ProjectExplorer: Use a functor for BuildSystem creation

... instead of creating the BuildSystem direct. This will help the
shift of BuildSystem owner ship as a Project will have potentially
multiple BuildSystem instances (one per BuildConfiguration), but
still be responsible for creating them with the Targets.

Change-Id: I2dd71c7687ed41af9e42c874b3f932ce704e7ee3
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/qbsprojectmanager/qbsnodes.cpp

@@ -365,8 +365,8 @@ QbsRootProjectNode::QbsRootProjectNode(QbsProject *project) :
 // QbsBuildSystem:
 // --------------------------------------------------------------------
 
-QbsBuildSystem::QbsBuildSystem(QbsProject *project)
-    : BuildSystem(project), m_project(project)
+QbsBuildSystem::QbsBuildSystem(Project *project)
+    : BuildSystem(project)
 {
 }
 
@@ -449,7 +449,7 @@ RemovedFilesFromProject QbsBuildSystem::removeFiles(Node *context, const QString
             return RemovedFilesFromProject::Error;
         }
 
-        return m_project->removeFilesFromProduct(filePaths, prdNode->qbsProductData(),
+        return project()->removeFilesFromProduct(filePaths, prdNode->qbsProductData(),
                                                  n->m_qbsGroupData, notRemoved);
     }
 
@@ -486,7 +486,7 @@ bool QbsBuildSystem::renameFile(Node *context, const QString &filePath, const QS
         if (!prdNode || !prdNode->qbsProductData().isValid())
             return false;
 
-        return m_project->renameFileInProduct(filePath, newFilePath,
+        return project()->renameFileInProduct(filePath, newFilePath,
                                               prdNode->qbsProductData(), n->m_qbsGroupData);
     }
 
@@ -502,5 +502,10 @@ bool QbsBuildSystem::renameFile(Node *context, const QString &filePath, const QS
     return BuildSystem::renameFile(context, filePath, newFilePath);
 }
 
+QbsProject *QbsBuildSystem::project() const
+{
+    return static_cast<QbsProject *>(BuildSystem::project());
+}
+
 } // namespace Internal
 } // namespace QbsProjectManager

src/plugins/qbsprojectmanager/qbsnodes.h

@@ -39,7 +39,7 @@ class QbsProject;
 class QbsBuildSystem : public ProjectExplorer::BuildSystem
 {
 public:
-    explicit QbsBuildSystem(QbsProject *project);
+    explicit QbsBuildSystem(ProjectExplorer::Project *project);
 
     bool supportsAction(ProjectExplorer::Node *context,
                         ProjectExplorer::ProjectAction action,
@@ -53,8 +53,7 @@ public:
     bool renameFile(ProjectExplorer::Node *context,
                     const QString &filePath, const QString &newFilePath) override;
 
-private:
-    QbsProject *m_project = nullptr;
+    QbsProject *project() const;
 };
 
 // --------------------------------------------------------------------

src/plugins/qbsprojectmanager/qbsproject.cpp

@@ -135,7 +135,7 @@ QbsProject::QbsProject(const FilePath &fileName)
     setProjectLanguages(Context(ProjectExplorer::Constants::CXX_LANGUAGE_ID));
     setCanBuildProducts();
 
-    setBuildSystem(std::make_unique<QbsBuildSystem>(this));
+    setBuildSystemCreator([](Project *p) { return new QbsBuildSystem(p); });
 
     rebuildProjectTree();