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error undefined reference to function that declared in header and dynamically linked

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  • S Offline
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    SGaist
    Lifetime Qt Champion
    wrote on 21 Dec 2016, 22:15 last edited by
    #4

    Hi and welcome to devnet,

    Are you sure that your version of libMPSSE is built for the same architecture as the Qt version your are using ?

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

    A 1 Reply Last reply 21 Dec 2016, 23:06
    1
    • S SGaist
      21 Dec 2016, 22:15

      Hi and welcome to devnet,

      Are you sure that your version of libMPSSE is built for the same architecture as the Qt version your are using ?

      A Offline
      A Offline
      ambershark
      wrote on 21 Dec 2016, 23:06 last edited by ambershark
      #5

      @SGaist said in error undefined reference to function that declared in header and dynamically linked:

      Hi and welcome to devnet,

      Are you sure that your version of libMPSSE is built for the same architecture as the Qt version your are using ?

      @tony2383 This is almost always the problem.. Especially in windows. People like to mix visual c++ libs and mingw and cygwin and any other type you can imagine. Needless to say it doesn't work however there are no errors thrown except the one you are seeing.

      Make sure you are linking libs that were built with the same compiler (i.e. mingw) and the same addressing i.e. 64 bit/32 bit, etc.

      If all else fails you can use the ar command to see if your library contains the symbols you think it does. ar only works with libs compiled with mingw/cygwin. Also to get the ar command you'll probably need cygwin unless you have a mingw install that has it as well.

      Edit:

      I checked your files for you. You have 3 libs in your directory dll/lib/a. Try removing the dll & lib and build again using the static library (the .a). That should resolve ambiguity. My guess is the dll and lib are not build with mingw and are causing the issue.

      Here is the result of the ar:

      [shockwave] ~/FTDI_QT > ar t libMPSSE.a
      ftdi_infra.o
      ftdi_mid.o
      ftdi_i2c.o
      

      So it has those 3 objects in there.

      Also please show the actual output of the build so we can see the exact error.

      My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

      1 Reply Last reply
      0
      • T Offline
        T Offline
        tony2383
        wrote on 22 Dec 2016, 13:21 last edited by
        #6

        @SGaist Yes the libMPSSE was built with MINGW 5.3.0 same as the compiler that I'm using within QT. I'm not sure that it would make a difference that I used a sepreate install of MINGW to compile the library outside the one that is provided with QT. @ambershark I build the library using MINGW32. Does it make a difference that the library was compiled using a C compiler (GCC ) instead of a C++ compiler (G++). I thought it wouldn't being that C code can be compiled using a C++ compiler. Also, I tried removing the the DLL and the LIB and compiling with a static link and I still receive the same error. The errors that I recieve are

        • list item"C:\qt_projects\build-new_sample-Desktop_Qt_5_7_1_MinGW_32bit-Debug\debug\mainwindow.o:-1: In function `ZN10MainWindow21on_pushButton_clickedEv':"

        • list item C:\qt_projects\new_sample\mainwindow.cpp:21: error: undefined reference to `Init_libMPSSE()'

        • list item collect2.exe:-1: error: error: ld returned 1 exit status

        A 1 Reply Last reply 22 Dec 2016, 18:47
        0
        • T tony2383
          22 Dec 2016, 13:21

          @SGaist Yes the libMPSSE was built with MINGW 5.3.0 same as the compiler that I'm using within QT. I'm not sure that it would make a difference that I used a sepreate install of MINGW to compile the library outside the one that is provided with QT. @ambershark I build the library using MINGW32. Does it make a difference that the library was compiled using a C compiler (GCC ) instead of a C++ compiler (G++). I thought it wouldn't being that C code can be compiled using a C++ compiler. Also, I tried removing the the DLL and the LIB and compiling with a static link and I still receive the same error. The errors that I recieve are

          • list item"C:\qt_projects\build-new_sample-Desktop_Qt_5_7_1_MinGW_32bit-Debug\debug\mainwindow.o:-1: In function `ZN10MainWindow21on_pushButton_clickedEv':"

