Thanks a lot, Manu, I'm a huge fan of this.Wrt. binding rvalues to mutable refs, we could introduce something like `-transition=rval_to_mutable_ref` to have the compiler list all matching call sites.
Wrt. `auto ref`, I'd very much like to see its semantics change to 'pass this argument in the most efficient way' (depending on type and ABI, not just lvalue-ness of argument) at some point in the future.
