Bump mypy from 1.20.2 to 2.3.0

[dependabot]

Bumps mypy from 1.20.2 to 2.3.0.

Changelog

Sourced from mypy's changelog.

Mypy Release Notes

Next Release

Packaging changes

• No longer provide mypyc-accelerated wheels for macOS x86_64 [mypyc-wheels #119](mypyc/mypy_mypyc-wheels#119)

Mypy 2.3

We've just uploaded mypy 2.3.0 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.

The Upcoming Switch to the New Native Parser

We are planning to enable the new native parser (--native-parser) by default soon. We recommend that you test the native parser in your projects and report any issues in the mypy issue tracker.

Mypyc Free-threading Memory Safety

Free-threaded Python builds that don't have the GIL require additional synchronization primitives or lock-free algorithms to ensure memory safety when there are race conditions (for example, when a thread reads a list item while another thread writes the same list item concurrently). This release greatly improves memory safety of free threading.

List operations are now memory-safe on free threaded Python builds, even in the presence of race conditions. This has some performance cost. For list-heavy workloads, using librt.vecs.vec instead of list is often significantly faster, but note that vec is not (and likely won't be) fully memory safe, and the user is expected to avoid race conditions. The newly introduced librt.threading.Lock helps with this. Using variable-length tuples can also be more efficient than lists, since tuples are immutable and don't require expensive synchronization to ensure memory safety.

Instance attribute access is also (mostly) memory safe now on free-threaded builds in the presence of race conditions. We are planning to fix the remaining unsafe cases in a future release.

Full list of changes:

• Make attribute access memory safe on free-threaded builds (Jukka Lehtosalo, PR 21705)
• Fix unsafe borrowing of instance attributes with free-threading (Jukka Lehtosalo, PR 21688)
• Make list get/set item more memory safe on free-threaded builds (Jukka Lehtosalo, PR 21683)
• Don't borrow list items on free-threaded builds (Jukka Lehtosalo, PR 21679)
• Make multiple assignment from list memory-safe on free-threaded builds (Jukka Lehtosalo, PR 21684)

... (truncated)

Commits

• 8aabf84 Drop +dev from version
• 4d8ad2a Update changelog for 2.3 release (#21728)
• 2c21546 [mypyc] Update documentation of race conditions under free threading (#21726)
• a9f62a3 [mypyc] Make attribute access memory safe on free-threaded builds (#21705)
• 0faa413 Use PYODIDE environment variable for Emscripten cross-compilation detection...
• 3d75cdb [mypyc] Borrow final attributes more aggressively (#21702)
• 24c237d [mypyc] Improve documentation of Final (#21713)
• b5be217 [mypyc] Update free threading Python compatibility docs (#21711)
• cbcb51a Narrow for frozendict membership check (#21709)
• af2bc0f Sync typeshed (#21707)
• Additional commits viewable in compare view

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[github-actions]

Hi @dependabot[bot], thank you for your contribution! 🎉

This PR comes from your fork git-mastery/exercises on branch dependabot/uv/mypy-2.3.0.

Before you request for a review, please ensure that you have tested your changes locally!

Important

The previously recommended way of using ./test-download.py is no longer the best way to test your changes locally.

Please read the following instructions for the latest instructions.

Prerequisites

Ensure that you have the gitmastery app installed locally (instructions)

Testing steps

If you already have a local Git-Mastery root to test, you can skip the following step.

Create a Git-Mastery root locally:

gitmastery setup

Navigate into the Git-Mastery root (defaults to gitmastery-exercises/):

cd gitmastery-exercises/

Edit the .gitmastery.json configuration file. You need to set the following values under the exercises_source key.

{
    # other fields...
    "exercises_source": {
        "username": "git-mastery",
        "repository": "exercises",
        "branch": "dependabot/uv/mypy-2.3.0"
    }
}

Then, you can use the gitmastery app to download and verify your changes locally.

gitmastery download <your new change>
gitmastery verify

Checklist

• (For exercises and hands-ons) I have verified that the downloading behavior works
• (For exercises only) I have verified that the verification behavior is accurate

Important

To any reviewers of this pull request, please use the same instructions above to test the changes.