From 8b4500d7acc699ec72bbac4aeed30db3e168a76d Mon Sep 17 00:00:00 2001
Message-ID: <8b4500d7acc699ec72bbac4aeed30db3e168a76d.1772599681.git.sam@gentoo.org>
In-Reply-To: <6086254f84186a7a28b86ee9948e6008a0e3e502.1772599681.git.sam@gentoo.org>
References: <6086254f84186a7a28b86ee9948e6008a0e3e502.1772599681.git.sam@gentoo.org>
From: Dobry Nikolov <dobry989@gmail.com>
Date: Tue, 3 Mar 2026 13:45:34 +0200
Subject: [PATCH 3/4] shellcorona: use QPointer for m_waitingPanels to
 futureproof against dangling pointers

Change m_waitingPanels to QList<QPointer<Plasma::Containment>> so that
any freed containment pointer auto-nulls in place rather than dangling.

- createWaitingPanels(): call removeAll(nullptr) at entry to discard
  any auto-nulled entries before iterating.
- checkAllDesktopsUiReady(): same removeAll(nullptr) before isEmpty()
  to avoid spuriously starting the timer for nulled entries.
- panelContainmentDestroyed(): the m_waitingPanels branch is now
  redundant since QPointer auto-nulls it; guard on m_panelViews
  instead to keep the PanelView cleanup path intact.
- isScreenUiReady(): null-check each QPointer before dereferencing.

BUG: 516937
(cherry picked from commit 7308d3153f5e9ee8607f89005aa05c2fd4f07dd6)
--- a/shell/shellcorona.cpp
+++ b/shell/shellcorona.cpp
@@ -1519,6 +1519,7 @@ void ShellCorona::checkAllDesktopsUiReady()
     ksplashProgressMessage.setArguments(QList<QVariant>() << QStringLiteral("desktop"));
     QDBusConnection::sessionBus().asyncCall(ksplashProgressMessage);
 
+    m_waitingPanels.removeAll(nullptr);
     if (!m_waitingPanels.isEmpty()) {
         m_waitingPanelsTimer.start();
     }
@@ -1576,7 +1577,9 @@ Plasma::Containment *ShellCorona::createContainmentForActivity(const QString &ac
 
 void ShellCorona::createWaitingPanels()
 {
-    QList<Plasma::Containment *> stillWaitingPanels;
+    m_waitingPanels.removeAll(nullptr);
+
+    QList<QPointer<Plasma::Containment>> stillWaitingPanels;
 
     for (Plasma::Containment *cont : std::as_const(m_waitingPanels)) {
         // ignore non existing (yet?) screens
@@ -1644,9 +1647,7 @@ void ShellCorona::panelContainmentDestroyed(QObject *obj)
 {
     auto *cont = static_cast<Plasma::Containment *>(obj);
 
-    // The destroyed panel containment was still in the m_waitingPanels list
-    if (m_waitingPanels.contains(cont)) {
-        m_waitingPanels.removeAll(cont);
+    if (!m_panelViews.contains(cont)) {
         return;
     }
 
@@ -2280,8 +2281,8 @@ bool ShellCorona::isScreenUiReady(int screen)
         return false;
     }
 
-    for (Plasma::Containment *cont : std::as_const(m_waitingPanels)) {
-        if (cont->lastScreen() == screen) {
+    for (const QPointer<Plasma::Containment> &cont : std::as_const(m_waitingPanels)) {
+        if (cont && cont->lastScreen() == screen) {
             return false;
         }
     }
--- a/shell/shellcorona.h
+++ b/shell/shellcorona.h
@@ -302,7 +302,7 @@ private:
     QHash<const Plasma::Containment *, int> m_pendingScreenChanges;
     KConfigGroup m_desktopDefaultsConfig;
     KConfigGroup m_lnfDefaultsConfig;
-    QList<Plasma::Containment *> m_waitingPanels;
+    QList<QPointer<Plasma::Containment>> m_waitingPanels;
     QHash<QString, QString> m_activityContainmentPlugins;
     QAction *m_addPanelAction;
     std::unique_ptr<QMenu> m_addPanelsMenu;
-- 
2.53.0