title: Error: Failed to build native gem extension
body: <p>I've tried following some of the advice to uninstall libv8 and reinstall it, then run bundle, but it doesn't seem to work. I'm trying to install twitter-bootstrap-rails with less.</p>
  
  <pre><code>&gt; gem install libv8 -v 3.16.14.3 -- --with-system-v8
  Done installing documentation for  after 0 seconds
  &gt; bundle update
  Updating git://github.com/seyhunak/twitter-bootstrap-rails.git
  Fetching gem metadata from https://rubygems.org/.........
  Fetching additional metadata from https://rubygems.org/..
  Resolving dependencies...
  Installing rake (10.3.1)
  Using i18n (0.6.9)
  Using minitest (4.7.5)
  Using multi_json (1.9.2)
  Installing thread_safe (0.3.3)
  Installing tzinfo (0.3.39)
  Using activesupport (4.0.2)
  Using builder (3.1.4)
  Using erubis (2.7.0)
  Using rack (1.5.2)
  Using rack-test (0.6.2)
  Using actionpack (4.0.2)
  Using mime-types (1.25.1)
  Using polyglot (0.3.4)
  Using treetop (1.4.15)
  Using mail (2.5.4)
  Using actionmailer (4.0.2)
  Using activemodel (4.0.2)
  Using activerecord-deprecated_finders (1.0.3)
  Using arel (4.0.2)
  Using activerecord (4.0.2)
  Using bcrypt (3.1.7)
  Using bundler (1.5.2)
  Using coffee-script-source (1.7.0)
  Using execjs (2.0.2)
  Using coffee-script (2.2.0)
  Installing thor (0.19.1)
  Using railties (4.0.2)
  Using coffee-rails (4.0.1)
  Using orm_adapter (0.5.0)
  Using warden (1.2.3)
  Installing devise (3.2.4)
  Using hike (1.2.3)
  Using jbuilder (1.5.3)
  Using jquery-rails (3.1.0)
  Using json (1.8.1)
  Using kaminari (0.15.1)
  Using libv8 (3.16.14.3)
  Using tilt (1.4.1)
  Using sprockets (2.11.0)
  Using sprockets-rails (2.0.1)
  Using rails (4.0.2)
  Using rdoc (4.1.1)
  Using ref (1.0.5)
  Installing sass (3.2.19)
  Installing sass-rails (4.0.3)
  Using sdoc (0.4.0)
  Using simple_form (3.0.2)
  Using sqlite3 (1.3.9)
  
  Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
      /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb 
  checking for main() in -lpthread... yes
  checking for main() in -lobjc... yes
  creating Makefile
  
  make "DESTDIR=" clean
  
  make "DESTDIR="
  compiling accessor.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling array.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling backref.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling constants.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling constraints.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling context.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling date.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling exception.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling external.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling function.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling gc.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling handles.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling heap.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling init.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  init.cc:11:20: warning: empty parentheses interpreted as a function declaration [-Wvexing-parse]
      v8::Locker lock();
                     ^~
  init.cc:11:20: note: remove parentheses to declare a variable
      v8::Locker lock();
                     ^~
  init.cc:11:16: warning: 'lock' has C-linkage specified, but returns user-defined type 'v8::Locker' which is incompatible with C [-Wreturn-type-c-linkage]
      v8::Locker lock();
                 ^
  2 warnings generated.
  compiling invocation.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling locker.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling message.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling object.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling primitive.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling rr.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling script.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling signature.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling stack.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling string.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling template.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling trycatch.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling v8.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  compiling value.cc
  clang: warning: argument unused during compilation: '-rdynamic'
  linking shared-object v8/init.bundle
  clang: error: unknown argument: '-multiply_definedsuppress' [-Wunused-command-line-argument-hard-error-in-future]
  clang: note: this will be a hard error (cannot be downgraded to a warning) in the future
  make: *** [init.bundle] Error 1
  
  make failed, exit code 2
  
  Gem files will remain installed in /Users/****/.bundler/tmp/63501/gems/therubyracer-0.12.1 for inspection.
  Results logged to /Users/****/.bundler/tmp/63501/extensions/universal-darwin-13/2.0.0/therubyracer-0.12.1/gem_make.out
  An error occurred while installing therubyracer (0.12.1), and Bundler cannot
  continue.
  Make sure that `gem install therubyracer -v '0.12.1'` succeeds before bundling.
  </code></pre>
  
  <p>I'm not sure what else to do at this point. Should I try uninstalling the gems and reinstalling them?</p>