Travis CI, update CMake using the packages cache

Question

I'm using this snippet to pre-install a desired compiler version inside a travis Virtual Machine

 - os: linux
  compiler: clang
  addons:
    apt:
      sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.5']
      packages: ['clang-3.5']
  env: COMPILER=clang++-3.5

This has the advantage of running the build inside a machine without using sudo which results in a faster build.

How do I use that to install cmake 2.8.12 (or more recent) both on linux and osx when using travis? I tried

  - os: linux
  compiler: clang
  addons:
    apt:
      sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.5', 'add-apt-repository']
      packages: ['clang-3.5', 'ppa:kalakris/cmake']
  env: COMPILER=clang++-3.5

without success

Answer 1

To install cmake from kalakris, use:

addons:
    apt:
      packages:
        - cmake
      sources:
        - kalakris-cmake

For a more recent CMake (from https://github.com/ldionne/hana/blob/master/.travis.yml)

if [[ "${TRAVIS_OS_NAME}" == "linux" ]]; then
  CMAKE_URL="http://www.cmake.org/files/v3.3/cmake-3.3.1-Linux-x86_64.tar.gz"
  mkdir cmake && travis_retry wget --quiet -O - ${CMAKE_URL} | tar --strip-components=1 -xz -C cmake
  export PATH=${DEPS_DIR}/cmake/bin:${PATH}
else
  brew install cmake
fi

A full snippet in your case is:

 - os: linux
  compiler: clang
  addons:
    apt:
      sources: ['ubuntu-toolchain-r-test', 'llvm-toolchain-precise-3.7', 'kalakris-cmake']
      packages: ['clang-3.7', 'cmake']
  env: COMPILER=clang++-3.7