$ cd /tmp
$ gem unpack libxml-ruby
Unpacked gem: '/private/tmp/libxml-ruby-1.1.4'
$ ls -1 libxml-ruby-1.1.4/ext/libxml/*.o
libxml-ruby-1.1.4/ext/libxml/libxml.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_attr.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_attr_decl.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_attributes.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_cbg.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_document.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_dtd.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_encoding.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_error.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_html_parser.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_html_parser_context.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_html_parser_options.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_input_cbg.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_io.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_namespace.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_namespaces.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_node.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_parser.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_parser_context.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_parser_options.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_reader.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_relaxng.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_sax2_handler.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_sax_parser.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_schema.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_xinclude.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_xpath.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_xpath_context.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_xpath_expression.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_xpath_object.o
libxml-ruby-1.1.4/ext/libxml/ruby_xml_xpointer.o
Building native extensions. This could take a while...
/Users/aman/.rvm/rubies/ruby-1.8.7-p174/bin/ruby extconf.rb
checking for socket() in -lsocket... no
checking for gethostbyname() in -lnsl... no
checking for atan() in -lm... no
checking for atan() in -lm... yes
checking for inflate() in -lz... yes
checking for iconv_open() in -liconv... yes
checking for xmlParseDoc() in -lxml2... yes
checking for libxml/xmlversion.h... yes
creating extconf.h
creating Makefile
make
cc -dynamic -bundle -undefined suppress -flat_namespace -o libxml_ruby.bundle libxml.o ruby_xml.o ruby_xml_attr.o ruby_xml_attr_decl.o ruby_xml_attributes.o ruby_xml_cbg.o ruby_xml_document.o ruby_xml_dtd.o ruby_xml_encoding.o ruby_xml_error.o ruby_xml_html_parser.o ruby_xml_html_parser_context.o ruby_xml_html_parser_options.o ruby_xml_input_cbg.o ruby_xml_io.o ruby_xml_namespace.o ruby_xml_namespaces.o ruby_xml_node.o ruby_xml_parser.o ruby_xml_parser_context.o ruby_xml_parser_options.o ruby_xml_reader.o ruby_xml_relaxng.o ruby_xml_sax2_handler.o ruby_xml_sax_parser.o ruby_xml_schema.o ruby_xml_xinclude.o ruby_xml_xpath.o ruby_xml_xpath_context.o ruby_xml_xpath_expression.o ruby_xml_xpath_object.o ruby_xml_xpointer.o -L. -L/Users/aman/.rvm/rubies/ruby-1.8.7-p174/lib -L/Users/aman/.rvm/rubies/ruby-1.8.7-p174/lib -L. -lxml2 -lxml2 -lz -lpthread -licucore -lm -liconv -lz -lm -ldl -lobjc
ld: warning: in libxml.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_attr.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_attr_decl.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_attributes.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_cbg.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_document.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_dtd.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_encoding.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_error.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_html_parser.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_html_parser_context.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_html_parser_options.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_input_cbg.o, file was built for unsupported file format which is not the architecture being linked (x86_64)
ld: warning: in ruby_xml_io.o, file was built for unsupported file format which is not the architecture being linked (x86_64)