Can not create/use DLL

SGaist

@JacobNovitsky please show the content of the files requested by @Paul-Colby.

JacobNovitsky

@SGaist sorry, just woke up :)

MyLib.pro

TEMPLATE = lib
DEFINES += MYLIB_LIBRARY

CONFIG += c++17

You can make your code fail to compile if it uses deprecated APIs.

In order to do so, uncomment the following line.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

SOURCES +=
mylib.cpp

HEADERS +=
MyLib_global.h
mylib.h

Default rules for deployment.

unix {
target.path = /usr/lib
}
!isEmpty(target.path): INSTALLS += target

useDll.pro
TEMPLATE = app
CONFIG += console c++17
CONFIG -= app_bundle
#CONFIG -= qt

QT += core

QT += gui
#QT += qapplication
QT += widgets quick

SOURCES +=
main.cpp

Paul Colby

Hi @JacobNovitsky ,

Your userDll.pro file appears to be missing a LIBS += line that would be pointing the the build output of the MyLib.pro file (ie the *.so files).

See the end of this page for some inspiration, ie this bit:

win32:CONFIG(release, debug|release): LIBS += -L$$OUT_PWD/../../../projects/mylib/release/ -lmylib
else:win32:CONFIG(debug, debug|release): LIBS += -L$$OUT_PWD/../../../projects/mylib/debug/ -lmylib
else:unix: LIBS += -L$$OUT_PWD/../../../projects/mylib/ -lmylib
INCLUDEPATH += $$PWD/../../../projects/mylib
DEPENDPATH += $$PWD/../../../projects/mylib
win32:CONFIG(release, debug|release): PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/release/mylib.lib
else:win32:CONFIG(debug, debug|release): PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/debug/mylib.lib
else:unix: PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/libmylib.a

Alternatively, since this seems to be a new project, I'd highly recommend you use cmake instead.

Cheers.

JacobNovitsky

@Paul-Colby I need to make DLL for my project build with qmake, but thanks for pointing out

should I add to MyLib.pro lines below?

win32:CONFIG(release, debug|release): LIBS += -L$$OUT_PWD/../../../projects/mylib/release/ -lmylib
else:win32:CONFIG(debug, debug|release): LIBS += -L$$OUT_PWD/../../../projects/mylib/debug/ -lmylib
else:unix: LIBS += -L$$OUT_PWD/../../../projects/mylib/ -lmylib
INCLUDEPATH += $$PWD/../../../projects/mylib
DEPENDPATH += $$PWD/../../../projects/mylib
win32:CONFIG(release, debug|release): PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/release/mylib.lib
else:win32:CONFIG(debug, debug|release): PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/debug/mylib.lib
else:unix: PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/libmylib.a

jsulm

@JacobNovitsky said in Can not create/use DLL:

should I add to MyLib.pro lines below?

No, to userDll.pro as @Paul-Colby wrote

JacobNovitsky

@jsulm great, ty

build folder
home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
source files folder
/home/supernova/MyLib

I'm I correct:
"If I use Ubuntu, I can somehow ignore win32 lines and keep it as in asample -> rest to be amended EXACTlLY like that".

win32:CONFIG(release, debug|release): LIBS += -L$$OUT_PWD/../../../projects/mylib/release/ -lmylib
else:win32:CONFIG(debug, debug|release): LIBS += -L$$OUT_PWD/../../../projects/mylib/debug/ -lmylib
else:unix: LIBS += -L$$OUT_PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug -lmylib
INCLUDEPATH += $$PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
DEPENDPATH += $$PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
win32:CONFIG(release, debug|release): PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/release/mylib.lib
else:win32:CONFIG(debug, debug|release): PRE_TARGETDEPS += $$OUT_PWD/../../../projects/mylib/debug/mylib.lib
else:unix: PRE_TARGETDEPS += $$OUT_PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

Please confirm, big thanks in advance

jsulm

@JacobNovitsky If you don't plan to build for Windows then you can remove all the win32 lines, but don't forget to alter other lines (like removing else:).

JacobNovitsky

@jsulm is this correct?

LIBS += -L$$OUT_PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug -lmylib
INCLUDEPATH += $$PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
DEPENDPATH += $$PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
PRE_TARGETDEPS += $$OUT_PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

Not sure If i need to include project source files, if need please advise where to include

jsulm

@JacobNovitsky said in Can not create/use DLL:

Not sure If i need to include project source files

If you want to link against a pre build lib then of course you do not have to include the lib sources in the project which links against it.

JacobNovitsky

just delete both projects and created new

pro:

QT -= gui

TEMPLATE = lib
DEFINES += MYLIB_LIBRARY

CONFIG += c++17

You can make your code fail to compile if it uses deprecated APIs.

In order to do so, uncomment the following line.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

SOURCES +=
mylib.cpp

HEADERS +=
MyLib_global.h
mylib.h

LIBS += -L$$OUT_PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug -lmylib

INCLUDEPATH += $$PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
DEPENDPATH += $$PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
PRE_TARGETDEPS += $$OUT_PWD/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

Default rules for deployment.

unix {
target.path = /usr/lib
}
!isEmpty(target.path): INSTALLS += target

compile output:
:-1: error: No rule to make target '/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug', needed by 'libMyLib.so.1.0.0'. Stop.

path correct, supernova@supernova-BOHB-WAX9:~/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug$ ls
libMyLib.so libMyLib.so.1.0 Makefile
libMyLib.so.1 libMyLib.so.1.0.0 mylib.o

please assist

JacobNovitsky

any ideas how to fix that?
compile output:
:-1: error: No rule to make target '/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug', needed by 'libMyLib.so.1.0.0'. Stop.

SGaist

Remove $$PWD from the corresponding lines.

Side question: are you going to use that library in any other project ?

JacobNovitsky

@SGaist not this, but after I learn how to use this, I gonna use it, for sure

JacobNovitsky

@SGaist side question too :)
where can I read about QMAKE?

SGaist

In the qmake manual

JacobNovitsky

Libtest.pro
QT = core

CONFIG += c++17 cmdline

You can make your code fail to compile if it uses deprecated APIs.

In order to do so, uncomment the following line.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

SOURCES +=
main.cpp

Default rules for deployment.

qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

LIBS +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
INCLUDEPATH +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
DEPENDPATH +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
PRE_TARGETDEPS +=/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

MyLib.pro

QT -= gui

TEMPLATE = lib
DEFINES += MYLIB_LIBRARY

CONFIG += c++17

You can make your code fail to compile if it uses deprecated APIs.

In order to do so, uncomment the following line.

#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0

SOURCES +=
mylib.cpp

HEADERS +=
MyLib_global.h
mylib.h

Default rules for deployment.

unix {
target.path = /usr/lib
}
!isEmpty(target.path): INSTALLS += target

:-1: error: cannot find /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug: file format not recognized

How to fix error above? There is still no DLL, if I comply with syntax, shall I get dll?

jsulm

@JacobNovitsky You should really read the link @SGaist gave you.
In LIBS you need to also specify the lib you want to link.

JacobNovitsky

@jsulm if I use in the LIBS line something with prefix -lmylib it does not work :)
what should I exactly insert to LIBS line?

JacobNovitsky

changed to

    LIBS += -L/home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug -lMyLib
    INCLUDEPATH += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
    DEPENDPATH += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug
    PRE_TARGETDEPS += /home/supernova/build-MyLib-Desktop_Qt_6_2_4_GCC_64bit-Debug

it builds, but how to gett .dll file?

JacobNovitsky

If I just link header which includes other project headers, it means my program auto include all headers which increase building and execution time?
same going to happen if I use dll, I'm I correct?