macos - OS X: installed gcc links to clang

Question

I already have gcc and g++ install:

$ which gcc
/usr/bin/gcc

$ which g++
/usr/bin/g++

$ brew install gcc
Warning: gcc-6.2.0 already installed

I follow Compile OpenMP programs with gcc compiler on OS X Yosemite to reinstall gcc via HomeBrew:

$ brew reinstall gcc --without-multilib

then

$ /usr/bin/g++ openmp.cpp
openmp.cpp:12:10: fatal error: 'omp.h' file not found
#include <omp.h>
         ^
1 error generated.

with -fopenmp

$ /usr/bin/g++ openmp.cpp -fopenmp
clang: error: unsupported option '-fopenmp'
clang: error: unsupported option '-fopenmp'

What's happening with this redirection? How could I use gcc/g++?

---

Though involved, it's not about OpenMP.

Answer 1

brew installs tools in /usr/local/bin. Use /usr/local/bin/g++6:

$ /usr/local/bin/g++-6 --version
g++-6 (Homebrew gcc 6.2.0) 6.2.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.