Re: [Rails] cannot install Mongrel gem w ruby-1.9.2-preview3 [ x86_64 ] and Rails 3.0.0.beta4 [OS X 10.6.4]

Looking at your error gcc -I. -I/Users/yves/.rvm/rubies/ruby-1.9.2-preview3/include/ruby-1.9.1/x86_64-darwin10.4.0 Do you see that there are 2 ruby versions there? RVM suggests you to always install gems without sudo (or if you installed your first one with sudo, keep doing that forever). Try to

[Rails] cannot install Mongrel gem w ruby-1.9.2-preview3 [ x86_64 ] and Rails 3.0.0.beta4 [OS X 10.6.4]

error in make ... yves$ sudo gem install mongrel Building native extensions. This could take a while... ERROR: Error installing mongrel: ERROR: Failed to build gem native extension. /Users/yves/.rvm/rubies/ruby-1.9.2-preview3/bin/ruby extconf.rb checking for main() in -lc... yes