What is this new feature which breaks stl_algo.h ? g++ -c loopstl.cpp In file included from /usr/local/gcc5.0/include/c++/5.0.0/functional:49:0, from loopstl.cpp:17: /usr/local/gcc5.0/include/c++/5.0.0/bits/stl_function.h:169:7: error: ‘_GLIBCXX14_CONSTEXPR’ does not name a type _GLIBCXX14_CONSTEXPR ^ I'm trying to use std::max_element et al in the old way which has worked for years, and was still working in g++ 5.0 build of Dec. 18. -- Tim Prince