g++ -c -pipe -O2 -Wall -W -pthread -D_THREAD_SAFE -fPIC -DQCAD_DLL -DPTHREADS 
  -DHAVE_PTHREAD_H -DQT_NO_DEBUG -DQT_WEBKIT_LIB -DQT_SCRIPT_LIB
  -DQT_SCRIPTTOOLS_LIB -DQT_SVG_LIB -DQT_SQL_LIB -DQT_XMLPATTERNS_LIB -DQT_XML_LIB
  -DQT_OPENGL_LIB -DQT_GUI_LIB -DQT_NETWORK_LIB -DQT_CORE_LIB -DQT_SHARED
  -I/usr/local/share/qt4/mkspecs/freebsd-g++ -I. -I/usr/local/include/qt4/QtHelp
  -I/usr/local/include/qt4/QtDesigner -I/usr/local/include/qt4/QtUiTools
  -I/usr/local/include/qt4/QtCore -I/usr/local/include/qt4/QtNetwork
  -I/usr/local/include/qt4/QtGui -I/usr/local/include/qt4/QtOpenGL
  -I/usr/local/include/qt4/QtXml -I/usr/local/include/qt4/QtXmlPatterns
  -I/usr/local/include/qt4/QtSql -I/usr/local/include/qt4/QtSvg
  -I/usr/local/include/qt4/QtScriptTools -I/usr/local/include/qt4/QtScript
  -I/usr/local/include/qt4/QtWebKit -I/usr/local/include/qt4 -I../../../../core
  -I../../../../core/math -I../../../../grid -I../../../../snap -I../../../../gui
  -I../../../../entity -I../../../../operations -I../../../../scripting
  -I../../../../stemmer -I../../../../scripting/ecmaapi
  -I../../../../scripting/ecmaapi/generated
  -I../../../../scripting/ecmaapi/adapters -I../../../../io/dxf
  -I../../../../spatialindex -I../../../../3rdparty -I. -I/usr/local/include
  -Irelease -I/usr/local/include/qt4 -I/usr/local/include -o
  release/qtscript_QPinchGesture.o
  ../../generated_cpp/com_trolltech_qt_gui/qtscript_QPinchGesture.cpp
../../generated_cpp/com_trolltech_qt_gui/qtscript_QPinchGesture.cpp:53: error: 
  redefinition of 'struct QMetaTypeId<QFlags<QPinchGesture::ChangeFlag> >'
/usr/local/include/qt4/QtGui/qgesture.h:202: error: previous definition of 
  'struct QMetaTypeId<QFlags<QPinchGesture::ChangeFlag> >'
../../generated_cpp/com_trolltech_qt_gui/qtscript_QPinchGesture.cpp:240: 
  warning: 'QScriptValue qtscript_QPinchGesture_prototype_call(QScriptContext*,
  QScriptEngine*)' defined but not used
*** [release/qtscript_QPinchGesture.o] Error code 1

$ sed '202!d' /usr/local/include/qt4/QtGui/qgesture.h
Q_DECLARE_METATYPE(QPinchGesture::ChangeFlags)

$ sed '53!d' <...>/qt-labs-qtscriptgenerator-4.8.5/<...>/qtscript_QPinchGesture.cpp
Q_DECLARE_METATYPE(QFlags<QPinchGesture::ChangeFlag>)

Using Qt version 4.8.5 in /usr/local/lib/qt4.