Installing libv8 for ree on Mountain Lion fails - ruby-on-rails

Question

I've been trying to find a solution to this for a few days now and no luck. If anyone has been successful installing the libv8 gem for REE 1.8.7 on ML, could you please let me know the process you followed?
I have both the XCode LLVM compiler as well as the kennethreitz GCC package for 10.7+ v2 installed.
The output when trying to install with native extensions is:
Building native extensions. This could take a while...
ERROR: Error installing libv8:
ERROR: Failed to build gem native extension.
/Users/XXXXX/.rvm/rubies/ree-1.8.7-2012.02/bin/ruby extconf.rb
*** 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/XXXXX/.rvm/rubies/ree-1.8.7-2012.02/bin/ruby
extconf.rb:13: uninitialized constant Gem (NameError)
Checking for Python...
Gem files will remain installed in /Users/XXXXX/.rvm/gems/ree-1.8.7-2012.02/gems/libv8-3.3.10.4 for inspection.
Results logged to /Users/XXXXX/.rvm/gems/ree-1.8.7-2012.02/gems/libv8-3.3.10.4/ext/libv8/gem_make.out
(The results logged are the exact same as the error).

Answer 1

This worked for me.
RUBYOPT=-rrubygems gem install therubyracer

Answer 2

I was able to successfully install the libv8 gem on Mountain Lion on a freshly installed ree-1.8.7. I believe the issue you're seeing stems from the GCC version being used.
As is now described in the osx-gcc-installer's README you should switch from Kenneth Reitz's LLVM-version of GCC to the GCC 4.2 that is available via Homebrew or Macports.
Homebrew instructions:
http://coderwall.com/p/dtbuqg
MacPorts instructions:
http://coderwall.com/p/pagj2w
Note that you will want to set the CC path and establish the necessary symlink as described in those articles.