Can't find the 'libpq-fe.h header when trying to install pg gem

Question

I am using the Ruby on Rails 3.1 pre version. I like to use PostgreSQL, but the problem is installing the pg gem. It gives me the following error:

Answer 1

I recently upgraded to Mac OS X v10.10 (Yosemite) and was having difficulty building the pg gem.

The error reported was the typical:

Using config values from /usr/local/bin/pg_config
checking for libpq-fe.h... *** extconf.rb failed ***

My solution was to gem uninstall pg and then bundle update pg to replace the gem with the latest. I did run brew update; brew upgrade after the Yosemite install to get the latest versions of packages I had installed previously.