We’ve been receiving various reports of intermittent errors while running Rails applications and regular Ruby stuff that goes something like this: “undefined method ‘include?’ for -517611318:Fixnum”.

It appears that this might be a problem with GCC 4.0-compilations of Ruby. Most platforms are still using GCC 3.3, so they don’t see the problem. But on OS X, GCC 4.0 is now default if you’ve installed the recent Xcode. To switch back to GCC 3.3, do: sudo gcc_select 3.3 and then recompile Ruby.

We’ve love to get more reports and evidence on what exactly the problem is. Perhaps we can get it fixed in time for Ruby 1.8.4. Please use the comments.