Incompatible type
This warning category is spelled [incompatible-type]
by qmllint.
Cannot assign to default property of incompatible type
What happened?
You assigned an object to a default property of an incompatible type.
Why is this bad?
The QML engine will not be able to assign the object at runtime.
Example
import QtQuick Item { component MyType: QtObject { default property list<Item> myDefaultProperty } MyType { QtObject {} // note: QtObject does not inherit from Item } }
To fix this warning, bind a compatible type to the property or, if you are the author of the default property, change the type in the definition:
import QtQuick Item { component MyType: QtObject { default property list<Item> myDefaultProperty } MyType { Item {} } component AlternativeMyType: QtObject { default property list<QtObject> myDefaultProperty } AlternativeMyType { QtObject {} // is ok for AlternativeMyType } }
On-binding for property has wrong type
What happened?
You used an invalid property modifier type.
Why is this bad?
The QML engine will not be able to use the property modifier type at runtime.
Example
import QtQuick Item { property int xxx Item on xxx { ... } }
To fix this warning, remove the on
or use a valid property modifier type:
import QtQuick Item { property int xxx Item { ... } // Alternative: use a valid property modifier type NumberAnimation on xxx { ... } }
Construction from string is deprecated; Use structured value type construction instead
What happened?
You constructed a QML_STRUCTURED_VALUE using a string.
Why is this bad?
This is deprecated and prone to typos.
Example
import QtQuick Item { property point p: "5, 6" }
To fix this warning, populate the structured value type as explained in the QML_STRUCTURED_VALUE description instead of binding a string to the property:
import QtQuick Item { property point p: ({ x: 5, y: 6 }) }
Function without return type annotation returns
What happened?
You returned a value from a function without return type annotation.
Why is this bad?
You annotated the function to not return anything so the function should not return anything. The QML tooling will not be able to process the method and the QML engine will ignore the returned value in a future Qt version.
Example
import QtQuick Item { function f(x: int) { ... return x } }
To fix this warning, adapt the function signature to the new return type or remove the return value:
import QtQuick Item { function f(x: int): int { ... return x } function alternativeF(x: int) { ... return } }
Cannot assign binding/object/literal
What happened?
You bound an object, literal, or expression to a property of an incompatible type.
Why is this bad?
The QML engine will not be able to assign the object, literal, or expression at runtime.
Example
import QtQuick Item { property date xxx: 42 }
To fix this warning, bind an object, value, or expression of a compatible type:
import QtQuick Item { property date xxx: new Date() }