I ran into a few forwarding issues while using std::expected in #163919.
Created attachment 297031 [details] patch
Comment on attachment 297031 [details] patch LGTM.
Comment on attachment 297031 [details] patch Clearing flags on attachment: 297031 Committed r209778: <http://trac.webkit.org/changeset/209778>
All reviewed patches have been landed. Closing bug.