Osmium in eclpse cdt

I need to use the C++ osmium library and I program using Eclipse cdt. To be sure my system is well configured, I managed to compile and link few of the examples by hand.

Osmium uses C++11 and it seems my Eclipse has a problem understanding it. I added -std=c++11 to the project properties under C++ Build -> Settings -> C++ compiler -> Miscellaneous and under C++ Build -> Discovery Options.

Strangely in my main file it seems the C++11 features are working, for example I can write

for (auto a : {1,2,3,4,5}) {}

but the osmium directory I copied in the project instead results filled of errors. It is not a missing include directory since the lines #include <osmium/so/and/so> show no errors.

I stuck, what can I do to set up Eclipse?