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  4. qmetatype.h -> error: constexpr variable 'len' must be initialized by a constant expression
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qmetatype.h -> error: constexpr variable 'len' must be initialized by a constant expression

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  • L Offline
    L Offline
    Lillo
    wrote on last edited by Lillo
    #1

    Hello, i have a QT3D project made in QT5.14.2 and i wanted to be able to run it in with Qt6.2, but in the build step i have this error in the qt file qmetatype.h. If someone can help me i would appreciate it very much. I attach a screenshot with the error.
    MicrosoftTeams-image.png

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    • sierdzioS Offline
      sierdzioS Offline
      sierdzio
      Moderators
      wrote on last edited by
      #2

      Try porting to Qt 5.15 first, it should print you some nice deprecation and porting messages during compilation and at runtime. This will help you fix the issues.

      A wild guess in this case: Qt 6 requires Q_PROPERTY types to be fully qualified (not forward declared). Go through your properties and make sure it's true.

      (Z(:^

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      • A Offline
        A Offline
        alirezaa
        wrote on last edited by alirezaa
        #3

        @Lillo
        I have just faced the same issue, when trying to port my project to Linux and using Qt 6.8.1.
        I noticed, that you have marked this topic as solved; then could you please elaborate on how, you've managed to resolve this issue and what the exact cause was?
        Many thanks, in advance

        jsulmJ 1 Reply Last reply
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        • A alirezaa

          @Lillo
          I have just faced the same issue, when trying to port my project to Linux and using Qt 6.8.1.
          I noticed, that you have marked this topic as solved; then could you please elaborate on how, you've managed to resolve this issue and what the exact cause was?
          Many thanks, in advance

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #4

          @alirezaa Did you follow what @sierdzio suggested?

          https://forum.qt.io/topic/113070/qt-code-of-conduct

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          • A Offline
            A Offline
            alirezaa
            wrote on last edited by alirezaa
            #5

            @jsulm
            I did check all Q_PROPERTY types in my project and didn't detect the possible issue @sierdzio had mentioned in any of them, but haven't tried first porting my project to Qt 5.15 yet, but I will.

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