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Link external library with MSCV compiler

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qtcreator 5.11librarylinker errorsmsvcmingw
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  • JonBJ JonB

    @elsa
    Are those external libraries compiled with MSVC or MinGW? If they are MinGW, I didn't think you could mix MSVC & MinGW libraries, it's one or the other, no? (Don't be alarmed, I may be wrong :) )

    E Offline
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    elsa
    wrote on last edited by
    #3

    @JonB I think this is the problem and I think you are right. I just have very little experience with compilers and linkers. I assume the libraries are compiled with MinGW, because this was the compiler I switched from. Is there a way to compile them again for MSCV?

    JonBJ 1 Reply Last reply
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    • E elsa

      @JonB I think this is the problem and I think you are right. I just have very little experience with compilers and linkers. I assume the libraries are compiled with MinGW, because this was the compiler I switched from. Is there a way to compile them again for MSCV?

      JonBJ Offline
      JonBJ Offline
      JonB
      wrote on last edited by JonB
      #4

      @elsa
      I assumed they were MinGW because you used to have that working. If the third-party library is not offered in MSVC (.LIB) form, you'd have to get the sources and try compiling the whole thing with MSVC, which I'm sure you won't want/can't do.

      I'll have a quick look around to see if you can combine MinGW libraries (are those .a instead of .lib?) with MSVC stuff, but if I don't get back soon, I haven't found anything...

      EDIT Well you can start out reading the whole of https://stackoverflow.com/questions/2529770/how-to-use-libraries-compiled-with-mingw-in-msvc. I don't like the look of:

      The libraries are compatible, but only if you supply a C interface. MSVC and g++ use different name-mangling schemes, so you cannot easily link C++ code created with one with code created by the other.

      Or https://stackoverflow.com/questions/2096519/from-mingw-static-library-a-to-visual-studio-static-library-lib:

      Finally, this mixed MinGW and Visual C++ linking generally works but for C modules and it does not work for C++, as far as I know.

      And on our forum here, https://forum.qt.io/topic/75458/compatibility-libraries-generated-by-msvc-and-mingw , the venerable @SGaist wrote:

      on Windows you can't mix and match libraries compiled with different compilers even if they all use Visual Studio. You have to build everything using the same compiler.

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      • JonBJ JonB

        @elsa
        I assumed they were MinGW because you used to have that working. If the third-party library is not offered in MSVC (.LIB) form, you'd have to get the sources and try compiling the whole thing with MSVC, which I'm sure you won't want/can't do.

        I'll have a quick look around to see if you can combine MinGW libraries (are those .a instead of .lib?) with MSVC stuff, but if I don't get back soon, I haven't found anything...

        EDIT Well you can start out reading the whole of https://stackoverflow.com/questions/2529770/how-to-use-libraries-compiled-with-mingw-in-msvc. I don't like the look of:

        The libraries are compatible, but only if you supply a C interface. MSVC and g++ use different name-mangling schemes, so you cannot easily link C++ code created with one with code created by the other.

        Or https://stackoverflow.com/questions/2096519/from-mingw-static-library-a-to-visual-studio-static-library-lib:

        Finally, this mixed MinGW and Visual C++ linking generally works but for C modules and it does not work for C++, as far as I know.

        And on our forum here, https://forum.qt.io/topic/75458/compatibility-libraries-generated-by-msvc-and-mingw , the venerable @SGaist wrote:

        on Windows you can't mix and match libraries compiled with different compilers even if they all use Visual Studio. You have to build everything using the same compiler.

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        elsa
        wrote on last edited by
        #5

        @JonB the libraries have both the .dll and .lib files and according to the library's website they support MSVC (right?).

        JonBJ 1 Reply Last reply
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        • E elsa

          @JonB the libraries have both the .dll and .lib files and according to the library's website they support MSVC (right?).

          JonBJ Offline
          JonBJ Offline
          JonB
          wrote on last edited by JonB
          #6

          @elsa
          That page would imply it's all MSVC anyway there's no mention of MinGW?
          So change your Qt project to link against MSVC .lib files?

