使用最新的 CMake 配置 Travis CI

Travis 上预装的 CMake 版本非常陈旧。你可以使用官方 Linux 二进制文件来构建更新版本。

这是 .travis.yml 的一个例子：

language: cpp

compiler:
  - gcc

# the install step will take care of deploying a newer cmake version
install:    
  # first we create a directory for the CMake binaries
  - DEPS_DIR="${TRAVIS_BUILD_DIR}/deps"
  - mkdir ${DEPS_DIR} && cd ${DEPS_DIR}
  # we use wget to fetch the cmake binaries
  - travis_retry wget --no-check-certificate https://cmake.org/files/v3.3/cmake-3.3.2-Linux-x86_64.tar.gz
  # this is optional, but useful:
  # do a quick md5 check to ensure that the archive we downloaded did not get compromised
  - echo "f3546812c11ce7f5d64dc132a566b749 *cmake-3.3.2-Linux-x86_64.tar.gz" > cmake_md5.txt
  - md5sum -c cmake_md5.txt
  # extract the binaries; the output here is quite lengthy,
  # so we swallow it to not clutter up the travis console
  - tar -xvf cmake-3.3.2-Linux-x86_64.tar.gz > /dev/null
  - mv cmake-3.3.2-Linux-x86_64 cmake-install
  # add both the top-level directory and the bin directory from the archive
  # to the system PATH. By adding it to the front of the path we hide the
  # preinstalled CMake with our own.
  - PATH=${DEPS_DIR}/cmake-install:${DEPS_DIR}/cmake-install/bin:$PATH
  # don't forget to switch back to the main build directory once you are done
  - cd ${TRAVIS_BUILD_DIR}

before_script:
  # create a build folder for the out-of-source build
  - mkdir build
  # switch to build directory
  - cd build
  # run cmake; here we assume that the project's
  # top-level CMakeLists.txt is located at '..'
  - cmake ..

script:
  # once CMake has done its job we just build using make as usual
  - make
  # if the project uses ctest we can run the tests like this
  - make test