First of all, love this work. Excited to see these commands come to SwiftPM
I wanted to quickly note that although it has been historically discouraged to use conditional compilation blocks in package manifests, we can’t ignore that there are legitimate reasons to add them. It’s more of an “avoid when unnecessary” than a “this is bad, period.” See this very recent recommendation RE static compilation for Linux, for example: Static linking on Linux in Swift 5.3.1 - #3 by drexin
My point being, it’s important we don’t ignore or intentionally avoid the topic in the context of package edit commands. Based on the above comments, this has been thought about and won’t break.