Who's actually expecting `xyz.com` here?
Spec: https://go.dev/ref/spec#Selectors > x.f resolves to the field/method at the shallowest depth in T. If there isn’t exactly one at that depth, it’s illegal.
Embedding promotes fields; on name collisions the shallowest wins. So `opts.URL` is `FooService.URL` (depth 1), not `BarConnectionOptions.URL` (depth 2).
That something is clearly specced doesn’t imply all developers actively know it.
Even given that it compiles, I wouldn’t exclude it being a runtime error.
But the big problem isn’t that it behaves as advertised, it’s that it is way too easy to write opts.URL where you mean opts.Bar.URL. Auto-complete will happily compete the wrong thing for you.