1 error: Undefined Behavior: trying to retag from <TAG> for Unique permission at ALLOC[0x0], but that tag does not exist in the borrow stack for this location
2 --> $DIR/buggy_split_at_mut.rs:LL:CC
4 LL | let (a, b) = safe::split_at_mut(&mut array, 0);
7 | trying to retag from <TAG> for Unique permission at ALLOC[0x0], but that tag does not exist in the borrow stack for this location
8 | this error occurs as part of retag at ALLOC[0x0..0x10]
10 = help: this indicates a potential bug in the program: it performed an invalid operation, but the Stacked Borrows rules it violated are still experimental
11 = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
12 help: <TAG> was created by a Unique retag at offsets [0x0..0x10]
13 --> $DIR/buggy_split_at_mut.rs:LL:CC
15 LL | from_raw_parts_mut(ptr, len - mid), // BUG: should be "mid" instead of "len - mid"
16 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
17 help: <TAG> was later invalidated at offsets [0x0..0x10] by a Unique retag
18 --> $DIR/buggy_split_at_mut.rs:LL:CC
20 LL | from_raw_parts_mut(ptr.offset(mid as isize), len - mid),
21 | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
23 = note: inside `main` at $DIR/buggy_split_at_mut.rs:LL:CC
25 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
27 error: aborting due to previous error