// Guide.qml
import QtQml

QtObject {
    readonly property int theAnswer: 42
}

// Main.qml
import QtQuick

Window {
    width: 640
    height: 480
    visible: true

    Guide { id: hitchhikersGuide }

    Component.onCompleted: console.log(hitchhikersGuide.theAnswer)
}

When we build this project, everything compiles and runs fine. Suppose we then delete theAnswer from Guide.qml and rebuild the project.

qmlsc only rebuilds Guide.qml (which remains a fully correct document), but doesn't rebuild Main.qml. As a result, we don't notice that our change has introduced an error until we run the application.

Suggestion

(Provide an option to) Recompile files whose dependencies have been updated