rust/src/test/compile-fail/object-lifetime-default-ambiguous.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 if a struct declares multiple region bounds for a given
// type parameter, an explicit lifetime bound is required on object
// lifetimes within.

#![allow(dead_code)]

trait Test {
    fn foo(&self) { }
}

struct Ref0<T:?Sized> {
    r: *mut T
}

struct Ref1<'a,T:'a+?Sized> {
    r: &'a T
}

struct Ref2<'a,'b:'a,T:'a+'b+?Sized> {
    r: &'a &'b T
}

fn a<'a,'b>(t: Ref2<'a,'b,Test>) {
    //~^ ERROR lifetime bound for this object type cannot be deduced from context
}

fn b(t: Ref2<Test>) {
    //~^ ERROR lifetime bound for this object type cannot be deduced from context
}

fn c(t: Ref2<&Test>) {
    // In this case, the &'a overrides.
}

fn d(t: Ref2<Ref1<Test>>) {
    // In this case, the lifetime parameter from the Ref1 overrides.
}

fn e(t: Ref2<Ref0<Test>>) {
    //~^ ERROR lifetime bound for this object type cannot be deduced from context
    //
    // In this case, Ref2 is ambiguous, and Ref0 inherits the
    // ambiguity.
}

fn f(t: &Ref2<Test>) {
    //~^ ERROR lifetime bound for this object type cannot be deduced from context
}

fn main() {
}