Revert "XCB: Do not create instance of QPlatformIntegration for invalid displays"

This reverts commit 67cc8fea106c35c7ca75bf476667d07b3bbf3257.

I forgot about this patch and now it makes rebasing the local changes
too time-consuming. Besides, 67cc8fea10 broke a build for -no-xcb-xlib.
I will restore this patch, with adaptations to the new QXcb*Connection
hierarchy.

Task-number: QTBUG-68859
Change-Id: I938f32b5da22ce18f95d761f9b34e77fff923e24
Reviewed-by: Gatis Paeglis <gatis.paeglis@qt.io>

1 files changed, 18 insertions, 8 deletions

diff --git a/src/plugins/platforms/xcb/qxcbintegration.cpp b/src/plugins/platforms/xcb/qxcbintegration.cpp
index db8dc09025..db8f816a86 100644
--- a/src/plugins/platforms/xcb/qxcbintegration.cpp
+++ b/src/plugins/platforms/xcb/qxcbintegration.cpp
@@ -192,15 +192,25 @@ QXcbIntegration::QXcbIntegration(const QStringList &parameters, int &argc, char
 
     const int numParameters = parameters.size();
     m_connections.reserve(1 + numParameters / 2);
+    auto conn = new QXcbConnection(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, displayName);
+    if (conn->isConnected())
+        m_connections << conn;
+    else
+        delete conn;
+
+    for (int i = 0; i < numParameters - 1; i += 2) {
+        qCDebug(lcQpaScreen) << "connecting to additional display: " << parameters.at(i) << parameters.at(i+1);
+        QString display = parameters.at(i) + QLatin1Char(':') + parameters.at(i+1);
+        conn = new QXcbConnection(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, display.toLatin1().constData());
+        if (conn->isConnected())
+            m_connections << conn;
+        else
+            delete conn;
+    }
 
-    if (QXcbConnection *defaultConnection = QXcbConnection::create(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, displayName)) {
-        m_connections.append(defaultConnection);
-        for (int i = 0; i < numParameters - 1; i += 2) {
-            qCDebug(lcQpaScreen) << "connecting to additional display: " << parameters.at(i) << parameters.at(i+1);
-            QString display = parameters.at(i) + QLatin1Char(':') + parameters.at(i+1);
-            if (QXcbConnection *connection = QXcbConnection::create(m_nativeInterface.data(), m_canGrab, m_defaultVisualId, display.toLatin1().constData()))
-                m_connections.append(connection);
-        }
+    if (m_connections.isEmpty()) {
+        qCritical("Could not connect to any X display.");
+        exit(1);
     }
 
     m_fontDatabase.reset(new QGenericUnixFontDatabase());