rust/src/test/run-pass/issue-2063.rs
Eli Friedman 0eea0f6e90 Allow writing types which "can't" be instantiated.
The borrow checker doesn't allow constructing such a type at runtime
using safe code, but there isn't any reason to ban them in the type checker.

Included in this commit is an example of a neat static doubly-linked list.

Feature-gated under the static_recursion gate to be on the safe side, but
there are unlikely to be any reasons this shouldn't be turned on by
default.
2015-07-24 19:18:16 -07:00

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Rust

// Copyright 2012-2014 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.
#![feature(static_recursion)]
// test that autoderef of a type like this does not
// cause compiler to loop. Note that no instances
// of such a type could ever be constructed.
struct T(Box<T>);
trait ToStr2 {
fn my_to_string(&self) -> String;
}
impl ToStr2 for T {
fn my_to_string(&self) -> String { "t".to_string() }
}
#[allow(dead_code)]
fn new_t(x: T) {
x.my_to_string();
}
fn main() {
}