* Package:    dev-ruby/psych-2.0.15
 * Repository: gentoo
 * Maintainer: ruby@gentoo.org
 * USE:        abi_x86_64 amd64 elibc_glibc kernel_linux ruby_targets_ruby20 ruby_targets_ruby21 userland_GNU
 * FEATURES:   preserve-libs sandbox userpriv usersandbox
>>> Unpacking source...
 * Running unpack phase for all ...
 * Unpacking .gem file... ...
 [ ok ]
 * Uncompressing metadata ...
 [ ok ]
 * Unpacking data.tar.gz ...
 [ ok ]
>>> Source unpacked in /var/tmp/portage/dev-ruby/psych-2.0.15/work
>>> Preparing source in /var/tmp/portage/dev-ruby/psych-2.0.15/work ...
 * Running prepare phase for all ...
 * Running source copy phase for ruby20 ...
 * Running source copy phase for ruby21 ...
>>> Source prepared.
>>> Configuring source in /var/tmp/portage/dev-ruby/psych-2.0.15/work ...
 * Running configure phase for ruby20 ...
checking for yaml.h... yes
checking for yaml_get_version() in -lyaml... yes
creating Makefile
 * Running configure phase for ruby21 ...
checking for yaml.h... *** 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}/lib64
	--with-make-prog
	--without-make-prog
	--srcdir=.
	--curdir
	--ruby=/usr/bin/ruby21
	--with-libyaml-dir
	--without-libyaml-dir
	--with-libyaml-include
	--without-libyaml-include=${libyaml-dir}/include
	--with-libyaml-lib
	--without-libyaml-lib=${libyaml-dir}/lib64
	--enable-bundled-libyaml
	--disable-bundled-libyaml
/usr/lib64/ruby/2.1.0/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
	from /usr/lib64/ruby/2.1.0/mkmf.rb:587:in `try_cpp'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:1114:in `block in find_header'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:912:in `block in checking_for'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:351:in `block (2 levels) in postpone'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:321:in `open'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:351:in `block in postpone'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:321:in `open'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:347:in `postpone'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:911:in `checking_for'
	from /usr/lib64/ruby/2.1.0/mkmf.rb:1113:in `find_header'
	from extconf.rb:9:in `<main>'
 * ERROR: dev-ruby/psych-2.0.15::gentoo failed (configure phase):
 *   (no error message)
 * 
 * Call stack:
 *     ebuild.sh, line   90:  Called src_configure
 *   environment, line 4393:  Called ruby-ng_src_configure
 *   environment, line 4085:  Called _ruby_each_implementation 'each_ruby_configure'
 *   environment, line  549:  Called _ruby_invoke_environment 'ruby21' 'each_ruby_configure'
 *   environment, line  644:  Called each_ruby_configure
 *   environment, line  931:  Called die
 * The specific snippet of code:
 *       ${RUBY} -Cext/${PN} extconf.rb || die
 * 
 * If you need support, post the output of `emerge --info '=dev-ruby/psych-2.0.15::gentoo'`,
 * the complete build log and the output of `emerge -pqv '=dev-ruby/psych-2.0.15::gentoo'`.
!!! When you file a bug report, please include the following information:
GENTOO_VM=  CLASSPATH="" JAVA_HOME=""
JAVACFLAGS="" COMPILER=""
and of course, the output of emerge --info =psych-2.0.15
 * The complete build log is located at '/var/log/portage/dev-ruby:psych-2.0.15:20151003-071618.log'.
 * For convenience, a symlink to the build log is located at '/var/tmp/portage/dev-ruby/psych-2.0.15/temp/build.log'.
 * The ebuild environment file is located at '/var/tmp/portage/dev-ruby/psych-2.0.15/temp/environment'.
 * Working directory: '/var/tmp/portage/dev-ruby/psych-2.0.15/work/ruby21/psych-2.0.15'
 * S: '/var/tmp/portage/dev-ruby/psych-2.0.15/work/ruby21/psych-2.0.15'