From 07cf229f53ab15bb87b943aa07617681a6088d53 Mon Sep 17 00:00:00 2001
From: David Redondo <qt@david-redondo.de>
Date: Thu, 27 Apr 2023 15:22:26 +0200
Subject: Properly clean up screens during reconnect

Otherwise the old screens are left dangling. Also create a placeholder
screen so the windows get assigned a valid screen upon reconnect.

Change-Id: Iea5d1da6f32be5e87464412447ae1449d91d8e75
Reviewed-by: David Edmundson <davidedmundson@kde.org>
---
 src/client/qwaylanddisplay.cpp                |  9 ++++++---
 tests/auto/client/reconnect/tst_reconnect.cpp | 25 +++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/client/qwaylanddisplay.cpp b/src/client/qwaylanddisplay.cpp
index b7e212ab..911004f8 100644
--- a/src/client/qwaylanddisplay.cpp
+++ b/src/client/qwaylanddisplay.cpp
@@ -420,6 +420,12 @@ void QWaylandDisplay::reconnect()
     qDeleteAll(mWaitingScreens);
     mWaitingScreens.clear();
 
+    const auto screens = std::exchange(mScreens, {});
+    ensureScreen();
+    for (QWaylandScreen *screen : screens) {
+        QWindowSystemInterface::handleScreenRemoved(screen);
+    }
+
     // mCompositor
     mShm.reset();
     mCursorThemes.clear();
@@ -449,9 +455,6 @@ void QWaylandDisplay::reconnect()
     qDeleteAll(std::exchange(mInputDevices, {}));
     mLastInputDevice = nullptr;
 
-    auto screens = mScreens;
-    mScreens.clear();
-
     for (const RegistryGlobal &global : mGlobals) {
         emit globalRemoved(global);
     }
diff --git a/tests/auto/client/reconnect/tst_reconnect.cpp b/tests/auto/client/reconnect/tst_reconnect.cpp
index 93007d4c..2b6c7558 100644
--- a/tests/auto/client/reconnect/tst_reconnect.cpp
+++ b/tests/auto/client/reconnect/tst_reconnect.cpp
@@ -101,6 +101,7 @@ private Q_SLOTS:
 //core
     void cleanup() { QTRY_VERIFY2(m_comp->isClean(), qPrintable(m_comp->dirtyMessage())); }
     void basicWindow();
+    void screens();
 
 //input
     void keyFocus();
@@ -141,6 +142,30 @@ void tst_WaylandReconnect::basicWindow()
     QCOMPOSITOR_TRY_VERIFY(m_comp->xdgToplevel());
 }
 
+void tst_WaylandReconnect::screens()
+{
+    QRasterWindow window;
+    window.resize(64, 48);
+    window.show();
+    QCOMPOSITOR_TRY_VERIFY(m_comp->xdgToplevel());
+
+    auto originalScreens = QGuiApplication::screens();
+
+    QSignalSpy screenRemovedSpy(qGuiApp, &QGuiApplication::screenRemoved);
+    QVERIFY(screenRemovedSpy.isValid());
+
+    triggerReconnect();
+
+    // All screens plus temporary placeholder screen removed
+    QCOMPARE(screenRemovedSpy.count(), originalScreens.count() + 1);
+    for (const auto &screen : std::as_const(screenRemovedSpy)) {
+        originalScreens.removeOne(screen[0].value<QScreen *>());
+    }
+    QVERIFY(originalScreens.isEmpty());
+    QVERIFY(window.screen());
+    QVERIFY(QGuiApplication::screens().contains(window.screen()));
+}
+
 void tst_WaylandReconnect::keyFocus()
 {
     TestWindow window;
-- 
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