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