id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
11876	Boost.Graph conflicts with Qt's foreach macro	richel@…	Jeremiah Willcock	"This is a similar problem as https://svn.boost.org/trac/boost/ticket/6455, where the Qt `foreach` macro conflicts with the `boost::foreach::tag` in file `/usr/include/boost/foreach.hpp`.

This is a simple Qt example that reproduces the error (also supplied as an attachment):

{{{
#include <boost/graph/adjacency_list.hpp>
#include <QCoreApplication>
#include <fstream>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/graphviz.hpp>

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  std::ofstream f(""filename.dot"");
  boost::write_graphviz(
    f,
    boost::adjacency_list<>()
  );
  return a.exec();
}
}}}

For the following Qt Creator project file:

{{{
QT       += core
QT       -= gui
CONFIG   += console
CONFIG   -= app_bundle
TEMPLATE = app
SOURCES += main.cpp
}}}

The error given is:

{{{
In file included from /usr/include/boost/graph/graphviz.hpp:35:0,
                 from ../CppBoostGraphAndQtConflictQtConsole/main.cpp:5:
/usr/include/boost/foreach.hpp:169:42: error: 'boost::Q_FOREACH::tag' has not been declared
 boost_foreach_is_lightweight_proxy(T *&, BOOST_FOREACH_TAG_DEFAULT) { return 0; }
}}}

The error does not occur if 'boost/graph/adjacency_list.hpp' is #included either before `QCoreApplication` or after. This is a workaround.

I cannot see if this error is still present in later versions of Boost. If it is still present, I hope I have contributed in letting Boost.Graph and Qt work together seamlessly. "	Bugs	new	To Be Determined	graph	Boost 1.54.0	Problem		Graph BGL Qt