1 error[E0594]: cannot assign to `counter`, as it is a captured variable in a `Fn` closure
2 --> $DIR/unboxed-closures-mutated-upvar-from-fn-closure.rs:11:9
4 LL | fn call<F>(f: F) where F : Fn() {
5 | - change this to accept `FnMut` instead of `Fn`
8 | ---- -- in this closure
10 | expects `Fn` instead of `FnMut`
12 | ^^^^^^^^^^^^ cannot assign
14 error: aborting due to previous error
16 For more information about this error, try `rustc --explain E0594`.