If you change a struct and don't re-run cloner,
your Cloner method might be inaccurate, leading to bad things.
To prevent this, write out the struct as it is at the moment that
cloner is caller, and attempt a conversion from that type.
If the struct gets changed in any way, this conversion will fail.
This will yield false positives: If you change a non-pointer field,
you will be forced to re-run cloner, even though the actual generated
code won't change. I think this is an acceptable cost: It is a minor
annoyance, which will prevent real bugs.
Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
