error: Undefined Behavior: trying to retag from for SharedReadWrite permission at ALLOC[0x0], but that tag does not exist in the borrow stack for this location --> $DIR/interior_mut2.rs:LL:CC | LL | let _val = *inner_shr.get(); | ^^^^^^^^^^^^^^^ | | | trying to retag from for SharedReadWrite permission at ALLOC[0x0], but that tag does not exist in the borrow stack for this location | this error occurs as part of retag at ALLOC[0x0..0x4] | = 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: was created by a SharedReadWrite retag at offsets [0x0..0x4] --> $DIR/interior_mut2.rs:LL:CC | LL | let inner_shr = &*inner_uniq; | ^^^^^^^^^^^^ help: was later invalidated at offsets [0x0..0x4] by a write access --> $DIR/interior_mut2.rs:LL:CC | LL | *c.get() = UnsafeCell::new(0); // now inner_shr gets invalidated | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ = note: BACKTRACE: = note: inside `main` at $DIR/interior_mut2.rs:LL:CC note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace error: aborting due to previous error