Support for the Ruby 2.4 series has ended. See here for reference.
# File rubygems/ext/rake_builder.rb, line 10 def self.build(extension, directory, dest_path, results, args=[], lib_dir=nil) if File.basename(extension) =~ /mkrf_conf/i then cmd = "#{Gem.ruby} #{File.basename extension}".dup cmd << " #{args.join " "}" unless args.empty? run cmd, results end # Deal with possible spaces in the path, e.g. C:/Program Files dest_path = '"' + dest_path.to_s + '"' if dest_path.to_s.include?(' ') rake = ENV['rake'] rake ||= begin "#{Gem.ruby} -rubygems #{Gem.bin_path('rake', 'rake')}" rescue Gem::Exception end rake ||= Gem.default_exec_format % 'rake' cmd = "#{rake} RUBYARCHDIR=#{dest_path} RUBYLIBDIR=#{dest_path}" # ENV is frozen run cmd, results results end