ProjectExplorer: Introduce priorities for RunControlFactories

This can be used by downstream plugins to overrule existing
RunControlFactories.

Change-Id: I23c8e3983827dfa1b5f780664d2e539e908944aa
Reviewed-by: Eike Ziller <eike.ziller@qt.io>
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/projectexplorer/projectexplorer.cpp

@@ -1980,10 +1980,18 @@ void ProjectExplorerPluginPrivate::buildStateChanged(Project * pro)
 // NBS TODO implement more than one runner
 static IRunControlFactory *findRunControlFactory(RunConfiguration *config, Core::Id mode)
 {
-    return ExtensionSystem::PluginManager::getObject<IRunControlFactory>(
+    auto factories = ExtensionSystem::PluginManager::getObjects<IRunControlFactory>(
         [&config, &mode](IRunControlFactory *factory) {
             return factory->canRun(config, mode);
         });
+
+    if (factories.isEmpty())
+        return nullptr;
+    auto it = std::max_element(factories.begin(), factories.end(),
+        [](IRunControlFactory *a, IRunControlFactory *b) {
+            return a->priority() < b->priority();
+         });
+    return *it;
 }
 
 void ProjectExplorerPluginPrivate::executeRunConfiguration(RunConfiguration *runConfiguration, Core::Id runMode)

src/plugins/projectexplorer/runconfiguration.cpp

@@ -501,6 +501,19 @@ IRunConfigurationAspect *IRunControlFactory::createRunConfigurationAspect(RunCon
     than it needs to be.
 */
 
+
+const char PRIORITY_KEY[] = "RunControlFactoryPriority";
+
+int ProjectExplorer::IRunControlFactory::priority() const
+{
+    return property(PRIORITY_KEY).toInt(); // 0 by default.
+}
+
+void IRunControlFactory::setPriority(int priority)
+{
+    setProperty(PRIORITY_KEY, priority);
+}
+
 namespace Internal {
 
 class RunControlPrivate

src/plugins/projectexplorer/runconfiguration.h

@@ -335,6 +335,10 @@ public:
     virtual RunControl *create(RunConfiguration *runConfiguration, Core::Id mode, QString *errorMessage) = 0;
 
     virtual IRunConfigurationAspect *createRunConfigurationAspect(RunConfiguration *rc);
+
+    int priority() const;
+protected:
+    void setPriority(int priority); // Higher values will be preferred.
 };
 
 class PROJECTEXPLORER_EXPORT RunConfigWidget : public QWidget