Build errors in C++/Qt project with 3rd party C library due to gmtime_r() declaration in <pthread.h>

  • Hello,

    I have a C++/Qt project in Windows 7 that uses the C library "libnova". Last time I worked on this project in November, everything built just fine. I use the MinGW compiler. This week, I started working again on this project and upgraded from Qt 5.2.1 to Qt 5.4. Now I can't compile my project because of some funny declarations in <pthread.h>. This header is included by almost anything, be it <QApplication>, <iostream> and others. Reverting back to 5.2.1 didn't help.

    Here's a small example:

    #include <iostream>
    #include <libnova/utility.h>

    int main()
    return 0;

    And this is the compiler output:

    22:12:15: Running steps for project CLibCompileTest...
    22:12:15: Configuration unchanged, skipping qmake step.
    22:12:15: Starting: "C:\Qt\Tools\mingw491_32\bin\mingw32-make.exe"
    C:/Qt/Tools/mingw491_32/bin/mingw32-make -f Makefile.Debug
    mingw32-make[1]: Entering directory 'D:/Andreas/Qt/build-CLibCompileTest-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
    g++ -c -pipe -fno-keep-inline-dllexport -g -frtti -Wall -Wextra -fexceptions -mthreads -DUNICODE -DQT_WIDGETS_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_NEEDS_QMAIN -I..\CLibCompileTest -I"......\Libraries\libnova-latest\src" -I"C:\Qt\5.4\mingw491_32\include" -I"C:\Qt\5.4\mingw491_32\include\QtWidgets" -I"C:\Qt\5.4\mingw491_32\include\QtGui" -I"C:\Qt\5.4\mingw491_32\include\QtCore" -I"debug" -I"." -I"C:\Qt\5.4\mingw491_32\mkspecs\win32-g++" -o debug\main.o ..\CLibCompileTest\main.cpp
    In file included from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/i686-w64-mingw32/bits/gthr-default.h:35:0,
    from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/i686-w64-mingw32/bits/gthr.h:148,
    from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/ext/atomicity.h:35,
    from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/bits/ios_base.h:39,
    from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/ios:42,
    from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/ostream:38,
    from C:/Qt/Tools/mingw491_32/i686-w64-mingw32/include/c++/iostream:39,
    from ..\CLibCompileTest\main.cpp:2:
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected unqualified-id before '{' token
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected ')' before '{' token
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected primary-expression before 'struct'
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected '}' before 'struct'
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected constructor, destructor, or type conversion before ';' token
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: '___tmp_tm' does not name a type
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected unqualified-id before 'if'
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: '___tmp_tm' does not name a type
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    ......\Libraries\libnova-latest\src/libnova/utility.h:230:12: error: expected unqualified-id before ')' token
    struct tm *gmtime_r (time_t *t, struct tm *gmt);
    In file included from ..\CLibCompileTest\main.cpp:3:0:
    ......\Libraries\libnova-latest\src/libnova/utility.h:258:1: error: expected declaration before '}' token
    Makefile.Debug:233: recipe for target 'debug/main.o' failed
    mingw32-make[1]: Leaving directory 'D:/Andreas/Qt/build-CLibCompileTest-Desktop_Qt_5_4_0_MinGW_32bit-Debug'
    makefile:34: recipe for target 'debug' failed
    mingw32-make[1]: *** [debug/main.o] Error 1
    mingw32-make: *** [debug] Error 2
    22:12:15: The process "C:\Qt\Tools\mingw491_32\bin\mingw32-make.exe" exited with code 2.
    Error while building/deploying project CLibCompileTest (kit: Desktop Qt 5.4.0 MinGW 32bit)
    When executing step "Make"
    22:12:15: Elapsed time: 00:01.

    As you can see in this output, the header file <libnova/utility.h> declares a gmtime_r() function and it probably is in conflict with the same function, that is declared (first) in <pthread.h> (included via <iostream>). In <pthread>, gmtime_r() is first undef'd, then defined again.
    When I change the order of those two includes, the project builds just fine.

    Is this supposed to be like this? Because I can't really imagine it.
    How should I handle this? I could insert some #ifndef gmtime_r into <libnova/utility.h> but it rather feels like, MinGW is to blame.

    Any advice?


  • Hi,

    This issue cannot have anything to do with Qt. Probably you have a different MinGW version which ships(???) with a different version of pthread.

    Maybe you should consider #include'ing the libnova header in a namespace so as to prevent the name clash.

  • @Andreas hi,
    Did you find a solution to compiling libnova in mingw?
    I have run into a similar situation and have not been able to manage conflicting declares.

Log in to reply

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.