15879))
*   Polymorphic inference: support for parameter specifications and lambdas (Ivan Levkivskyi, PR [15837](https://github.com/python/mypy/pull/15837))
*   Invalidate cache when adding \--new-type-inference (Marc Mueller, PR [16059](https://github.com/python/mypy/pull/16059))

**Note:** We are planning to enable \--new-type-inference by default in mypy 1.7. Please try this out and let us know if you encounter any issues.

ParamSpec Improvements

*   Support self-types containing ParamSpec (Ivan Levkivskyi, PR [15903](https://github.com/python/mypy/pull/15903))
*   Allow “…” in Concatenate, and clean up ParamSpec literals (Ivan Levkivskyi, PR [15905](https://github.com/python/mypy/pull/15905))
*   Fix ParamSpec inference for callback protocols (Ivan Levkivskyi, PR [15986](https://github.com/python/mypy/pull/15986))
*   Infer ParamSpec constraint from arguments (Ivan Levkivskyi, PR [15896](https://github.com/python/mypy/pull/15896))
*   Fix crash on invalid type variable with ParamSpec (Ivan Levkivskyi, PR [15953](https://github.com/python/mypy/pull/15953))
*   Fix subtyping between ParamSpecs (Ivan Levkivskyi, PR [15892](https://github.com/python/mypy/pull/15892))

Stubgen Improvements

*   Add option to include docstrings with stubgen (chylek, PR [13284](https://github.com/python/mypy/pull/13284))
*   Add required ... initializer to NamedTuple fields with default values (Nikita Sobolev, PR [15680](https://github.com/python/mypy/pull/15680))

Stubtest Improvements

*   Fix \_\_mypy-replace false positives (Alex Waygood, PR [15689](https://github.com/python/mypy/pull/15689))
*   Fix edge case for bytes enum subclasses (Alex Waygood, PR [15943](https://github.com/python/mypy/pull/15943))
*   Generate error if typeshed is missing modules from the stdlib (Alex Waygood, PR [15729](https://github.com/python/mypy/pull/15729))
*   Fixes to new check for missing stdlib modules (Alex Waygood, PR [15960](https://github.com/python/mypy/pull/15960))
*   Fix stubtest enum.Flag edge case (Alex Waygood, PR [15933](https://github.com/python/mypy/pull/15933))

Documentation Improvements

*   Do not advertise to create your own assert\_never helper (Nikita Sobolev, PR [15947](https://github.com/python/mypy/pull/15947))
*   Fix all the missing references found within the docs (Albert Tugushev, PR [15875](https://github.com/python/mypy/pull/15875))
*   Document await-not-async error code (Shantanu, PR [15858](https://github.com/python/mypy/pull/15858))
*   Improve documentation of disabling error codes (Shantanu, PR [15841](https://github.com/python/mypy/pull/15841))

Other Notable Changes and Fixes

*   Make unsupported PEP 695 features (introduced in Python 3.12) give a reasonable error message (Shantanu, PR [16013](https://github.com/python/mypy/pull/16013))
*   Remove the \--py2 command-line argument (Marc Mueller, PR [15670](https://github.com/python/mypy/pull/15670))
*   Change empty tuple from tuple\[\] to tuple\[()\] in error messages (Nikita Sobolev, PR [15783](https://github.com/python/mypy/pull/15783))
*   Fix assert\_type failures when some nodes are deferred (Nikita Sobolev, PR [15920](https://github.com/python/mypy/pull/15920))
*   Generate error on unbound TypeVar with values (Nikita Sobolev, PR [15732](https://github.com/python/mypy/pull/15732))
*   Fix over-eager types-google-cloud-ndb suggestion (Shantanu, PR [15347](https://github.com/python/mypy/pull/15347))
*   Fix type narrowing of \== None and in (None,) conditions (Marti Raudsepp, PR [15760](https://github.com/python/mypy/pull/15760))
*   Fix inference for attrs.fields (Shantanu, PR [15688](https://github.com/python/mypy/pull/15688))
*   Make “await in non-async function” a non-blocking error and give it an error code (Gregory Santosa, PR [15384](https://github.com/python/mypy/pull/15384))
*   Add basic support for decorated overloads (Ivan Levkivskyi, PR [15898](https://github.com/python/mypy/pull/15898))
*   Fix TypeVar regression with self types (Ivan Levkivskyi, PR [15945](https://github.com/python/mypy/pull/15945))
*   Add \_\_match\_args\_\_ to dataclasses with no fields (Ali Hamdan, PR [15749](https://github.com/python/mypy/pull/15749))
*   Include stdout and stderr in dmypy verbose output (Valentin Stanciu, PR [15881](https://github.com/python/mypy/pull/15881))
*   Improve match narrowing and reachability analysis (Shantanu, PR [15882](https://github.com/python/mypy/pull/15882))
*   Support \_\_bool\_\_ with Literal in \--warn-unreachable (Jannic Warken, PR [15645](https://github.com/python/mypy/pull/15645))
*   Fix inheriting from generic frozen attrs class (Ilya Priven, PR [15700](https://github.com/python/mypy/pull/15700))
*   Correctly narrow types for tuple\[type\[X\], ...\] (Nikita Sobolev, PR [15691](https://github.com/python/mypy/pull/15691))
*   Don't flag intentionally empty generators unreachable (Ilya Priven, PR [15722](https://github.com/python/mypy/pull/15722))
*   Add tox.ini to mypy sdist (Marcel Telka, PR [15853](https://github.com/python/mypy/pull/15853))
*   Fix mypyc regression with pretty (Shantanu, PR [16124](https://github.com/python/mypy/pull/16124))

Typeshed Updates

Typeshed is now modular and distributed as separate PyPI packages for everything except the standard library stubs. Please see [git log](https://github.com/python/typeshed/commits/main?after=6a8d653a671925b0a3af61729ff8cf3f90c9c662+0&branch=main&path=stdlib) for full list of typeshed changes.

