restricted-type.qdoc

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// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only
 
/*!
\ingroup qmllint-warnings-and-errors
 
\title Restricted type
\brief [restricted-type] A restricted type was accessed.
 
\qmllintwarningcategory restricted-type
 
\section1 You can't access an unscoped enum from here
 
\section2 What happened?
You accessed the value of an enum defined in C++ by its enum type name.
 
\section2 Why is this bad?
Unscoped enums defined in C++ can't be accessed by their enum type name.
They will be undefined at runtime.
 
\section2 Example
 
\qml
import QtQuick
import SomeModule // contains MyClass
 
Item {
    property int i: MyClass.Hello.World
}
 
\endqml
where MyClass is defined as
\code
class MyClass: public QObject
{
    Q_OBJECT
    QML_ELEMENT
 
public:
    enum Hello { World };
    Q_ENUM(Hello);
    ...
 
};
\endcode
To fix this warning, remove the unnecessary enum type name from its QML usage:
\qml
import QtQuick
 
Item {
    property int i: MyClass.World
}
 
\endqml
 
If you are the author of the enum, you can also modify the enum definition to use an enum
class instead of changing the QML code:
 
\code
class MyClass: public QObject
{
    Q_OBJECT
    QML_ELEMENT
 
public:
    enum class Hello { World };
    Q_ENUM(Hello);
    ...
};
\endcode
 
\note You can find more information about enum type registration
\l{qtqml-cppintegration-data.html#enumeration-types}{here}.
 
*/