title: Installing ruby debug19. Compiler failed to generate an executable file
body: <p>I am trying to install ruby debug 19 so I can run spork. I am getting errors though that are very frustrating. I've googled for a while to no avail. I am running 1.9.3-p194.</p>
  
  <p>Here's the error message:</p>
  
  <p>Building native extensions.  This could take a while...
  ERROR:  Error installing ruby-debug19:
      ERROR: Failed to build gem native extension.</p>
  
  <pre><code>    /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/bin/ruby extconf.rb
  checking for rb_method_entry_t.body in method.h... *** 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/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/bin/ruby
  --with-ruby-dir
  --without-ruby-dir
  --with-ruby-include
  --without-ruby-include=${ruby-dir}/include
  --with-ruby-lib
  --without-ruby-lib=${ruby-dir}/lib
  /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/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/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:491:in `block in try_compile'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:443:in `with_werror'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:491:in `try_compile'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:1002:in `block in have_struct_member'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:254:in `open'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
  from /Users/jasonvdm/.rvm/rubies/ruby-1.9.3-p194/lib/ruby/1.9.1/mkmf.rb:1001:in `have_struct_member'
  from extconf.rb:10:in `block in &lt;main&gt;'
  from /Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/ruby_core_source-0.1.5/lib/ruby_core_source.rb:18:in `call'
  from /Users/jasonvdm/.rvm/gems/ruby-1.9.3-p194@wheelz/gems/ruby_core_source-0.1.5/lib/ruby_core_source.rb:18:in `create_makefile_with_core'
  from extconf.rb:24:in `&lt;main&gt;'
  </code></pre>