title: Xcode version must be specified to use an Apple CROSSTOOL
body: <p>I try to build tensorflow-serving using bazel but I've encountered some errors during the building </p>
  
  <pre><code>ERROR:/private/var/tmp/_bazel_Kakadu/3f0c35881c95d2c43f04614911c03a57/external/local_config_cc/BUILD:49:5: in apple_cc_toolchain rule @local_config_cc//:cc-compiler-darwin_x86_64: Xcode version must be specified to use an Apple CROSSTOOL.
  
  ERROR: Analysis of target '//tensorflow_serving/sources/storage_path:file_system_storage_path_source_proto' failed; build aborted.
  </code></pre>
  
  <p>I've already tried to use <code>bazel clean</code> and <code>bazel clean --expunge</code> but it didn't help and still Bazel doesn't see my xcode (I suppose) but it's completely installed. I even reinstalled it to make sure that all works fine but the error didn't disappeared </p>
  
  <p>My Bazel version is </p>
  
  <pre><code>Build label: 0.5.2-homebrew
  Build target: bazel-out/darwin_x86_64-opt/bin/src/main/java/com/google/devtools/build/lib/bazel/BazelServer_deploy.jar
  Build time: Thu Jul 13 12:29:40 2017 (1499948980)
  Build timestamp: 1499948980
  Build timestamp as int: 1499948980
  KakaduDevs-Mac-mini:serving Kakadu$ 
  </code></pre>
  
  <p>OS is MacOS Sierra version 10.12.5</p>
  
  <p>What should I do to specify Xcode version in bazel to avoid this error? It seems that the error is common but I haven't found how I can make the bazel build.
  P.S I'm trying to install tensorflow-serving the way it's explained here.
  <a href="https://tensorflow.github.io/serving/setup" rel="noreferrer">https://tensorflow.github.io/serving/setup</a></p>