[1.16 apparent regression] mypy 1.16 fails to analyze pydantic 2.11.5 (succeeded in mypy 1.15)

[DaveShuckerow]

Bug Report

mypy 1.16 fails to analyze code that imports pydantic 2.11.5. Mypy analysis succeeded in mypy 1.15.

To Reproduce

import pydantic # I was using pydantic 2.11.5

Expected Behavior

mypy should successfully analyze the file.

Actual Behavior

[ERROR] Completed: Typecheck using MyPy - mypy - mypy failed (exit code 2).
.cache/pex_root/venvs/1/0e03c948bbef7584e6803ffeda803caff33dd8c6/e78a64e86d7066bde1606f95b893e7cfa75dbda9/lib/python3.10/site-packages/pydantic/_internal/_core_utils.py:17: error: Cannot find implementation or library stub for module named "rich.console"  [import-not-found]
.cache/pex_root/venvs/1/0e03c948bbef7584e6803ffeda803caff33dd8c6/e78a64e86d7066bde1606f95b893e7cfa75dbda9/lib/python3.10/site-packages/pydantic/_internal/_core_utils.py:17: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

packages/package_name/src/file.py: error: INTERNAL ERROR -- Please try using mypy master on GitHub:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
If this issue continues with mypy master, please report a bug at https://github.com/python/mypy/issues
version: 1.16.0

Your Environment

• Mypy version used: 1.16
• Mypy command-line flags:
• Mypy configuration options from mypy.ini (and other config files):
• Python version used: 3.10.16

[sterliakov]

Can't reproduce - with or without pydantic plugin, with or without --strict, checking import pydantic produces "no issues found". Are there any other relevant details?

cd "$(mktemp -d)"
uv venv --python 3.10 && . .venv/bin/activate
uv pip install 'mypy==1.16.0' 'pydantic==2.11.5'

cat <<EOF > mypy.ini
[mypy]
plugins = pydantic.mypy
EOF

printf 'import pydantic\n' > foo.py

mypy foo.py
# Success: no issues found in 1 source file

Could you post the traceback (--show-traceback flag) and try doing the same using the master version (pip install git+https://github.com/python/mypy)?

[DaveShuckerow]

I tried the latest mypy master today, and I'm no longer getting this issue.

I'll stick downgrade from 1.16 to 1.15 until the 1.17 release comes out.

Thank you Stanislav & team!