Seems to be like the best way to mitigate this would be to write a rust interpreter in assembly and use that to compile the compiler.
Yep. This was the original intention of the talk/paper; it was about _trust_, not attacking compilers. Attacking compilers is just a super cool example that was used.
I'm not even sure that the open source RISC-V initiative might prevent this, as theoretically the NSA could gain access to the manufacturing plant and insert their own core.
The only way to catch that at that point would be to X-ray the chip and look for their mod, or something. Anyway, assume the NSA has access to your shit, focus on preventing the random from grabbing your bank account access and stealing your money.
Hypothetically, Graydon could have inserted a trusting trust attack in the ocaml compiler that would also insert a version of itself inside rustc. Highly unlikely; very hard to do, but ... possible.
(This file is no longer in master because the compiler bootstraps from the previous stable release; too lazy to accurately isolate the last time it was updated)