title: therubyracer install error
body: <p>As you can see below, libv8 installs fine, but therubyracer doesn't. I'm using Mac 10.7.4.</p>
  
  <pre><code>~/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1&gt; gem install libv8
  Building native extensions.  This could take a while...
  Successfully installed libv8-3.11.8.3
  1 gem installed
  Installing ri documentation for libv8-3.11.8.3...
  Installing RDoc documentation for libv8-3.11.8.3...
  
  ~/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1&gt; gem install therubyracer
  Building native extensions.  This could take a while...
  ERROR:  Error installing therubyracer:
      ERROR: Failed to build gem native extension.
  
          /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/bin/ruby extconf.rb
  checking for main() in -lobjc... *** 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
      --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/rdp/.rvm/rubies/ruby-1.9.3-p125/bin/ruby
      --with-objclib
      --without-objclib
  /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
  You have to install development tools first.
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:461:in `try_link0'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:476:in `try_link'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:619:in `try_func'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:845:in `block in have_library'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:254:in `open'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:254:in `open'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
      from /Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/1.9.1/mkmf.rb:840:in `have_library'
      from extconf.rb:10:in `&lt;main&gt;'
  
  
  Gem files will remain installed in /Users/rdp/.rvm/gems/ruby-1.9.3-p125/gems/therubyracer-0.10.1 for inspection.
  Results logged to /Users/rdp/.rvm/gems/ruby-1.9.3-p125/gems/therubyracer-0.10.1/ext/v8/gem_make.out
  </code></pre>
  
  <p>Here's the <code>mkmf.log</code>, which is located in <code>~/.rvm/rubies/ruby-1.9.3-p125/lib/ruby/gems/1.9/gems/therubyracer-0.10.1/ext/v8&gt;</code>.</p>
  
  <p>File Edit Options Buffers Tools Help                                                                                                                                          </p>
  
  <pre><code>"/usr/bin/gcc-4.2 -o conftest -I/Users/rdp/.rvm/rubies/ruby-1.9.3-p125/include/ruby-1.9.1/x86_64-darwin11.3.0 -I/Users/rdp/.rvm/rubies/ruby-1.9.3-p125/include/ruby-1.9.1/rub\
  y/backward -I/Users/rdp/.rvm/rubies/ruby-1.9.3-p125/include/ruby-1.9.1 -I. -I/Users/rdp/.rvm/usr/include -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE    -O3 -ggdb -Wextra -Wno-unused-\
  parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-functio\
  n-declaration  -fno-common -pipe conftest.c  -L. -L/Users/rdp/.rvm/rubies/ruby-1.9.3-p125/lib -L/Users/rdp/.rvm/usr/lib -L.      -lruby.1.9.1  -lpthread -ldl -lobjc "
  checked program was:
  /* begin */
  1: #include "ruby.h"
  2:
  3: int main() {return 0;}
  /* end */
  </code></pre>