在 Macbook Pro 上使用 OSX 10.8.4 和 homebrew、xcode（带有命令行工具）和 libffi。
我已经安装了 rvm 和 ruby-1.9.3-p448 并且有一个名为 omega.ecoop 的 gemset。有一个 gemfile 列出了这个项目所需的 gem。但是，在运行捆绑检查后，我无法安装它们：
Bundler can't satisfy your Gemfile's dependencies.
这是正确的，因为它们没有安装。所以我使用：
bundle install
产生以下内容：
Sams-MacBook-Pro:ecoop Sam$ bundle install
Fetching gem metadata from https://rubygems.org/..........
Fetching gem metadata from https://rubygems.org/..
Resolving dependencies...
Using addressable (2.3.5)
Using chunky_png (1.2.8)
Using fssm (0.2.10)
Using sass (3.2.10)
Using compass (0.12.2)
Using breakpoint (2.0.6)
Using coderay (1.0.9)
Using compass-blend-modes (0.0.2)
Using color-schemer (0.2.5)
Using compass-normalize (1.4.3)
Using compass-rgbapng (0.2.1)
Using compass-validator (3.0.1)
Using css_parser (1.3.5)
Using eventmachine (1.0.3)
Using http_parser.rb (0.5.3)
Using em-websocket (0.5.0)
Installing ffi (1.9.0)
一切顺利，直到：
Installing ffi (1.9.0)
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/Users/Sam/.rvm/rubies/ruby-1.9.3-p448/bin/ruby extconf.rb
checking for ffi.h... no
checking for ffi.h in /usr/local/include,/usr/include/ffi... no
checking for rb_thread_blocking_region()... yes
checking for rb_thread_call_with_gvl()... yes
checking for rb_thread_call_without_gvl()... yes
checking for ffi_prep_cif_var()... no
creating extconf.h
creating Makefile
make
mkdir -p "/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c"/libffi-x86_64; (if [ ! -f "/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c"/libffi-x86_64/Makefile ]; then echo "Configuring libffi for x86_64"; cd "/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c"/libffi-x86_64 && env CC=" gcc-4.6" CFLAGS="-arch x86_64 " LDFLAGS="-arch x86_64" "/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c/libffi"/configure --disable-static --with-pic=yes --disable-dependency-tracking --host=x86_64-apple-darwin > /dev/null; fi); env MACOSX_DEPLOYMENT_TARGET=10.4 make -C "/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c"/libffi-x86_64
Configuring libffi for x86_64
configure: WARNING: if you wanted to set the --build type, don't use --host.
If a cross compiler is detected then cross compile mode will be used
configure: error: in `/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c/libffi-x86_64':
configure: error: C compiler cannot create executables
See `config.log' for more details
make[1]: *** No targets specified and no makefile found. Stop.
make: *** ["/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c"/libffi-x86_64/.libs/libffi_convenience.a] Error 2
Gem files will remain installed in /Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0 for inspection.
Results logged to /Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.9.0/ext/ffi_c/gem_make.out
An error occurred while installing ffi (1.9.0), and Bundler cannot continue.
Make sure that `gem install ffi -v '1.9.0'` succeeds before bundling.
这个命令也不起作用（gem install ffi -v '1.9.0'），我得到同样的错误。我试过了：
sudo ln -s /usr/bin/gcc /usr/bin/gcc-4.2
我读过了：
无法设置 ruby 环境 - 安装 fii gem 错误
不过还是没有运气。我按照本指南设置 RVM：
http://portertech.ca/2010/03/26/homebrew--rvm--awesome/
如果这有帮助，ffi-1.0.11 安装顺利，fff-1.9.0 将不会安装 ( http://rubygems.org/gems/ffi/versions )。
/Users/Sam/.rvm/gems/ruby-1.9.3-p448@omega.ecoop/gems/ffi-1.0.11 (no problem)
我想只使用命令行（而不是珠宝盒 GUI）来学习一些新技能，但还是卡在这里。任何帮助将不胜感激，谢谢。
编辑
所以我尝试了一种不同的方法，我想可能是 ruby 的版本不兼容：
rvm install 2.0.0
然后这次使用 ruby 2.0.0 创建 gemset
rvm use 2.0.0@omega.ecoop --create
检查它是否存在并选择为当前 gemset（准备安装一些 gem）
rvm gemset list
gemsets for ruby-2.0.0-p247 (found in /Users/Sam/.rvm/gems/ruby-2.0.0-p247)
(default)
global
=> omega.ecoop
是的，一切都很好。尝试安装
bundle install
Sams-MacBook-Pro:ecoop Sam$ bundle install
Fetching gem metadata from https://rubygems.org/..........
Fetching gem metadata from https://rubygems.org/..
Resolving dependencies...
Installing addressable (2.3.5)
Installing chunky_png (1.2.8)
Installing fssm (0.2.10)
Installing sass (3.2.10)
Installing compass (0.12.2)
Installing breakpoint (2.0.6)
Installing coderay (1.0.9)
Installing compass-blend-modes (0.0.2)
Installing color-schemer (0.2.5)
Installing compass-normalize (1.4.3)
Installing compass-rgbapng (0.2.1)
Installing compass-validator (3.0.1)
Installing css_parser (1.3.5)
Installing eventmachine (1.0.3)
Installing http_parser.rb (0.5.3)
Installing em-websocket (0.5.0)
Installing ffi (1.9.0)
Installing formatador (0.2.4)
Installing rb-fsevent (0.9.3)
Installing rb-inotify (0.9.1)
Installing rb-kqueue (0.2.0)
Installing listen (1.3.0)
Installing lumberjack (1.0.4)
Installing method_source (0.8.2)
Installing slop (3.4.6)
Installing pry (0.9.12.2)
Installing thor (0.18.1)
Installing guard (1.8.2)
Installing guard-compass (0.0.8)
Installing multi_json (1.7.9)
Installing guard-livereload (1.4.0)
Installing guard-shell (0.5.1)
Installing oily_png (1.1.0)
Installing rb-fchange (0.0.6)
Installing sass-globbing (1.1.0)
Installing sassy-strings (1.0.0)
Installing singularitygs (1.1.2)
Installing susy (1.0.9)
Installing toolkit (1.3.7)
Installing yajl-ruby (1.1.0)
Using bundler (1.3.5)
Your bundle is complete!
这次“安装 ffi (1.9.0)”没有问题。然后我删除了 ruby 1.9.3，因为我目前只将它用于 compass/sass/susy，如果 2.0.0 有效，那就这样吧。
Sams-MacBook-Pro:~ Sam$ ruby -v
ruby 2.0.0p247 (2013-06-27 revision 41674) [x86_64-darwin12.3.0]
Sams-MacBook-Pro:~ Sam$ cd drupal/ecoop/sites/default/themes/ecoop/
ruby-1.9.3-p448 is not installed.
To install do: 'rvm install ruby-1.9.3-p448' <<<<<< no thanks
Sams-MacBook-Pro:ecoop Sam$ compass watch
>>> Change detected at 12:35:09 to: reset.scss
overwrite css/reset.css
overwrite css/styles.css
>>> Compass is watching for changes. Press Ctrl-C to Stop.
现在适用于我的项目。不确定使用较新版本的 ruby 的任何后果，但已经浪费了足够的时间，需要做一些设计。显然，这对需要 1.9.3 的人没有帮助，因此关于为什么 ffi 不会安装的原始查询尚未得到解决。