I am trying to use a closure as function parameter:
fn foo(f: Box<Fn() -> bool>) -> bool { f() } fn main() { let bar = 42; foo(Box::new(|| bar != 42)); } but I get this lifetime error:
src/main.rs:7:24: 7:36 error: cannot infer an appropriate lifetime due to conflicting requirements src/main.rs:7 let n = foo(Box::new(|| bar != 42)); ^~~~~~~~~~~~ src/main.rs:7:15: 7:23 note: first, the lifetime cannot outlive the expression at 7:14... src/main.rs:7 let n = foo(Box::new(|| bar != 42)); ^~~~~~~~ src/main.rs:7:15: 7:23 note: ...so that the type `[closure src/main.rs:7:24: 7:36]` will meet its required lifetime bounds src/main.rs:7 let n = foo(Box::new(|| bar != 42)); ^~~~~~~~ src/main.rs:7:15: 7:37 note: but, the lifetime must be valid for the call at 7:14... src/main.rs:7 let n = foo(Box::new(|| bar != 42)); ^~~~~~~~~~~~~~~~~~~~~~ src/main.rs:7:24: 7:36 note: ...so that argument is valid for the call src/main.rs:7 let n = foo(Box::new(|| bar != 42)); ^~~~~~~~~~~~ error: aborting due to previous error I don't understand why the lifetime is not properly infered. What can I do to fix that ?
$ rustc --version rustc 1.0.0-nightly (6c065fc8c 2015-02-17) (built 2015-02-18) 
