Ech. I will prefer GOPATH over the hell that are C/C++ include paths any day of the week. How many are there on a modern Linux system? Six?
Holy hell, it's eight!
$ gcc -xc++ -E -v -
#include <...> search starts here:
/usr/include/c++/7
/usr/include/x86_64-linux-gnu/c++/7
/usr/include/c++/7/backward
/usr/lib/gcc/x86_64-linux-gnu/7/include
/usr/local/include
/usr/lib/gcc/x86_64-linux-gnu/7/include-fixed
/usr/include/x86_64-linux-gnu
/usr/include