title: Why doesn't Qt Creator find included headers in included paths - even though qmake is able to find them
body: <p>I joined an already existing (opensource-) Qt 4 project to add some functionality. The project compiles and runs perfectly on Linux Slackware with Qt 4.8.5. As IDE I first used KDevelop (comes with Slackware), but Qt project files aren't supported in KDevelop (since it primarily uses cmake, I had to use the makefile to import the project). Now I want to switch to Qt Creator, but header files in included (relative-) paths aren't recognized. For example the project file is in "dir0/programs/prog1/prog1.pro" and some extra headers are in "dir0/gui/extra.h". "dir0/gui" is added to the search path by the line <code>INCLUDEPATH  += ../../gui</code> in the project file. If I hover over <code>#include "extra.h"</code> in a .h file of the project I always get a popup saying "extra.h: No such file or directory".</p>
  
  <p>In KDevelop there was no problem and also qmake gets it. What's the problem of the Creator (I'm using 2.8, and also tried 3.0)</p>
  
  <p>Any help greatly appreciated :-)</p>
  
  <p>Konrad</p>
  
  <hr>
  
  <p>EDIT: I just realized, that the whole Qt framework isn't recognized by qt-creator as well. When I type <code>#include "</code> the headers suggested by auto-completion are all located either in "/usr/include" or the project directory. For example I even can't do <code>#include &lt;QtGui&gt;</code>.</p>
  
  <p>what might be the problem here?</p>
  
  <hr>
  
  <p>EDIT2: The project file also includes gui.pri and local.pri which are used by several other projects as well. I tried to compress the files a bit - it still compiles without problems.</p>
  
  <p>actual project file located in "dir0/programs/us_convert"</p>
  
  <pre><code>include( ../../gui.pri )
  QT           += xml
  
  TARGET        = us_convert
  
  HEADERS       = us_convert_gui.h       \
                  us_convert.h           \
                  us_convertio.h         \
                  us_experiment.h        \
                  us_experiment_gui.h    \
                  us_selectbox.h         \
                  us_intensity.h         \
                  us_get_dbrun.h         \
                  us_mwl_data.h
  
  SOURCES       = us_convert_gui.cpp     \
                  us_convert.cpp         \
                  us_convertio.cpp       \
                  us_experiment.cpp      \
                  us_experiment_gui.cpp  \
                  us_selectbox.cpp       \
                  us_intensity.cpp       \
                  us_get_dbrun.cpp       \
                  us_mwl_data.cpp
  </code></pre>
  
  <p>gui.pri located in "dir0/"</p>
  
  <pre><code># Profile include file for applications
  
  !include( local.pri ) error( "local.pri is missing.  Copy from local.pri.template and update variables as appropriate" )
  
  TEMPLATE     = app
  DESTDIR      = ../../bin
  MOC_DIR      = ./moc
  OBJECTS_DIR  = ./obj
  VER          = 10
  
  CONFIG       += $$DEBUGORRELEASE qt thread warn
  
  unix {
    LIBS       += -L../../lib -lus_gui -lus_utils
    LIBS       += -lcrypto
    LIBS       += -lqwtplot3d-qt4 -lGLU
    LIBS       += -L$$MYSQLDIR -lmysqlclient
    DEFINES    += INTEL LINUX
  
    INCLUDEPATH  += $$MYSQLPATH ../../$$QWT3D/include
    INCLUDEPATH  += ../../gui ../../utils $$QWTPATH/include ..
  }
  </code></pre>
  
  <p>And local.pri, also located in "dir0/"</p>
  
  <pre><code>DEBUGORRELEASE += debug 
  
  unix {
  
    MYSQLPATH   = /usr/include/mysql/
    QWTPATH     = /usr/local/qwt-5.2.2
    SINGLEDIR   = /usr/lib/qt/qt-solutions/qtsingleapplication/src
    MYSQLDIR    = /usr/include/mysql
    QWT3D = /qwtplot3d-qt4/
    LIBS        += -L/usr/local/qwt-5.2.2/lib -lqwt
  
  }
  </code></pre>