error[E0618]: expected function, found `main::Foo` --> $DIR/issue-46771.rs:13:23 | LL | struct Foo; | ----------- `main::Foo` defined here LL | (1 .. 2).find(|_| Foo(0) == 0); //~ ERROR expected function, found `main::Foo` | ^^^^^^ not a function error: aborting due to previous error For more information about this error, try `rustc --explain E0618`.