I have, with this code: 100: graph_traits::edge_iterator ei, eend; 101: for (tie(ei, eend) = boost::edges(graph); ei != eend; ei++) { I know this is not a major problem, as for the final release I will remove the -Wall flag from the compilation But then my question is why is the difference? Using boost 1.54 under Ubuntu 14.04 this warning shows on line 100 about variable ei /home/woodbri/work/pgrouting/src/apsp_johnson/src/apsp_johnson_boost_wrapper.cpp:100:40: warning: '*((void*)(& ei)+32).__gnu_cxx::__normal_iterator*, std::vector, std::allocator > > >:: _M_current' may be used uninitialized in this function [-Wmaybe-uninitialized] graph_traits::edge_iterator ei, eend; the complete code can be found : https://github.com/pgRouting/pgrouting/blob/develop/src/apsp_johnson/src/aps... in the cmake the compiler flags are set like this: set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fPIC -O2 -g -Wall -std=c++0x -frounding-math -Wno-deprecated") Complete setup can be found: https://github.com/pgRouting/pgrouting/blob/develop_2_1_0/CMakeLists.txt#L21... This is a test that has boost 1.46.1, no warning shows I also don't get a warning with boost 1.55 https://travis-ci.org/pgRouting/pgrouting/jobs/72064827#L1834 The complete conversation of the problem can be found here: https://github.com/pgRouting/pgrouting/issues/373#issuecomment-123749888