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          • JonBJ JonB

            @elsa
            That page would imply it's all MSVC anyway there's no mention of MinGW?
            So change your Qt project to link against MSVC .lib files?

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            elsa
            wrote on last edited by
            #7

            @JonB how do I do this? The code mentioned in my question was used for MinGW and doesn't work for MSCV, so how can I modify it? (I think these two lines link the .dll files, which are compatible with MinGW afaik, and for MSCV we need to explicitly tell it to choose the .lib files) You traditionally do not write the endings of the file name, so how can i specify it?
            (and sorry for not replying right away, I can only post every 600s -.-)

            JonBJ 1 Reply Last reply
            1
            • E elsa

              @JonB how do I do this? The code mentioned in my question was used for MinGW and doesn't work for MSCV, so how can I modify it? (I think these two lines link the .dll files, which are compatible with MinGW afaik, and for MSCV we need to explicitly tell it to choose the .lib files) You traditionally do not write the endings of the file name, so how can i specify it?
              (and sorry for not replying right away, I can only post every 600s -.-)

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by JonB
              #8

              @elsa
              I'm going to have to bow out, because I haven't used MinGW, I don't use Qt Creator/cmake/C++, someone else may know better than I.

              I will say, I'm confused, because if the libraries are from that page it only talks about MSVC, so I don't even know how MinGW came into it.

              I think you should:

              • Establish what/where your library files, and whether they are MSVC or MinGW.
              • Make sure however you configure your project to generate linker lines it's using the right linker and command-line options for whatever the correct files for it are. When you changed over from MinGW to MSVC you must have had to re-configure the makes from scratch I imagine, telling it which compiler/linker you're using, I imagine. I don't know, but those link library lines you show still look a bit gcc rather than msvc/link to me, but I could be mistaken.
              • Make sure your "unresolved"s are not because you are actually trying to call any functions which are not documented as exported from the third-party libraries.
              • Maybe find a couple of "typical" examples of the "unresolved external symbol errors" you are getting and show them here. It may give us an idea of just what sort of thing it's trying to find.
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              • mrjjM Offline
                mrjjM Offline
                mrjj
                Lifetime Qt Champion
                wrote on last edited by
                #9

                Hi
                From page
                http://arma.sourceforge.net/download.html
                seems they used VS 2012.

                Did you compile a new version with the new visual studio ( i assume you didn't use 2012) and new VS cannot load old VS dlls.

                what version of VS did u use ?

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                • JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by JonB
                  #10

                  In https://forum.qt.io/topic/75458/compatibility-libraries-generated-by-msvc-and-mingw/3 @SGaist also wrote

                  Thus if any of your dependencies needs a particular version of VS, you have to stay with it.

                  @elsa Please do show some examples of the error messages.

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                  • JonBJ JonB

                    In https://forum.qt.io/topic/75458/compatibility-libraries-generated-by-msvc-and-mingw/3 @SGaist also wrote

                    Thus if any of your dependencies needs a particular version of VS, you have to stay with it.

                    @elsa Please do show some examples of the error messages.

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                    elsa
                    wrote on last edited by
                    #11

                    @JonB see my edit.

                    JonBJ 1 Reply Last reply
                    0
                    • mrjjM mrjj

                      Hi
                      From page
                      http://arma.sourceforge.net/download.html
                      seems they used VS 2012.

                      Did you compile a new version with the new visual studio ( i assume you didn't use 2012) and new VS cannot load old VS dlls.

                      what version of VS did u use ?

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                      elsa
                      wrote on last edited by
                      #12

                      @mrjj hi, I have VS17 and VS15 installed, but yeah, good point. Microsoft has a redistributable for VS12. I will try using it and update you.

                      1 Reply Last reply
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                      • E elsa

                        @JonB see my edit.

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by
                        #13

                        @elsa
                        OK, at least that confirms the unresolveds are indeed from your libraries and not from, say, remaining references somewhere to MinGW functions. FWIW, those are "mangled" names which come from references to C++ functions.

                        I think you should work through the points I suggested. In particular it's now unclear how come MinGW ever came into it/worked, since the third-party link you provided talked only about MSVC....

