LionにしてからXCodeのアップデートするの忘れてた

Ruby

rvmで新しくgemset作って、最新のrailsを入れようとしたら以下のようなエラーが出た。

$ gem install rails
Building native extensions.  This could take a while...
ERROR:  Error installing rails:
	ERROR: Failed to build gem native extension.

        /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/bin/ruby extconf.rb
checking for re.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/yamazaki/.rvm/rubies/ruby-1.9.2-p180/bin/ruby
/Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/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/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:452:in `try_cpp'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:834:in `block in have_header'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:693:in `block in checking_for'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:280:in `block (2 levels) in postpone'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:254:in `open'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:280:in `block in postpone'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:254:in `open'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:276:in `postpone'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:692:in `checking_for'
	from /Users/yamazaki/.rvm/rubies/ruby-1.9.2-p180/lib/ruby/1.9.1/mkmf.rb:833:in `have_header'
	from extconf.rb:14:in `
'


Gem files will remain installed in /Users/yamazaki/.rvm/gems/ruby-1.9.2-p180@oshiri/gems/json-1.6.1 for inspection.
Results logged to /Users/yamazaki/.rvm/gems/ruby-1.9.2-p180@oshiri/gems/json-1.6.1/ext/json/ext/parser/gem_make.out

なんかコンパイルでエラーになってるようだけど、、と思ったらgccが入ってない。。あれれ？？
そういえばMacをLionにアップデートしてからXcodeのアップデートしてないなということでAppStoreからXcodeをダウンロードしてアップデート。無事にインストールできました^^