Although we depend on miri from https://github.com/rust-lang/miri directly, we require that the user installs a sysroot manually using cargo miri setup (since that comes from the miri rustup component). This means we are locked to the version of miri which is in https://github.com/rust-lang/rust. However, it would be better if we could instead use the rustc version which https://github.com/rust-lang/miri compiles with. This would allow us to update more frequently.

In particular, if we make changes to miri (such as rust-lang/miri#1736) then we need to wait for the miri update to reach nightly to use those changes.

cc @RalfJung the easiest way for us to make this possible would be for cargo miri [setup] to be callable as a library, although I suppose we could also install cargo miri directly from the repository. That does seem like a worse solution however.