Tuesday 19 July 2022

Mypy 0.971 Released

We’ve just uploaded mypy 0.971 to the Python Package Index (PyPI). 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.

Last Release Officially Supporting Python 2 and 3.6

Support for Python 2 will be completely removed in the next mypy feature release after this one, mypy 0.980.

Support for Python 3.6 will also be dropped in mypy 0.980, since Python 3.6 has reached its end of life. It will be still possible to target Python 3.6 using --python-version in future mypy versions, but no bugs will be fixed that affect only Python 3.6 (unless they are regressions). Also note that typeshed just recently dropped Python 3.6 support, so standard library features only available in Python 3.6 will not be supported.

Mypyc Improvements and Fixes

Mypyc compiles Python modules to C extensions and is bundled with mypy. It uses standard Python type hints to generate fast code (documentation).

  • Speed up accessing always defined native attributes (Jukka Lehtosalo, PR 12600)
  • Reduce the overhead of reference counting (Jukka Lehtosalo, PR 12805, PR 12810, PR 12817)
  • Fix Python 3.11 C API errors (97littleleaf11, PR 12850)
  • Generate smaller code for casts and some implicit type coercions (Jukka Lehtosalo, PR 12839)
  • Optimize calling Python objects with zero or one arguments (97littleleaf11, PR 12862)
  • Replace integer floor division by a power of two with a shift (Jukka Lehtosalo, PR 12870)
  • Add primitives for faster access of float and tuple type objects (Richard Si, PR 13078)
  • Fix compile error related to operator assignment in a generator function (Zsolt Dollenstein, PR 13144)

Stubtest Improvements

Stubtest is a tool for testing that stubs conform to the implementations.

  • Allow ellipsis as default argument (Shantanu, PR 12838)
  • Support --version (Shantanu, PR 12852)
  • Check type variables and ParamSpecs (Shantanu, PR 12851)
  • Add error summary and other output tweaks (KotlinIsland, PR 12855)

Other Notable Fixes and Improvements

  • Disallow assignments to awaited coroutines that do not return (Shantanu, PR 12853)
  • Search sys.path for PEP 561 compliant packages (Ashley Whetter, PR 11143)
  • Treat generators with await as async (Jared Hance, PR 12925)
  • Fix bug in constraints solver regarding ParamSpec upper bounds (Alex Waygood, PR 12938)
  • Fix crash on redefined class variable annotated with Final[<type>] (Alex Waygood, PR 12951)
  • Improve handling of overloads with ParamSpec (Alex Waygood, PR 12953)
  • Don’t suggest installing types packages for some third-party packages that now include types or are obsolete (Shantanu, PR 12959)
  • Add a short note when an error may be fixed by adding an await (Ivan Levkivskyi, PR 12958)
  • Support unannotated converters for attr.ib (t4lz, PR 12815)
  • Disallow undesirable implicit reexport with a from import (Shantanu, PR 12704)
  • Fix crash when subclass method has the same name as a type alias (Wesley Collin Wright, PR 13015)
  • Include end column offset in the mypy AST (bruno messias, PR 12972)
  • Fix "attribute 'arguments' of 'FuncDef' undefined" incremental crash (Frédéric Perrin, PR 12324)
  • Fix false positive error on multiple enum base classes (Alex Waygood, PR 12963)
  • Don't add __match_args__ for dataclasses and named tuples on Python versions lower than 3.10 (Stanislav K, PR 12503)
  • Fix crash when overriding partial-type attribute with method (Jake Lishman, PR 12943)
  • Fix editable installs to current working directory (Shantanu, PR 13161)

Typeshed Updates

Typeshed is now modular and distributed as separate PyPI packages for everything except the standard library stubs. Please see git log for full list of typeshed changes.


Thanks to all mypy contributors who contributed to this release:

  • 97littleleaf11
  • Alex Waygood
  • Ashley Whetter
  • Bruno Messias
  • denballakh
  • Erik Kemperman
  • Ethan Smith
  • Fabian Keller
  • Frédéric Perrin
  • Hal Blackburn
  • Ivan Levkivskyi
  • Jake Lishman
  • Jared Hance
  • Jingchen Ye
  • KotlinIsland
  • Poruri Sai Rahul
  • Pranav Rajpal
  • Ramazan Elsunakev
  • Richard Si
  • Shantanu
  • Stanislav K
  • t4lz
  • Wesley Collin Wright

I would like to thank Ivan Levkivskyi, in particular, who did most of the preparations for this mypy release. My contribution was mainly to finish and publish this blog post.

We’d also like to thank our employer, Dropbox, for funding the mypy core team.