Acknowledgements

Thanks to Max Murin, who did most of the release manager work for this release (I just did the final steps).

Thanks to all mypy contributors who contributed to this release:

*   Albert Tugushev
*   Alex Waygood
*   Ali Hamdan
*   chylek
*   EXPLOSION
*   Gregory Santosa
*   Ilya Priven
*   Ivan Levkivskyi
*   Jannic Warken
*   KotlinIsland
*   Marc Mueller
*   Marcel Johannesmann
*   Marcel Telka
*   Mark Byrne
*   Marti Raudsepp
*   Max Murin
*   Nikita Sobolev
*   Shantanu
*   Valentin Stanciu

Posted by Jukka Lehtosalo

1.5

[Thursday, 10 August 2023](https://mypy-lang.blogspot.com/2023/08/mypy-15-released.html)

We’ve just uploaded mypy 1.5 to the Python Package Index ([PyPI](https://pypi.org/project/mypy/)). Mypy is a static type checker for Python. This release includes new features, deprecations 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).

Drop Support for Python 3.7

Mypy no longer supports running with Python 3.7, which has reached end-of-life. This was contributed by Shantanu (PR [15566](https://github.com/python/mypy/pull/15566)).

Optional Check to Require Explicit override

If you enable the explicit-override error code, mypy will generate an error if a method override doesn’t use the typing.override decorator (as discussed in [PEP 698](https://peps.python.org/pep-0698/#strict-enforcement-per-project)). This way mypy will detect accidentally introduced overrides. Example:

python
mypy: enable-error-code="explicit-override"

from typing_extensions import override

class C:
 def foo(self) -> None: pass
 def bar(self) -> None: pass

class D(C):
  Error: Method "foo" is not using override but is
  overriding a method
 def foo(self) -> None:
     ...

 override
 def bar(self) -> None:   OK
     ...


You can enable the error code via \--enable-error-code=explicit-override on the mypy command line or enable\_error\_code = explicit-override in the mypy config file.

The override decorator will be available in typing in Python 3.12, but you can also use the backport from a recent version of `typing_extensions` on all supported Python versions.

This feature was contributed by Marc Mueller(PR [15512](https://github.com/python/mypy/pull/15512)).

More Flexible TypedDict Creation and Update

Mypy was previously overly strict when type checking TypedDict creation and update operations. Though these checks were often technically correct, they sometimes triggered for apparently valid code. These checks have now been relaxed by default. You can enable stricter checking by using the new \--extra-checks flag.

Construction using the `**` syntax is now more flexible:

python
from typing import TypedDict

class A(TypedDict):
 foo: int
 bar: int

class B(TypedDict):
 foo: int

a: A = {"foo": 1, "bar": 2}
b: B = {"foo": 3}
a2: A = { **a, **b}   OK (previously an error)


You can also call update() with a TypedDict argument that contains a subset of the keys in the updated TypedDict:
python
a.update(b)   OK (previously an error)


This feature was contributed by Ivan Levkivskyi (PR [15425](https://github.com/python/mypy/pull/15425)).

Deprecated Flag: \--strict-concatenate

The behavior of \--strict-concatenate is now included in the new \--extra-checks flag, and the old flag is deprecated.

Optionally Show Links to Error Code Documentation

If you use \--show-error-code-links, mypy will add documentation links to (many) reported errors. The links are not shown for error messages that are sufficiently obvious, and they are shown once per error code only.

Example output:

a.py:1: error: Need type annotation for "foo" (hint: "x: List[<type>] = ...")  [var-annotated]
a.py:1: note: See https://mypy.rtfd.io/en/stable/_refs.html#code-var-annotated for more info

This was contributed by Ivan Levkivskyi (PR [15449](https://github.com/python/mypy/pull/15449)).

Consistently Avoid Type Checking Unreachable Code

If a module top level has unreachable code, mypy won’t type check the unreachable statements. This is consistent with how functions behave. The behavior of \--warn-unreachable is also more consistent now.

This was contributed by Ilya Priven (PR [15386](https://github.com/python/mypy/pull/15386)).

Experimental Improved Type Inference for Generic Functions

You can use \--new-type-inference to opt into an experimental new type inference algorithm. It fixes issues when calling a generic functions with an argument that is also a generic function, in particular. This current implementation is still incomplete, but we encourage trying it out and reporting bugs if you encounter regressions. We are planning to enable the new algorithm by default in a future mypy release.

This feature was contributed by Ivan Levkivskyi (PR [15287](https://github.com/python/mypy/pull/15287)).

Partial Support for Python 3.12

Mypy and mypyc now support running on recent Python 3.12 development versions. Not all new Python 3.12 features are supported, and we don’t ship compiled wheels for Python 3.12 yet.

