Não pergunte o que é isso, apenas cole no console
rbenv local ree-1.8.7-2012.02
gem install bundler
git clone https://github.com/cowboyd/libv8
cd libv8
git checkout v3.16.14.3
echo "source 'https://rubygems.org'ngem 'rubyzip', '0.9.7' ngemspecn" > Gemfile
gem update --system
rake checkout
curl https://raw.githubusercontent.com/sikachu/libv8/20093a74bfc77bd5ef772d8173f14e603682c373/patches/clang51/no-unused-variable.patch -o patches/my-patch
git add patches/my-patch.patch
rake install
gem install therubyracer -v '0.12.0'Obrigado @oivoodoo por contribuir.