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error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template

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  • SGaistS SGaist

    Hi and welcome to devnet,

    Can you show your .pro file ?

    O Offline
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    OPit
    wrote on last edited by
    #4
    This post is deleted!
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    • O Offline
      O Offline
      OPit
      wrote on last edited by
      #5

      myStream lib

      TARGET = myStream
      DESTDIR = D:/Dev/Programme/myLibs/myStream/lib/ms
      TEMPLATE = lib
      CONFIG += static thread
      QT += widgets avwidgets
      
      UI_HEADERS_DIR = build/ms/h
      OBJECTS_DIR = build/ms/o
      RCC_DIR = build/ms/qrc
      MOC_DIR = build/ms/moc
      INCLUDEPATH = D:/Dev/Programme/3rdparty/ms/include
      LIBS = -LD:/Dev/Programme/3rdparty/ms/lib -lavformat
      
      HEADERS += \
          ../../src/inputstream.h \
          ../../src/dateparser.h \
          ../../src/inputstreammanager.h \
          ../../src/inputstreamcontrol.h \
          ../../src/inputscenecontrol.h \
          ../../src/inputstreamvideo.h \
          ../../src/inputstreampegasus.h \
          ../../src/inputstreaminfo.h \
          ../../src/inputstreamimages.h \
          ../../src/stabilizer.h \
          ../../src/inputstreampreviewslider.h \
          ../../src/inputstreampreview.h
       
      
      SOURCES += \     
          ../../src/inputstream.cpp \
          ../../src/dateparser.cpp \
          ../../src/inputstreammanager.cpp \
          ../../src/inputstreamcontrol.cpp \
          ../../src/inputscenecontrol.cpp \
          ../../src/inputstreamvideo.cpp \
          ../../src/inputstreampegasus.cpp \
          ../../src/inputstreamimages.cpp \
          ../../src/stabilizer.cpp \
          ../../src/inputstreampreviewslider.cpp \
          ../../src/inputstreampreview.cpp
      
      
      

      Application .pro

      QT += network widgets printsupport sql concurrent xml multimedia
      QT += webenginewidgets
      QT += avwidgets
      
      TEMPLATE = app
      DESTDIR = D:/Dev/Programme/AppTest/bin/ms
      VERSION = 4.0
      
      TARGET = AppTest
      DEFINES += TARGET_NAME=\\\"$$TARGET\\\"
      
      RC_FILE = ../../qrc/app.rc
      
      UI_HEADERS_DIR = h
      OBJECTS_DIR = o
      RCC_DIR = qrc
      MOC_DIR = moc
      
      INCLUDEPATH = D:/Dev/Programme/3rdparty/ms/include
      
      LIBS = -LD:/Dev/Programme/3rdparty/ms/lib \
              -lmyGUI \
              -lmyCharts \
              -lmyObject \
              -lmyStyleSheet \
              -lmyScene \
              -lmyStream -lswscale -lavformat -lavcodec -lavutil -lswresample -lws2_32 -lsecur32 \
              -lmyGraphics \
              -lmyCore \
              -lopencv_core400 \
              -lopencv_flann400 -ltbb -lzlib \
              -lgandalf \
              -lexiv2 -llibexpat \
              -llibcrypto \
              -lSMTPEmail \
              -lproj_5_2 \
              -lquazip
      
      RESOURCES += \
          ../../qrc/resource.qrc
      
      SOURCES += \
          ../../src/main.cpp \
          ../../src/core/interface.cpp \
          ../../src/core/core.cpp \
          ../../src/gui/maingui.cpp \
          ../../src/view/playerwidget.cpp \
          ../../src/view/sectionview.cpp \
          ../../src/view/inputstreampreview.cpp
      
      HEADERS += \
          ../../src/core/interface.h \
          ../../src/core/core.h \
          ../../src/gui/maingui.h \
          ../../src/view/playerwidget.h \
          ../../src/view/sectionview.h \
          ../../src/view/frame.h \
          ../../src/view/inputstreampreview.h
      
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      • kshegunovK kshegunov

        Three possibilities (in order of commonality):

