I read through the link and yes the code looks okay. I think this is a communication issue.
It would be good next time if you have better commit messages which provides enough info. about the change so reviewers can at least
take a look knowing what happens. In the case the reviewer requested a change, it would be good to send out information (as you did)
and wait for acknowledgement before merging.
So it's going to bit rot immediately?
No – turns out files aren't changed that frequently, and people who use the GN build usually fix up the build files pretty quickly. (git log --pretty=oneline --grep Merge llvm/utils/gn/)
what's the purpose of this GN work then?
gn runs 1000x faster than cmake, and it allows things like https://reviews.llvm.org/D56713 . It also has the effect of us reading the cmake files very closely and cleaning them up a bit :-)