Installing doesn't work about debugger HOT 6 CLOSED

Fetching: debugger-ruby_core_source-1.1.1.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing debugger:
        ERROR: Failed to build gem native extension.

        /Users/jstojanovski/.rbenv/versions/1.9.3-p0/bin/ruby extconf.rb --with-ruby-include=/Users/jstojanovski/.rbenv/versions/1.9.3-p0/include/ruby-1.9.1/ruby-1.9.3-p0
checking for vm_core.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
  --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/jstojanovski/.rbenv/versions/1.9.3-p0/bin/ruby
  --with-ruby-dir
  --without-ruby-dir
  --with-ruby-include=${ruby-dir}/include
  --with-ruby-lib
  --without-ruby-lib=${ruby-dir}/lib
/Users/jstojanovski/.rbenv/versions/1.9.3-p0/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/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:506:in `try_cpp'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:931:in `block in have_header'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:254:in `open'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:254:in `open'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:930:in `have_header'
  from extconf.rb:9:in `block in <main>'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/debugger-ruby_core_source-1.1.1/lib/debugger/ruby_core_source.rb:17:in `call'
  from /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/debugger-ruby_core_source-1.1.1/lib/debugger/ruby_core_source.rb:17:in `create_makefile_with_core'
  from extconf.rb:13:in `<main>'


Gem files will remain installed in /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/debugger-linecache-1.1.1 for inspection.
Results logged to /Users/jstojanovski/.rbenv/versions/1.9.3-p0/lib/ruby/gems/1.9.1/gems/debugger-linecache-1.1.1/ext/trace_nums/gem_make.out