1error[E0277]: expected a `Fn<()>` closure, found `extern "C" fn() {f}` 2 --> $DIR/extern-wrong-value-type.rs:9:11 3 | 4LL | is_fn(f); 5 | ----- ^ expected an `Fn<()>` closure, found `extern "C" fn() {f}` 6 | | 7 | required by a bound introduced by this call 8 | 9 = help: the trait `Fn<()>` is not implemented for `extern "C" fn() {f}` 10 = note: wrap the `extern "C" fn() {f}` in a closure with no arguments: `|| { /* code */ }` 11note: required by a bound in `is_fn` 12 --> $DIR/extern-wrong-value-type.rs:4:28 13 | 14LL | fn is_fn<F>(_: F) where F: Fn() {} 15 | ^^^^ required by this bound in `is_fn` 16 17error: aborting due to previous error 18 19For more information about this error, try `rustc --explain E0277`. 20