rust/src/test/ui/nll/relate_tys/hr-fn-aau-eq-abu.rs
2018-07-25 06:38:22 +03:00

39 lines
1.3 KiB
Rust

// Copyright 2017 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 an interesting corner case: a fn that takes two arguments that
// are references with the same lifetime is in fact equivalent to a fn
// that takes two references with distinct lifetimes. This is true
// because the two functions can call one another -- effectively, the
// single lifetime `'a` is just inferred to be the intersection of the
// two distinct lifetimes.
//
// compile-flags:-Zno-leak-check
#![feature(nll)]
use std::cell::Cell;
fn make_cell_aa() -> Cell<for<'a> fn(&'a u32, &'a u32)> {
panic!()
}
fn aa_eq_ab() {
let a: Cell<for<'a, 'b> fn(&'a u32, &'b u32)> = make_cell_aa();
//~^ ERROR higher-ranked subtype error
//
// FIXME -- this .. arguably ought to be accepted. However, the
// current leak check also rejects this example, and it's kind of
// a pain to support it. There are some comments in `relate_tys`
drop(a);
}
fn main() { }