Arch repos recently upped their ruby version to 2.0.0. A good thing in general, but it slightly messed up a rails project I was working on. Suddenly a bunch of things were broken. A quick Google search later, it was clear that RVM was the solution to my problems. It was, however, not being very nice to me.

$ rvm install ruby-1.9.3-p392
Searching for binary rubies, this might take some time.
No binary rubies available for: arch/libc-2.17/x86_64/ruby-1.9.3-p392.
Continuing with compilation. Please read 'rvm mount' to get more information on binary rubies.
Installing requirements for arch, might require sudo password.
error: package 'gcc' was not found
error: package 'libtool' was not found
Installing required packages: gcc, libtool......
Error running 'requirements_arch_libs_install gcc libtool',
please read /home/ward/.rvm/log/ruby-1.9.3-p392/1366392891_package_install_gcc_libtool.log

Essentially, it was not finding gcc. Something I definitely have installed, though it is provided by a different package, gcc-multilib, since I am on 64 bit Arch and still need some of the programs that only have a 32 bit version. Luckily I came across this bug report describing my problem exactly as well as, more importantly, a fix to the issue at hand.

The fix seems to be targeted for release in RVM 1.20, so there is a good chance all you need to do to fix your issue is update RVM. If that did not work, we can go and apply the commit ourselves already.

$ cd ~/.rvm/
$ wget
$ patch -p1 < 949f2a1708fa99b389af7c72c8bfd4fd7ae17322.diff

What this does is go into the RVM folder, download the commit from earlier as a diff file and finally apply it to our folder. Having done this, you should be able to install ruby versions without any problems as described in the RVM documentation.