Cross-compiling errors linking my own library

AlTro

Hi,
I cross-compiled qt5.7 with gcc4.7 linaro toolchain with no problems (I compiled many examples and all work)
After that I compiled my own library and all is ok, but when I tried to compile a project that links my library I got these errors:

/home/alex/sources/main.cpp:54:error: undefined reference to `typeinfo for mynamespace::myException'

/home/alex/sources/main.cpp:54:error: undefined reference to `mynamespace::myException::~myException()'

/home/alex/raspberry/sysroot/usr/lib/mylib.so: error: undefined reference to `vtable for mynamespace::myException'

collect2: error: ld returned 1 exit status

This is my .pro

CONFIG      +=  debug_and_release

QMAKE_CXXFLAGS += -std=c++11

QT  -= gui
QT  += dbus

SOURCES     += src/main.cpp \
                src/wd.cpp

HEADERS     += include/wd.h

LIBS        +=  -lmylib
INCLUDEPATH += include
DEPENDPATH  += /home/alex/raspberry/sysroot/usr/lib

OBJECTS_DIR = obj
MOC_DIR     = moc
DESTDIR     = bin

TARGET  =   wd
build_pass:CONFIG(debug, debug|release) {
    TARGET = $$join(TARGET,,,_debug)
}

target.path = /home/pi/dev/wd
INSTALLS += target

I think the problem is that the compiler doesn't find include files (that are in sysroot/usr/include) and the library (that is in sysroot/usr/lib).
I also controlled the compilation command in Qt Creator and it seems to be right.

How can I set properly the project to link my shared library? And if I have to link another third party library (like mosquitto)?

Thanks in advance

AlTro

The problem was because the cross-compilation is done with gcc4.7, that doesn't have full c++11 support, but the test compilation on the raspberry whit gcc4.9.

Because of this I changed the declaration of the destructor mynamespace::myException::~myException() adding "noexcept".

namespace mynamespace {
    class myException : public std::exception
    {
        public:
            myException( std::string whatHappened );
            virtual ~myException() noexcept;
            virtual const char* what() const throw();

        protected:
            std::string _whatHappened;

        private:
            static const std::string EXCEPTION_NAME;
    };
}

In .cpp the descructor was implemented but gcc4.7 want an inline implementation, so adding this to .h file and compiling all works.

           virtual ~myException() noexcept {};

SGaist

Hi,

Maybe a silly question but are you sure that your custom library is built for the right architecture ?

AlTro

Yes, I cross-compiled the library with without problems. I also deployed the lib on the raspberry and test it with a little software compiled directly on raspberry. All works great.

SGaist

Then, are you sure that the library itself is found when linking your Qt application ?

VRonin

Did you export myException in your library?
Can qmake find your library? try adding LIBS += -L"/home/alex/raspberry/sysroot/usr/lib"

AlTro

The problem was because the cross-compilation is done with gcc4.7, that doesn't have full c++11 support, but the test compilation on the raspberry whit gcc4.9.

Because of this I changed the declaration of the destructor mynamespace::myException::~myException() adding "noexcept".

namespace mynamespace {
    class myException : public std::exception
    {
        public:
            myException( std::string whatHappened );
            virtual ~myException() noexcept;
            virtual const char* what() const throw();

        protected:
            std::string _whatHappened;

        private:
            static const std::string EXCEPTION_NAME;
    };
}

In .cpp the descructor was implemented but gcc4.7 want an inline implementation, so adding this to .h file and compiling all works.

           virtual ~myException() noexcept {};