Subject: bug#53334: qbittorrent(<=4.4.0)'s search window fails with "Python is required to use the search engine but it does not seem to be installed"

From: Jacob Hrbek <[email-masked]>
Date: Tue, 18 Jan 2022 03:00:12 +0000

qbittorrent <=4.4.0 (current latest version) fails with:

```
Missing Python Runtime

Python is required to use the search engine but it does not seem to be
installed
```

which is triggered from `qbittorrent/src/gui/mainwindow.cpp`:

```cpp

/*https://github.com/qbittorrent/qBittorrent/blob/00f6bb7c8225285a7929426187a1513d247b582b/src/gui/mainwindow.cpp#L1847  */
void MainWindow::on_actionSearchWidget_triggered()
{
     if (!m_hasPython && m_ui->actionSearchWidget->isChecked())
     {
         const Utils::ForeignApps::PythonInfo pyInfo = Utils::ForeignApps::pythonInfo();

         // Not installed
         if (!pyInfo.isValid())
         {
             m_ui->actionSearchWidget->setChecked(false);
             Preferences::instance()->setSearchEnabled(false);

#ifdef Q_OS_WIN
             const QMessageBox::StandardButton buttonPressed = QMessageBox::question(this, tr("Missing Python Runtime")
                 , tr("Python is required to use the search eng
ine but it does not seem to be installed.\nDo you want to install it now?")
                 , (QMessageBox::Yes | QMessageBox::No), QMessageBox::Yes);
             if (buttonPressed == QMessageBox::Yes)
                 installPython();
#else
             QMessageBox::information(this, tr("Missing Python Runtime")
                 , tr("Python is required to use the search engine but it does not seem to be installed."));
#endif
             return;
         }

         // Check version requirement
         if (!pyInfo.isSupportedVersion())
         {
             m_ui->actionSearchWidget->setChecked(false);
             Preferences::instance()->setSearchEnabled(false);

#ifdef Q_OS_WIN
             const QMessageBox::StandardButton buttonPressed = QMessageBox::question(this, tr("Old Python Runtime")
                 , tr("Your Python version (%1) is outdated. Minimum requirement: %2.\nDo you want to install a newer version now?")
                     .arg(pyInfo.ve
rsion, QLatin1String("3.5.0"))
                 , (QMessageBox::Yes | QMessageBox::No), QMessageBox::Yes);
             if (buttonPressed == QMessageBox::Yes)
                 installPython();
#else
             QMessageBox::information(this, tr("Old Python Runtime")
                 , tr("Your Python version (%1) is outdated. Please upgrade to latest version for search engines to work.\nMinimum requirement: %2.")
                 .arg(pyInfo.version, QLatin1String("3.5.0")));
#endif
             return;
         }

         m_hasPython = true;
         m_ui->actionSearchWidget->setChecked(true);
         Preferences::instance()->setSearchEnabled(true);
     }

     displaySearchTab(m_ui->actionSearchWidget->isChecked());
}
```

To call `Utils::ForeignApps::pythonInfo()` definition in
`qbittorrent/src/base/utils/foreignapps.cpp` as:

```cpp

/*https://github.com/qbittorrent/qBittorrent/blob/5c0378a6845e3484023f4c76893ff9f0e5178460/src/base/utils/foreignapps.c
pp#L272  */
PythonInfo Utils::ForeignApps::pythonInfo()
{
     static PythonInfo pyInfo;
     if (!pyInfo.isValid())
     {
         if (testPythonInstallation("python3", pyInfo))
             return pyInfo;

         if (testPythonInstallation("python", pyInfo))
             return pyInfo;

#if defined(Q_OS_WIN)
         if (testPythonInstallation(findPythonPath(), pyInfo))
             return pyInfo;
#endif

         LogMsg(QCoreApplication::translate("Utils::ForeignApps", "Python not detected"), Log::INFO);
     }

     return pyInfo;
}
```

Where:

```cpp
if (testPythonInstallation("python3", pyInfo)) ...
```

Is important as it's checking for a `python3` (or `python`) executable
in PATH that is not provided by guix's build procedure -> The package
has compatibility issues with GNU Guix and has to be patched.

### Steps to reproduce:
0. Get qbittorrent on GNU Guix
1. Open the GUI: View > Search engine and observe the highlighted error
pre
venting to use the search engine functionality

Relevants:
R1. https://github.com/qbittorrent/qBittorrent/issues/16139

--
Jacob Hrbek