gem install therubyracer

gistfile1.txt

gem install therubyracer
Building native extensions.  This could take a while...
/Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/ext/builder.rb:73: warning: Insecure world writable dir /Users/paul/.rvm/rubies in PATH, mode 040777
ERROR:  Error installing therubyracer:
        ERROR: Failed to build gem native extension.

    /Users/paul/.rvm/rubies/ruby-2.1.2/bin/ruby extconf.rb
checking for main() in -lpthread... *** 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/paul/.rvm/rubies/ruby-2.1.2/bin/ruby
        --with-pthreadlib
        --without-pthreadlib
/Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:541:in `try_link0'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:556:in `try_link'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:742:in `try_func'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:973:in `block in have_library'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:918:in `block in checking_for'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:351:in `block (2 levels) in postpone'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:321:in `open'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:351:in `block in postpone'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:321:in `open'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:347:in `postpone'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:917:in `checking_for'
        from /Users/paul/.rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/mkmf.rb:968:in `have_library'
        from extconf.rb:3:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in /Users/paul/.rvm/gems/[email protected]/gems/therubyracer-0.12.1 for inspection.
Results logged to /Users/paul/.rvm/gems/[email protected]/extensions/x86_64-darwin-13/2.1.0-static/therubyracer-0.12.1/gem_make.out