qt5 库有什么问题？答案

【问题标题】：What is wrong with qt5 libs?qt5 库有什么问题？
【发布时间】：2020-11-13 22:32:08
【问题描述】：

我尝试在 qt5 上编写简单的练习：
main.py：

    import sys
    from PySide2.QtWidgets import QApplication, QLabel
    
    app = QApplication(sys.argv)
    label = QLabel("Hello World!")
    label.show()
    app.exec_()

当我尝试启动时，我遇到了与 Qt5 库相关的错误：

 (base) [redf1sh@redPC ~]$ export QT_DEBUG_PLUGINS=1
(base) [redf1sh@redPC ~]$ python3 main.py

...

Got keys from plugin meta data ("xcb")
QFactoryLoader::QFactoryLoader() checking directory path "/home/redf1sh/anaconda3/bin/platforms" ...
Cannot load library /home/redf1sh/anaconda3/plugins/platforms/libqxcb.so: (/home/redf1sh/anaconda3/plugins/platforms/../../lib/libQt5XcbQpa.so.5: undefined symbol: _ZN11QFontEngine14bitmapForGlyphEj6QFixedRK10QTransform, version Qt_5_PRIVATE_API)
QLibraryPrivate::loadPlugin failed on "/home/redf1sh/anaconda3/plugins/platforms/libqxcb.so" : "Cannot load library /home/redf1sh/anaconda3/plugins/platforms/libqxcb.so: (/home/redf1sh/anaconda3/plugins/platforms/../../lib/libQt5XcbQpa.so.5: undefined symbol: _ZN11QFontEngine14bitmapForGlyphEj6QFixedRK10QTransform, version Qt_5_PRIVATE_API)"
qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "" even though it was found.
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

Available platform plugins are: eglfs, minimal, minimalegl, offscreen, vnc, xcb.

我已经安装了 pyqt5 包，pyside2 和 pip。

你能帮我解决这个问题吗？

【问题讨论】：

如果您将缺少的符号输入谷歌，就会出现多个类似的问题。比如这个stackoverflow.com/q/59809703/14215102
您可以尝试使用ldd（在故障库上？）来了解您的环境和系统之间是否存在库冲突。

标签： python-3.x pyqt5

【解决方案1】：

我自己解决了。

首先，我找到系统中所有连接到qt的包并删除它们：

$ pip list | grep qt
$ pip uninstall *smth*

$ conda list | grep qt 
$ conda remove *smth*

$ pacman -Qe | grep qt
# pacman -R *smth*

其次是只从 pacman 明确安装（不是 pip 或 conda 中的插件）

# pacman -S qt5 pyside2 python-pyqt5

现在一切正常

【讨论】：