linking libraries

[jacek]

Does it link when you remove #include <qapplication.h> and change:

CONFIG += qt warn_on release

CONFIG += qt warn_on release

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to

CONFIG += warn_on release
CONFIG -= qt

CONFIG += warn_on release
CONFIG -= qt

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?

[wysota]

// main.cpp
#include <vortex.h>
 
void main( ){
    vortex_init();
}

// main.cpp
#include <vortex.h>
 
void main( ){
    vortex_init();
}

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g++ main.cpp `pkg-config vortex --cflags --libs` -o test

g++ main.cpp `pkg-config vortex --cflags --libs` -o test

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Does this compile?

[JustaStudent]

I found the problem! It is my bad actually, the Vortex library is a C library, not a C++ library.
So,

I changed the name of dummy.cpp to dummy.c,
I changed CXXFLAGS to CFLAGS in dummy.pro as below, then run

make clean && qmake && make.

Code compiled! I feel stupid that I did not realise this earlier!
Thank you for the troubleshooting!

> more dummy.c

#include <vortex.h>
 
int main( )
{
    vortex_init();
}

#include <vortex.h>

int main( )
{
    vortex_init();
}

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> more dummy.pro

TEMPLATE        = app
LANGUAGE        = C++
 
CONFIG  += qt warn_on release
 
SOURCES += dummy.c
 
LIBS += $$system(pkg-config --libs vortex)
 
QMAKE_CFLAGS += $$system(pkg-config --cflags vortex)
 
unix {
  UI_DIR = .ui
  MOC_DIR = .moc
  OBJECTS_DIR = .obj
}

TEMPLATE        = app
LANGUAGE        = C++

CONFIG  += qt warn_on release

SOURCES += dummy.c

LIBS += $$system(pkg-config --libs vortex)

QMAKE_CFLAGS += $$system(pkg-config --cflags vortex)

unix {
  UI_DIR = .ui
  MOC_DIR = .moc
  OBJECTS_DIR = .obj
}

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> make clean && qmake && make

qmake -o Makefile dummy.pro
rm -f .obj/dummy.o
rm -f *~ core *.core
gcc -c -pipe -pthread -I/usr/local/include/vortex -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/libxml2 -Wall -W -O2 -D_REENTRANT  -DQT_NO_DEBUG -DQT_THREAD_SUPPORT -DQT_SHARED -DQT_TABLET_SUPPORT -I/usr/share/qt3/mkspecs/default -I. -I/usr/include/qt3 -I.ui/ -I.moc/ -o .obj/dummy.o dummy.c
dummy.c: In function ‘main’:
dummy.c:6: warning: control reaches end of non-void function
g++  -o dummy .obj/dummy.o    -L/usr/share/qt3/lib -L/usr/X11R6/lib -pthread -L/usr/local/lib -lvortex -lgthread-2.0 -lxml2 -lz -lglib-2.0 -lqt-mt -lXext -lX11 -lm -lpthread

qmake -o Makefile dummy.pro
rm -f .obj/dummy.o
rm -f *~ core *.core
gcc -c -pipe -pthread -I/usr/local/include/vortex -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include -I/usr/include/libxml2 -Wall -W -O2 -D_REENTRANT  -DQT_NO_DEBUG -DQT_THREAD_SUPPORT -DQT_SHARED -DQT_TABLET_SUPPORT -I/usr/share/qt3/mkspecs/default -I. -I/usr/include/qt3 -I.ui/ -I.moc/ -o .obj/dummy.o dummy.c
dummy.c: In function ‘main’:
dummy.c:6: warning: control reaches end of non-void function
g++  -o dummy .obj/dummy.o    -L/usr/share/qt3/lib -L/usr/X11R6/lib -pthread -L/usr/local/lib -lvortex -lgthread-2.0 -lxml2 -lz -lglib-2.0 -lqt-mt -lXext -lX11 -lm -lpthread

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[jacek]

I found the problem! It is my bad actually, the Vortex library is a C library, not a C++ library.

Then you should use Vortex headers like this:

extern "C" {
#include <vortex.h>
};

extern "C" {
#include <vortex.h>
};

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Athough it's strange that Vortex authors didn't take care of it.

[JustaStudent]

Right. Thanks again for the help! Youv'e saved me some days to finish a prototype of the project

(I renamed file to dummy.cpp and used CXXFLAGS again in dummy.pro, then put extern "C" in dummy.cpp as you mentioned & recompiled)

[JustaStudent]

Ok, now to the next problem.. This should fit under the same topic.

I want to build a static executable with this vortex library included. I have tried putting "static" in my "CONFIG +=" in my .pro file, but that just makes no difference. (same size of executable, and not working on other machine with same distro)

[jacek]

Do you have a static version of that library?

[JustaStudent]

no, not that i know of.
the library is compiled with --enable-static but I dont know where the static library is installed..

[jacek]

If you don't have a static version of that library you can't link statically with it. Look for libvortex.a or something similar on your filesystem.

[JustaStudent]

Found it!

/usr/local/lib/libvortex.a

how do i now compile my Qt project with this statically?

(thanks for the help, btw! you seem to really know this stuff.)

[jacek]

If you use pkg-config, then try changing --libs to --static.

[JustaStudent]

I changed the libs in project settings from "$$system(pkg-config --libs vortex)" to "--static $$system(pkg-config --libs vortex)"

Now I get this error message;

/usr/bin/ld: cannot find -lqt-mt

[jacek]

Now I get this error message;

/usr/bin/ld: cannot find -lqt-mt

It looks like it tries to link statically with Qt.

Try:

-static $$system(pkg-config --libs vortex) -dy