Attached property reuse

This warning category is spelled [attached-property-reuse] by qmllint.

Using attached type already initialized in a parent scope

What happened?

You initialized a propagating attached type multiple times.

Why is this bad?

Propagating attached objects consume memory for each instantiation but only need to be initialized once.

Example

 import QtQuick
 import QtQuick.Templates as T
 import QtQuick.Controls.Material // contains the Material attached type

 T.ToolBar {
     id: control

     // first instantiation of Material's attached property
     property color c: Material.toolBarColor

     background: Rectangle {
          // second instantiation of Material's attached property, wrong!
         color: Material.toolBarColor
     }
 }

To fix this warning, query the attached type from the parent:

 import QtQuick
 import QtQuick.Templates as T
 import QtQuick.Controls.Material // contains the Material attached type

 T.ToolBar {
     id: control

     // first instantiation of Material's attached property
     property color c: Material.toolBarColor

     background: Rectangle {
         // use control's attached property, correct!
         color: control.Material.toolBarColor
     }
 }