message: upgrade to gcc10
diff: @@ -15,7 +15,8 @@ matrix:
  packages:
  - g++-7
  env:
  - - MATRIX_EVAL="CC=gcc-7 && CXX=g++-7"
  + - MATRIX_EVAL="CC=gcc-10 && CXX=g++-10"
  +# - MATRIX_EVAL="CC=gcc-7 && CXX=g++-7"
  # - os: osx
  # osx_image: xcode11.2
  # env:
  