*   Fix ast warnings for Python 3.12 (Nikita Sobolev, PR [15558](https://github.com/python/mypy/pull/15558))
*   mypyc: Fix multiple inheritance with a protocol on Python 3.12 (Jukka Lehtosalo, PR [15572](https://github.com/python/mypy/pull/15572))
*   mypyc: Fix self-compilation on Python 3.12 (Jukka Lehtosalo, PR [15582](https://github.com/python/mypy/pull/15582))
*   mypyc: Fix 3.12 issue with pickling of instances with \_\_dict\_\_ (Jukka Lehtosalo, PR [15574](https://github.com/python/mypy/pull/15574))
*   mypyc: Fix i16 on Python 3.12 (Jukka Lehtosalo, PR [15510](https://github.com/python/mypy/pull/15510))
*   mypyc: Fix int operations on Python 3.12 (Jukka Lehtosalo, PR [15470](https://github.com/python/mypy/pull/15470))
*   mypyc: Fix generators on Python 3.12 (Jukka Lehtosalo, PR [15472](https://github.com/python/mypy/pull/15472))
*   mypyc: Fix classes with \_\_dict\_\_ on 3.12 (Jukka Lehtosalo, PR [15471](https://github.com/python/mypy/pull/15471))
*   mypyc: Fix coroutines on Python 3.12 (Jukka Lehtosalo, PR [15469](https://github.com/python/mypy/pull/15469))
*   mypyc: Don't use \_PyErr\_ChainExceptions on 3.12, since it's deprecated (Jukka Lehtosalo, PR [15468](https://github.com/python/mypy/pull/15468))
*   mypyc: Add Python 3.12 feature macro (Jukka Lehtosalo, PR [15465](https://github.com/python/mypy/pull/15465))

Improvements to Dataclasses

*   Improve signature of dataclasses.replace (Ilya Priven, PR [14849](https://github.com/python/mypy/pull/14849))
*   Fix dataclass/protocol crash on joining types (Ilya Priven, PR [15629](https://github.com/python/mypy/pull/15629))
*   Fix strict optional handling in dataclasses (Ivan Levkivskyi, PR [15571](https://github.com/python/mypy/pull/15571))
*   Support optional types for custom dataclass descriptors (Marc Mueller, PR [15628](https://github.com/python/mypy/pull/15628))
*   Add `__slots__` attribute to dataclasses (Nikita Sobolev, PR [15649](https://github.com/python/mypy/pull/15649))
*   Support better \_\_post\_init\_\_ method signature for dataclasses (Nikita Sobolev, PR [15503](https://github.com/python/mypy/pull/15503))

Mypyc Improvements

*   Support unsigned 8-bit native integer type: mypy\_extensions.u8 (Jukka Lehtosalo, PR [15564](https://github.com/python/mypy/pull/15564))
*   Support signed 16-bit native integer type: mypy\_extensions.i16 (Jukka Lehtosalo, PR [15464](https://github.com/python/mypy/pull/15464))
*   Define mypy\_extensions.i16 in stubs (Jukka Lehtosalo, PR [15562](https://github.com/python/mypy/pull/15562))
*   Document more unsupported features and update supported features (Richard Si, PR [15524](https://github.com/python/mypy/pull/15524))
*   Fix final NamedTuple classes (Richard Si, PR [15513](https://github.com/python/mypy/pull/15513))
*   Use C99 compound literals for undefined tuple values (Jukka Lehtosalo, PR [15453](https://github.com/python/mypy/pull/15453))
*   Don't explicitly assign NULL values in setup functions (Logan Hunt, PR [15379](https://github.com/python/mypy/pull/15379))

Stubgen Improvements

*   Teach stubgen to work with complex and unary expressions (Nikita Sobolev, PR [15661](https://github.com/python/mypy/pull/15661))
*   Support ParamSpec and TypeVarTuple (Ali Hamdan, PR [15626](https://github.com/python/mypy/pull/15626))
*   Fix crash on non-str docstring (Ali Hamdan, PR [15623](https://github.com/python/mypy/pull/15623))

Documentation Updates

*   Add documentation for additional error codes (Ivan Levkivskyi, PR [15539](https://github.com/python/mypy/pull/15539))
*   Improve documentation of type narrowing (Ilya Priven, PR [15652](https://github.com/python/mypy/pull/15652))
*   Small improvements to protocol documentation (Shantanu, PR [15460](https://github.com/python/mypy/pull/15460))
*   Remove confusing instance variable example in cheat sheet (Adel Atallah, PR [15441](https://github.com/python/mypy/pull/15441))

Other Notable Fixes and Improvements

*   Constant fold additional unary and binary expressions (Richard Si, PR [15202](https://github.com/python/mypy/pull/15202))
*   Exclude the same special attributes from Protocol as CPython (Kyle Benesch, PR [15490](https://github.com/python/mypy/pull/15490))
*   Change the default value of the slots argument of attrs.define to True, to match runtime behavior (Ilya Priven, PR [15642](https://github.com/python/mypy/pull/15642))
*   Fix type of class attribute if attribute is defined in both class and metaclass (Alex Waygood, PR [14988](https://github.com/python/mypy/pull/14988))
*   Handle type the same as typing.Type in the first argument of classmethods (Erik Kemperman, PR [15297](https://github.com/python/mypy/pull/15297))
*   Fix \--find-occurrences flag (Shantanu, PR [15528](https://github.com/python/mypy/pull/15528))
*   Fix error location for class patterns (Nikita Sobolev, PR [15506](https://github.com/python/mypy/pull/15506))
*   Fix re-added file with errors in mypy daemon (Ivan Levkivskyi, PR [15440](https://github.com/python/mypy/pull/15440))
*   Fix dmypy run on Windows (Ivan Levkivskyi, PR [15429](https://github.com/python/mypy/pull/15429))
*   Fix abstract and non-abstract variant error for property deleter (Shantanu, PR [15395](https://github.com/python/mypy/pull/15395))
*   Remove special casing for "cannot" in error messages (Ilya Priven, PR [15428](https://github.com/python/mypy/pull/15428))
*   Add runtime `__slots__` attribute to attrs classes (Nikita Sobolev, PR [15651](https://github.com/python/mypy/pull/15651))
*   Add get\_expression\_type to CheckerPluginInterface (Ilya Priven, PR [15369](https://github.com/python/mypy/pull/15369))
*   Remove parameters that no longer exist from NamedTuple.\_make() (Alex Waygood, PR [15578](https://github.com/python/mypy/pull/15578))
*   Allow using typing.Self in `__all__` with an explicit staticmethod decorator (Erik Kemperman, PR [15353](https://github.com/python/mypy/pull/15353))
*   Fix self types in subclass methods without Self annotation (Ivan Levkivskyi, PR [15541](https://github.com/python/mypy/pull/15541))
*   Check for abstract class objects in tuples (Nikita Sobolev, PR [15366](https://github.com/python/mypy/pull/15366))

