じぶんの
$ sudo gem install watir-webdriver --no-ri --no-rdoc
次のエラーで常に失敗します
（Fedora 17、64ビットを実行しており、ruby-develがインストールされています）
------------------------
Building native extensions. This could take a while...
...........
ERROR: Error installing watir-webdriver:
ERROR: Failed to build gem native extension.
/usr/bin/ruby extconf.rb
checking for ffi.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=/usr/bin/ruby
--with-ffi_c-dir
--without-ffi_c-dir
--with-ffi_c-include
--without-ffi_c-include=${ffi_c-dir}/include
--with-ffi_c-lib
--without-ffi_c-lib=${ffi_c-dir}/lib
--with-libffi-config
--without-libffi-config
--with-pkg-config
--without-pkg-config
/usr/share/ruby/mkmf.rb:381:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
from /usr/share/ruby/mkmf.rb:506:in `try_cpp'
from /usr/share/ruby/mkmf.rb:931:in `block in have_header'
from /usr/share/ruby/mkmf.rb:790:in `block in checking_for'
from /usr/share/ruby/mkmf.rb:284:in `block (2 levels) in postpone'
from /usr/share/ruby/mkmf.rb:254:in `open'
from /usr/share/ruby/mkmf.rb:284:in `block in postpone'
from /usr/share/ruby/mkmf.rb:254:in `open'
from /usr/share/ruby/mkmf.rb:280:in `postpone'
from /usr/share/ruby/mkmf.rb:789:in `checking_for'
from /usr/share/ruby/mkmf.rb:930:in `have_header'
from extconf.rb:9:in `<main>'
Gem files will remain installed in /usr/local/share/gems/gems/ffi-1.0.11 for inspection.
Results logged to /usr/local/share/gems/gems/ffi-1.0.11/ext/ffi_c/gem_make.out