message: In .travis.yml, enable ccache for the "Mac: Serial + Debug" job.
diff: @@ -242,6 +242,14 @@ jobs:
  # osx_image: xcode7.3
  compiler: clang
  name: "Mac: Serial + Debug"
  + addons:
  + homebrew:
  + packages:
  + - ccache
  + cache:
  + ccache: true
  + directories:
  + - $HOME/Library/Caches/Homebrew
  env: DEBUG=YES
  MPI=NO
  CODECOV=NO
  @@ -304,6 +312,14 @@ before_install:
  # brew install open-mpi;
  # fi
  + # Enable ccache on mac os:
  + - if [ $TRAVIS_OS_NAME == "osx" ]; then
  + export PATH="/usr/local/opt/ccache/libexec:$PATH";
  + fi
  +
  + - printf "which \$CC = "; which $CC;
  + printf "which \$CXX = "; which $CXX
  +
  # On Mac OS X, build and cache OpenMPI 2.1.1:
  - if [ $TRAVIS_OS_NAME == "osx" ] && [ $MPI == "YES" ]; then
  if [ ! -e $HOME/local-cached/bin/mpicc ]; then
  