Typeshed Updates

Typeshed is now modular and distributed as separate PyPI packages for everything except the standard library stubs. Please see [git log](https://github.com/python/typeshed/commits/main?after=fc7d4722eaa54803926cee5730e1f784979c0531+0&branch=main&path=stdlib) for full list of typeshed changes.

Acknowledgements

Thanks to all mypy contributors who contributed to this release:

*   Adel Atallah
*   Alex Waygood
*   Ali Hamdan
*   Erik Kemperman
*   Federico Padua
*   Ilya Priven
*   Ivan Levkivskyi
*   Jelle Zijlstra
*   Jared Hance
*   Jukka Lehtosalo
*   Kyle Benesch
*   Logan Hunt
*   Marc Mueller
*   Nikita Sobolev
*   Richard Si
*   Shantanu
*   Stavros Ntentos
*   Valentin Stanciu

Posted by Valentin Stanciu

1.4

[Tuesday, 20 June 2023](https://mypy-lang.blogspot.com/2023/06/mypy-140-released.html)

We’ve just uploaded mypy 1.4 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).

The Override Decorator

Mypy can now ensure that when renaming a method, overrides are also renamed. You can explicitly mark a method as overriding a base class method by using the typing.override decorator ([PEP 698](https://peps.python.org/pep-0698/)). If the method is then renamed in the base class while the method override is not, mypy will generate an error. The decorator will be available in typing in Python 3.12, but you can also use the backport from a recent version of `typing_extensions` on all supported Python versions.

This feature was contributed byThomas M Kehrenberg (PR [14609](https://github.com/python/mypy/pull/14609)).

Propagating Type Narrowing to Nested Functions

Previously, type narrowing was not propagated to nested functions because it would not be sound if the narrowed variable changed between the definition of the nested function and the call site. Mypy will now propagate the narrowed type if the variable is not assigned to after the definition of the nested function:

python
def outer(x: str | None = None) -> None:
 if x is None:
     x = calculate_default()
 reveal_type(x)   "str" (narrowed)

 def nested() -> None:
     reveal_type(x)   Now "str" (used to be "str | None")

 nested()


This may generate some new errors because asserts that were previously necessary may become tautological or no-ops.

This was contributed by Jukka Lehtosalo (PR [15133](https://github.com/python/mypy/pull/15133)).

Narrowing Enum Values Using “==”

Mypy now allows narrowing enum types using the \== operator. Previously this was only supported when using the is operator. This makes exhaustiveness checking with enum types more usable, as the requirement to use the is operator was not very intuitive. In this example mypy can detect that the developer forgot to handle the value MyEnum.C in example

python
from enum import Enum

class MyEnum(Enum):
 A = 0
 B = 1
 C = 2

def example(e: MyEnum) -> str:   Error: Missing return statement
 if e == MyEnum.A:
     return 'x'
 elif e == MyEnum.B:
     return 'y'


Adding an extra elif case resolves the error:

python
...
def example(e: MyEnum) -> str:   No error -- all values covered
 if e == MyEnum.A:
     return 'x'
 elif e == MyEnum.B:
     return 'y'
 elif e == MyEnum.C:
     return 'z'


This change can cause false positives in test cases that have assert statements like assert o.x == SomeEnum.X when using \--strict-equality. Example:

python
mypy: strict-equality

from enum import Enum

class MyEnum(Enum):
 A = 0
 B = 1

class C:
 x: MyEnum
 ...

def test_something() -> None:
 c = C(...)
 assert c.x == MyEnum.A
 c.do_something_that_changes_x()
 assert c.x == MyEnum.B   Error: Non-overlapping equality check


These errors can be ignored using \ type: ignore\[comparison-overlap\], or you can perform the assertion using a temporary variable as a workaround:

python
...
def test_something() -> None:
 ...
 x = c.x
 assert x == MyEnum.A   Does not narrow c.x
 c.do_something_that_changes_x()
 x = c.x
 assert x == MyEnum.B   OK


This feature was contributed by Shantanu (PR [11521](https://github.com/python/mypy/pull/11521)).

