我安装了XCode和XCode CLI，安装任何其他宝石都没有任何问题，但是当我尝试安装therubyracer时会发生什么：
gem install therubyracer
Building native extensions. This could take a while...
ERROR: Error installing therubyracer:
ERROR: Failed to build gem native extension.
/Users/me/.rvm/rubies/ruby-1.9.3-p125/bin/ruby extconf.rb
checking for main() in -lpthread... yes
checking for main() in -lobjc... yes
creating Makefile
make
compiling accessor.cc
make: g++-4.2: No such file or directory
make: *** [accessor.o] Error 1
当我这样做时：g ++ -v，这就是我所看到的：
g++ -v
Using built-in specs.
Target: i686-apple-darwin11
Configured with: /private/var/tmp/llvmgcc42/llvmgcc42-2336.11~148/src/configure --disable-checking --enable-werror --prefix=/Applications/Xcode.app/Contents/Developer/usr/llvm-gcc-4.2 --mandir=/share/man --enable-languages=c,objc,c++,obj-c++ --program-prefix=llvm- --program-transform-name=/^[cg][^.-]*$/s/$/-4.2/ --with-slibdir=/usr/lib --build=i686-apple-darwin11 --enable-llvm=/private/var/tmp/llvmgcc42/llvmgcc42-2336.11~148/dst-llvmCore/Developer/usr/local --program-prefix=i686-apple-darwin11- --host=x86_64-apple-darwin11 --target=i686-apple-darwin11 --with-gxx-include-dir=/usr/include/c++/4.2.1
Thread model: posix
gcc version 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.11.00)
我最终为我工作的是将Gemfile中的条目更改为 gem'therubyracer'，'0.10.1'。
如果我没有指定此版本，那么它会尝试安装0.10.2并且该版本似乎有问题。