I tried installing the Command-T-plugin in OS X 10.9.2 with a current command line-vim installed via homebrew. When I did the make-command I got the following error:
linking shared-object ext.bundle
clang: error: unknown argument: '-multiply_definedsuppress'
[-Wunused-command-line-argument-hard-error-in-future]
clang: note: this will be a hard error (cannot be downgraded to a
warning) in the future
make: *** [ext.bundle] Error 1
The solution I found was to edit the Makefile in the folder ruby/command-t of the plug-in. I just commented out the ‘-multiply_definedsuppress’ in the following line:
dldflags = -undefineddynamic_lookup -multiply_definedsuppress
So it looks now like this:
dldflags = -undefineddynamic_lookup #-multiply_definedsuppress
after that make ran without any problems and command-t works for me. I didn't try it with MacVim yet and there might be problems because of different ruby-versions (this is described in the manual). But I use usually the command line-version anyways.