Performance Improvements

*   Speed up simplification of large union types and also fix a recursive tuple crash (Shantanu, PR [15128](https://github.com/python/mypy/pull/15128))
*   Speed up union subtyping (Shantanu, PR [15104](https://github.com/python/mypy/pull/15104))
*   Don't type check most function bodies when type checking third-party library code, or generally when ignoring errors (Jukka Lehtosalo, PR [14150](https://github.com/python/mypy/pull/14150))

Improvements to Plugins

*   attrs.evolve: Support generics and unions (Ilya Konstantinov, PR [15050](https://github.com/python/mypy/pull/15050))
*   Fix ctypes plugin (Alex Waygood)

Fixes to Crashes

*   Fix a crash when function-scope recursive alias appears as upper bound (Ivan Levkivskyi, PR [15159](https://github.com/python/mypy/pull/15159))
*   Fix crash on follow\_imports\_for\_stubs (Ivan Levkivskyi, PR [15407](https://github.com/python/mypy/pull/15407))
*   Fix stubtest crash in explicit init subclass (Shantanu, PR [15399](https://github.com/python/mypy/pull/15399))
*   Fix crash when indexing TypedDict with empty key (Shantanu, PR [15392](https://github.com/python/mypy/pull/15392))
*   Fix crash on NamedTuple as attribute (Ivan Levkivskyi, PR [15404](https://github.com/python/mypy/pull/15404))
*   Correctly track loop depth for nested functions/classes (Ivan Levkivskyi, PR [15403](https://github.com/python/mypy/pull/15403))
*   Fix crash on joins with recursive tuples (Ivan Levkivskyi, PR [15402](https://github.com/python/mypy/pull/15402))
*   Fix crash with custom ErrorCode subclasses (Marc Mueller, PR [15327](https://github.com/python/mypy/pull/15327))
*   Fix crash in dataclass protocol with self attribute assignment (Ivan Levkivskyi, PR [15157](https://github.com/python/mypy/pull/15157))
*   Fix crash on lambda in generic context with generic method in body (Ivan Levkivskyi, PR [15155](https://github.com/python/mypy/pull/15155))
*   Fix recursive type alias crash in make\_simplified\_union (Ivan Levkivskyi, PR [15216](https://github.com/python/mypy/pull/15216))

Improvements to Error Messages

*   Use lower-case built-in collection types such as list\[…\] instead of List\[…\] in errors when targeting Python 3.9+ (Max Murin, PR [15070](https://github.com/python/mypy/pull/15070))
*   Use X | Y union syntax in error messages when targeting Python 3.10+ (Omar Silva, PR [15102](https://github.com/python/mypy/pull/15102))
*   Use type instead of Type in errors when targeting Python 3.9+ (Rohit Sanjay, PR [15139](https://github.com/python/mypy/pull/15139))
*   Do not show unused-ignore errors in unreachable code, and make it a real error code (Ivan Levkivskyi, PR [15164](https://github.com/python/mypy/pull/15164))
*   Don’t limit the number of errors shown by default (Rohit Sanjay, PR [15138](https://github.com/python/mypy/pull/15138))
*   Improver message for truthy functions (madt2709, PR [15193](https://github.com/python/mypy/pull/15193))
*   Output distinct types when type names are ambiguous (teresa0605, PR [15184](https://github.com/python/mypy/pull/15184))
*   Update message about invalid exception type in try (AJ Rasmussen, PR [15131](https://github.com/python/mypy/pull/15131))
*   Add explanation if argument type is incompatible because of an unsupported numbers type (Jukka Lehtosalo, PR [15137](https://github.com/python/mypy/pull/15137))
*   Add more detail to 'signature incompatible with supertype' messages for non-callables (Ilya Priven, PR [15263](https://github.com/python/mypy/pull/15263))

Documentation Updates

*   Add \--local-partial-types note to dmypy docs (Alan Du, PR [15259](https://github.com/python/mypy/pull/15259))
*   Update getting started docs for mypyc for Windows (Valentin Stanciu, PR [15233](https://github.com/python/mypy/pull/15233))
*   Clarify usage of callables regarding type object in docs (Viicos, PR [15079](https://github.com/python/mypy/pull/15079))
*   Clarify difference between disallow\_untyped\_defs and disallow\_incomplete\_defs (Ilya Priven, PR [15247](https://github.com/python/mypy/pull/15247))
*   Use attrs and attrs.define in documentation and tests (Ilya Priven, PR [15152](https://github.com/python/mypy/pull/15152))

Mypyc Improvements

*   Fix unexpected TypeError for certain variables with an inferred optional type (Richard Si, PR [15206](https://github.com/python/mypy/pull/15206))
*   Inline math literals (Logan Hunt, PR [15324](https://github.com/python/mypy/pull/15324))
*   Support unpacking mappings in dict display (Richard Si, PR [15203](https://github.com/python/mypy/pull/15203))

Changes to Stubgen

*   Do not remove Generic from base classes (Ali Hamdan, PR [15316](https://github.com/python/mypy/pull/15316))
*   Support yield from statements (Ali Hamdan, PR [15271](https://github.com/python/mypy/pull/15271))
*   Fix missing total from TypedDict class (Ali Hamdan, PR [15208](https://github.com/python/mypy/pull/15208))
*   Fix call-based namedtuple omitted from class bases (Ali Hamdan, PR [14680](https://github.com/python/mypy/pull/14680))
*   Support TypedDict alternative syntax (Ali Hamdan, PR [14682](https://github.com/python/mypy/pull/14682))
*   Make stubgen respect MYPY\_CACHE\_DIR (Henrik Bäärnhielm, PR [14722](https://github.com/python/mypy/pull/14722))
*   Fixes and simplifications (Ali Hamdan, PR [15232](https://github.com/python/mypy/pull/15232))

