message: trying to get gcc 6/7/8 working on the latest osx image
diff: @@ -353,12 +353,15 @@ install:
  fi
  if [[ "${COMPILER}" = "g++-6" ]]; then
  brew install gcc6
  + brew link --overwrite gcc@6
  fi
  if [[ "${COMPILER}" = "g++-7" ]]; then
  brew install gcc7
  + brew link --overwrite gcc@7
  fi
  if [[ "${COMPILER}" = "g++-8" ]]; then
  brew install gcc8
  + brew link --overwrite gcc@8
  fi
  fi
  