Unable to install Ruby with RVM - ruby-on-rails

Question

I'm having trouble installing Ruby with RVM, and this one has me stumped. I'm running on OS Mavericks, with the latest XCode and xcode command line tools. I have a (to my knowledge) identical set up on another machine with no problems.
RVM appeared to install with no problems.
Upon an attempt to rvm install 2.1, I received the following error message:
ruby-2.1.1 - #removing src/ruby-2.1.1..
Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.9/x86_64/ruby-2.1.1.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for osx.
Certificates in '/usr/local/etc/openssl/cert.pem' already are up to date.
Requirements installation successful.
Installing Ruby from source to: /Users/user/.rvm/rubies/ruby-2.1.1, this may take a while depending on your cpu(s)...
ruby-2.1.1 - #downloading ruby-2.1.1, this may take a while depending on your connection...
ruby-2.1.1 - #extracting ruby-2.1.1 to /Users/user/.rvm/src/ruby-2.1.1...
ruby-2.1.1 - #applying patch /Users/user/.rvm/patches/ruby/changeset_r45225.diff.
ruby-2.1.1 - #applying patch /Users/user/.rvm/patches/ruby/changeset_r45240.diff.
ruby-2.1.1 - #configuring.
Error running './configure --prefix=/Users/user/.rvm/rubies/ruby-2.1.1 --with-opt-dir=/usr/local/opt/libyaml:/usr/local/opt/readline:/usr/local/opt/libksba:/usr/local/opt/openssl --enable-shared',
showing last 15 lines of /Users/user/.rvm/log/1394918736_ruby-2.1.1/configure.log
[2014-03-15 21:25:55] ./configure
current path: /Users/user/.rvm/src/ruby-2.1.1
PATH=/usr/local/opt/pkg-config/bin:/usr/local/opt/libtool/bin:/usr/local/opt/automake/bin:/usr/local/opt/autoconf/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/Users/user/.rvm/bin
command(4): ./configure --prefix=/Users/user/.rvm/rubies/ruby-2.1.1 --with-opt-dir=/usr/local/opt/libyaml:/usr/local/opt/readline:/usr/local/opt/libksba:/usr/local/opt/openssl --enable-shared
checking build system type... x86_64-apple-darwin13.1.0
checking host system type... x86_64-apple-darwin13.1.0
checking target system type... x86_64-apple-darwin13.1.0
<stdin>:2:3: error: #error premature clang
#error premature clang
^
1 error generated.
configure: error: clang version 3.0 or later is required
There has been an error while running configure. Halting the installation.
My first thought was to run RVM requirements, which resulted in another error message
Checking requirements for osx.
Installing requirements for osx.
Updating system....
Installing required packages: gcc46.....
Error running 'requirements_osx_brew_libs_install gcc46',
showing last 15 lines of /Users/user/.rvm/log/1394919146/package_install_gcc46.log
+ case "$1" in
+ [[ -t 1 ]]
+ return 1
+ printf %b 'There were package installation errors, make sure to read the log.
Try `brew tap --repair` and make sure `brew doctor` looks reasonable.
Check Homebrew requirements https://github.com/mxcl/homebrew/wiki/Installation\n'
There were package installation errors, make sure to read the log.
Try `brew tap --repair` and make sure `brew doctor` looks reasonable.
Check Homebrew requirements https://github.com/mxcl/homebrew/wiki/Installation
+ case "$_system_version" in
+ return 1
Requirements installation failed with status: 1.
I followed the advice here, and have spent hours now looking online, but no solution yet has worked for me. Any thoughts and ideas are most welcome - this one has me stumped.

Answer 1

Once you have gcc46 insall you need to set it as the default compiler. You can find information on different ways to do that here: Setting GCC 4.2 as the default compiler on Mac OS X Leopard
Then as that output says, use brew tap --repair and brew doctor which gives you more info.