rust/src/test/ui/run-pass/issues/issue-20575.rs

// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

// Test that overloaded calls work with zero arity closures

// pretty-expanded FIXME #23616

fn main() {
    let functions: [Box<Fn() -> Option<()>>; 1] = [Box::new(|| None)];

    let _: Option<Vec<()>> = functions.iter().map(|f| (*f)()).collect();
}