[INFO] cloning repository https://github.com/benjamincudi/advent_of_rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/benjamincudi/advent_of_rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenjamincudi%2Fadvent_of_rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenjamincudi%2Fadvent_of_rust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 3319076069d1a1c17646008ed816dd3070f0bf08
[INFO] testing benjamincudi/advent_of_rust against 1.60.0 for beta-1.61-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenjamincudi%2Fadvent_of_rust" "/workspace/builds/worker-24/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-24/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/benjamincudi/advent_of_rust on toolchain 1.60.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/benjamincudi/advent_of_rust
[INFO] finished tweaking git repo https://github.com/benjamincudi/advent_of_rust
[INFO] tweaked toml for git repo https://github.com/benjamincudi/advent_of_rust written to /workspace/builds/worker-24/source/Cargo.toml
[INFO] crate git repo https://github.com/benjamincudi/advent_of_rust already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 8d4c9d9331f1f19ee11a2f1a24526b5ae4d2643f9c0b5f8eec5d6d15e59bc3b8
[INFO] running `Command { std: "docker" "start" "-a" "8d4c9d9331f1f19ee11a2f1a24526b5ae4d2643f9c0b5f8eec5d6d15e59bc3b8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8d4c9d9331f1f19ee11a2f1a24526b5ae4d2643f9c0b5f8eec5d6d15e59bc3b8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8d4c9d9331f1f19ee11a2f1a24526b5ae4d2643f9c0b5f8eec5d6d15e59bc3b8", kill_on_drop: false }`
[INFO] [stdout] 8d4c9d9331f1f19ee11a2f1a24526b5ae4d2643f9c0b5f8eec5d6d15e59bc3b8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/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=warn" "-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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] fa21939d7cbc30e0d862cb85726d0748167e4f452f0f8809dd5b4a16c9f19dc8
[INFO] running `Command { std: "docker" "start" "-a" "fa21939d7cbc30e0d862cb85726d0748167e4f452f0f8809dd5b4a16c9f19dc8", kill_on_drop: false }`
[INFO] [stderr]    Compiling advent_of_rust v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/eight.rs:23:32
[INFO] [stdout]    |
[INFO] [stdout] 23 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout]    |                                ^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[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] 23 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 23 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/four.rs:50:32
[INFO] [stdout]    |
[INFO] [stdout] 50 |     fn cause(&self) -> Option<&error::Error> {
[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] 50 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 50 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/six.rs:46:32
[INFO] [stdout]    |
[INFO] [stdout] 46 |     fn cause(&self) -> Option<&error::Error> {
[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] 46 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 46 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/ten.rs:28:32
[INFO] [stdout]    |
[INFO] [stdout] 28 |     fn cause(&self) -> Option<&error::Error> {
[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] 28 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 28 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/three.rs:28:32
[INFO] [stdout]    |
[INFO] [stdout] 28 |     fn cause(&self) -> Option<&error::Error> {
[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] 28 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 28 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 2.29s
[INFO] running `Command { std: "docker" "inspect" "fa21939d7cbc30e0d862cb85726d0748167e4f452f0f8809dd5b4a16c9f19dc8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fa21939d7cbc30e0d862cb85726d0748167e4f452f0f8809dd5b4a16c9f19dc8", kill_on_drop: false }`
[INFO] [stdout] fa21939d7cbc30e0d862cb85726d0748167e4f452f0f8809dd5b4a16c9f19dc8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/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=warn" "-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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ed75003fd4dcec37a31e12801ecb97b2f7ccda7b4feb646966fded9b5e4d4c35
[INFO] running `Command { std: "docker" "start" "-a" "ed75003fd4dcec37a31e12801ecb97b2f7ccda7b4feb646966fded9b5e4d4c35", kill_on_drop: false }`
[INFO] [stderr]    Compiling advent_of_rust v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/eight.rs:23:32
[INFO] [stdout]    |
[INFO] [stdout] 23 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout]    |                                ^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[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] 23 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 23 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/four.rs:50:32
[INFO] [stdout]    |
[INFO] [stdout] 50 |     fn cause(&self) -> Option<&error::Error> {
[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] 50 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 50 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/six.rs:46:32
[INFO] [stdout]    |
[INFO] [stdout] 46 |     fn cause(&self) -> Option<&error::Error> {
[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] 46 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 46 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/ten.rs:28:32
[INFO] [stdout]    |
[INFO] [stdout] 28 |     fn cause(&self) -> Option<&error::Error> {
[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] 28 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 28 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/three.rs:28:32
[INFO] [stdout]    |
[INFO] [stdout] 28 |     fn cause(&self) -> Option<&error::Error> {
[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] 28 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 28 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stdout]    | 
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.46s
[INFO] running `Command { std: "docker" "inspect" "ed75003fd4dcec37a31e12801ecb97b2f7ccda7b4feb646966fded9b5e4d4c35", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ed75003fd4dcec37a31e12801ecb97b2f7ccda7b4feb646966fded9b5e4d4c35", kill_on_drop: false }`
[INFO] [stdout] ed75003fd4dcec37a31e12801ecb97b2f7ccda7b4feb646966fded9b5e4d4c35
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/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=warn" "-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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] f51a85198e375bf8beb6d856d754d8d3fc9ca62adb29cc0e62166a097cf0075b
[INFO] running `Command { std: "docker" "start" "-a" "f51a85198e375bf8beb6d856d754d8d3fc9ca62adb29cc0e62166a097cf0075b", kill_on_drop: false }`
[INFO] [stdout] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout] running 0 tests
[INFO] [stderr]   --> src/eight.rs:23:32
[INFO] [stdout] 
[INFO] [stderr]    |
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr] 23 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stdout] 
[INFO] [stderr]    |                                ^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 23 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr] 23 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/four.rs:50:32
[INFO] [stderr]    |
[INFO] [stderr] 50 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr]    |                                ^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 50 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr] 50 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/six.rs:46:32
[INFO] [stderr]    |
[INFO] [stderr] 46 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr]    |                                ^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 46 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr] 46 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/ten.rs:28:32
[INFO] [stderr]    |
[INFO] [stderr] 28 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr]    |                                ^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 28 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr] 28 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/three.rs:28:32
[INFO] [stderr]    |
[INFO] [stderr] 28 |     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr]    |                                ^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stderr]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stderr] help: use `dyn`
[INFO] [stderr]    |
[INFO] [stderr] 28 -     fn cause(&self) -> Option<&error::Error> {
[INFO] [stderr] 28 +     fn cause(&self) -> Option<&dyn error::Error> {
[INFO] [stderr]    | 
[INFO] [stderr] 
[INFO] [stderr] warning: `advent_of_rust` (bin "advent_of_rust" test) generated 5 warnings
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.02s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/advent_of_rust-a44f3563cbdc50aa)
[INFO] running `Command { std: "docker" "inspect" "f51a85198e375bf8beb6d856d754d8d3fc9ca62adb29cc0e62166a097cf0075b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f51a85198e375bf8beb6d856d754d8d3fc9ca62adb29cc0e62166a097cf0075b", kill_on_drop: false }`
[INFO] [stdout] f51a85198e375bf8beb6d856d754d8d3fc9ca62adb29cc0e62166a097cf0075b