rust/src/test/compile-fail/variance-use-covariant-struct-2.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 a covariant struct permits the lifetime of a reference to
// be shortened.

#![allow(dead_code)]
#![feature(rustc_attrs)]

struct SomeStruct<T>(T);

fn foo<'min,'max>(v: SomeStruct<&'max ()>)
                  -> SomeStruct<&'min ()>
    where 'max : 'min
{
    v
}

#[rustc_error] fn main() { } //~ ERROR compilation successful