在干净安装了Mac OS 10.9后，从10.7.5升级到现在，我似乎无法安装libxml-ruby gem。 我使用Homebrew和RVM来管理我的环境，并安装了以下内容：
brew list
apple-gcc42 gcc46 libmpc08 mpfr2 postgresql
autoconf gmp4 libtool mysql55 ppl011
automake libgpg-error libxml2 openssl readline
cloog-ppl015 libiconv libxslt ossp-uuid wget
cmake libksba libyaml pkg-config
输入 brew doctor 后会返回以下内容：
Your system is ready to brew.
运行
bundle install会产生以下输出，我已经删除了链接。显然，我无法在没有10个声望的情况下发布超过两个链接：Fetching source index from . . .
Fetching source index from . . .
Fetching source index from . . .
Resolving dependencies..............................................................................................
Using rake (10.0.4)
Using Platform (0.4.0)
Using open4 (1.3.0)
Using POpen4 (0.1.4)
等等，最后到达:
Using nokogiri (1.5.9)
etc.
Installing libxml-ruby (2.3.3)
Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
/Users/iandonovan/.rvm/rubies/ruby-1.9.3-p392/bin/ruby extconf.rb --with-opt-include=/usr/local/Cellar/libxml2/2.9.1/include/
extconf.rb:17: Use RbConfig instead of obsolete and deprecated Config.
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
compiling libxml.c
compiling ruby_xml.c
ruby_xml.c: In function 'rxml_default_tree_indent_string_set':
ruby_xml.c:612:23: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
compiling ruby_xml_attr.c
compiling ruby_xml_attr_decl.c
ruby_xml_attr_decl.c: In function 'rxml_attr_decl_name_get':
ruby_xml_attr_decl.c:57:5: warning: pointer targets in passing argument 2 of 'rxml_new_cstr' differ in signedness [-Wpointer-sign]
ruby_xml_encoding.h:11:7: note: expected 'const char *' but argument is of type 'const xmlChar *'
compiling ruby_xml_attributes.c
compiling ruby_xml_cbg.c
compiling ruby_xml_document.c
ruby_xml_document.c: In function 'rxml_document_canonicalize':
ruby_xml_document.c:232:10: warning: unused variable 'list_in' [-Wunused-variable]
ruby_xml_document.c:334:3: warning: passing argument 4 of 'xmlC14NDocDumpMemory' from incompatible pointer type [enabled by default]
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/libxml2/libxml/c14n.h:76:3: note: expected 'xmlChar **' but argument is of type 'xmlChar * (*)[256]'
ruby_xml_document.c:199:7: warning: variable 'length' set but not used [-Wunused-but-set-variable]
ruby_xml_document.c: In function 'rxml_document_root_set':
ruby_xml_document.c:757:14: warning: variable 'xroot' set but not used [-Wunused-but-set-variable]
ruby_xml_document.c: In function 'rxml_document_save':
ruby_xml_document.c:805:13: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
compiling ruby_xml_dtd.c
compiling ruby_xml_encoding.c
compiling ruby_xml_error.c
compiling ruby_xml_html_parser.c
compiling ruby_xml_html_parser_context.c
ruby_xml_html_parser_context.c: In function 'rxml_html_parser_context_options_set':
ruby_xml_html_parser_context.c:307:7: warning: variable 'result' set but not used [-Wunused-but-set-variable]
compiling ruby_xml_html_parser_options.c
compiling ruby_xml_input_cbg.c
compiling ruby_xml_io.c
compiling ruby_xml_namespace.c
compiling ruby_xml_namespaces.c
compiling ruby_xml_node.c
ruby_xml_node.c: In function 'rxml_node_to_s':
ruby_xml_node.c:622:54: error: dereferencing pointer to incomplete type
ruby_xml_node.c:624:56: error: dereferencing pointer to incomplete type
make: *** [ruby_xml_node.o] Error 1
Gem files will remain installed in /Users/iandonovan/.rvm/gems/ruby-1.9.3-p392@standard-set/gems/libxml-ruby-2.3.3 for inspection.
Results logged to /Users/iandonovan/.rvm/gems/ruby-1.9.3-p392@standard-set/gems/libxml-ruby-2.3.3/ext/libxml/gem_make.out
An error occurred while installing libxml-ruby (2.3.3), and Bundler cannot continue
Make sure that `gem install libxml-ruby -v '2.3.3'` succeeds before bundling.
运行独立的gem安装命令
gem install libxml-ruby -v '2.3.3'，会返回相同的错误信息。
已经安装了XCode 5.0.1和开发工具。由于“网络问题”（根据对话框），我无法通过 xcode-select --install 安装dev工具，而是从developer.apple.com下载了Mavericks软件包。
有其他人遇到过这个问题吗？Nokogiri似乎可以很好地安装（捆绑了1.5.9版本），但是libxml-ruby无法完成安装。