rust/src/test/compile-fail/issue28498-reject-trait-bound.rs

51 lines
1.6 KiB
Rust

// 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.
// Demonstrate that having a trait bound causes dropck to reject code
// that might indirectly access previously dropped value.
//
// Compare with run-pass/issue28498-ugeh-with-trait-bound.rs
use std::fmt;
#[derive(Debug)]
struct ScribbleOnDrop(String);
impl Drop for ScribbleOnDrop {
fn drop(&mut self) {
self.0 = format!("DROPPED");
}
}
struct Foo<T:fmt::Debug>(u32, T);
impl<T:fmt::Debug> Drop for Foo<T> {
fn drop(&mut self) {
// Use of `unsafe_destructor_blind_to_params` is unsound,
// because we access `T` fmt method when we pass `self.1`
// below, and thus potentially read from borrowed data.
println!("Dropping Foo({}, {:?})", self.0, self.1);
}
}
fn main() {
let (last_dropped, foo0);
let (foo1, first_dropped);
last_dropped = ScribbleOnDrop(format!("last"));
first_dropped = ScribbleOnDrop(format!("first"));
foo0 = Foo(0, &last_dropped);
//~^ ERROR `last_dropped` does not live long enough
foo1 = Foo(1, &first_dropped);
//~^ ERROR `first_dropped` does not live long enough
println!("foo0.1: {:?} foo1.1: {:?}", foo0.1, foo1.1);
}