src/test/compile-fail/regions-normalize-in-where-clause-list.rs

// Copyright 2016 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 we are able to normalize in the list of where-clauses,
// even if `'a: 'b` is required.

trait Project<'a, 'b> {
    type Item;
}

impl<'a, 'b> Project<'a, 'b> for ()
    where 'a: 'b
{
    type Item = ();
}

// No error here, we have 'a: 'b. We used to report an error here
// though, see https://github.com/rust-lang/rust/issues/45937.
fn foo<'a: 'b, 'b>()
    where <() as Project<'a, 'b>>::Item : Eq
{
}

// Here we get an error: we need `'a: 'b`.
fn bar<'a, 'b>() //~ ERROR cannot infer
    where <() as Project<'a, 'b>>::Item : Eq
{
}

fn main() { }