title: Build a gem with native extension (Gem::Installer::ExtensionBuildError)
body: <p>I have the following configuration:</p>
  
  <ul>
  <li><strong>uname -a :</strong> Linux 2.6.24.2 i686 GNU/Linux (Ubuntu)</li>
  <li><strong>ruby -v :</strong> ruby 1.9.0 (2007-12-25 revision 14709) [i486-linux]</li>
  <li><strong>rails -v :</strong> Rails 3.0.0.beta3</li>
  <li><strong>gem -v</strong> : 1.3.5</li>
  <li><strong>rake --version :</strong> rake, version 0.8.7</li>
  <li><strong>make -v :</strong> GNU Make 3.81</li>
  <li><strong>gem env :</strong>
  
  <ul>
  <li>RUBYGEMS VERSION: 1.3.5</li>
  <li>RUBY VERSION: 1.9.0 (2007-12-25 patchlevel 0) [i486-linux]</li>
  <li>INSTALLATION DIRECTORY: /usr/lib/ruby1.9/gems/1.9.0</li>
  <li>RUBY EXECUTABLE: /usr/bin/ruby1.9</li>
  <li>EXECUTABLE DIRECTORY: /usr/bin</li>
  <li>RUBYGEMS PLATFORMS:</li>
  <li>ruby</li>
  <li>x86-linux</li>
  <li>GEM PATHS:
  
  <ul>
  <li>/usr/lib/ruby1.9/gems/1.9.0</li>
  <li>/root/.gem/ruby/1.9.0</li>
  </ul></li>
  <li>GEM CONFIGURATION:
  
  <ul>
  <li>:update_sources => true</li>
  <li>:verbose => true</li>
  <li>:benchmark => false</li>
  <li>:backtrace => false</li>
  <li>:bulk_threshold => 1000</li>
  </ul></li>
  <li>REMOTE SOURCES:
  
  <ul>
  <li><a href="http://gems.rubyforge.org/" rel="noreferrer">http://gems.rubyforge.org/</a></li>
  </ul></li>
  </ul></li>
  </ul>
  
  <p>And when I try this simple command:</p>
  
  <pre><code>gem install nokogiri
  </code></pre>
  
  <p>Here is what I get:</p>
  
  <pre>
  # gem install nokogiri
  Building native extensions.  This could take a while...
  ERROR:  Error installing nokogiri:
          ERROR: Failed to build gem native extension.
  
  /usr/bin/ruby1.9 extconf.rb
  checking for iconv.h in /opt/local/include/,/opt/local/include/libxml2,/opt/local/include,/opt/local/include,/opt/local/include/libxml2,/usr/local/include,/usr/local/include/libxml2,/usr/include,/usr/include/libxml2,/usr/include,/usr/include/libxml2... yes
  checking for libxml/parser.h in /opt/local/include/,/opt/local/include/libxml2,/opt/local/include,/opt/local/include,/opt/local/include/libxml2,/usr/local/include,/usr/local/include/libxml2,/usr/include,/usr/include/libxml2,/usr/include,/usr/include/libxml2... yes
  checking for libxslt/xslt.h in /opt/local/include/,/opt/local/include/libxml2,/opt/local/include,/opt/local/include,/opt/local/include/libxml2,/usr/local/include,/usr/local/include/libxml2,/usr/include,/usr/include/libxml2,/usr/include,/usr/include/libxml2... yes
  checking for libexslt/exslt.h in /opt/local/include/,/opt/local/include/libxml2,/opt/local/include,/opt/local/include,/opt/local/include/libxml2,/usr/local/include,/usr/local/include/libxml2,/usr/include,/usr/include/libxml2,/usr/include,/usr/include/libxml2... yes
  checking for xmlParseDoc() in -lxml2... yes
  checking for xsltParseStylesheetDoc() in -lxslt... yes
  checking for exsltFuncRegister() in -lexslt... yes
  checking for xmlRelaxNGSetParserStructuredErrors()... yes
  checking for xmlRelaxNGSetParserStructuredErrors()... yes
  checking for xmlRelaxNGSetValidStructuredErrors()... yes
  checking for xmlSchemaSetValidStructuredErrors()... yes
  checking for xmlSchemaSetParserStructuredErrors()... yes
  creating Makefile
  
  make
  cc -I. -I/usr/include/libxml2 -I/usr/include -I/usr/include/ruby-1.9.0/i486-linux -I/usr/include/ruby-1.9.0 -I. -DHAVE_XMLRELAXNGSETPARSERSTRUCTUREDERRORS -DHAVE_XMLRELAXNGSETPARSERSTRUCTUREDERRORS -DHAVE_XMLRELAXNGSETVALIDSTRUCTUREDERRORS -DHAVE_XMLSCHEMASETVALIDSTRUCTUREDERRORS -DHAVE_XMLSCHEMASETPARSERSTRUCTUREDERRORS -I/opt/local/include/ -I/opt/local/include/libxml2 -I/opt/local/include  -D_FILE_OFFSET_BITS=64  -fPIC -fno-strict-aliasing -g  -fPIC   -g -DXP_UNIX -O3 -Wall -Wcast-qual -Wwrite-strings -Wconversion -Wmissing-noreturn -Winline  -o xml_document_fragment.o -c xml_document_fragment.c
  In the included file starting at ./nokogiri.h:75,
            From ./xml_document_fragment.h:4,
            From xml_document_fragment.c:1:
  ./xml_document.h:5:16: error: st.h : No file or folder with this type
  make: *** [xml_document_fragment.o] Error 1
  
  
  Gem files will remain installed in /usr/lib/ruby1.9/gems/1.9.0/gems/nokogiri-1.4.1 for inspection.
  Results logged to /usr/lib/ruby1.9/gems/1.9.0/gems/nokogiri-1.4.1/ext/nokogiri/gem_make.out
  </pre>
  
  <p>The "gem_make.out" file contains the exact same information as described above.</p>
  
  <p>If I try with another gem:</p>
  
  <pre><code>gem install gherkin
  </code></pre>
  
  <p>Here is what I get:</p>
  
  <pre>
  u# gem install gherkin
  Building native extensions.  This could take a while...
  ERROR:  Error installing gherkin:
          ERROR: Failed to build gem native extension.
  
  /usr/bin/ruby1.9 extconf.rb
  checking for main() in -lc... yes
  creating Makefile
  
  make
  cc -I. -I/usr/include/ruby-1.9.0/i486-linux -I/usr/include/ruby-1.9.0 -I. -D_FILE_OFFSET_BITS=64  -fPIC -fno-strict-aliasing -g  -fPIC   -o gherkin_lexer_ar.o -c gherkin_lexer_ar.c
  /Users/aslakhellesoy/scm/gherkin/tasks/../ragel/i18n/ar.c.rl:11:16: erreur: re.h : Aucun fichier ou dossier de ce type
  make: *** [gherkin_lexer_ar.o] Erreur 1
  
  
  Gem files will remain installed in /usr/lib/ruby1.9/gems/1.9.0/gems/gherkin-1.0.30 for inspection.
  Results logged to /usr/lib/ruby1.9/gems/1.9.0/gems/gherkin-1.0.30/ext/gherkin_lexer_ar/gem_make.out
  </pre>
  
  <p>In fact whenever I try to <strong>install a gem with native extension</strong>, I get the same type of error.</p>
  
  <p>Would that ring a bell to anyone?</p>