          • list item C:\qt_projects\new_sample\mainwindow.cpp:21: error: undefined reference to `Init_libMPSSE()'

          • list item collect2.exe:-1: error: error: ld returned 1 exit status

          A Offline
          A Offline
          ambershark
          wrote on 22 Dec 2016, 18:47 last edited by
          #7

          @tony2383 said in error undefined reference to function that declared in header and dynamically linked:

          @SGaist Yes the libMPSSE was built with MINGW 5.3.0 same as the compiler that I'm using within QT. I'm not sure that it would make a difference that I used a sepreate install of MINGW to compile the library outside the one that is provided with QT. @ambershark I build the library using MINGW32. Does it make a difference that the library was compiled using a C compiler (GCC ) instead of a C++ compiler (G++). I thought it wouldn't being that C code can be compiled using a C++ compiler. Also, I tried removing the the DLL and the LIB and compiling with a static link and I still receive the same error. The errors that I recieve are

          As long as you use g++ as the actual linker you should be fine. Easy to test though and just build the lib with g++. But you definitely need to use g++ and not gcc to do the linking step or it won't work.

          • list item"C:\qt_projects\build-new_sample-Desktop_Qt_5_7_1_MinGW_32bit-Debug\debug\mainwindow.o:-1: In function `ZN10MainWindow21on_pushButton_clickedEv':"

          • list item C:\qt_projects\new_sample\mainwindow.cpp:21: error: undefined reference to `Init_libMPSSE()'

          • list item collect2.exe:-1: error: error: ld returned 1 exit status

          Which object that my ar command listed is the Init_libMPSSE() function in?

          My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

          1 Reply Last reply
          0
          • M Offline
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            mrjj
            Lifetime Qt Champion
            wrote on 22 Dec 2016, 19:00 last edited by
            #8

            Hi
            Small question.
            If compiled with c compiler, will it not need
            extern "c" {
            }
            To be used from c++ ?
            Or is that automatically with g++ ?

            A 1 Reply Last reply 22 Dec 2016, 19:02
            0
            • M mrjj
              22 Dec 2016, 19:00

              Hi
              Small question.
              If compiled with c compiler, will it not need
              extern "c" {
              }
              To be used from c++ ?
              Or is that automatically with g++ ?

              A Offline
              A Offline
              ambershark
              wrote on 22 Dec 2016, 19:02 last edited by
              #9

              @mrjj said in error undefined reference to function that declared in header and dynamically linked:

              Hi
              Small question.
              If compiled with c compiler, will it not need
              extern "c" {
              }
              To be used from c++ ?
              Or is that automatically with g++ ?

              Extern c goes the other way. It's for a c++ compiler to not name mangle the function so it can be used from c code. So since his end product will be in c++ it wouldn't need the extern c's since c++ would understand the name mangled functions.

              My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

              M 1 Reply Last reply 22 Dec 2016, 19:10
              0
              • A ambershark
                22 Dec 2016, 19:02

                @mrjj said in error undefined reference to function that declared in header and dynamically linked:

                Hi
                Small question.
                If compiled with c compiler, will it not need
                extern "c" {
                }
                To be used from c++ ?
                Or is that automatically with g++ ?

                Extern c goes the other way. It's for a c++ compiler to not name mangle the function so it can be used from c code. So since his end product will be in c++ it wouldn't need the extern c's since c++ would understand the name mangled functions.

                M Offline
                M Offline
                mrjj
                Lifetime Qt Champion
                wrote on 22 Dec 2016, 19:10 last edited by
                #10

                @ambershark
                Ok, I most likely read it wrong then.
                As i saw
                LIB created with c compiling
                No name mangling.

                We link this to c++ program and
                to make it see the c names, we
                do
                extern "c" {
                void libFunc1(p1, p2);
                void libFunc2();
                }

                Sorry. Too much coffee I guess :)

                1 Reply Last reply
                0
                • S Offline
                  S Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on 22 Dec 2016, 21:12 last edited by
                  #11

                  Again, did you check that the architecture of your built library is indeed 32bit like Qt ?

