title: Can't install rdiscount gem after installing RubyInstaller and DevKit on Windows
body: <p>I'm having some errors trying to set up RoR on my Windows 7 machine. I installed Ruby with the RubyInstaller and DevKit. In their directions it says to execute <code>gem install rdiscount --platform=ruby</code> to ensure that it's installed correctly. I get the following error:</p>
  
  <pre><code>C:\Windows\system32&gt;cd ../../DevKit
  
  C:\DevKit&gt;gem install rdiscount --platform=ruby
  Temporarily enhancing PATH to include DevKit...
  Building native extensions.  This could take a while...
  ERROR:  Error installing rdiscount:
          ERROR: Failed to build gem native extension.
  
      C:/Ruby200-x64/bin/ruby.exe extconf.rb
  checking for random()... *** 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=C:/Ruby200-x64/bin/ruby
          --with-rdiscount-dir
          --without-rdiscount-dir
          --with-rdiscount-include
          --without-rdiscount-include=${rdiscount-dir}/include
          --with-rdiscount-lib
          --without-rdiscount-lib=${rdiscount-dir}/
  C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:431:in `try_do': The compiler failed to ge
  nerate an executable file. (RuntimeError)
  You have to install development tools first.
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:516:in `try_link0'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:531:in `try_link'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:717:in `try_func'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:1001:in `block in have_func'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:892:in `block in checking_for
  '
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:337:in `block (2 levels) in p
  ostpone'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:307:in `open'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:337:in `block in postpone'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:307:in `open'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:333:in `postpone'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:891:in `checking_for'
          from C:/Ruby200-x64/lib/ruby/2.0.0/mkmf.rb:1000:in `have_func'
          from extconf.rb:5:in `&lt;main&gt;'
  
  
  Gem files will remain installed in C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rdisc
  ount-2.0.7.1 for inspection.
  Results logged to C:/Ruby200-x64/lib/ruby/gems/2.0.0/gems/rdiscount-2.0.7.1/ext/
  gem_make.out
  </code></pre>
  
  <p>I've tried <a href="https://github.com/oneclick/rubyinstaller/wiki/Troubleshooting#wiki-devkit_dll_conflict" rel="nofollow">this suggestion</a>, and removed a duplicate <code>libiconv-2.dll</code> file but the problem is persisting. Any suggestions?</p>