tree c9daf14daa02a957893c6f8d67da4974b0932d64
parent 4471b81a0a0b94c75bad6e81d0413860944ecb1f
author Thomas Lively <tlively@google.com> 1674265334 -0800
committer Thomas Lively <tlively@google.com> 1674265334 -0800

[NFC] Experiment with C++20 coroutines for expression traversal

Add a gtest file that is only included in the build when using C++20 or greater
that defines a generator utility in terms of C++20 coroutines and then uses that
to define generators for traversing Expressions. Unlike our current traversal
utilities, these generators leave control flow up to their callers, making it
trivial to do things like stop the traversal early or run multiple traversals
concurrently, for example to compare two expression trees.