rust/src/test/compile-fail/issue-2392.rs

// Copyright 2014 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.

#![feature(core)]
use std::boxed::FnBox;

struct Obj<F> where F: FnOnce() -> u32 {
    closure: F,
    not_closure: usize,
}

struct BoxedObj {
    boxed_closure: Box<FnBox() -> u32>,
}

struct Wrapper<F> where F: FnMut() -> u32 {
    wrap: Obj<F>,
}

fn func() -> u32 {
    0
}

fn check_expression() -> Obj<Box<FnBox() -> u32>> {
    Obj { closure: Box::new(|| 42_u32) as Box<FnBox() -> u32>, not_closure: 42 }
}

fn main() {
    // test variations of function
    let o_closure = Obj { closure: || 42, not_closure: 42 };
    o_closure.closure(); //~ ERROR no method named `closure` found
    //~^ NOTE use `(o_closure.closure)(...)` if you meant to call the function stored in the `closure` field

    o_closure.not_closure(); //~ ERROR no method named `not_closure` found
    //~^ NOTE did you mean to write `o_closure.not_closure`?

    let o_func = Obj { closure: func, not_closure: 5 };
    o_func.closure(); //~ ERROR no method named `closure` found
    //~^ NOTE use `(o_func.closure)(...)` if you meant to call the function stored in the `closure` field

    let boxed_fn = BoxedObj { boxed_closure: Box::new(func) };
    boxed_fn.boxed_closure();//~ ERROR no method named `boxed_closure` found
    //~^ NOTE use `(boxed_fn.boxed_closure)(...)` if you meant to call the function stored in the `boxed_closure` field

    let boxed_closure = BoxedObj { boxed_closure: Box::new(|| 42_u32) as Box<FnBox() -> u32> };
    boxed_closure.boxed_closure();//~ ERROR no method named `boxed_closure` found
    //~^ NOTE use `(boxed_closure.boxed_closure)(...)` if you meant to call the function stored in the `boxed_closure` field

    // test expression writing in the notes
    let w = Wrapper { wrap: o_func };
    w.wrap.closure();//~ ERROR no method named `closure` found
    //~^ NOTE use `(w.wrap.closure)(...)` if you meant to call the function stored in the `closure` field
    w.wrap.not_closure();//~ ERROR no method named `not_closure` found
    //~^ NOTE did you mean to write `w.wrap.not_closure`?

    check_expression().closure();//~ ERROR no method named `closure` found
    //~^ NOTE use `(check_expression().closure)(...)` if you meant to call the function stored in the `closure` field
}