False positive [override] check, superclass signature wrong

[pebenito]

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

[pebenito]

This is pure speculation, but the root cause of this might be the same as #16429.

[pebenito]

Seen in 1.7.0: https://github.com/pebenito/setools/actions/runs/6851507057/job/18627922726#step:8:37

[JelleZijlstra]

I looked at this a little but couldn't find anything. I suspect mypy may be looking at a different set of types for PyQt6 than you're using.

I don't know what #16429 has to do with this issue.

[pebenito]

I looked at this a little but couldn't find anything. I suspect mypy may be looking at a different set of types for PyQt6 than you're using.

I'm not sure I understand what you're saying but I checked PyQt5 and this method has the same signature. It reproduces on my Fedora systems and also in the Ubuntu VMs in GitHub actions, plus using tox. If mypy is using the wrong .pyi files, I can't see how I could tell with this particular method.

I don't know what #16429 has to do with this issue.

The only reason I suggested that is because the symptom is making stuff Optional when it's not. I don't mypy code at all, so this could simply be a coincidence.