05e3248a79
This can break code that looked like:
impl Foo for Box<Any> {
fn f(&self) { ... }
}
let x: Box<Any + Send> = ...;
x.f();
Change such code to:
impl Foo for Box<Any> {
fn f(&self) { ... }
}
let x: Box<Any> = ...;
x.f();
That is, upcast before calling methods.
This is a conservative solution to #5781. A more proper treatment (see
the xfail'd `trait-contravariant-self.rs`) would take variance into
account. This change fixes the soundness hole.
Some library changes had to be made to make this work. In particular,
`Box<Any>` is no longer showable, and only `Box<Any+Send>` is showable.
Eventually, this restriction can be lifted; for now, it does not prove
too onerous, because `Any` is only used for propagating the result of
task failure.
This patch also adds a test for the variance inference work in #12828,
which accidentally landed as part of DST.
Closes #5781.
[breaking-change]
32 lines
1015 B
Rust
32 lines
1015 B
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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extern crate serialize;
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use std::io::MemWriter;
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use std::io;
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use serialize::{Encodable, Encoder};
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pub fn buffer_encode<'a,
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T:Encodable<serialize::json::Encoder<'a>,io::IoError>>(
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to_encode_object: &T)
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-> Vec<u8> {
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let mut m = MemWriter::new();
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{
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let mut encoder =
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serialize::json::Encoder::new(&mut m as &mut io::Writer);
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//~^ ERROR `m` does not live long enough
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to_encode_object.encode(&mut encoder);
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}
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m.unwrap()
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}
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fn main() {}
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