[PySide6]super().__init__() only calls first parent's __init__ if a class inherits QMainWindow and has multiple inheritance

[yinkaisheng]

class_test.py

import os
import sys
from PySide6.QtWidgets import QApplication, QMainWindow


class First:
    def __init__(self):
        print('First init')
        super().__init__()

    def __del__(self):
        print('First del')


class Second():
    def __init__(self):
        print('Second init')
        super().__init__()
        self.second = 2

    def __del__(self):
        print('Second del')


class Third(QMainWindow, Second):
    def __init__(self):
        print('Third init')
        super().__init__()
        print(f'senond={self.second}')  # error in PySide6, self.second, object has no attribute 'second'

    def __del__(self):
        print('Third del')


def main():
    app = QApplication(sys.argv)
    ob = Third()


if __name__ == '__main__':
    main()

The result:
d:\Codes\Python\automation>class_test.py
Third init
Traceback (most recent call last):
File "D:\Codes\Python\automation\class_test.py", line 41, in <module>
main()
File "D:\Codes\Python\automation\class_test.py", line 37, in main
ob = Third()
File "D:\Codes\Python\automation\class_test.py", line 29, in init
print(f'senond={self.second}')
AttributeError: 'Third' object has no attribute 'second'
Third del

If I change PySide6 to PyQt5, or set 'class Third(First, Second)', the scirpt runs without any error.
Is it an error in PySide6?

[SGaist]

Hi,

Did you check PySide2 as well ?

[yinkaisheng]

@SGaist I don't have PySide2 installed.
My app runs well when I use PyQt5, but when I tried my app with PySide6, I met the error.
I need to write

class Third(QMainWindow, Second):
    def __init__(self):
        print('Third init')
        #super().__init__()
        QMainWindow.__init__(self)
        Second.__init__(self)

I must refer to the base classes name explicitly in PySide6.

[SGaist]

If not already existing, you should open a ticket on the bug tracker about that matter.