swift

b3e49510 - [AutoDiff] flag for cross-file derivative registration (#28891)

[AutoDiff] flag for cross-file derivative registration (#28891) Since cross-file derivative registration requires a lot of distinct fixes and tests (some of which are drafted in https://github.com/apple/swift/pull/28790), it would be nice to be able to develop it on `tensorflow` under a flag. This PR adds a flag and a very tiny testcase -- the only situation that I'm aware of that currently works without any of the fixes.