The only non-obvious changes:
- `building/storage_live_dead_in_statics.rs` has a `#[rustfmt::skip]`
attribute to avoid reformating a table of data.
- Two `.mir` files have slight changes involving line numbers.
- In `unusual_item_types.rs` an `EMIT_MIR` annotation is moved to
outside a function, which is the usual spot, because `tidy` complains
if such a comment is indented.
The commit also tweaks the comments in `rustfmt.toml`.
never patterns: lower never patterns to `Unreachable` in MIR
This lowers a `!` pattern to "goto Unreachable". Ideally I'd like to read from the place to make it clear that the UB is coming from an invalid value, but that's tricky so I'm leaving it for later.
r? `@compiler-errors` how do you feel about a lil bit of MIR lowering
