ADI doesn't seem to me to have enough bits to effectively protect against vtable type confusion.

Besides, nothing stops a wasm compiler from emitting such checks itself, if it wants to.

Not sure about that, it does seem quite effective, though.

Having the compiler emiting it wouldn't be an option, as hardware enabled solutions seem to be the only ones accepted by C devs, as shown by SPARC and now ARM.

I think there is the possibility of integrating the source maps and the WASM with special purpose execution envs to apply these checks.