        1. You haven't specified the library for linking, or it is not found. See @SGaist's request and provide the project file so we can inspect it.
        2. You and/or the library you're using is missing __declspec(dllimport) and/or __declspec(dllexport) for some reason. Make sure when compiling the library that the relevant macros are defined and list the symbols from the dll so you can make sure they're exported.
        3. You're mixing incompatible compilers - the library is compiled with something e.g. mingw while you're trying to link with msvc (also versions matter).
        O Offline
        O Offline
        OPit
        wrote on last edited by
        #6

        @kshegunov

        1. QtAV is imported in Qt config, so I think all is good for that (just add QT += avwidgets)
        2. I have thinking about this problem but I don't know how to see if it's OK are not.
        3. I've checked, and it's ok about that.
        kshegunovK 1 Reply Last reply
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        • O OPit

          @kshegunov

          1. QtAV is imported in Qt config, so I think all is good for that (just add QT += avwidgets)
          2. I have thinking about this problem but I don't know how to see if it's OK are not.
          3. I've checked, and it's ok about that.
          kshegunovK Offline
          kshegunovK Offline
          kshegunov
          Moderators
          wrote on last edited by
          #7

          @OPit said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

          1. QtAV is imported in Qt config, so I think all is good for that (just add QT += avwidgets)

          Did you build that module yourself?

          1. I have thinking about this problem but I don't know how to see if it's OK are not.

          Firstly, use dependency walker to find out what the module links against, from there you could also see what kinds of symbols are exported. Then you can do the same for your library and see if everything matches.

          1. I've checked, and it's ok about that.

          How did you check? Where did you get the qtav module from, or did you compiled it yourself?

          Read and abide by the Qt Code of Conduct

          O 1 Reply Last reply
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          • kshegunovK kshegunov

            @OPit said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

            1. QtAV is imported in Qt config, so I think all is good for that (just add QT += avwidgets)

            Did you build that module yourself?

            1. I have thinking about this problem but I don't know how to see if it's OK are not.

            Firstly, use dependency walker to find out what the module links against, from there you could also see what kinds of symbols are exported. Then you can do the same for your library and see if everything matches.

            1. I've checked, and it's ok about that.

            How did you check? Where did you get the qtav module from, or did you compiled it yourself?

            O Offline
            O Offline
            OPit
            wrote on last edited by
            #8

            @kshegunov Yes, I've built myself the QtAv lib (because the last precompile binaries not use the last version of QtAv).
            I've checked which compiler was used during compilation, and it was the same for each module.

            NB : if I link the moc_inputstreampreview.obj file directly in my app, it works ?!?

            LIBS += path/of/file/moc_inputstreampreview.obj
            
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            • O Offline
              O Offline
              OPit
              wrote on last edited by
              #9

              If I open QtAvWidget1.dll, I found the function :

              ?metaObject@VideoPreviewWidget@QtAV@@UEBAPEBUQMetaObject@@XZ
              

              I can't read .lib file from dependency walker, how can I check these files ?

              kshegunovK 1 Reply Last reply
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              • SGaistS Offline
                SGaistS Offline
                SGaist
                Lifetime Qt Champion
                wrote on last edited by
                #10

                In your build output, can you see whether the QtAV libraries are currently getting linked to your application ?

                Interested in AI ? www.idiap.ch
                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                • O Offline
                  O Offline
                  OPit
                  wrote on last edited by OPit
                  #11

                  Hi,
                  I'm using QtCreator with visual studio compiler and I don't have a lot of informations during linking :

                  link /NOLOGO /DYNAMICBASE /NXCOMPAT /INCREMENTAL:NO /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /VERSION:4.0 /MANIFEST:embed /OUT:..\..\bin\ms\L2R_Video.exe @c:\Temp\L2R_Video.exe.4652.31672.jom
                  myStream.lib(moc_inputstreampreview.obj) : error LNK2001: symbole externe non résolu "public: static struct QMetaObject const QtAV::VideoPreviewWidget::staticMetaObject" (?staticMetaObject@VideoPreviewWidget@QtAV@@2UQMetaObject@@B)
                  ..\..\bin\ms\L2R_Video.exe : fatal error LNK1120: 1 externes non résolus
                  

