error[E0382]: use of moved value: `f`
  --> $DIR/generator_capture_.rs:21:17
   |
LL |     let f = {
   |         - move occurs because `f` has type `{gen closure@$DIR/generator_capture_.rs:10:17: 10:24}`, which does not implement the `Copy` trait
...
LL |     let mut i = f();
   |                 --- `f` moved due to this call
...
LL |     let mut i = f();
   |                 ^ value used here after move
   |
note: this value implements `FnOnce`, which causes it to be moved when called
  --> $DIR/generator_capture_.rs:16:17
   |
LL |     let mut i = f();
   |                 ^
help: consider cloning the value if the performance cost is acceptable
   |
LL |     let mut i = f.clone()();
   |                  ++++++++

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0382`.