Bump mypy from 1.20.2 to 2.1.0

[dependabot]

Bumps mypy from 1.20.2 to 2.1.0.

Changelog

Sourced from mypy's changelog.

Mypy Release Notes

Next Release

Mypy 2.1

We’ve just uploaded mypy 2.1.0 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.

librt.vecs: Fast Growable Array Type for Mypyc

The new librt.vecs module provides an efficient growable array type vec that is optimized for mypyc use. It provides fast, packed arrays with integer and floating point value types, which can be several times faster than list, and tens of times faster than array.array in code compiled using mypyc. It also supports nested vec objects and non-value-type items, such as vec[vec[str]].

Refer to the documentation for the details.

Contributed by Jukka Lehtosalo.

librt.random: Fast Pseudo-Random Number Generation

The new librt.random module provides fast pseudo-random number generation that is optimized for code compiled using mypyc. It can be 3x to 10x faster than the stdlib random module in compiled code.

Refer to the documentation for the details.

Contributed by Jukka Lehtosalo (PR 21433).

Mypyc Improvements

• Make compilation order with multiple files consistent (Piotr Sawicki, PR 21419)
• Fix crash on accessing StopAsyncIteration (Piotr Sawicki, PR 21406)
• Fix incremental compilation with separate flag (Vaggelis Danias, PR 21299)

Fixes to Crashes

• Fix crash on partial type with --allow-redefinition and global declaration (Jukka Lehtosalo, PR 21428)
• Fix broken awaitable generator patching (Ivan Levkivskyi, PR 21435)

Changes to Messages

... (truncated)

Commits

• c1c336d Remove +dev from version
• 74df14b Add changelog for mypy 2.1 (#21464)
• 022d9bc Revert "TypeForm: Enable by default (#21262)"
• 8826288 [mypyc] Document librt.random (#21463)
• 3f4067b Bump librt version to 0.11.0 (#21458)
• 2b1eb58 [mypyc] Enable incremental self-compilation (#21369)
• 8152f4a Respect file config comments for stale modules (#21444)
• 116d60b Fix nondeterminism from nonassociativity of overload joins (#21455)
• 6c4af8e Fix function call message change for small number of args (#21432)
• 4b8fdca [mypyc] Add librt.random module (#21433)
• Additional commits viewable in compare view

[redreceipt]

Risk: MEDIUM — mypy 1.x → 2.x major

mypy 2.0 is a major release with stricter defaults and several removed/renamed flags. Full CI here (mypy, ruff, unit-tests, gunicorn-smoke) is green on the latest run, which is the strongest signal we have — but a major mypy bump can also widen what gets typechecked and silently pass while letting new error classes through depending on config.

Migration checklist

• Confirm mypy --version ≥ 2.0 in the CI image; re-run with --show-error-codes and diff against master to make sure no new categories are silently treated as warnings.
• Audit pyproject.toml / mypy.ini for removed/renamed flags (--strict-optional semantics, deprecated --follow-imports=skip behavior, plugin loading changes).
• Re-export check: 2.x is stricter about __all__ and implicit re-exports — look for breakage in package boundaries.
• Verify the type-checked surface didn't shrink (e.g., a now-failing plugin silently disabling checks for a file).
• Smoke test locally: mypy . against a checkout to confirm error count parity with master.

Risk

MEDIUM. Auto-mergeable in principle since CI is green, but a quick eyeball of the mypy job output and a local mypy . run before merge would be prudent. Holding approval pending that check.

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Generated by Claude Code

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Generated by Claude Code

[redreceipt]

Status update — CI is green on the latest head

All required checks are green on ddd2072105: mypy, ruff, vulture, unit-tests, gunicorn-smoke (CodeQL is neutral/info-only). The migration-plan checklist items that were tractable from CI are now satisfied — the typecheck job is passing under mypy 2.1.0 with the existing pyproject.toml / mypy.ini config, and the test/smoke jobs are green.

Remaining unverified items from the plan (would need a local checkout):

• Local mypy --show-error-codes . + diff vs master to confirm no new categories of error are being silently swallowed.
• Manual audit of pyproject.toml / mypy.ini for removed/renamed flags in 2.x.

If those local checks pass for a human reviewer, this is ready to approve and merge.

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Generated by Claude Code