Device: Don't cache qmlRunCommand

Caching makes the settings page less snappy.

Also fixed searching for qml runtime if not set in
QmlProjectRunConfiguration

Fixes: QTCREATORBUG-29341
Change-Id: Ia3ce72f3e3b857a857f706694794304dcbf1793c
Reviewed-by: hjk <hjk@qt.io>
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>
Reviewed-by: Robert Löhning <robert.loehning@qt.io>

src/plugins/projectexplorer/devicesupport/idevice.cpp

@@ -141,7 +141,7 @@ public:
     PortList freePorts;
     FilePath debugServerPath;
     FilePath debugDumperPath = Core::ICore::resourcePath("debugger/");
-    std::optional<FilePath> qmlRunCommand;
+    FilePath qmlRunCommand;
     bool emptyCommandAllowed = false;
 
     QList<Icon> deviceIcons;
@@ -482,8 +482,7 @@ void IDevice::fromMap(const QVariantMap &map)
 
     d->debugServerPath = FilePath::fromSettings(map.value(QLatin1String(DebugServerKey)));
     const FilePath qmlRunCmd = FilePath::fromSettings(map.value(QLatin1String(QmlRuntimeKey)));
-    if (!qmlRunCmd.isEmpty())
-        d->qmlRunCommand = qmlRunCmd;
+    d->qmlRunCommand = qmlRunCmd;
     d->extraData = map.value(ExtraDataKey).toMap();
 }
 
@@ -516,8 +515,7 @@ QVariantMap IDevice::toMap() const
     map.insert(QLatin1String(VersionKey), d->version);
 
     map.insert(QLatin1String(DebugServerKey), d->debugServerPath.toSettings());
-    map.insert(QLatin1String(QmlRuntimeKey),
-               d->qmlRunCommand ? d->qmlRunCommand->toSettings() : FilePath().toSettings());
+    map.insert(QLatin1String(QmlRuntimeKey), d->qmlRunCommand.toSettings());
 
     map.insert(ExtraDataKey, d->extraData);
 
@@ -607,23 +605,12 @@ void IDevice::setDebugServerPath(const FilePath &path)
 
 FilePath IDevice::qmlRunCommand() const
 {
-    if (d->qmlRunCommand)
-        return *d->qmlRunCommand;
-
-    const FilePath newPath = searchExecutableInPath("qml");
-    if (newPath.isEmpty())
-        return {};
-
-    d->qmlRunCommand = newPath;
-    return *d->qmlRunCommand;
+    return d->qmlRunCommand;
 }
 
 void IDevice::setQmlRunCommand(const FilePath &path)
 {
-    if (path.isEmpty())
-        d->qmlRunCommand.reset();
-    else
-        d->qmlRunCommand = path;
+    d->qmlRunCommand = path;
 }
 
 void IDevice::setExtraData(Id kind, const QVariant &data)

src/plugins/qmlprojectmanager/qmlprojectrunconfiguration.cpp

@@ -207,15 +207,15 @@ FilePath QmlProjectRunConfiguration::qmlRuntimeFilePath() const
 
     // We might not have a full Qt version for building, but the device
     // might know what is good for running.
-    if (IDevice::ConstPtr dev = DeviceKitAspect::device(kit)) {
+    IDevice::ConstPtr dev = DeviceKitAspect::device(kit);
+    if (dev) {
         const FilePath qmlRuntime = dev->qmlRunCommand();
         if (!qmlRuntime.isEmpty())
             return qmlRuntime;
     }
 
-    // The Qt version might know. That's the "build" Qt version,
-    // i.e. not necessarily something the device can use, but the
-    // device had its chance above.
+    // The Qt version might know, but we need to make sure
+    // that the device can reach it.
     if (QtVersion *version = QtKitAspect::qtVersion(kit)) {
         // look for puppet as qmlruntime only in QtStudio Qt versions
         if (version->features().contains("QtStudio") &&
@@ -229,13 +229,13 @@ FilePath QmlProjectRunConfiguration::qmlRuntimeFilePath() const
             }
         }
         const FilePath qmlRuntime = version->qmlRuntimeFilePath();
-        if (!qmlRuntime.isEmpty())
+        if (!qmlRuntime.isEmpty() && (!dev || dev->ensureReachable(qmlRuntime)))
             return qmlRuntime;
     }
 
     // If not given explicitly by run device, nor Qt, try to pick
     // it from $PATH on the run device.
-    return "qml";
+    return dev ? dev->filePath("qml").searchInPath() : "qml";
 }
 
 void QmlProjectRunConfiguration::createQtVersionAspect()