Gem.suffixes

# File tmp/rubies/ruby-3.3.0/lib/rubygems.rb, line 935
def self.suffixes
  @suffixes ||= ["",
                 ".rb",
                 *%w[DLEXT DLEXT2].map do |key|
                   val = RbConfig::CONFIG[key]
                   next unless val && !val.empty?
                   ".#{val}"
                 end].compact.uniq
end