False positive [override] check, superclass signature wrong

Bug Report

mypy is using an incorrect method signature on [override] checks. The code looks like this:

from PyQt6 import QtCore, QtGui, QtWidgets

class SEToolsTreeWidget(QtWidgets.QTreeWidget):

    def contextMenuEvent(self, event: QtGui.QContextMenuEvent) -> None:
        ...

Full code: https://github.com/pebenito/setools/blob/pyqt-rework/setoolsgui/widgets/views/treewidget.py

When inspecting the PyQt6 definitions, the contextMenuEvent() parameter is not optional:

$ grep 'def contextMenuEvent' /usr/lib64/python3.11/site-packages/PyQt6/*.pyi
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, a0: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, a0: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, e: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, a0: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, e: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, event: 'QGraphicsSceneContextMenuEvent') -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, event: 'QGraphicsSceneContextMenuEvent') -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, event: 'QGraphicsSceneContextMenuEvent') -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, event: 'QGraphicsSceneContextMenuEvent') -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, event: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, ev: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, a0: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, event: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, contextMenuEvent: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, e: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, a0: QtGui.QContextMenuEvent) -> None: ...
/usr/lib64/python3.11/site-packages/PyQt6/QtWidgets.pyi:    def contextMenuEvent(self, e: QtGui.QContextMenuEvent) -> None: ...

Expected Behavior

No errors

Actual Behavior

setoolsgui/widgets/views/treewidget.py:15: error: Argument 1 of "contextMenuEvent" is incompatible with supertype "QAbstractScrollArea"; supertype defines the argument type as "QContextMenuEvent | None"  [override]
        def contextMenuEvent(self, event: QtGui.QContextMenuEvent) -> None:
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
setoolsgui/widgets/views/treewidget.py:15: note: This violates the Liskov substitution principle
setoolsgui/widgets/views/treewidget.py:15: note: See https://mypy.readthedocs.io/en/stable/common_issues.html#incompatible-overrides
setoolsgui/widgets/views/treewidget.py:15: error: Argument 1 of "contextMenuEvent" is incompatible with supertype "QWidget"; supertype defines the argument type as "QContextMenuEvent | None"  [override]
        def contextMenuEvent(self, event: QtGui.QContextMenuEvent) -> None:
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Example run: https://github.com/pebenito/setools/actions/runs/6804093923/job/18500854778#step:8:36

Your Environment

This is running in tox. I hit this both on my Fedora 38 system and also GitHub actions (Ubuntu). tox.ini if useful: https://github.com/pebenito/setools/blob/pyqt-rework/tox.ini

• Mypy version used: 1.6.0, 1.6.1, 1.7.0
• Mypy command-line flags: only -p to specify package
• Mypy configuration options from mypy.ini (and other config files): from pyproject.toml

[tool.mypy]
no_implicit_optional = true
pretty = true

[[tool.mypy.overrides]]
module = ['networkx.*',
          'pytestqt.*']
ignore_missing_imports = true

[[tool.mypy.overrides]]
module = ['tests-gui.*']
disable_error_code = ["union-attr"]

• Python version used: 3.10-3.12

Reproduce the report with setoolsgui/widgets/views/treewidget.py using the tox.ini environment and the pyproject.toml mypy settings. Start by tracing the override check for the PyQt6 contextMenuEvent signature; done means the shown valid override produces no false-positive errors while incompatible overrides remain diagnosed.