Rollup merge of #73133 - doctorn:unwind-mir-validation, r=jonas-schievink
Rollup merge of #73133 - doctorn:unwind-mir-validation, r=jonas-schievink

Enforce unwind invariants

I had a quick look at #72959. The failure message probably needs to be more detailed but I just wanted to check I got the right idea. I have no idea how to right a test for this either...

r? @jonas-schievink

Resolves #72959 (hypothetically)

graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,aidancully/rust