ProjectExplorer: Don't hide empty resource files like empty directories

Task-number: QTCREATORBUG-18748
Change-Id: I4de59743c42b99ce0b402f814b4cd0ba5d299338
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/projectexplorer/projectmodels.cpp

@@ -323,14 +323,15 @@ void FlatModel::addFolderNode(WrapperNode *parent, FolderNode *folderNode, QSet<
 
 bool FlatModel::trimEmptyDirectories(WrapperNode *parent)
 {
-    if (!parent->m_node->asFolderNode())
+    const FolderNode *fn = parent->m_node->asFolderNode();
+    if (!fn)
         return false;
 
     for (int i = parent->childCount() - 1; i >= 0; --i) {
         if (trimEmptyDirectories(parent->childAt(i)))
             parent->removeChildAt(i);
     }
-    return parent->childCount() == 0;
+    return parent->childCount() == 0 && !fn->showWhenEmpty();
 }
 
 Qt::DropActions FlatModel::supportedDragActions() const

src/plugins/projectexplorer/projectnodes.cpp

@@ -730,6 +730,11 @@ bool FolderNode::showInSimpleTree() const
     return false;
 }
 
+bool FolderNode::showWhenEmpty() const
+{
+    return false;
+}
+
 /*!
   \class ProjectExplorer::VirtualFolderNode
 

src/plugins/projectexplorer/projectnodes.h

@@ -272,6 +272,8 @@ public:
 
     // determines if node will be shown in the flat view, by default folder and projects aren't shown
     virtual bool showInSimpleTree() const;
+    // determines if node will always be shown when hiding empty directories
+    virtual bool showWhenEmpty() const;
 
     void addNode(Node *node);
     void removeNode(Node *node);

src/plugins/resourceeditor/resourcenode.cpp

@@ -492,6 +492,11 @@ bool ResourceTopLevelNode::showInSimpleTree() const
     return true;
 }
 
+bool ResourceTopLevelNode::showWhenEmpty() const
+{
+    return true;
+}
+
 ResourceFolderNode::ResourceFolderNode(const QString &prefix, const QString &lang, ResourceTopLevelNode *parent)
     : FolderNode(FileName(parent->filePath()).appendPath(prefix)),
       // TOOD Why add existing directory doesn't work

src/plugins/resourceeditor/resourcenode.h

@@ -51,6 +51,7 @@ public:
 
     AddNewInformation addNewInformation(const QStringList &files, Node *context) const override;
     bool showInSimpleTree() const override;
+    bool showWhenEmpty() const override;
     bool removeNonExistingFiles();
 
     QString contents() const { return m_contents; }