rust/src/test/ui/impl-header-lifetime-elision/dyn-trait.rs
Scott McMurray 37393576ec Stabilize impl_header_lifetime_elision in 2015
It's already stable in 2018; this finishes the stabilization.
2018-10-19 21:57:52 -07:00

41 lines
1.1 KiB
Rust

// Copyright 2018 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 `impl MyTrait<'_> for &i32` is equivalent to `impl<'a,
// 'b> MyTrait<'a> for &'b i32`.
#![allow(warnings)]
use std::fmt::Debug;
// Equivalent to `Box<dyn Debug + 'static>`:
trait StaticTrait { }
impl StaticTrait for Box<dyn Debug> { }
// Equivalent to `Box<dyn Debug + 'static>`:
trait NotStaticTrait { }
impl NotStaticTrait for Box<dyn Debug + '_> { }
fn static_val<T: StaticTrait>(_: T) {
}
fn with_dyn_debug_static<'a>(x: Box<dyn Debug + 'a>) {
static_val(x); //~ ERROR cannot infer
}
fn not_static_val<T: NotStaticTrait>(_: T) {
}
fn with_dyn_debug_not_static<'a>(x: Box<dyn Debug + 'a>) {
not_static_val(x); // OK
}
fn main() {
}