[PATCH] D48504: [WIP] Add InsertionOrderSet, with constant-time insertion and removal.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

I could have used DenseMapInfo::getTombstoneKey() here instead of Optional, I think.  But making remove() swap might still be worthwhile; it would give random-access iteration, and more flexibility with the keys (with a different underlying hashtable, we could allow keys which don't have tombstones).


Repository:
  rL LLVM

https://reviews.llvm.org/D48504