rust-clippy/tests/run-pass/issue-2862.rs

// Copyright 2014-2018 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution.
//
// 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.

pub trait FooMap {
    fn map<B, F: Fn() -> B>(&self, f: F) -> B;
}

impl FooMap for bool {
    fn map<B, F: Fn() -> B>(&self, f: F) -> B {
        f()
    }
}

fn main() {
    let a = true;
    a.map(|| false);
}