Unable to install Rails extconf.rb failed - ruby-on-rails

Question

I'm new to Ruby on Rails, and I'm getting the below error when I'm installing it.
Please note, I have installed the latest Xcode and installed command line tools, and I'm using OSX 10.8.4. I've installed Ruby 2.0.0 as well.
-bash-3.2$ sudo gem install rails
Password:
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
/Users/WillieTran/.rvm/rubies/ruby-2.0.0-p247/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/WillieTran/.rvm/rubies/ruby-2.0.0-p247/bin/ruby
--with-atomic_reference-dir
--without-atomic_reference-dir
--with-atomic_reference-include
--without-atomic_reference-include=${atomic_reference-dir}/include
--with-atomic_reference-lib
--without-atomic_reference-lib=${atomic_reference-dir}/
/Users/WillieTran/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /Users/WillieTran/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:519:in `try_link0'
from /Users/WillieTran/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:817:in `try_run'
from extconf.rb:24:in `<main>'
Gem files will remain installed in /Users/WillieTran/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/gems/2.0.0/gems/atomic-1.1.12 for inspection.
Results logged to /Users/WillieTran/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/gems/2.0.0/gems/atomic-1.1.12/ext/gem_make.out

Answer 1

I had similar problem and it gets solved by installing command line tools:
xcode-select --install

Answer 2

The symlinking did not solve the problem for me. I uninstalled my ruby that I previously had installed using rvm by typing rvm uninstall ruby-2.0.0 and then I typed rvm requirements. This command found that I needed a few other things, such as gcc46. It's strange that the gcc compiler was needed, even though I had installed the xcode command line tools, and gcc was most definitely installed on my system.
So, if none of the usual methods are working, give rvm requirements a shot!

Answer 3

I guess it's a same problem with this question.
Try sudo ln -s /usr/bin/{llvm-,}gcc-4.2 and gem install rails again.
By the way, you're in your own home directory, you don't have to use sudo.

Answer 4

I just ran into this with ruby 2.5.3 and was able to install cairo by calling:
PKG_CONFIG_PATH=/usr/local/opt/libffi/lib/pkgconfig gem install cairo -v '1.15.2'
Took a while to find something that worked, as I already had the command line tools installed, and am using asdf not rvm.
Thanks to this thread for helping with the fix: https://github.com/ruby-gnome2/ruby-gnome2/issues/259#issuecomment-59751807