El otro día actualicé a Mac OSX Lion. Rompió la instalación de mis rieles ya que tuve que volver a compilar mysql. Si bien tengo ese trabajo, reinstalar la gema mysql2 se ha vuelto problemático. Anteriormente estaba ejecutando leopard, así que voy de 32 a 64 bits.

  ~/code/rails/london (master)$ gem install mysql2 -- --with-mysql-dir=/usr/local/mysql
  Building native extensions.  This could take a while...
  ERROR:  Error installing mysql2:
    ERROR: Failed to build gem native extension.

          /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/bin/ruby extconf.rb --with-mysql-dir=/usr/local/mysql
  checking for rb_thread_blocking_region()... *** 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/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/bin/ruby
  /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:368:in `try_do': The complier failed to generate an executable file. (RuntimeError)
  You have to install development tools first.
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:435:in `try_link0'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:440:in `try_link'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:552:in `try_func'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:797:in `block in have_func'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:693:in `block in checking_for'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:280:in `block (2 levels) in postpone'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:280:in `block in postpone'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:254:in `open'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:276:in `postpone'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:692:in `checking_for'
    from /Users/stewartmatheson/.rvm/rubies/ruby-1.9.2-p0/lib/ruby/1.9.1/mkmf.rb:796:in `have_func'
    from extconf.rb:9:in `<main>'


  Gem files will remain installed in /Users/stewartmatheson/.rvm/gems/ruby-1.9.2-p0@london/gems/mysql2-0.3.7 for inspection.
  Results logged to /Users/stewartmatheson/.rvm/gems/ruby-1.9.2-p0@london/gems/mysql2-0.3.7/ext/mysql2/gem_make.out

Hasta ahora he compilado e instalado MySQL y he actualizado RVM a la cabeza. También instalé Xcode, pero no tuve suerte.

Sugerencias?