[issue40574] segfault causing regression from PEP 573 implementation

[STINNER Victor]

STINNER Victor <vstinner at python.org> added the comment:

Ah, if I install Python, I can install PyQt5. I installed PyQt5:
   python -X faulthandler -c "import PyQt5.QtCore; PyQt5.QtCore.Qt.Key_Control""
doesn't crash.

I also tested the following hello world, it doesn't crash neither.
---
# https://pythonprogramminglanguage.com/pyqt5-hello-world/
import sys
from PyQt5 import QtCore, QtWidgets
from PyQt5.QtWidgets import QMainWindow, QLabel, QGridLayout, QWidget
from PyQt5.QtCore import QSize    

class HelloWindow(QMainWindow):
    def __init__(self):
        QMainWindow.__init__(self)

        self.setMinimumSize(QSize(640, 480))    
        self.setWindowTitle("Hello world - pythonprogramminglanguage.com") 

        centralWidget = QWidget(self)          
        self.setCentralWidget(centralWidget)   

        gridLayout = QGridLayout(self)     
        centralWidget.setLayout(gridLayout)  

        title = QLabel("Hello World from PyQt", self) 
        title.setAlignment(QtCore.Qt.AlignCenter) 
        gridLayout.addWidget(title, 0, 0)

if __name__ == "__main__":
    app = QtWidgets.QApplication(sys.argv)
    mainWin = HelloWindow()
    mainWin.show()
    sys.exit( app.exec_() )
---

I built Python with:

./configure --cache-file=../python-config.cache --with-pydebug CFLAGS=-O0 --prefix=/opt/py39 --with-system-expat --with-system-ffi
make
make install

What is your OS? How did you build Python? Which SIP and PyQt5 versions did you try?

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue40574>
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