error: Undefined Behavior: attempting a read access using at ALLOC[$HEX], but that tag does not exist in the borrow stack for this location --> $DIR/illegal_read5.rs:LL:CC | LL | let _val = *xref; // the mutable one is dead and gone | ^^^^^ | | | attempting a read access using at ALLOC[$HEX], but that tag does not exist in the borrow stack for this location | this error occurs as part of an access at ALLOC[$HEX..$HEX] | = 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 retag at offsets [$HEX..$HEX] --> $DIR/illegal_read5.rs:LL:CC | LL | let xref: &mut i32 = &mut *refmut; | ^^^^^^^^^^^^ help: was later invalidated at offsets [$HEX..$HEX] --> $DIR/illegal_read5.rs:LL:CC | LL | mem::forget(unsafe { ptr::read(xshr) }); // but after reading through the shared ref | ^^^^^^^^^^^^^^^ = note: backtrace: = note: inside `main` at $DIR/illegal_read5.rs:LL:CC note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace error: aborting due to previous error