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                        • JonBJ JonB

                          @elsa
                          I'm going to have to bow out, because I haven't used MinGW, I don't use Qt Creator/cmake/C++, someone else may know better than I.

                          I will say, I'm confused, because if the libraries are from that page it only talks about MSVC, so I don't even know how MinGW came into it.

                          I think you should:

                          • Establish what/where your library files, and whether they are MSVC or MinGW.
                          • Make sure however you configure your project to generate linker lines it's using the right linker and command-line options for whatever the correct files for it are. When you changed over from MinGW to MSVC you must have had to re-configure the makes from scratch I imagine, telling it which compiler/linker you're using, I imagine. I don't know, but those link library lines you show still look a bit gcc rather than msvc/link to me, but I could be mistaken.
                          • Make sure your "unresolved"s are not because you are actually trying to call any functions which are not documented as exported from the third-party libraries.
                          • Maybe find a couple of "typical" examples of the "unresolved external symbol errors" you are getting and show them here. It may give us an idea of just what sort of thing it's trying to find.
                          E Offline
                          E Offline
                          elsa
                          wrote on last edited by
                          #14

                          @JonB said in Link external library with MSCV compiler:

                          • Make sure however you configure your project to generate linker lines it's using the right linker and command-line options for whatever the correct files for it are. When you changed over from MinGW to MSVC you must have had to re-configure the makes from scratch I imagine, telling it which compiler/linker you're using, I imagine. I don't know, but those link library lines you show still look a bit gcc rather than msvc/link to me, but I could be mistaken.

                          how does MSCV linking look like? and by "reconfigure" you mean choosing the new kit/compiler and running qmake or is there something else?

                          JonBJ 1 Reply Last reply
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                          • E elsa

                            @JonB said in Link external library with MSCV compiler:

                            • Make sure however you configure your project to generate linker lines it's using the right linker and command-line options for whatever the correct files for it are. When you changed over from MinGW to MSVC you must have had to re-configure the makes from scratch I imagine, telling it which compiler/linker you're using, I imagine. I don't know, but those link library lines you show still look a bit gcc rather than msvc/link to me, but I could be mistaken.

                            how does MSCV linking look like? and by "reconfigure" you mean choosing the new kit/compiler and running qmake or is there something else?

                            JonBJ Offline
                            JonBJ Offline
                            JonB
                            wrote on last edited by JonB
                            #15

                            @elsa
                            I'm not sure about the MSVC command-line. I was thinking it would use LINK and have something like /LIB and/or mention of blas_win32_MT.LIB, I'm niggled by the suspicion it's still trying to link with MinGW libraries, but I'm not sure. You could look at/show the actual linker line that's being executed?

                            Yes, you needed to pick new compiler/linker kit and re-run qmake, or similar. It's very important that you cleaned everything out --- perferably restarted in a clean folder --- as you don't want any artefacts left over from old compiler/configuration. If it were me, at this point I'd be tempted to set up a brand new project in a new directory which just makes a couple of calls to those libraries and get it all working with MSVC from scratch.

                            P.S.
                            blas_win32_MT, lapack_win32_MT: Apart from the fact that you need to check you're compiling & linking your code with /MT, those must be 32-bit libraries. You are compiling your code for 32-bit too, right?

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                            • JonBJ JonB

                              @elsa
                              I'm not sure about the MSVC command-line. I was thinking it would use LINK and have something like /LIB and/or mention of blas_win32_MT.LIB, I'm niggled by the suspicion it's still trying to link with MinGW libraries, but I'm not sure. You could look at/show the actual linker line that's being executed?

                              Yes, you needed to pick new compiler/linker kit and re-run qmake, or similar. It's very important that you cleaned everything out --- perferably restarted in a clean folder --- as you don't want any artefacts left over from old compiler/configuration. If it were me, at this point I'd be tempted to set up a brand new project in a new directory which just makes a couple of calls to those libraries and get it all working with MSVC from scratch.

                              P.S.
                              blas_win32_MT, lapack_win32_MT: Apart from the fact that you need to check you're compiling & linking your code with /MT, those must be 32-bit libraries. You are compiling your code for 32-bit too, right?

