error: Undefined Behavior: trying to retag from for SharedReadOnly permission at ALLOC[0x4], but that tag does not exist in the borrow stack for this location --> RUSTLIB/core/src/slice/mod.rs:LL:CC | LL | unsafe { &*index.get_unchecked(self) } | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ | | | trying to retag from for SharedReadOnly permission at ALLOC[0x4], but that tag does not exist in the borrow stack for this location | this error occurs as part of retag at ALLOC[0x4..0x8] | = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information help: would have been created here, but this is a zero-size retag ([0x0..0x0]) so the tag in question does not exist anywhere --> $DIR/zst_slice.rs:LL:CC | LL | assert_eq!(*s.get_unchecked(1), 2); | ^^^^^^^^^^^^^^^^^^ = note: backtrace: = note: inside `core::slice::::get_unchecked::` at RUSTLIB/core/src/slice/mod.rs:LL:CC note: inside `main` at $DIR/zst_slice.rs:LL:CC --> $DIR/zst_slice.rs:LL:CC | LL | assert_eq!(*s.get_unchecked(1), 2); | ^^^^^^^^^^^^^^^^^^ note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace error: aborting due to previous error