[INFO] fetching crate romeo 0.0.5...
[INFO] checking romeo-0.0.5 against master#e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682 for beta-170-4
[INFO] extracting crate romeo 0.0.5 into /workspace/builds/worker-6-tc2/source
[INFO] validating manifest of crates.io crate romeo 0.0.5 on toolchain e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate romeo 0.0.5
[INFO] finished tweaking crates.io crate romeo 0.0.5
[INFO] tweaked toml for crates.io crate romeo 0.0.5 written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" __CARGO_TEST_CHANNEL_OVERRIDE_DO_NOT_USE_THIS="nightly" "/workspace/cargo-home/bin/cargo" "+e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:19e73879b68f455e41552ea35293514db52ea292d993f571636dbffedb77a1ee" "/opt/rustwide/cargo-home/bin/cargo" "+e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 69389ea6378d3b5d87351e1740432e5c7de0de12a973925cf11a1d2e6f342472
[INFO] running `Command { std: "docker" "start" "-a" "69389ea6378d3b5d87351e1740432e5c7de0de12a973925cf11a1d2e6f342472", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "69389ea6378d3b5d87351e1740432e5c7de0de12a973925cf11a1d2e6f342472", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "69389ea6378d3b5d87351e1740432e5c7de0de12a973925cf11a1d2e6f342472", kill_on_drop: false }`
[INFO] [stdout] 69389ea6378d3b5d87351e1740432e5c7de0de12a973925cf11a1d2e6f342472
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:19e73879b68f455e41552ea35293514db52ea292d993f571636dbffedb77a1ee" "/opt/rustwide/cargo-home/bin/cargo" "+e6e4f7ed1589e03bc2f6c5931c1a72e7947e8682" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 64d9f0dd3f81935f0c3d1edcac2a7aa864101a79f8fb35da81fe3cd84bfc64f1
[INFO] running `Command { std: "docker" "start" "-a" "64d9f0dd3f81935f0c3d1edcac2a7aa864101a79f8fb35da81fe3cd84bfc64f1", kill_on_drop: false }`
[INFO] [stderr]     Checking rand_core v0.4.2
[INFO] [stderr]     Checking scopeguard v0.3.3
[INFO] [stderr]    Compiling arrayvec v0.4.12
[INFO] [stderr]     Checking nodrop v0.1.14
[INFO] [stderr]    Compiling log v0.4.18
[INFO] [stderr]     Checking memoffset v0.2.1
[INFO] [stderr]     Checking crossbeam-utils v0.5.0
[INFO] [stderr]     Checking num_cpus v1.15.0
[INFO] [stderr]     Checking owning_ref v0.4.1
[INFO] [stderr]     Checking crossbeam-utils v0.6.6
[INFO] [stderr]     Checking uuid v0.6.5
[INFO] [stderr]    Compiling parking_lot_core v0.3.1
[INFO] [stderr]     Checking smallvec v0.6.14
[INFO] [stderr]     Checking lock_api v0.1.5
[INFO] [stderr]     Checking rand_core v0.3.1
[INFO] [stderr]     Checking rand v0.5.6
[INFO] [stderr]     Checking crossbeam-epoch v0.6.1
[INFO] [stderr]     Checking parking_lot v0.6.4
[INFO] [stderr]     Checking crossbeam-channel v0.2.6
[INFO] [stderr]     Checking romeo v0.0.5 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0432]: unresolved import `std::boxed::FnBox`
[INFO] [stdout]  --> src/address.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use std::boxed::FnBox;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^ no `FnBox` in `boxed`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0432]: unresolved import `std::boxed::FnBox`
[INFO] [stdout]  --> src/cell.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::boxed::FnBox;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^ no `FnBox` in `boxed`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0432]: unresolved import `std::boxed::FnBox`
[INFO] [stdout]  --> src/address.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use std::boxed::FnBox;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^ no `FnBox` in `boxed`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0432]: unresolved import `std::boxed::FnBox`
[INFO] [stdout]  --> src/cell.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::boxed::FnBox;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^ no `FnBox` in `boxed`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0635]: unknown feature `fnbox`
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(fnbox)]
[INFO] [stdout]   |            ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:19:25
[INFO] [stdout]    |
[INFO] [stdout] 19 |     actor_producer: Box<Fn() -> A>,
[INFO] [stdout]    |                         ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 19 |     actor_producer: Box<dyn Fn() -> A>,
[INFO] [stdout]    |                         +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0635]: unknown feature `fnbox`
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(fnbox)]
[INFO] [stdout]   |            ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:18:27
[INFO] [stdout]    |
[INFO] [stdout] 18 |     cells: RwLock<Vec<Arc<ACell>>>,
[INFO] [stdout]    |                           ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 18 |     cells: RwLock<Vec<Arc<dyn ACell>>>,
[INFO] [stdout]    |                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:21:38
[INFO] [stdout]    |
[INFO] [stdout] 21 |     actor_starts: Mutex<VecDeque<Arc<ACell>>>,
[INFO] [stdout]    |                                      ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 21 |     actor_starts: Mutex<VecDeque<Arc<dyn ACell>>>,
[INFO] [stdout]    |                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:22:38
[INFO] [stdout]    |
[INFO] [stdout] 22 |     actor_stops:  Mutex<VecDeque<Arc<ACell>>>,
[INFO] [stdout]    |                                      ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 22 |     actor_stops:  Mutex<VecDeque<Arc<dyn ACell>>>,
[INFO] [stdout]    |                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:91:20
[INFO] [stdout]    |
[INFO] [stdout] 91 | impl PartialEq for ACell {
