error[E0277]: expected a `Fn<()>` closure, found `fn() {foo}` --> $DIR/fn-traits.rs:24:10 | LL | call(foo); | ---- ^^^ expected an `Fn<()>` closure, found `fn() {foo}` | | | required by a bound introduced by this call | = help: the trait `Fn<()>` is not implemented for fn item `fn() {foo}` = note: wrap the `fn() {foo}` in a closure with no arguments: `|| { /* code */ }` = note: `#[target_feature]` functions do not implement the `Fn` traits note: required by a bound in `call` --> $DIR/fn-traits.rs:11:17 | LL | fn call(f: impl Fn()) { | ^^^^ required by this bound in `call` error[E0277]: expected a `FnMut<()>` closure, found `fn() {foo}` --> $DIR/fn-traits.rs:25:14 | LL | call_mut(foo); | -------- ^^^ expected an `FnMut<()>` closure, found `fn() {foo}` | | | required by a bound introduced by this call | = help: the trait `FnMut<()>` is not implemented for fn item `fn() {foo}` = note: wrap the `fn() {foo}` in a closure with no arguments: `|| { /* code */ }` = note: `#[target_feature]` functions do not implement the `Fn` traits note: required by a bound in `call_mut` --> $DIR/fn-traits.rs:15:21 | LL | fn call_mut(f: impl FnMut()) { | ^^^^^^^ required by this bound in `call_mut` error[E0277]: expected a `FnOnce<()>` closure, found `fn() {foo}` --> $DIR/fn-traits.rs:26:15 | LL | call_once(foo); | --------- ^^^ expected an `FnOnce<()>` closure, found `fn() {foo}` | | | required by a bound introduced by this call | = help: the trait `FnOnce<()>` is not implemented for fn item `fn() {foo}` = note: wrap the `fn() {foo}` in a closure with no arguments: `|| { /* code */ }` = note: `#[target_feature]` functions do not implement the `Fn` traits note: required by a bound in `call_once` --> $DIR/fn-traits.rs:19:22 | LL | fn call_once(f: impl FnOnce()) { | ^^^^^^^^ required by this bound in `call_once` error[E0277]: expected a `Fn<()>` closure, found `unsafe fn() {foo_unsafe}` --> $DIR/fn-traits.rs:28:10 | LL | call(foo_unsafe); | ---- ^^^^^^^^^^ call the function in a closure: `|| unsafe { /* code */ }` | | | required by a bound introduced by this call | = help: the trait `Fn<()>` is not implemented for fn item `unsafe fn() {foo_unsafe}` = note: wrap the `unsafe fn() {foo_unsafe}` in a closure with no arguments: `|| { /* code */ }` = note: `#[target_feature]` functions do not implement the `Fn` traits note: required by a bound in `call` --> $DIR/fn-traits.rs:11:17 | LL | fn call(f: impl Fn()) { | ^^^^ required by this bound in `call` error[E0277]: expected a `FnMut<()>` closure, found `unsafe fn() {foo_unsafe}` --> $DIR/fn-traits.rs:30:14 | LL | call_mut(foo_unsafe); | -------- ^^^^^^^^^^ call the function in a closure: `|| unsafe { /* code */ }` | | | required by a bound introduced by this call | = help: the trait `FnMut<()>` is not implemented for fn item `unsafe fn() {foo_unsafe}` = note: wrap the `unsafe fn() {foo_unsafe}` in a closure with no arguments: `|| { /* code */ }` = note: `#[target_feature]` functions do not implement the `Fn` traits note: required by a bound in `call_mut` --> $DIR/fn-traits.rs:15:21 | LL | fn call_mut(f: impl FnMut()) { | ^^^^^^^ required by this bound in `call_mut` error[E0277]: expected a `FnOnce<()>` closure, found `unsafe fn() {foo_unsafe}` --> $DIR/fn-traits.rs:32:15 | LL | call_once(foo_unsafe); | --------- ^^^^^^^^^^ call the function in a closure: `|| unsafe { /* code */ }` | | | required by a bound introduced by this call | = help: the trait `FnOnce<()>` is not implemented for fn item `unsafe fn() {foo_unsafe}` = note: wrap the `unsafe fn() {foo_unsafe}` in a closure with no arguments: `|| { /* code */ }` = note: `#[target_feature]` functions do not implement the `Fn` traits note: required by a bound in `call_once` --> $DIR/fn-traits.rs:19:22 | LL | fn call_once(f: impl FnOnce()) { | ^^^^^^^^ required by this bound in `call_once` error: aborting due to 6 previous errors For more information about this error, try `rustc --explain E0277`.