Skip to content

Commit 787f9f4

Browse files
oli-obkoli-obk
committed
Prevent fmt::Arguments from being shared across threads
Fixes #45197
1 parent 264aafe commit 787f9f4

File tree

3 files changed

+55
-0
lines changed

3 files changed

+55
-0
lines changed

‎src/libcore/fmt/mod.rs

+1
Original file line numberDiff line numberDiff line change
@@ -261,6 +261,7 @@ pub struct Formatter<'a> {
261261

262262
struct Void {
263263
_priv: (),
264+
_oibit_remover: PhantomData<*mut Fn()>,
264265
}
265266

266267
/// This struct represents the generic "argument" which is taken by the Xprintf

‎src/test/ui/fmt/send-sync.rs

+20
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,20 @@
1+
// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
2+
// file at the top-level directory of this distribution and at
3+
// http://rust-lang.org/COPYRIGHT.
4+
//
5+
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6+
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7+
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8+
// option. This file may not be copied, modified, or distributed
9+
// except according to those terms.
10+
11+
fn send<T: Send>(_: T) {}
12+
fn sync<T: Sync>(_: T) {}
13+
14+
fn main() {
15+
// `Cell` is not `Sync`, so `&Cell` is neither `Sync` nor `Send`,
16+
// `std::fmt::Arguments` used to forget this...
17+
let c = std::cell::Cell::new(42);
18+
send(format_args!("{:?}", c));
19+
sync(format_args!("{:?}", c));
20+
}

‎src/test/ui/fmt/send-sync.stderr

+34
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
error[E0277]: the trait bound `*mut std::ops::Fn() + 'static: std::marker::Sync` is not satisfied in `[std::fmt::ArgumentV1<'_>]`
2+
--> $DIR/send-sync.rs:18:5
3+
|
4+
18 | send(format_args!("{:?}", c));
5+
| ^^^^ `*mut std::ops::Fn() + 'static` cannot be shared between threads safely
6+
|
7+
= help: within `[std::fmt::ArgumentV1<'_>]`, the trait `std::marker::Sync` is not implemented for `*mut std::ops::Fn() + 'static`
8+
= note: required because it appears within the type `std::marker::PhantomData<*mut std::ops::Fn() + 'static>`
9+
= note: required because it appears within the type `core::fmt::Void`
10+
= note: required because it appears within the type `&core::fmt::Void`
11+
= note: required because it appears within the type `std::fmt::ArgumentV1<'_>`
12+
= note: required because it appears within the type `[std::fmt::ArgumentV1<'_>]`
13+
= note: required because of the requirements on the impl of `std::marker::Send` for `&[std::fmt::ArgumentV1<'_>]`
14+
= note: required because it appears within the type `std::fmt::Arguments<'_>`
15+
= note: required by `send`
16+
17+
error[E0277]: the trait bound `*mut std::ops::Fn() + 'static: std::marker::Sync` is not satisfied in `std::fmt::Arguments<'_>`
18+
--> $DIR/send-sync.rs:19:5
19+
|
20+
19 | sync(format_args!("{:?}", c));
21+
| ^^^^ `*mut std::ops::Fn() + 'static` cannot be shared between threads safely
22+
|
23+
= help: within `std::fmt::Arguments<'_>`, the trait `std::marker::Sync` is not implemented for `*mut std::ops::Fn() + 'static`
24+
= note: required because it appears within the type `std::marker::PhantomData<*mut std::ops::Fn() + 'static>`
25+
= note: required because it appears within the type `core::fmt::Void`
26+
= note: required because it appears within the type `&core::fmt::Void`
27+
= note: required because it appears within the type `std::fmt::ArgumentV1<'_>`
28+
= note: required because it appears within the type `[std::fmt::ArgumentV1<'_>]`
29+
= note: required because it appears within the type `&[std::fmt::ArgumentV1<'_>]`
30+
= note: required because it appears within the type `std::fmt::Arguments<'_>`
31+
= note: required by `sync`
32+
33+
error: aborting due to 2 previous errors
34+

0 commit comments

Comments
 (0)