def check_that_user_bin_dir_is_in_path
user_bin_dir = @bin_dir || Gem.bindir(gem_home)
user_bin_dir.gsub!(File::SEPARATOR, File::ALT_SEPARATOR) if File::ALT_SEPARATOR
path = ENV['PATH']
if Gem.win_platform? then
path = path.downcase
user_bin_dir = user_bin_dir.downcase
end
unless path.split(File::PATH_SEPARATOR).include? user_bin_dir then
unless self.class.path_warning then
alert_warning "You don't have #{user_bin_dir} in your PATH,\n\t gem executables will not run."
self.class.path_warning = true
end
end
end