I encountered an error when I installed the 1.8.3 version of the json gem:
dyld: lazy symbol binding failed: Symbol not found: _rb_str_new_static
Referenced from: /Users/gnerkus/.rvm/gems/ruby-2.2.3/gems/json- 1.8.3/lib/json/ext/parser.bundle
Expected in: flat namespace
It was recommended on the json issue thread that libgmp3-dev be installed.
There are instructions for installing it on Linux but I've been unable to find any instructions for installing it on OSX.
The issue resolved itself after a reboot. There was no need to install libgmp3-dev as this was already installed by xcode.
I discovered that the issue was not caused by the json module but by rvm when it discovers a ruby binary.