error: Undefined Behavior: read access through <TAG> at ALLOC[0x0] is forbidden
  --> tests/fail/both_borrows/outdated_local.rs:LL:CC
   |
LL |     assert_eq!(unsafe { *y }, 1);
   |                         ^^ Undefined Behavior occurred here
   |
   = help: this indicates a potential bug in the program: it performed an invalid operation, but the Tree Borrows rules it violated are still experimental
   = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/tree-borrows.md for further information
   = help: the accessed tag <TAG> has state Disabled which forbids this child read access
help: the accessed tag <TAG> was created here, in the initial state Frozen
  --> tests/fail/both_borrows/outdated_local.rs:LL:CC
   |
LL |     let y: *const i32 = &x;
   |                         ^^
help: the accessed tag <TAG> later transitioned to Disabled due to a foreign write access at offsets [0x0..0x4]
  --> tests/fail/both_borrows/outdated_local.rs:LL:CC
   |
LL |     x = 1; // this invalidates y by reactivating the lowermost uniq borrow for this local
   |     ^^^^^
   = help: this transition corresponds to a loss of read permissions
   = note: BACKTRACE (of the first span):
   = note: inside `main` at tests/fail/both_borrows/outdated_local.rs:LL:CC

note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace

error: aborting due to 1 previous error