error[E0499]: cannot borrow `f` as mutable more than once at a time
  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:22:16
   |
LL |       f(Box::new(|| {
   |       -          ^^ second mutable borrow occurs here
   |       |
   |  _____first mutable borrow occurs here
   | |
LL | |     //~^ ERROR: cannot borrow `f` as mutable more than once
LL | |         f((Box::new(|| {})))
   | |         - second borrow occurs due to use of `f` in closure
LL | |     }));
   | |_______- borrow later used here

error[E0596]: cannot borrow `*f` as mutable, as it is behind a `&` reference
  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:35:5
   |
LL | fn test2<F>(f: &F) where F: FnMut() {
   |                -- help: consider changing this to be a mutable reference: `&mut F`
LL |     (*f)();
   |     ^^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable

error[E0596]: cannot borrow `*f.f` as mutable, as it is behind a `&` reference
  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:44:5
   |
LL | fn test4(f: &Test) {
   |             ----- help: consider changing this to be a mutable reference: `&mut Test<'_>`
LL |     f.f.call_mut(())
   |     ^^^ `f` is a `&` reference, so the data it refers to cannot be borrowed as mutable

error[E0507]: cannot move out of captured variable in an `FnMut` closure
  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:66:13
   |
LL |         foo(f);
   |             ^ cannot move out of captured variable in an `FnMut` closure

error[E0505]: cannot move out of `f` because it is borrowed
  --> $DIR/borrowck-call-is-borrow-issue-12224.rs:65:16
   |
LL |       f(Box::new(|a| {
   |       -          ^^^ move out of `f` occurs here
   |       |
   |  _____borrow of `f` occurs here
   | |
LL | |         foo(f);
   | |             - move occurs due to use in closure
LL | |         //~^ ERROR cannot move `f` into closure because it is borrowed
LL | |         //~| ERROR cannot move out of captured outer variable in an `FnMut` closure
LL | |     }), 3);
   | |__________- borrow later used here

error: aborting due to 5 previous errors

Some errors occurred: E0499, E0505, E0507, E0596.
For more information about an error, try `rustc --explain E0499`.