rust/src/test/ui/coercion/coerce-issue-49593-box-never.rs

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// 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.
// compile-pass
#![feature(never_type)]
#![allow(unreachable_code)]
use std::error::Error;
use std::char::ParseCharError; /* some Error */
fn raw_ptr_box<T>(t: T) -> *mut T {
panic!()
}
fn foo(x: !) -> Box<Error> {
/* *mut $0 is coerced to *mut Error here */ Box::<_ /* ! */>::new(x)
}
fn foo_raw_ptr(x: !) -> *mut Error {
/* *mut $0 is coerced to *mut Error here */ raw_ptr_box::<_ /* ! */>(x)
}
fn no_coercion(d: *mut Error) -> *mut Error {
/* an unsize coercion won't compile here, and it is indeed not used
because there is nothing requiring the _ to be Sized */
d as *mut _
}
trait Xyz {}
struct S;
struct T;
impl Xyz for S {}
impl Xyz for T {}
fn foo_no_never() {
let mut x /* : Box<S> */ = None;
let mut first_iter = false;
loop {
if !first_iter {
let y: Box<Xyz>
= /* Box<$0> is coerced to Box<Xyz> here */ Box::new(x.unwrap());
}
x = Some(S);
first_iter = true;
}
}
fn main() {
}