我在使用 rvm 安装 Rails 4 时遇到问题。我看到了另一个从我的系统中删除 rvm 的解决方案，但这不是一个选项，因为我需要隔离的 gemset。这是我的终端：
Edmunds-MacBook-Pro:pipetask edmundmai$ rvm current
ruby-2.0.0-p247@pipetask
Edmunds-MacBook-Pro:pipetask edmundmai$ ls
Gemfile README.rdoc app config db lib public
Gemfile.lock Rakefile bin config.ru gcc-4.2 log vendor
Edmunds-MacBook-Pro:pipetask edmundmai$ gem install rails -v=4.0.0
Building native extensions. This could take a while...
ERROR: Error installing rails:
ERROR: Failed to build gem native extension.
/Users/edmundmai/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers. Check the mkmf.log file for more details. You may
need configuration options.
Provided configuration options:
--with-opt-dir
--without-opt-dir
--with-opt-include
--without-opt-include=${opt-dir}/include
--with-opt-lib
--without-opt-lib=${opt-dir}/lib
--with-make-prog
--without-make-prog
--srcdir=.
--curdir
--ruby=/Users/edmundmai/.rvm/rubies/ruby-2.0.0-p247/bin/ruby
--with-atomic_reference-dir
--without-atomic_reference-dir
--with-atomic_reference-include
--without-atomic_reference-include=${atomic_reference-dir}/include
--with-atomic_reference-lib
--without-atomic_reference-lib=${atomic_reference-dir}/
/Users/edmundmai/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:434:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /Users/edmundmai/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:519:in `try_link0'
from /Users/edmundmai/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/mkmf.rb:817:in `try_run'
from extconf.rb:26:in `<main>'
Gem files will remain installed in /Users/edmundmai/.rvm/gems/ruby-2.0.0-p247@pipetask/gems/atomic-1.1.14 for inspection.
Results logged to /Users/edmundmai/.rvm/gems/ruby-2.0.0-p247@pipetask/gems/atomic-1.1.14/ext/gem_make.out
Edmunds-MacBook-Pro:pipetask edmundmai$
我将如何调试这个？我什至不知道mkmf.log它在说什么，当我这样做时，我有 50 个locate mkmf.log。什么是开发工具？我有 xcode 5 和命令行工具。
==更新
这可能是它所指的 mkmf.log 文件？
Edmunds-MacBook-Pro:bin edmundmai$ more /Users/emai/mkmf.log
have_func: checking for rb_hash_foreach()... -------------------- yes
"clang -o conftest -I/Users/emai/.rvm/rubies/ruby-2.0.0-p0/include/ruby-2.0.0/x86_64-darwin11.4.2 -I/Users/emai/.rvm/rubies/ruby-2.0.0-p0/include/ruby-2.0.0/ruby/backward -I/Users/emai/.rvm/rubies/ruby-2.0.0-p0/include/ruby-2.0.0 -I. -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -D_DARWIN_UNLIMITED_SELECT -D_REENTRANT -I/Users/emai/.rvm/usr/include -I/Users/emai/.rvm/usr/include -O3 -g3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -pipe conftest.c -L. -L/Users/emai/.rvm/rubies/ruby-2.0.0-p0/lib -L/Users/emai/.rvm/usr/lib -L. -fstack-protector -L/Users/emai/.rvm/usr/lib -L/Users/emai/.rvm/usr/lib -lruby-static -lpthread -ldl -lobjc "
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main(void) {return 0;}
/* end */
"clang -o conftest -I/Users/emai/.rvm/rubies/ruby-2.0.0-p0/include/ruby-2.0.0/x86_64-darwin11.4.2 -I/Users/emai/.rvm/rubies/ruby-2.0.0-p0/include/ruby-2.0.0/ruby/backward -I/Users/emai/.rvm/rubies/ruby-2.0.0-p0/include/ruby-2.0.0 -I. -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -D_DARWIN_UNLIMITED_SELECT -D_REENTRANT -I/Users/emai/.rvm/usr/include -I/Users/emai/.rvm/usr/include -O3 -g3 -Wall -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wunused-variable -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -pipe conftest.c -L. -L/Users/emai/.rvm/rubies/ruby-2.0.0-p0/lib -L/Users/emai/.rvm/usr/lib -L. -fstack-protector -L/Users/emai/.rvm/usr/lib -L/Users/emai/.rvm/usr/lib -lruby-static -lpthread -ldl -lobjc "
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: /*top*/
4: int main(void) {return 0;}
5: extern int t(void);
6: int t(void) { void ((*volatile p)()); p = (void ((*)()))rb_hash_foreach; return 0; }
/* end */
--------------------