compiler:
    - gcc
    - clang

language: c

os:
    - linux
    - osx

addons:
  apt:
    sources:
    - ubuntu-toolchain-r-test
    packages:
    - gcc-5

install:
    - if [ "$CC" == "gcc" ] ; then export CC="gcc-5"; fi
    
script:
    - make

compiler:
    - gcc
    - clang

language: c

os:
    - linux
    - osx

addons:
  apt:
    sources:
    - ubuntu-toolchain-r-test
    packages:
    - gcc-5

install:
    - if [ "$TRAVIS_OS_NAME" == "linux" ] && [ "$CC" == "gcc" ] ; then export CC="gcc-5"; fi
    - if [ "$TRAVIS_OS_NAME" = "osx" ] && [ "$CC" = "gcc" ]; then export CC="gcc-4.8"; fi
    
script:
    - make

Use gcc-4.8 for Travis-CI on OS X
Use gcc-4.8 for Travis-CI on OS X