Unfortunately this is a more fundamental problem than setting the C++ standard.
The Projucer uses LLVM’s JIT under the hood, but the JIT is far from feature complete and cannot compile some of the more common
std:: headers - it will also choke on
map and a few more . Fixing this in LLVM-land is far from trivial. JUCE contains it’s own implementation of
std::function which we use with the live build (and when targeting very old versions of OS X), but replacing any of the others would be a much bigger job.
@ed95 is currently upgrading the live build backend of the latest version of Clang, but, unfortunately, there’s no guarantee that it will improve things in this regard.