                  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
                  • T Offline
                    T Offline
                    tony2383
                    wrote on 2 Jan 2017, 15:13 last edited by
                    #12

                    @SGaist the library was built with MINGW 5.3.0, same as the compiler that I'm using within QT. @ambershark the init_libMPSSE function was removed from the library in the most recent version of the library source code. But the effects is still the same when I use any other function call. I have updated my repo to use function I2C_GetNumChannels and still receive the same error. The function can be found in the ftdi_i2c.o.

                    kshegunovK A 2 Replies Last reply 2 Jan 2017, 19:17
                    0
                    • T tony2383
                      2 Jan 2017, 15:13

                      @SGaist the library was built with MINGW 5.3.0, same as the compiler that I'm using within QT. @ambershark the init_libMPSSE function was removed from the library in the most recent version of the library source code. But the effects is still the same when I use any other function call. I have updated my repo to use function I2C_GetNumChannels and still receive the same error. The function can be found in the ftdi_i2c.o.

                      kshegunovK Offline
                      kshegunovK Offline
                      kshegunov
                      Moderators
                      wrote on 2 Jan 2017, 19:17 last edited by
                      #13

                      You compiled said library (libMPSSE) with C or C++ compiler? If you compiled it with a c++ compiler, then you need to match it and use the same compiler in your application code. If you compiled with a C compiler, then you need to instruct your C++ compiler (the one you're using in the application) to not put references to decorated functions. That means you need to extern "C" {} the includes. E.g.:

                      extern "C" 
                      {
                           #include <mpsse.h>
                           // ...
                      }
                      

                      C-linkage is compatible across all compilers, so there's no need to match the compiler (but you do need to match architecture) in this case.

                      Read and abide by the Qt Code of Conduct

                      T 1 Reply Last reply 3 Jan 2017, 19:27
                      2
                      • T tony2383
                        2 Jan 2017, 15:13

                        @SGaist the library was built with MINGW 5.3.0, same as the compiler that I'm using within QT. @ambershark the init_libMPSSE function was removed from the library in the most recent version of the library source code. But the effects is still the same when I use any other function call. I have updated my repo to use function I2C_GetNumChannels and still receive the same error. The function can be found in the ftdi_i2c.o.

                        A Offline
                        A Offline
                        ambershark
                        wrote on 2 Jan 2017, 20:07 last edited by
                        #14

                        @tony2383 Since you said you compiled with the same version of mingw for the lib as well as your project then the above comment probably won't help you.

                        Continuing down that line of thought and assuming (huge assumption here) that your libs are correctly matched, please post the output of make VERBOSE=1 for me to take a look at.

                        Just so you know this problem is almost always a wrongly built library though. So it's more likely that the MPSSE lib is built different than your program.

                        Do you potentially have a copy of libMPSSE somewhere else in your lib path that is getting pulled in instead of the one you built? Are you absolutely sure your build of libMPSSE uses the same bit depth and compiler as your application?

                        My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

                        kshegunovK 1 Reply Last reply 2 Jan 2017, 20:08
                        0
                        • A ambershark
                          2 Jan 2017, 20:07

                          @tony2383 Since you said you compiled with the same version of mingw for the lib as well as your project then the above comment probably won't help you.

                          Continuing down that line of thought and assuming (huge assumption here) that your libs are correctly matched, please post the output of make VERBOSE=1 for me to take a look at.

                          Just so you know this problem is almost always a wrongly built library though. So it's more likely that the MPSSE lib is built different than your program.

                          Do you potentially have a copy of libMPSSE somewhere else in your lib path that is getting pulled in instead of the one you built? Are you absolutely sure your build of libMPSSE uses the same bit depth and compiler as your application?

                          kshegunovK Offline
                          kshegunovK Offline
                          kshegunov
                          Moderators
                          wrote on 2 Jan 2017, 20:08 last edited by
                          #15

                          @ambershark said in error undefined reference to function that declared in header and dynamically linked:

                          Since you said you compiled with the same version of mingw for the lib as well as your project then the above comment probably won't help you.