Other Notable Fixes and Improvements

*   Fix nested async functions when using TypeVar value restriction (Jukka Lehtosalo, PR [14705](https://github.com/python/mypy/pull/14705))
*   Always allow returning Any from lambda (Ivan Levkivskyi, PR [15413](https://github.com/python/mypy/pull/15413))
*   Add foundation for TypeVar defaults (PEP 696) (Marc Mueller, PR [14872](https://github.com/python/mypy/pull/14872))
*   Update semantic analyzer for TypeVar defaults (PEP 696) (Marc Mueller, PR [14873](https://github.com/python/mypy/pull/14873))
*   Make dict expression inference more consistent (Ivan Levkivskyi, PR [15174](https://github.com/python/mypy/pull/15174))
*   Do not block on duplicate base classes (Nikita Sobolev, PR [15367](https://github.com/python/mypy/pull/15367))
*   Generate an error when both staticmethod and classmethod decorators are used (Juhi Chandalia, PR [15118](https://github.com/python/mypy/pull/15118))
*   Fix assert\_type behaviour with literals (Carl Karsten, PR [15123](https://github.com/python/mypy/pull/15123))
*   Fix match subject ignoring redefinitions (Vincent Vanlaer, PR [15306](https://github.com/python/mypy/pull/15306))
*   Support `__all__`.remove (Shantanu, PR [15279](https://github.com/python/mypy/pull/15279))

Typeshed Updates

Typeshed is now modular and distributed as separate PyPI packages for everything except the standard library stubs. Please see [git log](https://github.com/python/typeshed/commits/main?after=877e06ad1cfd9fd9967c0b0340a86d0c23ea89ce+0&branch=main&path=stdlib) for full list of typeshed changes.

Acknowledgements

Thanks to all mypy contributors who contributed to this release:

*   Adrian Garcia Badaracco
*   AJ Rasmussen
*   Alan Du
*   Alex Waygood
*   Ali Hamdan
*   Carl Karsten
*   dosisod
*   Ethan Smith
*   Gregory Santosa
*   Heather White
*   Henrik Bäärnhielm
*   Ilya Konstantinov
*   Ilya Priven
*   Ivan Levkivskyi
*   Juhi Chandalia
*   Jukka Lehtosalo
*   Logan Hunt
*   madt2709
*   Marc Mueller
*   Max Murin
*   Nikita Sobolev
*   Omar Silva
*   Özgür
*   Richard Si
*   Rohit Sanjay
*   Shantanu
*   teresa0605
*   Thomas M Kehrenberg
*   Tin Tvrtković
*   Tushar Sadhwani
*   Valentin Stanciu
*   Viicos
*   Vincent Vanlaer
*   Wesley Collin Wright
*   William Santosa
*   yaegassy

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

Posted by Jared Hance

1.3

[Wednesday, 10 May 2023](https://mypy-lang.blogspot.com/2023/05/mypy-13-released.html)

We’ve just uploaded mypy 1.3 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).

Performance Improvements

*   Improve performance of union subtyping (Shantanu, PR [15104](https://github.com/python/mypy/pull/15104))
*   Add negative subtype caches (Ivan Levkivskyi, PR [14884](https://github.com/python/mypy/pull/14884))

Stub Tooling Improvements

*   Stubtest: Check that the stub is abstract if the runtime is, even when the stub is an overloaded method (Alex Waygood, PR [14955](https://github.com/python/mypy/pull/14955))
*   Stubtest: Verify stub methods or properties are decorated with final if they are decorated with final at runtime (Alex Waygood, PR [14951](https://github.com/python/mypy/pull/14951))
*   Stubtest: Fix stubtest false positives with TypedDicts at runtime (Alex Waygood, PR [14984](https://github.com/python/mypy/pull/14984))
*   Stubgen: Support functools.cached\_property (Nikita Sobolev, PR [14981](https://github.com/python/mypy/pull/14981))
*   Improvements to stubgenc (Chad Dombrova, PR [14564](https://github.com/python/mypy/pull/14564))

Improvements to attrs

*   Add support for converters with TypeVars on generic attrs classes (Chad Dombrova, PR [14908](https://github.com/python/mypy/pull/14908))
*   Fix attrs.evolve on bound TypeVar (Ilya Konstantinov, PR [15022](https://github.com/python/mypy/pull/15022))

Documentation Updates

*   Improve async documentation (Shantanu, PR [14973](https://github.com/python/mypy/pull/14973))
*   Improvements to cheat sheet (Shantanu, PR [14972](https://github.com/python/mypy/pull/14972))
*   Add documentation for bytes formatting error code (Shantanu, PR [14971](https://github.com/python/mypy/pull/14971))
*   Convert insecure links to use HTTPS (Marti Raudsepp, PR [14974](https://github.com/python/mypy/pull/14974))
*   Also mention overloads in async iterator documentation (Shantanu, PR [14998](https://github.com/python/mypy/pull/14998))
*   stubtest: Improve allowlist documentation (Shantanu, PR [15008](https://github.com/python/mypy/pull/15008))
*   Clarify "Using types... but not at runtime" (Jon Shea, PR [15029](https://github.com/python/mypy/pull/15029))
*   Fix alignment of cheat sheet example (Ondřej Cvacho, PR [15039](https://github.com/python/mypy/pull/15039))
*   Fix error for callback protocol matching against callable type object (Shantanu, PR [15042](https://github.com/python/mypy/pull/15042))

Error Reporting Improvements

*   Improve bytes formatting error (Shantanu, PR [14959](https://github.com/python/mypy/pull/14959))

Mypyc Improvements

*   Fix unions of bools and ints (Tomer Chachamu, PR [15066](https://github.com/python/mypy/pull/15066))

Other Fixes and Improvements

*   Fix narrowing union types that include Self with isinstance (Christoph Tyralla, PR [14923](https://github.com/python/mypy/pull/14923))
*   Allow objects matching SupportsKeysAndGetItem to be unpacked (Bryan Forbes, PR [14990](https://github.com/python/mypy/pull/14990))
*   Check type guard validity for staticmethods (EXPLOSION, PR [14953](https://github.com/python/mypy/pull/14953))
*   Fix sys.platform when cross-compiling with emscripten (Ethan Smith, PR [14888](https://github.com/python/mypy/pull/14888))

Typeshed Updates

Typeshed is now modular and distributed as separate PyPI packages for everything except the standard library stubs. Please see [git log](https://github.com/python/typeshed/commits/main?after=b0ed50e9392a23e52445b630a808153e0e256976+0&branch=main&path=stdlib) for full list of typeshed changes.

