Enums are not types

This warning category is spelled [enums-are-not-types] by qmllint.

QML enumerations are not types

What happened?

You used an enum name inside a type annotation.

Why is that bad?

An enum name is not a type and therefore can't be used in a type annotation. QML tooling is not able to use the type annotation: the compiler can't compile this method to C++ and qmllint as well as QML Language Server can't analyze this method.

Example

// Main.qml
import QtQuick

Item {
    enum HelloWorld { Hello, World }
    function f(e: Main.HelloWorld): bool {
        return e == World
    }
}

To fix this warning, replace the enum name in the type annotation with the underlying type, like int if the underlying type needs at most 32 bit, or otherwise double, for example.

import QtQuick

Item {
    enum HelloWorld { Hello, World }
    function f(e: int): bool {
        return e === World
    }
}