how to fix " Missing argument to '-L' " error ?

Eddy

If you lucky you can clean (or even delete) the target folder)
Then run qmake + build.

Did you change any folders or library names?

Do you use a version system? Then you can compare the differences?

koahnig

@Ahti said in how to fix " Missing argument to '-L' " error ?:

#-------------------------------------------------
#
# Project created by Ahtisham 2016-08-16T13:18:59
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = testMyProject
TEMPLATE = app


SOURCES += main.cpp\
       eyecare.cpp \
   others.cpp

HEADERS  += eyecare.h \
   others.h

FORMS    += eyecare.ui

RESOURCES += \
   images.qrc


win32:CONFIG(release,debug|release): LIBS += -L&&PWD/Dll/ -ldxva2
win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Library/ -ldxva2
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/Library/ -ldxva2
else:unix: LIBS += -L$$PWD/Library/ -ldxva2

INCLUDEPATH += $$PWD/Library
DEPENDPATH += $$PWD/Library

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/Library/ -luser32
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/Library/ -luser32
else:unix: LIBS += -L$$PWD/Library/ -luser32

INCLUDEPATH += $$PWD/Library
DEPENDPATH += $$PWD/Library

DISTFILES +=

no neither restart nor update occurred but i don't know what caused this problem it was working fine.

In here shall be probably a '$' sign

win32:CONFIG(release,debug|release): LIBS += -L&&PWD/Dll/ -ldxva2

change to

win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2

Ahti

@koahnig

Now i get these errors:

https://ibb.co/eE4GiQ

:(

Ahti

After doing what @Eddy said the app started to work :)

Eddy

@Ahti

Good deal!

Ahti

@Eddy lol it still gives those 3 errors :(

Eddy

Good to see it's funny to you ;-)

Can you edit the link to you image or just copy the text here? We cannot see the image in your previous post.
You can use an image provider to show it to us by following this topic
There is still a problem with the uploading of image in the Qt forum. The admins are working on it though.

Edit : did you check the hint from @koahnig ?

Ahti

@Eddy see i edited the post

changing from && to $$ ? yes i did that but now i am gettings those errors

note the problem is with those Dll files i know it because when i delete them and run my project it works.

Eddy

why do you have those 2 lines?

win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2
win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Library/ -ldxva2

Is one of them not enough?
The Dll path seems redundant since you don't use it further on

Ahti

@Eddy

Okay removed everything except :

win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2

but still getting those 3 errors

I use that Dll file for getting some windows functions that i need in my project.
functions like :
GetDesktopWindow();
MonitorFromWIndow();
GetCurrentBrightness();
etc

Eddy

what is in your $$PWD/Dll/ folder?

koahnig

@Ahti said in how to fix " Missing argument to '-L' " error ?:

@Eddy

Okay removed everything except :
win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2
but still getting those 3 errors

I use that Dll file for getting some windows functions that i need in my project.
functions like :
GetDesktopWindow();
MonitorFromWIndow();
GetCurrentBrightness();
etc

The problem ist that this is only working for release. Therefore, you need to be sure that you are in release mode.
Also sometimes it is good to rerun qmake and possibly rebuild your libraries.

Ahti

@Eddy

3 windows dll files

dxva2.dll, dxva264.dll and user32.dll

koahnig

@Ahti said in how to fix " Missing argument to '-L' " error ?:

@Eddy

3 windows dll files

dxva2.dll, dxva264.dll and user32.dll

no libs with those file names?
The dlls are used during run time, but while linking you need to have the libs created together with the dlls there.

Ahti

@koahnig

now i got the libs but still getting that error :(

koahnig

@Ahti said in how to fix " Missing argument to '-L' " error ?:

@koahnig

now i got the libs but still getting that error :(

What is the actual error message with your current configuration?
Probably it would be good also to post the current .pro file.

Ahti

@koahnig

those three errors that i already mentioned.

my new pro file:

#-------------------------------------------------
#
# Project created by Ahtisham 2016-08-16T13:18:59
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = testMyProject
TEMPLATE = app


SOURCES += main.cpp\
        eyecare.cpp \
    others.cpp

HEADERS  += eyecare.h \
    others.h

FORMS    += eyecare.ui

RESOURCES += \
    images.qrc


win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Dll/ -ldxva2
win32:CONFIG(release,debug|release): LIBS += -L$$PWD/Library/ -ldxva2
else:win32:CONFIG(debug,debug|release): LIBS += -L$$PWD/Library/ -ldxva2
else:unix: LIBS += -L$$PWD/Library/ -ldxva2

INCLUDEPATH += $$PWD/Library
DEPENDPATH += $$PWD/Library

win32:CONFIG(release, debug|release): LIBS += -L$$PWD/Library/ -luser32
else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/Library/ -luser32
else:unix: LIBS += -L$$PWD/Library/ -luser32

INCLUDEPATH += $$PWD/Library
DEPENDPATH += $$PWD/Library

DISTFILES +=

koahnig

@Ahti

Which means that the stubs in the lib-file are missing?
Do you have the import and export keyword handled correctly?

The dll and the stub-lib are generâted with the same tool chain?

Ahti

@koahnig what do you mean by "stubs in the lib-file" what is that ? i don't know anything about that. I just copied all the required dll and lib files from the system32 to Dll and Library folders of my project respectively. And what is import and export keyword ?

I am creating this app just to let user change screen brightness and for that i need to use windows API and that is why i need those dll and lib files.

have a look:

https://msdn.microsoft.com/en-us/library/windows/desktop/dd692939(v=vs.85).aspx

goto the link and see at the end in "Requirements" heading it clearly mentions which library and dll files you need to include in order to use that specific windows api function.

koahnig

@Ahti

When creating a dll you will also create a library (it may have .lib as extension or .a depending on compiler). You need to link the library to your application which is using your dll. The library contains basically a reduced, short part (stub as the rest of tree when you have cut it down) .

dllimport and dllexport it is called for MS compilers. An inpedendent way is with Q_DECL_IMPORT and Q_DECL_EXPORT

What compiler are you using for creating your application?