View Full Version : Make environement problem: `Qt' undeclared (first use in this function)

24th June 2009, 08:55

I've been using Qt Creator for a while now and yesterday I created a new shared library using the Qt Creator wizard, but the compilation of the library doesn't want to get through compilation.

The error messages are below:

In file included from c:/Tools/Qt/2009.02/qt/include/QtCore/qnamespace.h:1,
from c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/kernel/qobjectdefs.h:45,
from c:/Tools/Qt/2009.02/qt/include/QtCore/qobjectdefs.h:1,
from c:/Tools/Qt/2009.02/qt/include/QtGui/../../src/gui/kernel/qwindowdefs.h:45,
from c:/Tools/Qt/2009.02/qt/include/QtGui/qwindowdefs.h:1,
from c:/Tools/Qt/2009.02/qt/include/QtGui/../../src/gui/kernel/qwidget.h:45,
from c:/Tools/Qt/2009.02/qt/include/QtGui/qwidget.h:1,
from c:/Tools/Qt/2009.02/qt/include/QtGui/QWidget:1,
from include\QtObserverLibrary\ObserverCollectionDetail sWidget.h:4:
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:54: error: syntax error before "namespace"
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:58: error: syntax error before '{' token
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:135: warning: return type defaults to `int'
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h: In function `Q_DECLARE_FLAGS':
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:136: error: `Qt' undeclared (first use in this function)
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:136: error: (Each undeclared identifier is reported only once
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:136: error: for each function it appears in.)
c:/Tools/Qt/2009.02/qt/include/QtCore/../../src/corelib/global/qnamespace.h:136: confused by earlier errors, bailing out
mingw32-make[1]: Leaving directory `D:/ScinericSoftware/Products/QtObserverLibrary/trunk'
mingw32-make: Leaving directory `D:/ScinericSoftware/Products/QtObserverLibrary/trunk'
mingw32-make[1]: *** [tmp/ObserverCollectionDetailsWidget.o] Error 1
mingw32-make: *** [debug] Error 2
Exited with code 2.

And below is my .pro file:

CONFIG += qt dll ordered
QT += xml

TARGET = QtObserverLibrary


DEPENDPATH += include/QtObserverLibrary \
INCLUDEPATH += include/QtObserverLibrary \

win32:UI_HEADERS_DIR = include/QtObserverLibrary
win32:DLLDESTDIR = bin
win32:DESTDIR = bin
win32:OBJECTS_DIR = tmp
win32:MOC_DIR = tmp
win32:RCC_DIR = tmp
win32:UI_DIR = tmp

+ Some headers, forms and sources

Maybe I'm missing something simple, but I just can't seem to get it working. Shouldn't the Qt environment exposed to make by default?

Thanks for any inputs,

24th June 2009, 10:19
Just a wild guess: Maybe there's something wrong in a header file included before <QWidget>. Put #include <QWidget> on the first line of ObserverCollectionDetailsWidget.h and try again.

24th June 2009, 10:33

Thanks for the guess, but nope its not the problem:


#include <QWidget>

Its not related to a specific file, its related to the project setup I believe.

24th June 2009, 13:13
What happens if you remove "CONFIG+=qt" from the project? Also do you have a class or namespace called Qt in your own code?

24th June 2009, 13:33
1) Removing the Config += qt line does not help, no.
2) I'm sure I don't have any Qt namespace in my project.

Below is the gcc call that is generated by Qt Creator:

gcc -c -g -Wall -DUNICODE -DQT_LARGEFILE_SUPPORT -DQTOBSERVERLIBRARY_LIBRARY -DQT_DLL -DQT_XML_LIB -DQT_GUI_LIB -DQT_CORE_LIB -DQT_THREAD_SUPPORT -I"c:\Tools\Qt\2009.02\qt\include\QtCore" -I"c:\Tools\Qt\2009.02\qt\include\QtGui" -I"c:\Tools\Qt\2009.02\qt\include\QtXml" -I"c:\Tools\Qt\2009.02\qt\include" -I"include\QtObserverLibrary" -I"source" -I"c:\Tools\Qt\2009.02\qt\include\ActiveQt" -I"tmp" -I"include\QtObserverLibrary" -I"c:\Tools\Qt\2009.02\qt\mkspecs\win32-g++" -o tmp\ObserverCollectionDetailsWidget.o include\QtObserverLibrary\ObserverCollectionDetail sWidget.h

And below is the gcc call from a different project which works fine:

g++ -c -g -frtti -fexceptions -mthreads -Wall -DUNICODE -DQT_LARGEFILE_SUPPORT -DQT_DLL -DQT_GUI_LIB -DQT_CORE_LIB -DQT_THREAD_SUPPORT -DQT_NEEDS_QMAIN -I"c:\Tools\Qt\2009.02\qt\include\QtCore" -I"c:\Tools\Qt\2009.02\qt\include\QtGui" -I"c:\Tools\Qt\2009.02\qt\include" -I"c:\Tools\Qt\2009.02\qt\include\ActiveQt" -I"debug" -I"." -I"c:\Tools\Qt\2009.02\qt\mkspecs\win32-g++" -o debug\main.o main.cpp

The only difference that I can see is -DQT_NEEDS_QMAIN. But adding this define to the shared library project does not resolve anything.

24th June 2009, 15:16
Both lines look fine to me. The error has to be in your source file. Try deleting it and typing in the contents manually again (don't paste it as you could paste some non-readable character).

24th June 2009, 15:27
Thanks for the reply again Wysota.

I figured it out, and it was my mistake. I accidentally had all my sources under HEADERS += and all my headers under SOURCES +=.

Thanks again,