Can't build gem native extensions - ruby

Question

I'm not too sure why, but I can't seem to install any gem that involves building native extensions. Can anyone suggest how to start debugging this issue? Here's the output I get with gem install debugger
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/bin/ruby extconf.rb
checking for rb_method_entry_t.called_id in method.h... *** 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/Chintan/.rvm/rubies/ruby-1.9.3-p0/bin/ruby
--with-ruby-dir
--without-ruby-dir
--with-ruby-include=${ruby-dir}/include
--with-ruby-lib
--without-ruby-lib=${ruby-dir}/lib
/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:491:in `block in try_compile'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:443:in `with_werror'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:491:in `try_compile'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:1002:in `block in have_struct_member'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:790:in `block in checking_for'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:284:in `block (2 levels) in postpone'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:254:in `open'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:284:in `block in postpone'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:254:in `open'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:280:in `postpone'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:789:in `checking_for'
from /Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:1001:in `have_struct_member'
from extconf.rb:34:in `block in <main>'
from /Users/Chintan/.rvm/gems/ruby-1.9.3-p0/gems/debugger-ruby_core_source-1.2.3/lib/debugger/ruby_core_source.rb:21:in `call'
from /Users/Chintan/.rvm/gems/ruby-1.9.3-p0/gems/debugger-ruby_core_source-1.2.3/lib/debugger/ruby_core_source.rb:21:in `create_makefile_with_core'
from extconf.rb:87:in `<main>'
Gem files will remain installed in /Users/Chintan/.rvm/gems/ruby-1.9.3-p0/gems/debugger-1.6.0 for inspection.
Results logged to /Users/Chintan/.rvm/gems/ruby-1.9.3-p0/gems/debugger-1.6.0/ext/ruby_debug/gem_make.out
An error occurred while installing debugger (1.6.0), and Bundler cannot continue.
Also, I recently re-installed homebrew, so that might be the issue? And I've definitely got the XCode Developre Tools installed.
Here's the contents of mkmf.log:
○ cat /Users/Chintan/.rvm/gems/ruby-1.9.3-p0/gems/debugger-1.6.0/ext/ruby_debug/mkmf.log
"/usr/local/bin/gcc-4.2 -o conftest -I/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/include/ruby-1.9.1/x86_64-darwin12.2.1 -I/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/include/ruby-1.9.1/ruby/backward -I/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/include/ruby-1.9.1 -I. -I/Users/Chintan/.rvm/src/ruby-1.9.3-p0 -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE -O3 -ggdb -Wextra -Wno-unused-parameter -Wno-parentheses -Wno-long-long -Wno-missing-field-initializers -Wpointer-arith -Wwrite-strings -Wdeclaration-after-statement -Wshorten-64-to-32 -Wimplicit-function-declaration -I/Users/Chintan/.rvm/usr/include -fno-common -pipe conftest.c -L. -L/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib -L. -L/Users/Chintan/.rvm/usr/lib -lruby.1.9.1 -lpthread -ldl -lobjc "
/Users/Chintan/.rvm/rubies/ruby-1.9.3-p0/lib/ruby/1.9.1/mkmf.rb:317: warning: Insecure world writable dir /usr/local/heroku/bin in PATH, mode 040777
checked program was:
/* begin */
1: #include "ruby.h"
2:
3: int main() {return 0;}
/* end */

Answer 1

This worked for me:
gem update debugger-ruby_core_source