error[E0499]: cannot borrow `f` as mutable more than once at a time --> $DIR/borrowck-call-is-borrow-issue-12224.rs:12:16 | LL | f(Box::new(|| { | - ^^ second mutable borrow occurs here | | | first mutable borrow occurs here | first borrow later used by call LL | LL | f((Box::new(|| {}))) | - second borrow occurs due to use of `f` in closure error[E0596]: cannot borrow `*f` as mutable, as it is behind a `&` reference --> $DIR/borrowck-call-is-borrow-issue-12224.rs:25:5 | LL | (*f)(); | ^^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable | help: consider changing this to be a mutable reference | LL | fn test2(f: &mut F) where F: FnMut() { | +++ error[E0596]: cannot borrow `f.f` as mutable, as it is behind a `&` reference --> $DIR/borrowck-call-is-borrow-issue-12224.rs:34:5 | LL | f.f.call_mut(()) | ^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable | help: consider changing this to be a mutable reference | LL | fn test4(f: &mut Test) { | +++ error[E0507]: cannot move out of `f`, a captured variable in an `FnMut` closure --> $DIR/borrowck-call-is-borrow-issue-12224.rs:57:13 | LL | let mut f = move |g: Box, b: isize| { | ----- captured outer variable ... LL | f(Box::new(|a| { | --- captured by this `FnMut` closure LL | LL | foo(f); | ^ move occurs because `f` has type `[closure@$DIR/borrowck-call-is-borrow-issue-12224.rs:52:17: 52:58]`, which does not implement the `Copy` trait error[E0505]: cannot move out of `f` because it is borrowed --> $DIR/borrowck-call-is-borrow-issue-12224.rs:55:16 | LL | let mut f = move |g: Box, b: isize| { | ----- binding `f` declared here ... LL | f(Box::new(|a| { | - ^^^ move out of `f` occurs here | | | borrow of `f` occurs here LL | LL | foo(f); | - move occurs due to use in closure error: aborting due to 5 previous errors Some errors have detailed explanations: E0499, E0505, E0507, E0596. For more information about an error, try `rustc --explain E0499`.