libxml-ruby: Failed to build gem native extension

Question

I'm trying to install libxml-ruby. I have installed libxml2, libxslt and coreutils

I have also read other posts regarding the issue but none solved it for me.

brew list libxslt

/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/bin/xslt-config
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/bin/xsltproc
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/include/libexslt/ (3 files)
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/include/libxslt/ (21 files)
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/lib/libexslt.0.dylib
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/lib/libxslt.1.dylib
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/lib/pkgconfig/ (2 files)
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/lib/ (5 other files)
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/share/aclocal/libxslt.m4
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/share/doc/ (90 files)
/opt/boxen/homebrew/Cellar/libxslt/1.1.28_1/share/man/ (3 files)

brew list libxml2

/opt/boxen/homebrew/Cellar/libxml2/2.9.4/bin/xml2-config
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/bin/xmlcatalog
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/bin/xmllint
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/include/libxml2/ (47 files)
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/lib/libxml2.2.dylib
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/lib/cmake/libxml2/libxml2-config.cmake
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/lib/pkgconfig/libxml-2.0.pc
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/lib/ (3 other files)
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/share/aclocal/libxml.m4
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/share/doc/ (153 files)
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/share/gtk-doc/ (55 files)
/opt/boxen/homebrew/Cellar/libxml2/2.9.4/share/man/ (4 files)

gem install libxml-ruby produces the following error:

Building native extensions.  This could take a while...
ERROR:  Error installing libxml-ruby:
    ERROR: Failed to build gem native extension.

    current directory: /opt/rubies/2.3.0/lib/ruby/gems/2.3.0/gems/libxml-ruby-2.9.0/ext/libxml
/opt/boxen/rbenv/versions/2.3.0/bin/ruby -r ./siteconf20160630-68248-1qaz7dk.rb extconf.rb
checking for libxml/xmlversion.h in /opt/include/libxml2,/opt/local/include/libxml2,/usr/local/include/libxml2,/usr/include/libxml2... no
*** 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=/opt/boxen/rbenv/versions/2.3.0/bin/$(RUBY_BASE_NAME)
    --with-xml2-config
    --without-xml2-config
    --with-xml2-dir
    --without-xml2-dir
    --with-xml2-include
    --without-xml2-include=${xml2-dir}/include
    --with-xml2-lib
    --without-xml2-lib=${xml2-dir}/lib
 extconf failure: need libxml2.

    Install the library or try one of the following options to extconf.rb:

      --with-xml2-config=/path/to/xml2-config
      --with-xml2-dir=/path/to/libxml2
      --with-xml2-lib=/path/to/libxml2/lib
      --with-xml2-include=/path/to/libxml2/include


To see why this extension failed to compile, please check the mkmf.log which can be found here:

  /opt/boxen/rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/extensions/x86_64-darwin-14/2.3.0-static/libxml-ruby-2.9.0/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /opt/boxen/rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/gems/libxml-ruby-2.9.0 for inspection.
Results logged to /opt/boxen/rbenv/versions/2.3.0/lib/ruby/gems/2.3.0/extensions/x86_64-darwin-14/2.3.0-static/libxml-ruby-2.9.0/gem_make.out

Answer 1

I had a similar issue after I had used brew to install libxml2

Brew link solved the issue brew link --force libxml2

Answer 2

Life after upgrading to macOS Mojave.

xcode-select --install
brew install libxml2
brew link --force libxml2
gem install libxml-ruby -v '2.9.0' -- --use-system-libraries=true --with-xml2-include="$(xcrun --show-sdk-path)"/usr/include/libxml2

In my example I installed version 2.9.0 of the libxml-ruby gem. Change the version string to suit your needs. If available, examine the Gemfile.lock to identify which version of libxml-ruby Bundler is needs to install.