Acknowledgements

Thanks to all mypy contributors who contributed to this release:

*   Alex Waygood
*   Amin Alaee
*   Bryan Forbes
*   Chad Dombrova
*   Charlie Denton
*   Christoph Tyralla
*   dosisod
*   Ethan Smith
*   EXPLOSION
*   Ilya Konstantinov
*   Ivan Levkivskyi
*   Jon Shea
*   Jukka Lehtosalo
*   KotlinIsland
*   Marti Raudsepp
*   Nikita Sobolev
*   Ondřej Cvacho
*   Shantanu
*   sobolevn
*   Tomer Chachamu
*   Yaroslav Halchenko

Posted by Wesley Collin Wright.

1.2

[Thursday, 6 April 2023](https://mypy-lang.blogspot.com/2023/04/mypy-12-released.html)

We’ve just uploaded mypy 1.2 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).

Improvements to Dataclass Transforms

*   Support implicit default for "init" parameter in field specifiers (Wesley Collin Wright and Jukka Lehtosalo, PR [15010](https://github.com/python/mypy/pull/15010))
*   Support descriptors in dataclass transform (Jukka Lehtosalo, PR [15006](https://github.com/python/mypy/pull/15006))
*   Fix frozen\_default in incremental mode (Wesley Collin Wright)
*   Fix frozen behavior for base classes with direct metaclasses (Wesley Collin Wright, PR [14878](https://github.com/python/mypy/pull/14878))

Mypyc: Native Floats

Mypyc now uses a native, unboxed representation for values of type float. Previously these were heap-allocated Python objects. Native floats are faster and use less memory. Code that uses floating-point operations heavily can be several times faster when using native floats.

Various float operations and math functions also now have optimized implementations. Refer to the [documentation](https://mypyc.readthedocs.io/en/latest/float_operations.html) for a full list.

This can change the behavior of existing code that uses subclasses of float. When assigning an instance of a subclass of float to a variable with the float type, it gets implicitly converted to a float instance when compiled:

python
from lib import MyFloat   MyFloat ia a subclass of "float"

def example() -> None:
 x = MyFloat(1.5)
 y: float = x   Implicit conversion from MyFloat to float
 print(type(y))   float, not MyFloat


Previously, implicit conversions were applied to int subclasses but not float subclasses.

Also, int values can no longer be assigned to a variable with type float in compiled code, since these types now have incompatible representations. An explicit conversion is required:

python
def example(n: int) -> None:
 a: float = 1   Error: cannot assign "int" to "float"
 b: float = 1.0   OK
 c: float = n   Error
 d: float = float(n)   OK


This restriction only applies to assignments, since they could otherwise narrow down the type of a variable from float to int. int values can still be implicitly converted to float when passed as arguments to functions that expect float values.

Note that mypyc still doesn’t support arrays of unboxed float values. Using list\[float\] involves heap-allocated float objects, since list can only store boxed values. Support for efficient floating point arrays is one of the next major planned mypyc features.

Related changes:

*   Use a native unboxed representation for floats (Jukka Lehtosalo, PR [14880](https://github.com/python/mypy/pull/14880))
*   Document native floats and integers (Jukka Lehtosalo, PR [14927](https://github.com/python/mypy/pull/14927))
*   Fixes to float to int conversion (Jukka Lehtosalo, PR [14936](https://github.com/python/mypy/pull/14936))

Mypyc: Native Integers

Mypyc now supports signed 32-bit and 64-bit integer types in addition to the arbitrary-precision int type. You can use the types mypy\_extensions.i32 and mypy\_extensions.i64 to speed up code that uses integer operations heavily.

Simple example:
python
from mypy_extensions import i64

def inc(x: i64) -> i64:
 return x + 1


Refer to the [documentation](https://mypyc.readthedocs.io/en/latest/using_type_annotations.html#native-integer-types) for more information. This feature was contributed by Jukka Lehtosalo.

Other Mypyc Fixes and Improvements

*   Support iterating over a TypedDict (Richard Si, PR [14747](https://github.com/python/mypy/pull/14747))
*   Faster coercions between different tuple types (Jukka Lehtosalo, PR [14899](https://github.com/python/mypy/pull/14899))
*   Faster calls via type aliases (Jukka Lehtosalo, PR [14784](https://github.com/python/mypy/pull/14784))
*   Faster classmethod calls via cls (Jukka Lehtosalo, PR [14789](https://github.com/python/mypy/pull/14789))

Fixes to Crashes

*   Fix crash on class-level import in protocol definition (Ivan Levkivskyi, PR [14926](https://github.com/python/mypy/pull/14926))
*   Fix crash on single item union of alias (Ivan Levkivskyi, PR [14876](https://github.com/python/mypy/pull/14876))
*   Fix crash on ParamSpec in incremental mode (Ivan Levkivskyi, PR [14885](https://github.com/python/mypy/pull/14885))

