Don't session-restore invalid paths

When session restore is populating the main window, it's unconditional;
you'll get whatever was there before. This can be a problem if any of
those things are now missing. For example, maybe you were browsing files
on a removable disk, then quit Dolphin, and finally removed the disk. The
next time you launch Dolphin again, it will try to show you the
view from the now-missing removable disk.

To prevent this, we now look at all the URLs in all of the view
containers that were created after session-restore has finished doing
its thing; if any of them are invalid local URLs, we change the URL to
the home folder instead to avoid showing the user a view with an invalid
location in it.

BUG: 427619
FIXED-IN: 20.12

src/dolphinmainwindow.cpp

@@ -216,6 +216,20 @@ QVector<DolphinViewContainer*> DolphinMainWindow::viewContainers() const
     return viewContainers;
 }
 
+void DolphinMainWindow::setViewsWithInvalidPathsToHome()
+{
+    const QVector<DolphinViewContainer*> theViewContainers = viewContainers();
+    for (DolphinViewContainer *viewContainer : theViewContainers) {
+
+        // Only consider local dirs, not remote locations and abstract protocols
+        if (viewContainer->url().isLocalFile()) {
+            if (!QFileInfo::exists(viewContainer->url().toLocalFile())) {
+                viewContainer->setUrl(QUrl::fromLocalFile(QDir::homePath()));
+            }
+        }
+    }
+}
+
 void DolphinMainWindow::openDirectories(const QList<QUrl>& dirs, bool splitView)
 {
     m_tabWidget->openDirectories(dirs, splitView);

src/dolphinmainwindow.h

@@ -102,6 +102,12 @@ public:
      */
     void setViewsToHomeIfMountPathOpen(const QString& mountPath);
 
+    /**
+     * Sets any of the window's view containers which are currently displaying
+     * invalid locations to the home path
+     */
+    void setViewsWithInvalidPathsToHome();
+
 public slots:
     /**
      * Opens each directory in \p dirs in a separate tab. If \a splitView is set,

src/main.cpp

@@ -191,6 +191,10 @@ extern "C" Q_DECL_EXPORT int kdemain(int argc, char **argv)
                 if (startedWithURLs) {
                     mainWindow->openDirectories(urls, splitView);
                 }
+
+                // Now handle invalid locations in the set of active views to
+                // avoid issues like https://bugs.kde.org/show_bug.cgi?id=427619
+                mainWindow->setViewsWithInvalidPathsToHome();
             } else {
                 qCWarning(DolphinDebug) << "Unknown class " << className << " in session saved data!";
             }