                  But in my Makefile.Release file, the QtAv libs are well written :

                  LIBS          = /LIBPATH:D:\Dev\Programme\3rdparty\ms\lib 
                  D:\Dev\Programme\3rdparty\ms\lib\myStream.lib 
                  D:\Dev\Programme\3rdparty\ms\lib\swscale.lib 
                  D:\Dev\Programme\3rdparty\ms\lib\avformat.lib 
                  D:\Dev\Programme\3rdparty\ms\lib\avcodec.lib 
                  D:\Dev\Programme\3rdparty\ms\lib\avutil.lib 
                  D:\Dev\Programme\3rdparty\ms\lib\swresample.lib 
                  secur32.lib 
                  D:\Dev\Programme\3rdparty\ms\lib\myGraphics.lib 
                  ws2_32.lib shell32.lib advapi32.lib gdi32.lib User32.lib 
                  /LIBPATH:D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5WebEngineWidgets.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5PrintSupport.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5AVWidgets.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5OpenGL.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5Widgets.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5Multimedia.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5WebEngineCore.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5Quick.lib 
                  D:\Dev\Environnement\ms\Qt\5.12.0\msvc2017_64\lib\Qt5AV.lib 
                  ...
                  
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                  • SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #12

                    Might be a silly question but are linking to libraries of the same type ? Meaning matching debug/release builds.

                    Interested in AI ? www.idiap.ch
                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                    1 Reply Last reply
                    1
                    • O Offline
                      O Offline
                      OPit
                      wrote on last edited by
                      #13

                      @SGaist said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

                      silly

                      Sadly it's not the problem ...

                      aha_1980A 1 Reply Last reply
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                      • O OPit

                        @SGaist said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

                        silly

                        Sadly it's not the problem ...

                        aha_1980A Offline
                        aha_1980A Offline
                        aha_1980
                        Lifetime Qt Champion
                        wrote on last edited by
                        #14

                        @OPit And both have the same architecture, i.e. 32 vs. 64 bit?

                        Qt has to stay free or it will die.

                        O 1 Reply Last reply
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                        • O OPit

                          If I open QtAvWidget1.dll, I found the function :

                          ?metaObject@VideoPreviewWidget@QtAV@@UEBAPEBUQMetaObject@@XZ
                          

                          I can't read .lib file from dependency walker, how can I check these files ?

                          kshegunovK Offline
                          kshegunovK Offline
                          kshegunov
                          Moderators
                          wrote on last edited by kshegunov
                          #15

                          This:

                          @OPit said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

                          ?metaObject@VideoPreviewWidget@QtAV@@UEBAPEBUQMetaObject@@XZ
                          

                          Is very different from this:

                          ?staticMetaObject@VideoPreviewWidget@QtAV@@2UQMetaObject@@B
                          

                          The former is a method, the latter is a (global) variable. Please try again. Could you also provide the content of the moc file in question (the one that fixes the issue if linked with)?

                          Read and abide by the Qt Code of Conduct

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                          • aha_1980A aha_1980

                            @OPit And both have the same architecture, i.e. 32 vs. 64 bit?

                            O Offline
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                            OPit
                            wrote on last edited by OPit
                            #16

                            @aha_1980 yes, the same architecture

                            @kshegunov this is a link to download the file (I can't upload from the forum) :
                            https://we.tl/t-bhEPIToZV2

                            Thanks.

                            kshegunovK 1 Reply Last reply
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                            • hskoglundH Offline
                              hskoglundH Offline
                              hskoglund
                              wrote on last edited by
                              #17

                              Hi, perhaps it's a namespace problem, you could try changing to a using statement in your InputStreamPreview.h:

                              #include <QtAVWidgets/VideoPreviewWidget.h>
                              
                              using namespace QtAV;
                              
                              class InputStreamPreview : public VideoPreviewWidget
                              {
                              Q_OBJECT
                              ...
                              
