btree_map::OccupiedEntry: Send regression #76686
Description
The code below does not compile on new versions of rustc (bisect below)
use std::collections::{btree_map::Entry, BTreeMap};
use std::thread::spawn;
fn main() {
let map = BTreeMap::<i32, i32>::new();
let map = Box::leak(Box::new(map));
match map.entry(1) {
Entry::Occupied(entry) => {
spawn(move || {
entry.get();
});
}
_ => (),
}
}error[E0277]: `NonNull<BTreeMap<i32, i32>>` cannot be sent between threads safely
--> src/main.rs:10:13
|
10 | spawn(move || {
| _____________^^^^^_-
| | |
| | `NonNull<BTreeMap<i32, i32>>` cannot be sent between threads safely
11 | | entry.get();
12 | | });
| |_____________- within this `[closure@src/main.rs:10:19: 12:14 entry:std::collections::btree_map::OccupiedEntry<'_, i32, i32>]`
|
::: /home/antek/.local/opt/rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/std/src/thread/mod.rs:596:8
|
596 | F: Send + 'static,
| ---- required by this bound in `spawn`
|
= help: within `[closure@src/main.rs:10:19: 12:14 entry:std::collections::btree_map::OccupiedEntry<'_, i32, i32>]`, the trait `Send` is not implemented for `NonNull<BTreeMap<i32, i32>>`
= note: required because it appears within the type `alloc::collections::btree::borrow::DormantMutRef<'_, BTreeMap<i32, i32>>`
= note: required because it appears within the type `std::collections::btree_map::OccupiedEntry<'_, i32, i32>`
= note: required because it appears within the type `[closure@src/main.rs:10:19: 12:14 entry:std::collections::btree_map::OccupiedEntry<'_, i32, i32>]`
Bisect
searched nightlies: from nightly-2020-09-11 to nightly-2020-09-12
regressed nightly: nightly-2020-09-12
searched commits: from a1947b3 to 9911160
regressed commit: ee04f9a
bisected with cargo-bisect-rustc v0.5.2
Host triple: x86_64-unknown-linux-gnu
Reproduce with:
cargo bisect-rustc --start 2020-09-11