This can be done reliably, though. You can just do

if a == b { ...

Just that the check will be replaced at compiletime with a constant, since the borrow-checker tracks all objects lifetimes and can use that information to optimize the check away.

The objects themselves don't make it into the compiled binary, since they have no size, but all the required information about them will make it in. So you can treat them like ordinary objects and do all the usual operations on it, without wasting any memory during runtime.