error[E0595]: closure cannot assign to immutable local variable `n`
  --> $DIR/unboxed-closures-mutate-upvar.rs:24:27
   |
LL |     let n = 0;
   |         - help: make this binding mutable: `mut n`
LL |     let mut f = to_fn_mut(|| { //~ ERROR closure cannot assign
   |                           ^^ cannot borrow mutably

error[E0594]: cannot assign to captured outer variable in an `FnMut` closure
  --> $DIR/unboxed-closures-mutate-upvar.rs:42:9
   |
LL |     let n = 0;
   |         - help: consider making `n` mutable: `mut n`
...
LL |         n += 1; //~ ERROR cannot assign
   |         ^^^^^^

error[E0594]: cannot assign to captured outer variable in an `Fn` closure
  --> $DIR/unboxed-closures-mutate-upvar.rs:56:9
   |
LL |         n += 1; //~ ERROR cannot assign
   |         ^^^^^^
   |
   = note: `Fn` closures cannot capture their enclosing environment for modifications
help: consider changing this closure to take self by mutable reference
  --> $DIR/unboxed-closures-mutate-upvar.rs:55:23
   |
LL |       let mut f = to_fn(move || {
   |  _______________________^
LL | |         n += 1; //~ ERROR cannot assign
LL | |     });
   | |_____^

error[E0594]: cannot assign to captured outer variable in an `Fn` closure
  --> $DIR/unboxed-closures-mutate-upvar.rs:63:9
   |
LL |         n += 1; //~ ERROR cannot assign
   |         ^^^^^^
   |
   = note: `Fn` closures cannot capture their enclosing environment for modifications
help: consider changing this closure to take self by mutable reference
  --> $DIR/unboxed-closures-mutate-upvar.rs:62:23
   |
LL |       let mut f = to_fn(move || {
   |  _______________________^
LL | |         n += 1; //~ ERROR cannot assign
LL | |     });
   | |_____^

error: aborting due to 4 previous errors

Some errors occurred: E0594, E0595.
For more information about an error, try `rustc --explain E0594`.