我正在尝试通过RVM将Ruby更新为1.9.3-p327。输入rvm install 1.9.3-p327后，我明白了：
No binary rubies available for: downloads/ruby-1.9.3-p327.
Continuing with compilation. Please read 'rvm mount' to get more information on binary rubies.
Installing Ruby from source to: /usr/local/rvm/rubies/ruby-1.9.3-p327, this may take a while depending on your cpu(s)...
ruby-1.9.3-p327 - #downloading ruby-1.9.3-p327, this may take a while depending on your connection...
ruby-1.9.3-p327 - #extracted to /usr/local/rvm/src/ruby-1.9.3-p327 (already extracted)
ruby-1.9.3-p327 - #configuring
Error running 'env LDFLAGS=-L/opt/sm/pkg/active/lib CFLAGS=-I/opt/sm/pkg/active/include CPATH=/opt/sm/pkg/active/include ./configure --enable-shared --disable-install-doc --prefix=/usr/local/rvm/rubies/ruby-1.9.3-p327 --with-opt-dir=/usr/local/rvm/usr', please read /usr/local/rvm/log/ruby-1.9.3-p327/configure.log
There has been an error while running configure. Halting the installation.
然后，我查看ruby 1.9.3-p327/configure.log中的配置日志，其中我看到了：
[2012-12-24 22:39:14] env LDFLAGS=-L/opt/sm/pkg/active/lib CFLAGS=- I/opt/sm/pkg/active/include CPATH=/opt/sm/pkg/active/include ./configure --enable-shared --disable-install-doc --prefix=/usr/local/rvm/rubies/ruby-1.9.3-p327 --with-opt-dir=/usr/local/rvm/usr
checking build system type... x86_64-apple-darwin11.4.2
checking host system type... x86_64-apple-darwin11.4.2
checking target system type... x86_64-apple-darwin11.4.2
checking whether the C compiler works... no
configure: error: in `/usr/local/rvm/src/ruby-1.9.3-p327':
configure: error: C compiler cannot create executables
See `config.log' for more details
我已经安装了最新的Xcode 4.5.2以及通过Xcode安装CLT。看起来C编译器无法工作，我不知道如何修复它。有什么建议吗？