Gem::BasicSpecification#have_file?

# File tmp/rubies/ruby-4.0.0/lib/rubygems/basic_specification.rb, line 371
def have_file?(file, suffixes)
  return true if raw_require_paths.any? do |path|
    base = File.join(gems_dir, full_name, path, file)
    suffixes.any? {|suf| File.file? base + suf }
  end

  if have_extensions?
    base = File.join extension_dir, file
    suffixes.any? {|suf| File.file? base + suf }
  else
    false
  end
end