pymysql error: "CLIENT" is not a known attribute of module ".constants"

[mickvangelderen]

Something isn't right about the pymysql typestubs.

Found out by updating pyright from 1.1.402 to 1.1.403 which comes with new typestubs, see microsoft/pyright#10690 (comment).

Reproduction repository: https://github.com/mickvangelderen/pyright-issue-10690

main.py

import pymysql.constants.CLIENT

def main():
    print(f"MULTI_STATEMENTS: {pymysql.constants.CLIENT.MULTI_STATEMENTS}")


if __name__ == "__main__":
    main()

pyproject.toml

[project]
name = "pyright-403-pymysql"
version = "0.1.0"
description = "Add your description here"
readme = "README.md"
requires-python = ">=3.12"
dependencies = [
    "pymysql>=1.1.1",
]

[dependency-groups]
dev = [
    "pyright>=1.1.403",
]

uv run pyright

/home/mick/projects/pyright-403-pymysql/main.py
  /home/mick/projects/pyright-403-pymysql/main.py:4:50 - error: "CLIENT" is not a known attribute of module ".constants" (reportAttributeAccessIssue)
1 error, 0 warnings, 0 informations

[zanieb]

Here's a similar reproduction for ER

# Write the test file
❯ echo "import pymysql.constants.ER; print(pymysql.constants.ER)" > example.py

# The issue does not occur with the old stubs
❯ uvx --with pymysql==1.1.1 --with types-pymysql==1.1.0.20250516 pyright==1.1.403 example.py
Installed 5 packages in 69ms
0 errors, 0 warnings, 0 informations 

# The issue does occur with the new stubs
❯ uvx --with pymysql==1.1.1 --with types-pymysql==1.1.0.20250708 pyright==1.1.403 example.py
/private/tmp/example/example.py
  /private/tmp/example/example.py:1:54 - error: "ER" is not a known attribute of module ".constants" (reportAttributeAccessIssue)
1 error, 0 warnings, 0 informations 

# The issue persists with the new stubs and an older pyright version
❯ uvx --with pymysql==1.1.1 --with types-pymysql==1.1.0.20250708 'pyright<1.1.403' example.py
Installed 5 packages in 96ms
WARNING: there is a new pyright version available (v1.1.402 -> v1.1.403).
Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`

/private/tmp/example/example.py
  /private/tmp/example/example.py:1:54 - error: "ER" is not a known attribute of module ".constants" (reportAttributeAccessIssue)
1 error, 0 warnings, 0 informations 

# The issue never occurs on mypy
❯ uvx --with pymysql==1.1.1 --with types-pymysql==1.1.0.20250708 mypy example.py
Success: no issues found in 1 source file

[zanieb]

cc @donBarbos I don't see how #14335 caused this, but that's the only relevant change

[donBarbos]

I found problem line :) if we remove from . import constatns from the main __init__.pyi the problem will disappear:

typeshed/stubs/PyMySQL/pymysql/__init__.pyi

Line 5 in 9317dc6

from . import connections, constants, converters, cursors

[srittau]

According to microsoft/pyright#10690, this is actually a bug in pyright. Since I came to the same conclusion independently, I'm closing this here, thanks for reporting!