                              1 Reply Last reply
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                              • O OPit

                                @aha_1980 yes, the same architecture

                                @kshegunov this is a link to download the file (I can't upload from the forum) :
                                https://we.tl/t-bhEPIToZV2

                                Thanks.

                                kshegunovK Offline
                                kshegunovK Offline
                                kshegunov
                                Moderators
                                wrote on last edited by kshegunov
                                #18

                                @OPit said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

                                this is a link to download the file (I can't upload from the forum)

                                I'm sorry I wasn't clear. I meant the generated moc_XXX.cpp file. I have no tools to inspect the object file even if I wanted to because I work exclusively on Linux.

                                @hskoglund said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

                                Hi, perhaps it's a namespace problem, you could try changing to a using statement in your InputStreamPreview.h

                                A decent idea, but I don't think that's it. moc, while not too smart, does recognize namespaces and generates code accordingly. I do use them and everything links fine.

                                Read and abide by the Qt Code of Conduct

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                                • O Offline
                                  O Offline
                                  OPit
                                  wrote on last edited by
                                  #19

                                  @kshegunov oh sorry, this is the cpp file.

                                  https://we.tl/t-NXhNCGkSmc

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                                  • hskoglundH Offline
                                    hskoglundH Offline
                                    hskoglund
                                    wrote on last edited by
                                    #20

                                    Hi, do you have a moc_VideoPreviewWidget.cpp that's compiled using Qt 5.12? (The one in the link is built with Qt 5.9.1)

                                    O 1 Reply Last reply
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                                    • hskoglundH hskoglund

                                      Hi, do you have a moc_VideoPreviewWidget.cpp that's compiled using Qt 5.12? (The one in the link is built with Qt 5.9.1)

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                                      OPit
                                      wrote on last edited by
                                      #21

                                      @hskoglund yes of course : https://we.tl/t-Uhhsre7Vzm

                                      the problem is the same with version 5.9.1 or 5.12 (and also VS2017 or VS2015)

                                      1 Reply Last reply
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                                      • hskoglundH Offline
                                        hskoglundH Offline
                                        hskoglund
                                        wrote on last edited by
                                        #22

                                        Hi, if you look in the .pro files above for your application and myStream.lib, both .pro files have a inputstreampreview.cpp and a inputstreampreview.h included. They are not located in the same directory (one pair is in ../../src/ and the other pair is in ../../src/view/) but if they have the same contents then maybe the linker gets confused when you build your app (together with your myStream.lib).

                                        If they do not have the same contents (i.e. just a stroke of bad luck with the naming of your files) then rename one of the pairs. Otherwise, you could try building your app again but with only of the pairs, for example commenting out ../../src/view/inputstreampreview.cpp from the SOURCES section in your Application.pro file.

                                        O 1 Reply Last reply
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                                        • hskoglundH hskoglund

                                          Hi, if you look in the .pro files above for your application and myStream.lib, both .pro files have a inputstreampreview.cpp and a inputstreampreview.h included. They are not located in the same directory (one pair is in ../../src/ and the other pair is in ../../src/view/) but if they have the same contents then maybe the linker gets confused when you build your app (together with your myStream.lib).

                                          If they do not have the same contents (i.e. just a stroke of bad luck with the naming of your files) then rename one of the pairs. Otherwise, you could try building your app again but with only of the pairs, for example commenting out ../../src/view/inputstreampreview.cpp from the SOURCES section in your Application.pro file.

                                          O Offline
                                          O Offline
                                          OPit
                                          wrote on last edited by
                                          #23

                                          @hskoglund said in error LNK2001: unresolved external symbol "public: static struct QMetaObject .. from lib template:

                                          inputstreampreview.cpp

                                          thanks for your answer, but I don't understand well what you want to say.
                                          inputstreampreview.cpp/.h are only included in myStream.lib (in src folder).
                                          For my main app, I just include the .h with INCLUDEPATH keyword and link myStream lib with LIBS+= -lmyStream
                                          I don't know why and where you can see ../../src/view/ path ??

                                          kshegunovK 1 Reply Last reply
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