Mac (El Capitan) で nokogiri のインストール @Ruby 2.3.1 でハマった

いつものように

$ ~/.rbenv/plugins/ruby-build

$ git fetch origin

$ git rebase origin/master

$ rbenv install 2.3.1

$ rbenv global 2.3.1

$ gem install bundler

$ rbenv rehash

ここまでは全く問題なし。

つづいて Rails ディレクトリへ、

$ ~/projext_hogehoge/

$ rm -rf vendor/bundle

$ bundle install

....
....
Installing nokogiri 1.6.7.2 with native extensions

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    current directory: /Users/nyangry/workspace/some_project/vendor/bundle/gems/nokogiri-1.6.7.2/ext/nokogiri
/Users/nyangry/.rbenv/versions/2.3.1/bin/ruby -r ./siteconf20160513-85661-v1vt0k.rb extconf.rb --use-system-libraries
checking if the C compiler accepts ... yes
checking if the C compiler accepts -Wno-error=unused-command-line-argument-hard-error-in-future... no
Building nokogiri using system libraries.
libxml2 version 2.6.21 or later is required!
*** 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=/Users/nyangry/.rbenv/versions/2.3.1/bin/$(RUBY_BASE_NAME)
        --help
        --clean
        --use-system-libraries
        --with-zlib-dir
        --without-zlib-dir
        --with-zlib-include
        --without-zlib-include=${zlib-dir}/include
        --with-zlib-lib
        --without-zlib-lib=${zlib-dir}/lib
        --with-xml2-dir
        --without-xml2-dir
        --with-xml2-include
        --without-xml2-include=${xml2-dir}/include
        --with-xml2-lib
        --without-xml2-lib=${xml2-dir}/lib
        --with-libxml-2.0-config
        --without-libxml-2.0-config
        --with-pkg-config
        --without-pkg-config
        --with-xslt-dir
        --without-xslt-dir
        --with-xslt-include
        --without-xslt-include=${xslt-dir}/include
        --with-xslt-lib
        --without-xslt-lib=${xslt-dir}/lib
        --with-libxslt-config
        --without-libxslt-config
        --with-exslt-dir
        --without-exslt-dir
        --with-exslt-include
        --without-exslt-include=${exslt-dir}/include
        --with-exslt-lib
        --without-exslt-lib=${exslt-dir}/lib
        --with-libexslt-config
        --without-libexslt-config

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

  /Users/nyangry/workspace/some_project/vendor/bundle/extensions/x86_64-darwin-15/2.3.0-static/nokogiri-1.6.7.2/mkmf.log

extconf failed, exit code 1

Gem files will remain installed in /Users/nyangry/workspace/some_project/vendor/bundle/gems/nokogiri-1.6.7.2 for inspection.
Results logged to /Users/nyangry/workspace/some_project/vendor/bundle/extensions/x86_64-darwin-15/2.3.0-static/nokogiri-1.6.7.2/gem_make.out
An error occurred while installing nokogiri (1.6.7.2), and Bundler cannot continue.
Make sure that `gem install nokogiri -v '1.6.7.2'` succeeds before bundling.

libxml2 あたりっぽい・・・当然設定は

$ cat ~/.bundle/config
---
BUNDLE_BUILD__NOKOGIRI: "--use-system-libraries"
BUNDLE_BUILD__LIBV8: "--with-system-v8"
BUNDLE_PATH: vendor/bundle
BUNDLE_BIN: vendor/bundle_bin
BUNDLE_JOBS: '8'

$ cat .bundle/config
---
BUNDLE_DISABLE_SHARED_GEMS: true

で --use-system-libraries しているし、

$ brew list | grep lib
libevent
libiconv
libpng
libtiff
libtool
libxml2
libxslt

libxml2 も入っている。

いろいろ試して結局

 brew link --force libxml2

で解決。

少し前に El Capitan にアップデートした際にシンボリックリンク周りが壊れたっぽい。（アップデート /usr/local/ 周りが壊れるのはよくある・・）