Alias Cycle

Alias Property Is Part Of An Alias Cycle

What happened?

A property alias resolves to itself or to another alias resolving to itself.

Usually, a property alias should reference another property either directly, or indirectly by passing through another alias property.

If a property alias directly or indirectly references itself, then it forms an alias cycle. The warning indicates that the current alias property is inside or references an alias cycle, see Example.

Why is this bad?

Instances of components with alias cycles will not be created at runtime: they will be null instead.

Example

 import QtQuick

 Item {
     id: someId
     property alias myself: someId.myself // not ok: referring to itself

     property alias cycle: someId.cycle2 // not ok: indirectly referring to itself
     property alias cycle2: someId.cycle

     property alias indirect: someId.cycle // not ok: referring to alias indirectly referring to itself
 }

You can fix this warning by breaking up the alias cycles:

 import QtQuick

 Item {
     id: someId
     Item {
         id: anotherId
         property string myself
         property int cycle
     }
     property alias myself: anotherId.myself // ok: referring to a property

     property alias cycle: someId.cycle2 // ok: does not refer to itself anymore
     property alias cycle2: anotherId.cycle // ok: not a cycle anymore

     property alias indirect: someId.cycle // ok: cycle does not form an alias cycle anymore
 }