Trouble compiling code from LLVM Kaleidoscope tutorial

Question

When I used g++ -std=c++17 toy.cpp -o toy to compile the toy.cpp file without the header #include "llvm/ADT/STLExtras.h" in the toy.cpp file, everything was fine and I produced a "working" binary file.

However, when I added the #include "llvm/ADT/STLExtras.h" line to the toy.cpp file and compile it with the command g++ -std=c++17 toy.cpp -o toy , the terminal crushed me with the following output:

-bash: llvm-config: command not found
toy.cpp:1:10: fatal error: 'llvm/ADT/STLExtras.h' file not found
#include "llvm/ADT/STLExtras.h"

The same thing still happens even if I used "clang++ -g -O3 toy.cpp llvm-config --cxxflags --ldflags --system-libs --libs core -o toy" instead of "clang++ -g -O3 toy.cpp llvm-config --cxxflag " in the tutorial. My guess is that there's something wrong with the llvm-config thing. It's been bothering me for a while, please teach me how to solve it.

Link to the toy.cpp code

Answer 1

The answer to this is "llvm-config" is not working as expected.

Just check with which llvm-config to figure out whether you got this program. (mine is /usr/local/opt/llvm@8/bin/llvm-config ). Or you can install with brew install llvm .

By the way, I came up with the same issue lately on kaleidoscope tutorial (ch2), but I want to know why the #include "llvm/ADT/STLExtras.h fails after several attempts on $(llvm-config --cxxflags --ldflags) , etc or we aren't able to compile following chapter's code simply by removing the header declaration when llvm include files are necessary.