                          mingw does compile C code (with C linkage), you know ...

                          Read and abide by the Qt Code of Conduct

                          A 1 Reply Last reply 2 Jan 2017, 20:17
                          0
                          • kshegunovK kshegunov
                            2 Jan 2017, 20:08

                            @ambershark said in error undefined reference to function that declared in header and dynamically linked:

                            Since you said you compiled with the same version of mingw for the lib as well as your project then the above comment probably won't help you.

                            mingw does compile C code (with C linkage), you know ...

                            A Offline
                            A Offline
                            ambershark
                            wrote on 2 Jan 2017, 20:17 last edited by
                            #16

                            @kshegunov said in error undefined reference to function that declared in header and dynamically linked:

                            @ambershark said in error undefined reference to function that declared in header and dynamically linked:

                            Since you said you compiled with the same version of mingw for the lib as well as your project then the above comment probably won't help you.

                            mingw does compile C code (with C linkage), you know ...

                            Yea, it would be a lot easier to diagnose his problem if he actually posted his build output. It would be pretty obvious if he was mixing C/C++ at that point.

                            The reason I said that extern C'ing his stuff wasn't the solution is he assured us he was using the same compiler for all his stuff. That to me means he knew the difference between a C compiler and a C++ one. It definitely doesn't hurt to throw the extern c around the includes though to test it. I wasn't meaning to downplay your answer at all. Sorry if it seemed like that. :)

                            My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

                            kshegunovK 1 Reply Last reply 2 Jan 2017, 20:20
                            0
                            • A ambershark
                              2 Jan 2017, 20:17

                              @kshegunov said in error undefined reference to function that declared in header and dynamically linked:

                              @ambershark said in error undefined reference to function that declared in header and dynamically linked:

                              Since you said you compiled with the same version of mingw for the lib as well as your project then the above comment probably won't help you.

                              mingw does compile C code (with C linkage), you know ...

                              Yea, it would be a lot easier to diagnose his problem if he actually posted his build output. It would be pretty obvious if he was mixing C/C++ at that point.

                              The reason I said that extern C'ing his stuff wasn't the solution is he assured us he was using the same compiler for all his stuff. That to me means he knew the difference between a C compiler and a C++ one. It definitely doesn't hurt to throw the extern c around the includes though to test it. I wasn't meaning to downplay your answer at all. Sorry if it seemed like that. :)

                              kshegunovK Offline
                              kshegunovK Offline
                              kshegunov
                              Moderators
                              wrote on 2 Jan 2017, 20:20 last edited by
                              #17

                              @ambershark said in error undefined reference to function that declared in header and dynamically linked:

                              Yea, it would be a lot easier to diagnose his problem if he actually posted his build output. It would be pretty obvious if he was mixing C/C++ at that point.
                              The reason I said that extern C'ing his stuff wasn't the solution is he assured us he was using the same compiler for all his stuff.

                              He might've stumbled on some "default behavior" (how can you not love C/C++) where the C compiler is invoked when it sees .c extension. So it may be really transparent from afar, and yet to happen so there's mixing of C and C++ compiled code.

                              I wasn't meaning to downplay your answer at all. Sorry if it seemed like that.

                              No offence taken, I have thicker skin than that. :)

                              Read and abide by the Qt Code of Conduct

                              A 1 Reply Last reply 2 Jan 2017, 20:45
                              1
                              • kshegunovK kshegunov
                                2 Jan 2017, 20:20

                                @ambershark said in error undefined reference to function that declared in header and dynamically linked:

                                Yea, it would be a lot easier to diagnose his problem if he actually posted his build output. It would be pretty obvious if he was mixing C/C++ at that point.
                                The reason I said that extern C'ing his stuff wasn't the solution is he assured us he was using the same compiler for all his stuff.

                                He might've stumbled on some "default behavior" (how can you not love C/C++) where the C compiler is invoked when it sees .c extension. So it may be really transparent from afar, and yet to happen so there's mixing of C and C++ compiled code.

                                I wasn't meaning to downplay your answer at all. Sorry if it seemed like that.

