message: travis: explicit build matrix
diff: sudo: required
  dist: xenial
  language: python
  -python:
  - - '2.7'
  - - '3.5'
  - - '3.6'
  -# - "nightly"
  git:
  depth: 1
  @@ -14,8 +9,17 @@ cache:
  - apt: true
  - pip : true
  -# clang is required because there is not enought ram for gcc
  -compiler: gcc
  +matrix:
  + include:
  + - name: "Python 2.7 gcc-8"
  + python: 2.7
  + env: CC=gcc-8 CXX=g++-8
  + - name: "Python 3.5 gcc-8"
  + python: 3.5
  + env: CC=gcc-8 CXX=g++-8
  + - name: "Python 3.7 gcc-8"
  + python: 3.7
  + env: CC=gcc-8 CXX=g++-8
  addons:
  apt:
  @@ -27,9 +31,6 @@ addons:
  - cython
  - g++-8
  - gcc-8
  - #- clang-3.9
  -#env: CC=clang-3.9 CXX=clang-3.9
  -env: CC=gcc-8 CXX=g++-8
  # command to install dependencies
  