def warn_for_outdated_bundler_version
return unless bundler_version
prerelease_text = bundler_version.prerelease? ? " --pre" : ""
current_version = Gem::Version.create(Bundler::VERSION)
case current_version.segments.first <=> bundler_version.segments.first
when -1
raise LockfileError, "You must use Bundler #{bundler_version.segments.first} or greater with this lockfile."
when 0
if current_version < bundler_version
Bundler.ui.warn "Warning: the running version of Bundler is older " \
"than the version that created the lockfile. We suggest you " \
"upgrade to the latest version of Bundler by running `gem " \
"install bundler#{prerelease_text}`.\n"
end
end
end