                                No offence taken, I have thicker skin than that. :)

                                A Offline
                                A Offline
                                ambershark
                                wrote on 2 Jan 2017, 20:45 last edited by
                                #18

                                @kshegunov said in error undefined reference to function that declared in header and dynamically linked:

                                He might've stumbled on some "default behavior" (how can you not love C/C++) where the C compiler is invoked when it sees .c extension. So it may be really transparent from afar, and yet to happen so there's mixing of C and C++ compiled code.

                                Absolutely true! I have myself stumbled across that a few times. It always throws me off for a second too.

                                No offence taken, I have thicker skin than that. :)

                                Oh good! You never know with written word. I never mean to insult people but sometimes I do online, so now I try to apologize if I feel I might have. :)

                                My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

                                1 Reply Last reply
                                2
                                • kshegunovK kshegunov
                                  2 Jan 2017, 19:17

                                  You compiled said library (libMPSSE) with C or C++ compiler? If you compiled it with a c++ compiler, then you need to match it and use the same compiler in your application code. If you compiled with a C compiler, then you need to instruct your C++ compiler (the one you're using in the application) to not put references to decorated functions. That means you need to extern "C" {} the includes. E.g.:

                                  extern "C" 
                                  {
                                       #include <mpsse.h>
                                       // ...
                                  }
                                  

                                  C-linkage is compatible across all compilers, so there's no need to match the compiler (but you do need to match architecture) in this case.

                                  T Offline
                                  T Offline
                                  tony2383
                                  wrote on 3 Jan 2017, 19:27 last edited by
                                  #19

                                  @kshegunov @ambershark that worked. Still having a problem with FTDI libraries, but I will hop on one of there forums to address those issues. Thanks everyone for their help.

                                  1 Reply Last reply
                                  0
                                  • M Offline
                                    M Offline
                                    mrjj
                                    Lifetime Qt Champion
                                    wrote on 4 Jan 2017, 07:55 last edited by
                                    #20

                                    So in the end
                                    my hopeless formulated question
                                    about use extern "c" , turned out to be the case ?
                                    My very old compiler does like that. hence I asked :)

                                    A 1 Reply Last reply 4 Jan 2017, 20:09
                                    1
                                    • M mrjj
                                      4 Jan 2017, 07:55

                                      So in the end
                                      my hopeless formulated question
                                      about use extern "c" , turned out to be the case ?
                                      My very old compiler does like that. hence I asked :)

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                                      A Offline
                                      ambershark
                                      wrote on 4 Jan 2017, 20:09 last edited by
                                      #21

                                      @mrjj said in error undefined reference to function that declared in header and dynamically linked:

                                      So in the end
                                      my hopeless formulated question
                                      about use extern "c" , turned out to be the case ?
                                      My very old compiler does like that. hence I asked :)

                                      Indeed it was. :) I was quick to shrug it off too thinking no that can't be it... But then you and @kshegunov proved me quite wrong there. ;)

                                      My L-GPL'd C++ Logger github.com/ambershark-mike/sharklog

                                      M 1 Reply Last reply 5 Jan 2017, 07:37
                                      1
                                      • A ambershark
                                        4 Jan 2017, 20:09

                                        @mrjj said in error undefined reference to function that declared in header and dynamically linked:

                                        So in the end
                                        my hopeless formulated question
                                        about use extern "c" , turned out to be the case ?
                                        My very old compiler does like that. hence I asked :)

                                        Indeed it was. :) I was quick to shrug it off too thinking no that can't be it... But then you and @kshegunov proved me quite wrong there. ;)

                                        M Offline
                                        M Offline
                                        mrjj
                                        Lifetime Qt Champion
                                        wrote on 5 Jan 2017, 07:37 last edited by
                                        #22

                                        @ambershark

                                        well, i would (also) have bet my money
                                        on mixed libs/compiler or incorrect LIBS +=
                                        and not extern "c" so that is very understandable.

                                        Also, very informative as i did not knew mingw would do that :)
                                        Cheers

                                        1 Reply Last reply
                                        1

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