Chapter 2 says that the first code example can be compiled with:
clang++ -g -O3 toy.cpp
but this doesn't compile because of the use of:
One way to solve this is to change this to std::make_unique and add -std=c++-14
to the command line. But since the tutorial's aim is to use LLVM anyway, a
minimal change is to just add llvm-config --cxxflags.