gistfile1.txt

Installing atomic (1.1.14)
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.

    /Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/bin/ruby extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
	--with-opt-dir
	--without-opt-dir
	--with-opt-include
	--without-opt-include=${opt-dir}/include
	--with-opt-lib
	--without-opt-lib=${opt-dir}/lib
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/bin/ruby
	--with-atomic_reference-dir
	--without-atomic_reference-dir
	--with-atomic_reference-include
	--without-atomic_reference-include=${atomic_reference-dir}/include
	--with-atomic_reference-lib
	--without-atomic_reference-lib=${atomic_reference-dir}/
/Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:430:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
	from /Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:515:in `try_link0'
	from /Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:813:in `try_run'
	from extconf.rb:26:in `<main>'


Gem files will remain installed in /Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/atomic-1.1.14 for inspection.
Results logged to /Users/seo.naotoshi/.rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/atomic-1.1.14/ext/gem_make.out

An error occurred while installing atomic (1.1.14), and Bundler cannot continue.
Make sure that `gem install atomic -v '1.1.14'` succeeds before bundling.

http://qiita.com/ma2ge/items/a68f4441c9bd14233175