error[E0502]: cannot borrow `self.thing` as mutable because it is also borrowed as immutable --> $DIR/issue-51268.rs:14:9 | LL | self.thing.bar(|| { | ^ --- -- immutable borrow occurs here | | | | _________| immutable borrow later used by call | | LL | | LL | | &self.number; | | ----------- first borrow occurs due to use of `self` in closure LL | | }); | |__________^ mutable borrow occurs here error: aborting due to previous error For more information about this error, try `rustc --explain E0502`.