Bump mypy from 1.19.1 to 1.20.2

[dependabot]

Bumps mypy from 1.19.1 to 1.20.2.

Changelog

Sourced from mypy's changelog.

Mypy Release Notes

Next Release

Enabling --local-partial-types by default

This flag affects the inference of types based on assignments in other scopes. For now, explicitly disabling this continues to be supported, but this support will be removed in the future as the legacy behaviour is hard to support with other current and future features in mypy, like the daemon or the new implementation of flexible redefinitions.

Contributed by Ivan Levkivskyi, Jukka Lehtosalo, Shantanu in PR 21163

Enabling --strict-bytes by default

Per PEP 688, mypy no longer treats bytearray and memoryview values as assignable to the bytes type.

Contributed by Shantanu in PR 18371

Drop Support for Targeting Python 3.9

Mypy no longer supports type checking code with --python-version 3.9. Use --python-version 3.10 or newer.

Contributed by Shantanu, Marc Mueller in PR 21243

Remove special casing of legacy bundled stubs

Mypy used to bundle stubs for a few packages in versions 0.812 and earlier. To navigate the transition, mypy used to report missing types for these packages even if --ignore-missing-imports was set. Mypy now consistently respects --ignore-missing-imports for all packages.

Contributed by Shantanu in PR 18372

Prevent assignment to None for non-Optional class variables with type comments

Mypy used to allow assignment to None for class variables when using type comments. This was a common idiom in Python 3.5 and earlier, prior to the introduction of variable annotations. However, this was a soundness hole and has now been removed.

Contributed by Shantanu in PR 20054

Mypy 1.20

We’ve just uploaded mypy 1.20.0 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

... (truncated)

Commits

• 145a062 Bump version to 1.20.2
• 81cd492 Fix slicing with nonstrict optional (#21282)
• 908d344 [mypyc] Set dunder attrs when adding module to sys.modules (#21275)
• ba28610 Initial support for Python 3.15.0a8 (#21255)
• 7b0e09f Fix match statement semantics for "or" pattern (#21156)
• 92b74f2 Avoid widening types in conditional_types (#21242)
• 0dcbfaa Fix is_overlapping_types for generic callables (#21208)
• 210f518 Correctly aggregate narrowing information on parent expressions (#21206)
• c34530e Only set journal mode in coordinator (#21217)
• 79a3ec6 Use WAL with SQLite cache, fix close (#21154)
• Additional commits viewable in compare view

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.92%. Comparing base (b0601d6) to head (2899776).
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #12411   +/-   ##
=======================================
  Coverage   98.92%   98.92%           
=======================================
  Files         134      134           
  Lines       46741    46741           
  Branches     2429     2429           
=======================================
  Hits        46239    46239           
  Misses        373      373           
  Partials      129      129           

Flag	Coverage Δ
CI-GHA	98.98% <ø> (ø)
OS-Linux	98.72% <ø> (-0.01%)	⬇️
OS-Windows	96.98% <ø> (ø)
OS-macOS	97.89% <ø> (-0.01%)	⬇️
Py-3.10.11	97.39% <ø> (-0.01%)	⬇️
Py-3.10.20	97.86% <ø> (+<0.01%)	⬆️
Py-3.11.15	98.11% <ø> (-0.01%)	⬇️
Py-3.11.9	97.65% <ø> (-0.01%)	⬇️
Py-3.12.10	97.73% <ø> (ø)
Py-3.12.13	98.20% <ø> (-0.01%)	⬇️
Py-3.13.13	98.45% <ø> (+<0.01%)	⬆️
Py-3.14.4	98.50% <ø> (-0.01%)	⬇️
Py-3.14.4t	97.51% <ø> (ø)
Py-pypy3.11.15-7.3.21	97.35% <ø> (ø)
VM-macos	97.89% <ø> (-0.01%)	⬇️
VM-ubuntu	98.72% <ø> (-0.01%)	⬇️
VM-windows	96.98% <ø> (ø)
cython-coverage	38.08% <ø> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

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[codspeed-hq]

Merging this PR will degrade performance by 11.2%

❌ 1 regressed benchmark
✅ 66 untouched benchmarks
⏩ 4 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	test_one_hundred_get_requests_iter_chunks_on_10mb_chunked_payload[pyloop]	1.1 s	1.3 s	-11.2%

---

_{Comparing dependabot/pip/mypy-1.20.2 (2899776) with master (b0601d6)}

Footnotes

1. 4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