[INFO] [stdout]    |                    ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 91 | impl PartialEq for dyn ACell {
[INFO] [stdout]    |                    +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:96:13
[INFO] [stdout]    |
[INFO] [stdout] 96 | impl Eq for ACell {}
[INFO] [stdout]    |             ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 96 | impl Eq for dyn ACell {}
[INFO] [stdout]    |             +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:19:25
[INFO] [stdout]    |
[INFO] [stdout] 19 |     actor_producer: Box<Fn() -> A>,
[INFO] [stdout]    |                         ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 19 |     actor_producer: Box<dyn Fn() -> A>,
[INFO] [stdout]    |                         +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:27:43
[INFO] [stdout]    |
[INFO] [stdout] 27 |     pub(crate) fn new(actor_producer: Box<Fn() -> A>, scheduler: Weak<Scheduler>) -> Arc<Self> {
[INFO] [stdout]    |                                           ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 27 |     pub(crate) fn new(actor_producer: Box<dyn Fn() -> A>, scheduler: Weak<Scheduler>) -> Arc<Self> {
[INFO] [stdout]    |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:92:26
[INFO] [stdout]    |
[INFO] [stdout] 92 |     fn eq(&self, other: &ACell) -> bool {
[INFO] [stdout]    |                          ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 92 |     fn eq(&self, other: &dyn ACell) -> bool {
[INFO] [stdout]    |                          +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:35:54
[INFO] [stdout]    |
[INFO] [stdout] 35 |     pub(crate) fn register_new_cell(&self, cell: Arc<ACell>) {
[INFO] [stdout]    |                                                      ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 35 |     pub(crate) fn register_new_cell(&self, cell: Arc<dyn ACell>) {
[INFO] [stdout]    |                                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:18:27
[INFO] [stdout]    |
[INFO] [stdout] 18 |     cells: RwLock<Vec<Arc<ACell>>>,
[INFO] [stdout]    |                           ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 18 |     cells: RwLock<Vec<Arc<dyn ACell>>>,
[INFO] [stdout]    |                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:21:38
[INFO] [stdout]    |
[INFO] [stdout] 21 |     actor_starts: Mutex<VecDeque<Arc<ACell>>>,
[INFO] [stdout]    |                                      ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 21 |     actor_starts: Mutex<VecDeque<Arc<dyn ACell>>>,
[INFO] [stdout]    |                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:22:38
[INFO] [stdout]    |
[INFO] [stdout] 22 |     actor_stops:  Mutex<VecDeque<Arc<ACell>>>,
[INFO] [stdout]    |                                      ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 22 |     actor_stops:  Mutex<VecDeque<Arc<dyn ACell>>>,
[INFO] [stdout]    |                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:91:20
[INFO] [stdout]    |
[INFO] [stdout] 91 | impl PartialEq for ACell {
[INFO] [stdout]    |                    ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 91 | impl PartialEq for dyn ACell {
[INFO] [stdout]    |                    +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:96:13
[INFO] [stdout]    |
[INFO] [stdout] 96 | impl Eq for ACell {}
[INFO] [stdout]    |             ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 96 | impl Eq for dyn ACell {}
[INFO] [stdout]    |             +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:27:43
[INFO] [stdout]    |
[INFO] [stdout] 27 |     pub(crate) fn new(actor_producer: Box<Fn() -> A>, scheduler: Weak<Scheduler>) -> Arc<Self> {
[INFO] [stdout]    |                                           ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 27 |     pub(crate) fn new(actor_producer: Box<dyn Fn() -> A>, scheduler: Weak<Scheduler>) -> Arc<Self> {
[INFO] [stdout]    |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/cell.rs:92:26
[INFO] [stdout]    |
[INFO] [stdout] 92 |     fn eq(&self, other: &ACell) -> bool {
[INFO] [stdout]    |                          ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 92 |     fn eq(&self, other: &dyn ACell) -> bool {
[INFO] [stdout]    |                          +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/scheduler.rs:35:54
[INFO] [stdout]    |
[INFO] [stdout] 35 |     pub(crate) fn register_new_cell(&self, cell: Arc<ACell>) {
[INFO] [stdout]    |                                                      ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 35 |     pub(crate) fn register_new_cell(&self, cell: Arc<dyn ACell>) {
[INFO] [stdout]    |                                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors; 9 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0432, E0635.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0432`.
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors; 9 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0432, E0635.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0432`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `romeo` (lib) due to 4 previous errors; 9 warnings emitted
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: could not compile `romeo` (lib test) due to 4 previous errors; 9 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "64d9f0dd3f81935f0c3d1edcac2a7aa864101a79f8fb35da81fe3cd84bfc64f1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "64d9f0dd3f81935f0c3d1edcac2a7aa864101a79f8fb35da81fe3cd84bfc64f1", kill_on_drop: false }`
[INFO] [stdout] 64d9f0dd3f81935f0c3d1edcac2a7aa864101a79f8fb35da81fe3cd84bfc64f1