                              E Offline
                              E Offline
                              elsa
                              wrote on last edited by
                              #16

                              @JonB said in Link external library with MSCV compiler:

                              @elsa
                              I'm not sure about the MSVC command-line. I was thinking it would use LINK and have something like /LIB and/or mention of blas_win32_MT.LIB, I'm niggled by the suspicion it's still trying to link with MinGW libraries, but I'm not sure. You could look at/show the actual linker line that's being executed?

                              I thought this is just the line from the .pro file that I linked in the question. Is linking also defined somewhere else?

                              P.S.
                              blas_win32_MT, lapack_win32_MT: Apart from the fact that you need to check you're compiling & linking your code with /MT, those must be 32-bit libraries. You are compiling your code for 32-bit too, right?

                              Okay maybe this is the problem!
                              BIG UPDATE: The above mentioned errors get produced using the 64bit compiler, which -now that you say it- maybe explains why it doesn't work..
                              The weird thing is, however, when running the 32 bit compiler I get the following error:

                              error: LNK1112: module machine type 'x86' conflicts with target machine type 'x64'
                              

                              so I am confused now. Is 32bit or 64bit correct?

                              JonBJ 1 Reply Last reply
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                              • E elsa

                                @JonB said in Link external library with MSCV compiler:

                                @elsa
                                I'm not sure about the MSVC command-line. I was thinking it would use LINK and have something like /LIB and/or mention of blas_win32_MT.LIB, I'm niggled by the suspicion it's still trying to link with MinGW libraries, but I'm not sure. You could look at/show the actual linker line that's being executed?

                                I thought this is just the line from the .pro file that I linked in the question. Is linking also defined somewhere else?

                                P.S.
                                blas_win32_MT, lapack_win32_MT: Apart from the fact that you need to check you're compiling & linking your code with /MT, those must be 32-bit libraries. You are compiling your code for 32-bit too, right?

                                Okay maybe this is the problem!
                                BIG UPDATE: The above mentioned errors get produced using the 64bit compiler, which -now that you say it- maybe explains why it doesn't work..
                                The weird thing is, however, when running the 32 bit compiler I get the following error:

                                error: LNK1112: module machine type 'x86' conflicts with target machine type 'x64'
                                

                                so I am confused now. Is 32bit or 64bit correct?

                                JonBJ Offline
                                JonBJ Offline
                                JonB
                                wrote on last edited by JonB
                                #17

                                @elsa

                                I thought this is just the line from the .pro file that I linked in the question. Is linking also defined somewhere else?

                                All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

                                error: LNK1112: module machine type 'x86' conflicts with target machine type 'x64'

                                so I am confused now. Is 32bit or 64bit correct?

                                x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

                                E 1 Reply Last reply
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                                • JonBJ JonB

                                  @elsa

                                  I thought this is just the line from the .pro file that I linked in the question. Is linking also defined somewhere else?

                                  All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

                                  error: LNK1112: module machine type 'x86' conflicts with target machine type 'x64'

                                  so I am confused now. Is 32bit or 64bit correct?

                                  x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

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                                  elsa
                                  wrote on last edited by elsa
                                  #18

                                  @JonB

                                  All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

                                  link /NOLOGO /DYNAMICBASE /NXCOMPAT /DEBUG /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /MANIFEST:embed /OUT:debug\DecaRangeRTLS.exe @C:\Users\FRHMELSA\AppData\Local\Temp\DecaRangeRTLS.exe.10468.50531.jom
                                  

                                  x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

                                  yes I have reached that assumption as well, but then how do I change the target machine type? :/

                                  JonBJ jsulmJ 2 Replies Last reply
                                  0
                                  • E elsa

                                    @JonB

                                    All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

                                    link /NOLOGO /DYNAMICBASE /NXCOMPAT /DEBUG /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /MANIFEST:embed /OUT:debug\DecaRangeRTLS.exe @C:\Users\FRHMELSA\AppData\Local\Temp\DecaRangeRTLS.exe.10468.50531.jom
                                    

                                    x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

                                    yes I have reached that assumption as well, but then how do I change the target machine type? :/

                                    JonBJ Offline
                                    JonBJ Offline
                                    JonB
                                    wrote on last edited by
                                    #19

                                    @elsa
                                    I don't know in Qt Creator, but it can hardly be difficult, presumably you specify it at some point when you set up your project. Google for it.

