Linter issue: mypy<1.14 pulls in incompatible dependencies due to pydandic release

[courtneypacheco]

Background / Context

Breaking Changes

We use Mypy to perform lint checks during PR builds (see this line in tox.ini). However, one of mypy's dependencies, pydantic, was recently updated and mypy is no longer fully compatible with pydantic's latest code. This compatibility issue is problematic because mypy<1.14 seems to pull in the latest pydantic release by default through a dependency chain, which means mypy<1.14 no longer works in certain situations.

Screenshot Example

I unfortunately forgot to grab a screenshot of the issue in this particular repo, but here is a screenshot of a nearly identical mypy error in the instructlab/instructlab repo caused by the same mypy issue:

Relevant Issues Filed

I have found two relevant issues filed for both mypy and pydantic, but there may be more as time marches on:

• Limited inference with union of callables and assignment to a union python/mypy#18191
• mypy type-checking issues affecting a Field's default value or default_factory after upgrade to 2.10 pydantic/pydantic#10950

Proposed Solution

Pin mypy<1.14 for now and force it to use pydantic<=2.9.2 by specifying pydantic<=2.9.2 as a dependency in the affected tox.ini file:

sdg/tox.ini

Line 77 in c220b5f

mypy>=1.10.0,<2.0