Adds a conditional impact that represents that impact if the replacement node is added to the kernel AST. This is a soundness fix for conditional impacts as the replacement node might have a different set of impacts than the "source".
It's worth noting that the only way this could lead to an incorrect compilation for protobufs is if *every* metadata field was erased. The impact of each "source" is a superset of the impact for every "replacement" node.
This code is new and behind a flag so this bug certainly won't have been visible to anyone.
Change-Id: Ifa3cb7d6b9aa46221c736a1566aa79d73f99917c
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/353940
Commit-Queue: Nate Biggs <natebiggs@google.com>
Reviewed-by: Mayank Patke <fishythefish@google.com>
Nate Biggs
c0304fa0c6