a72d6c114b
Make stable_mir::with_tables sound See the first commit for the actual soundness fix. The rest is just fallout from that and is entirely safe code. Includes most of #120120 The major difference to #120120 is that we don't need an unsafe trait, as we can now rely on the type system (the only unsafe part, and the actual source of the unsoundness was in `with_tables`) r? `@celinval`