Debugger: Only use random QML port if none was given

This is a cherry-pick of 20db17e4f07c298874f01eb0f9ebeb26a7887fdd from
4.1. The problem also occurs in 4.0 and as another version of 4.0 might
be released, we should fix it there, too.

Change-Id: I3cf42abfa9d0ea5812495be6e2728264dc115ba9
Task-number: QTCREATORBUG-16708
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

1 files changed, 11 insertions, 8 deletions

diff --git a/src/plugins/debugger/debuggerruncontrol.cpp b/src/plugins/debugger/debuggerruncontrol.cpp
index 9f077c4652..e925f7896f 100644
--- a/src/plugins/debugger/debuggerruncontrol.cpp
+++ b/src/plugins/debugger/debuggerruncontrol.cpp
@@ -450,15 +450,18 @@ void DebuggerRunControlCreator::enrich(const RunConfiguration *runConfig, const
 
     if (m_rp.languages & QmlLanguage) {
         if (m_rp.device && m_rp.device->type() == ProjectExplorer::Constants::DESKTOP_DEVICE_TYPE) {
-            QTcpServer server;
-            const bool canListen = server.listen(QHostAddress::LocalHost)
-                    || server.listen(QHostAddress::LocalHostIPv6);
-            if (!canListen) {
-                m_errors.append(DebuggerPlugin::tr("Not enough free ports for QML debugging.") + QLatin1Char(' '));
-                return;
+            if (m_rp.qmlServerAddress.isEmpty() || m_rp.qmlServerPort == InvalidPort) {
+                QTcpServer server;
+                const bool canListen = server.listen(QHostAddress::LocalHost)
+                        || server.listen(QHostAddress::LocalHostIPv6);
+                if (!canListen) {
+                    m_errors.append(DebuggerPlugin::tr("Not enough free ports for QML debugging.")
+                                    + QLatin1Char(' '));
+                    return;
+                }
+                m_rp.qmlServerAddress = server.serverAddress().toString();
+                m_rp.qmlServerPort = server.serverPort();
             }
-            m_rp.qmlServerAddress = server.serverAddress().toString();
-            m_rp.qmlServerPort = server.serverPort();
 
             // Makes sure that all bindings go through the JavaScript engine, so that
             // breakpoints are actually hit!