Generate a static library instead.

Er… I mean I don’t want to use .so or .dll files.

Static libraries [en.wikipedia.org] are libraries that are linked into your program. You won’t be needing a dll or so in that case.

Ah-oh. Awkward. Thanks.

Well, I successfully generated libcommon.a in common/; but I don’t know how to make the final executables use it.

I tried to insert these lines into the .pri files, but it seems not working.
DEPENDPATH += ../common/
INCLUDEPATH += ../
POST_TARGETDEPS += ../common/libcommon.a

Here is the error log:
g++ -Wl,-O1 -Wl,-rpath,/usr/lib64/qt4 -o ../saye build/main.o build/Saye.o build/GameWindow.o build/SayeMainWindow.o build/moc_Saye.o build/moc_GameWindow.o build/moc_SayeMainWindow.o -L/usr/lib64/qt4 -L/usr/X11R6/lib -lSimpleAV_SDL -lSimpleAV `sdl-config —libs` -lSDL_mixer -L/usr/local/lib -pthread -lavformat -lavcodec -ldl -lasound -lbz2 -lz -lswscale -lavutil -lm -lQtXml -L/usr/lib64 -L/usr/lib64/qt4 -lQtOpenGL -L/usr/X11R6/lib -lQtGui -lQtCore -lgthread-2.0 -lrt -lglib-2.0 -lGLU -lGL -lpthread
build/Saye.o: In function `Saye::openProject()’:
Saye.cpp:(.text+0×730): undefined reference to `SayaMap::SayaMap(QString)’
Saye.cpp:(.text+0×7b8): undefined reference to `SayaMap::dump()’
collect2: ld returned 1 exit status
make: *** [../saye] Error 1

The SayaMap class is defined in common/. Almost everything works well; this issue happens when linking the object files.

Something like

Adding the path to common libs is only necessary if they’re not already in your search path. You could try with -lcommon first to see if it has the desired effect already.

Nmmm… In fact I tried

But here comes another question: what if we later updated common? Code used it should be recompiled, but make will not think it needs to do so.

Maybe I should switch back to shared libraries.

I’m not sure how to handle it directly with qmake, but you can always touch a header file (Saye.h for example) to force a rebuild & relink. Of course just a relink only would be nicest.

This worked for me on unix/linux:

This ensures that the final target is rebuilt, once libcommon.a has changed.

So it will be different on Windows?

wecing wrote:

So it will be different on Windows?

For MinGW this should work too, as it’s a gnu toolchain. It should work for the visual studio toolchain together with Qt Creator as IDE too.

I don’t know if it works with full Visual Studio usage (including the IDE/GUI).