Documentation Updates

*   Update adopting \--strict documentation for 1.0 (Shantanu, PR [14865](https://github.com/python/mypy/pull/14865))
*   Some minor documentation tweaks (Jukka Lehtosalo, PR [14847](https://github.com/python/mypy/pull/14847))
*   Improve documentation of top level mypy: disable-error-code comment (Nikita Sobolev, PR [14810](https://github.com/python/mypy/pull/14810))

Error Reporting Improvements

*   Add error code to `typing_extensions` suggestion (Shantanu, PR [14881](https://github.com/python/mypy/pull/14881))
*   Add a separate error code for top-level await (Nikita Sobolev, PR [14801](https://github.com/python/mypy/pull/14801))
*   Don’t suggest two obsolete stub packages (Jelle Zijlstra, PR [14842](https://github.com/python/mypy/pull/14842))
*   Add suggestions for pandas-stubs and lxml-stubs (Shantanu, PR [14737](https://github.com/python/mypy/pull/14737))

Other Fixes and Improvements

*   Multiple inheritance considers callable objects as subtypes of functions (Christoph Tyralla, PR [14855](https://github.com/python/mypy/pull/14855))
*   stubtest: Respect final runtime decorator and enforce it in stubs (Nikita Sobolev, PR [14922](https://github.com/python/mypy/pull/14922))
*   Fix false positives related to type\[<type-var>\] (sterliakov, PR [14756](https://github.com/python/mypy/pull/14756))
*   Fix duplication of ParamSpec prefixes and properly substitute ParamSpecs (EXPLOSION, PR [14677](https://github.com/python/mypy/pull/14677))
*   Fix line number if `__iter__` is incorrectly reported as missing (Jukka Lehtosalo, PR [14893](https://github.com/python/mypy/pull/14893))
*   Fix incompatible overrides of overloaded generics with self types (Shantanu, PR [14882](https://github.com/python/mypy/pull/14882))
*   Allow SupportsIndex in slice expressions (Shantanu, PR [14738](https://github.com/python/mypy/pull/14738))
*   Support if statements in bodies of dataclasses and classes that use dataclass\_transform (Jacek Chałupka, PR [14854](https://github.com/python/mypy/pull/14854))
*   Allow iterable class objects to be unpacked (including enums) (Alex Waygood, PR [14827](https://github.com/python/mypy/pull/14827))
*   Fix narrowing for walrus expressions used in match statements (Shantanu, PR [14844](https://github.com/python/mypy/pull/14844))
*   Add signature for attr.evolve (Ilya Konstantinov, PR [14526](https://github.com/python/mypy/pull/14526))
*   Fix Any inference when unpacking iterators that don't directly inherit from typing.Iterator (Alex Waygood, PR [14821](https://github.com/python/mypy/pull/14821))
*   Fix unpack with overloaded `__iter__` method (Nikita Sobolev, PR [14817](https://github.com/python/mypy/pull/14817))
*   Reduce size of JSON data in mypy cache (dosisod, PR [14808](https://github.com/python/mypy/pull/14808))
*   Improve “used before definition” checks when a local definition has the same name as a global definition (Stas Ilinskiy, PR [14517](https://github.com/python/mypy/pull/14517))
*   Honor NoReturn as \_\_setitem\_\_ return type to mark unreachable code (sterliakov, PR [12572](https://github.com/python/mypy/pull/12572))

Typeshed Updates

Typeshed is now modular and distributed as separate PyPI packages for everything except the standard library stubs. Please see [git log](https://github.com/python/typeshed/commits/main?after=a544b75320e97424d2d927605316383c755cdac0+0&branch=main&path=stdlib) for full list of typeshed changes.

Acknowledgements

Thanks to all mypy contributors who contributed to this release:

*   Alex Waygood
*   Avasam
*   Christoph Tyralla
*   dosisod
*   EXPLOSION
*   Ilya Konstantinov
*   Ivan Levkivskyi
*   Jacek Chałupka
*   Jelle Zijlstra
*   Jukka Lehtosalo
*   Marc Mueller
*   Max Murin
*   Nikita Sobolev
*   Richard Si
*   Shantanu
*   Stas Ilinskiy
*   sterliakov
*   Wesley Collin Wright

Posted by Jukka Lehtosalo

1.1.1

[Monday, 6 March 2023](https://mypy-lang.blogspot.com/2023/03/mypy-111-released.html)

We’ve just uploaded mypy 1.1.1 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 for `dataclass_transform``

This release adds full support for the dataclass\_transform decorator defined in [PEP 681](https://peps.python.org/pep-0681/#decorator-function-example). This allows decorators, base classes, and metaclasses that generate a \_\_init\_\_ method or other methods based on the properties of that class (similar to dataclasses) to have those methods recognized by mypy.

This was contributed by Wesley Collin Wright.

Dedicated Error Code for Method Assignments

Mypy can’t safely check all assignments to methods (a form of monkey patching), so mypy generates an error by default. To make it easier to ignore this error, mypy now uses the new error code method-assign for this. By disabling this error code in a file or globally, mypy will no longer complain about assignments to methods if the signatures are compatible.

Mypy also supports the old error code assignment for these assignments to prevent a backward compatibility break. More generally, we can use this mechanism in the future if we wish to split or rename another existing error code without causing backward compatibility issues.

This was contributed by Ivan Levkivskyi (PR [14570](https://github.co

@pyup-bot pyup-bot mentioned this pull request Nov 23, 2023
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Closing this in favor of #281

@pyup-bot pyup-bot closed this Dec 21, 2023
@Mulugruntz Mulugruntz deleted the pyup-update-mypy-1.0.0-to-1.7.1 branch December 21, 2023 19:27
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