El Capitan で library not found for -lgmp が発生する時の対処法

OS を El Capitan にアップデートしてから遭遇した問題のメモ。

library not found for -lgmp が発生

gem をインストールしようとしたら下記のようなエラーが発生。

guest1-107:app t-fujiki$ bundle install
Fetching gem metadata from https://rubygems.org/.............
Fetching version metadata from https://rubygems.org/...
Fetching dependency metadata from https://rubygems.org/..
Using i18n 0.7.0
Installing json 1.8.3 with native extensions

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

    /Users/t-fujiki/.rbenv/versions/2.2.3/bin/ruby -r ./siteconf20151005-20477-hk2ir0.rb extconf.rb
creating Makefile

make "DESTDIR=" clean

make "DESTDIR="
compiling generator.c
linking shared-object json/ext/generator.bundle
ld: library not found for -lgmp
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make: *** [generator.bundle] Error 1

make failed, exit code 2

Gem files will remain installed in /Users/t-fujiki/Development/iOS/iosApp/vendor/bundler/ruby/2.2.0/gems/json-1.8.3 for inspection.
Results logged to /Users/t-fujiki/Development/iOS/iosApp/vendor/bundler/ruby/2.2.0/extensions/x86_64-darwin-14/2.2.0-static/json-1.8.3/gem_make.out
An error occurred while installing json (1.8.3), and Bundler cannot continue.
Make sure that `gem install json -v '1.8.3'` succeeds before bundling.

対処法

コマンドラインツールをインストールしたら成功するようになりました。

xcode-select --install