QIcon: remove icon from cache if the cached engine fails to load

An icon that is not null by the time it is inserted in the cache can
become null, depending on the QIconEngine implementation.

For example, when an application with a shortcut exists on the desktop,
uninstall the application, and then install the application again, the
acquisition of the application icon will fail. The reason is that after
installing the application for the second time, the qtIconCache will not
be updated when the icon is acquired.

Done-with: Volker Hilsheimer <volker.hilsheimer@qt.io>
Pick-to: 5.15 6.2 6.3 6.4
Change-Id: I6dc8cf435815b92da270d74fe992843336af23e2
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

1 files changed, 8 insertions, 4 deletions

diff --git a/src/gui/image/qicon.cpp b/src/gui/image/qicon.cpp
index 38e66b1dc0..08c4667c6c 100644
--- a/src/gui/image/qicon.cpp
+++ b/src/gui/image/qicon.cpp
@@ -1276,11 +1276,15 @@ void QIcon::setFallbackThemeName(const QString &name)
 */
 QIcon QIcon::fromTheme(const QString &name)
 {
-    QIcon icon;
 
-    if (qtIconCache()->contains(name)) {
-        icon = *qtIconCache()->object(name);
-    } else if (QDir::isAbsolutePath(name)) {
+    if (QIcon *cachedIcon = qtIconCache()->object(name)) {
+        if (!cachedIcon->isNull())
+            return *cachedIcon;
+        qtIconCache()->remove(name);
+    }
+
+    QIcon icon;
+    if (QDir::isAbsolutePath(name)) {
         return QIcon(name);
     } else {
         QPlatformTheme * const platformTheme = QGuiApplicationPrivate::platformTheme();