error[E0597]: `*a` does not live long enough --> $DIR/destructor-restrictions.rs:8:10 | LL | let a = Box::new(RefCell::new(4)); | - binding `a` declared here LL | *a.borrow() + 1 | ^--------- | | | borrowed value does not live long enough | a temporary with access to the borrow is created here ... LL | }; | -- ... and the borrow might be used here, when that temporary is dropped and runs the destructor for type `Ref<'_, i32>` | | | `*a` dropped here while still borrowed | = note: the temporary is part of an expression at the end of a block; consider forcing this temporary to be dropped sooner, before the block's local variables are dropped help: for example, you could save the expression's value in a new local variable `x` and then make `x` be the expression at the end of the block | LL | let x = *a.borrow() + 1; x | +++++++ +++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0597`.