message: construction_worker: added GCC7
diff: @@ -191,6 +191,14 @@ matrix:
  sources: ['ubuntu-toolchain-r-test']
  packages: g++-6
  + - os: linux
  + compiler: gcc
  + env: COMPILER=g++-7
  + addons:
  + apt:
  + sources: ['ubuntu-toolchain-r-test']
  + packages: g++-7
  +
  # Linux / Clang
  - os: linux
  