                                    Unless the error is from one of your libraries already being compiled 64-bit. Check whether those libraries with win32 in them are indeed 32-bit, not 64-bit.

                                    Come on, you can do this, I can't answer!

                                    1 Reply Last reply
                                    1
                                    • E elsa

                                      @JonB

                                      All you have shown is a LIBS += ... line in a .pro file. When you compile (link) it must also show the actual command-line it has constructed and is executing using these, presumably in whatever "compiler output window" it has.

                                      link /NOLOGO /DYNAMICBASE /NXCOMPAT /DEBUG /SUBSYSTEM:WINDOWS "/MANIFESTDEPENDENCY:type='win32' name='Microsoft.Windows.Common-Controls' version='6.0.0.0' publicKeyToken='6595b64144ccf1df' language='*' processorArchitecture='*'" /MANIFEST:embed /OUT:debug\DecaRangeRTLS.exe @C:\Users\FRHMELSA\AppData\Local\Temp\DecaRangeRTLS.exe.10468.50531.jom
                                      

                                      x86 means 32-bit, x64 means 64-bit. Assuming from the names that those libraries you have are compiled 32-bit, you must compile everything else 32-bit (or get/compile 64-bit version of the libraries). The fact that you have a message target machine type 'x64' must indicate that somewhere you have told Qt Creator (the .pro file?) that your target is 64-bit, and that does not look good....

                                      yes I have reached that assumption as well, but then how do I change the target machine type? :/

                                      jsulmJ Offline
                                      jsulmJ Offline
                                      jsulm
                                      Lifetime Qt Champion
                                      wrote on last edited by
                                      #20

                                      @elsa said in Link external library with MSCV compiler:

                                      but then how do I change the target machine type?

                                      Use Qt for that target machine type

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

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                                        elsa
                                        wrote on last edited by
                                        #21

                                        @JonB @jsulm @mrjj I will try to start doing all the steps from scratch, because I am getting frustrated and cannot get on with the project because of this linker problem..
                                        I am running Qt5.11.1. So what I read is that it only supports up to VS15, so I installed VS15. Qt, however, did not auto-detect the VS 14.0 compiler, so I had to add it manually. I found the path of the compiler .dll file but Qt also wants a make path (where is it?). This is where I am stuck now. Which make executable do I need for the compiler? and what else am I missing? I am sorry if my questions are to confusing or too easy. I am just trying to understand, because I never dealt with compilers and linkers in detail before and this problem came very unexpected.

                                        jsulmJ 1 Reply Last reply
                                        0
                                        • E elsa

                                          @JonB @jsulm @mrjj I will try to start doing all the steps from scratch, because I am getting frustrated and cannot get on with the project because of this linker problem..
                                          I am running Qt5.11.1. So what I read is that it only supports up to VS15, so I installed VS15. Qt, however, did not auto-detect the VS 14.0 compiler, so I had to add it manually. I found the path of the compiler .dll file but Qt also wants a make path (where is it?). This is where I am stuck now. Which make executable do I need for the compiler? and what else am I missing? I am sorry if my questions are to confusing or too easy. I am just trying to understand, because I never dealt with compilers and linkers in detail before and this problem came very unexpected.

                                          jsulmJ Offline
                                          jsulmJ Offline
                                          jsulm
                                          Lifetime Qt Champion
                                          wrote on last edited by jsulm
                                          #22

                                          @elsa said in Link external library with MSCV compiler:

                                          So what I read is that it only supports up to VS15

                                          This is wrong - it supports VS17. But since VS15 and VS17 C++ compiler are compatible this does not matter. If you use Qt online installer you will see what compiler Qt 5.11.1 supports.

                                          "but Qt also wants a make path" - can you please tell us exactly what it asks (screen-shot)?

                                          If my understanding is correct the lib you want to use is built for x86, right? Official Qt build for Windows/VS are all x86_64. You will need a x86_64 build of that lib or build it by yourself.

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

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