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  1. Qt
  2. QTBUG-104899

QML(_NAMED)_ELEMENT should generate a clear error if the type in not default constructible

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    • 6bdeafcad (dev), 83697e49e (6.5)

      If a type is marked with QML_ELEMENT, but does not have a default ctor, it becomes uncreatable. Unless the type has been explicitly marked as such, that should create an actionable warning message, or even a compile time error.

       

      We might be able to get a compilation error by having the macro expand to 

      consteval void check() {
    using Self = std::remove_cvref_t<decltype(*this);
    static_assert(!std::is_default_constructible<Self>> || is_uncreatable<Self>);
}

      However, we would need to evaluate the compile time overhead of such a solution, and potentially deal with shadowing warning.

        For Gerrit Dashboard: QTBUG-104899
        # Subject Branch Project Status CR V
        454308,6 QML: Output a warning for creatable object types without default ctor dev qt/qtdeclarative Status: MERGED +2 0
        455827,2 QML: Output a warning for creatable object types without default ctor 6.5 qt/qtdeclarative Status: MERGED +2 0

            ulherman Ulf Hermann
            fabiankosmale Fabian Kosmale
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              Created:
              Updated:
              Resolved:

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