Overloads from PySide2 don't seem to work correctly

[rggjan]

I have this code in test.py:

1 from PySide2.QtCore import QRect
2 from PySide2.QtGui import QPixmap
3 
4 a = QPixmap()
5 
6 reveal_type(a.depth())
7 reveal_type(a.copy(rect=QRect()))
8 reveal_type(a.copy(1, 2, 3, 4))
9 reveal_type(a.copy())

Running mypy test.py produces:

test.py:6: note: Revealed type is 'builtins.int'
test.py:7: note: Revealed type is 'Any'
test.py:8: note: Revealed type is 'Any'
test.py:9: note: Revealed type is 'Any'

So the stubs are found and the non overloaded function on line 6 is evaluated correctly to int.

However, from the overload signature in PySide2/QtGui.pyi:

6188 class QPixmap(PySide2.QtGui.QPaintDevice):
...
6210     @typing.overload
6211     def copy(self, rect:PySide2.QtCore.QRect=...) -> PySide2.QtGui.QPixmap: ...
6212     @typing.overload
6213     def copy(self, x:int, y:int, width:int, height:int) -> PySide2.QtGui.QPixmap: ...
...
6218     def depth(self) -> int: ...

I would expect lines 7 to 9 to evaluate to QPixmap instead of Any...

[rggjan]

Actually, could this be a python3.6 issue?

I'm using

• mypy 0.720
• python 3.6.8
• PySide2 5.13.1

[JelleZijlstra]

Could you give a more self-contained example, or at least link to the full .pyi files you're using?

One possible reason is that mypy doesn't know what PySide2.QtGui.QPixmap is and therefore treats is as Any.

[rggjan]

I installed pyside via pip, so you can get the pyi files I used from here:
https://pypi.org/project/PySide2/#files

Is it possible that it doesn't work because QPixmap is not known inside the definition of QPixmap in python 3.6?

[JukkaL]

Can you try reveal_type(a.copy)? It might produce useful output.

[rggjan]

reveal_type(a.copy) produces:

note: Revealed type is 'Overload(def (*Any, **Any) -> Any)'

[ilevkivskyi]

I looked at the stubs, and here is what I see: these stubs are autogenerated and are seriously broken. In particular they use typing.Optional, typing.overload etc., but typing appears as:

from PySide2.support.signature import typing

Looking at PySide2/support directory I see it is almost empty, this means that lots of types in stubs are just Any. I would recommend reporting this to PySide2 maintainers.

[ctismer]

@ilevkivskyi Yes, the above statement works perfectly with PySide2, but only if the import really happens. If the analysis of mypy does everything without an import, then it cannot see anything.

I can probably change this, because I mainly did that to support Python2 in the early days when to external typing module was available. Maybe we can do this?

try:
    import typing
except ImportError:
    from PySide2.support.signature import typing

[ilevkivskyi]

IIUC we are now talking about code in stub files (i.e. in *.pyi files), right? Normally these files aren't supposed to be ever imported at runtime, so you can use just import typing, this will work for mypy and other static type checkers even if typing is not present at runtime.