title: Error installing pg gem on osx
body: <p>I am on osx 10.6.7 trying to run bundle install on a new rails 3.0.7 app and it keeps failing when trying to build the pg gem. It keeps telling me that I have need the developer tools. But as far as I can tell I have the developer tools installed.</p>
  
  <p>Here is the output of xcodebuild -version</p>
  
  <pre><code>Xcode 3.2.6
  Component versions: DevToolsCore-1809.0; DevToolsSupport-1806.0
  BuildVersion: 10M2518
  </code></pre>
  
  <p>Here is the output of the failed pg gem build</p>
  
  <pre><code>/Users/bm/.rvm/rubies/ruby-1.9.2-head/bin/ruby extconf.rb --with-pg-config=/Library/PostgreSQL/8.4/bin/pg_config
  Using config values from /Library/PostgreSQL/8.4/bin/pg_config
  checking for libpq-fe.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/bm/.rvm/rubies/ruby-1.9.2-head/bin/ruby
      --with-pg
      --without-pg
      --with-pg-dir
      --without-pg-dir
      --with-pg-include
      --without-pg-include=${pg-dir}/include
      --with-pg-lib
      --without-pg-lib=${pg-dir}/lib
      --with-pg-config
  /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:368:in `try_do': The complier failed to generate an executable file. (RuntimeError)
  You have to install development tools first.
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:452:in `try_cpp'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:853:in `block in find_header'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:693:in `block in checking_for'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:280:in `block (2 levels) in postpone'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:254:in `open'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:280:in `block in postpone'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:254:in `open'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:276:in `postpone'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:692:in `checking_for'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/mkmf.rb:852:in `find_header'
      from extconf.rb:31:in `&lt;main&gt;'
  
  
  Gem files will remain installed in /Users/bm/.rvm/gems/ruby-1.9.2-head@rc_search/gems/pg-0.11.0 for inspection.
  Results logged to /Users/bm/.rvm/gems/ruby-1.9.2-head@rc_search/gems/pg-0.11.0/ext/gem_make.out
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/rubygems/installer.rb:486:in `block in build_extensions'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/rubygems/installer.rb:446:in `each'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/rubygems/installer.rb:446:in `build_extensions'
      from /Users/bm/.rvm/rubies/ruby-1.9.2-head/lib/ruby/1.9.1/rubygems/installer.rb:198:in `install'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/source.rb:100:in `install'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/installer.rb:55:in `block in run'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/spec_set.rb:12:in `block in each'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/spec_set.rb:12:in `each'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/spec_set.rb:12:in `each'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/installer.rb:44:in `run'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/installer.rb:8:in `install'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/cli.rb:217:in `install'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/vendor/thor/task.rb:22:in `run'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/vendor/thor/invocation.rb:118:in `invoke_task'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/vendor/thor.rb:246:in `dispatch'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/lib/bundler/vendor/thor/base.rb:389:in `start'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/gems/bundler-1.0.0/bin/bundle:13:in `&lt;top (required)&gt;'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/bin/bundle:19:in `load'
      from /Users/bm/.rvm/gems/ruby-1.9.2-head@global/bin/bundle:19:in `&lt;main&gt;'
  </code></pre>
  
  <p>Any help would be immensely appreciated. FYI I also tried building the app with a mysql and essentially got the same stack. So I'm pretty sure I'm missing some sort of developer build tools, but I just don't know which ones. :(</p>