sudo gem install pg FAIL

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

    /usr/bin/ruby -r ./siteconf20151220-3007-tiu1t.rb extconf.rb
checking for pg_config... yes
Using config values from /bin/pg_config
*** 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/$(RUBY_BASE_NAME)
	--with-pg
	--without-pg
	--enable-windows-cross
	--disable-windows-cross
	--with-pg-config
	--without-pg-config
	--with-pg_config
	--without-pg_config
	--with-pg-dir
	--without-pg-dir
	--with-pg-include
	--without-pg-include=${pg-dir}/include
	--with-pg-lib
	--without-pg-lib=${pg-dir}/lib64
/usr/share/ruby/mkmf.rb:456:in `try_do': The compiler failed to generate an executable file. (RuntimeError)
You have to install development tools first.
	from /usr/share/ruby/mkmf.rb:541:in `try_link0'
	from /usr/share/ruby/mkmf.rb:556:in `try_link'
	from extconf.rb:36:in `<main>'

extconf failed, exit code 1

Gem files will remain installed in /usr/local/share/gems/gems/pg-0.18.4 for inspection.
Results logged to /usr/local/lib64/gems/ruby/pg-0.18.4/gem_make.out