They seem to have fixed this by requiring stringiohttps://github.com/rubocop/rubocop/pull/13234 (Note: This happens with --parser=parse.y as well, so it has nothing to do with Prism), so this PR follows it. We should be able to remove this once they publish the fix to rubygems.org.
I don't know what triggered this, but with the current Ruby master, rubocop fails to look up the
StringIO
constant:They seem to have fixed this by requiring
stringio
https://github.com/rubocop/rubocop/pull/13234 (Note: This happens with--parser=parse.y
as well, so it has nothing to do with Prism), so this PR follows it. We should be able to remove this once they publish the fix to rubygems.org.