[INFO] cloning repository https://github.com/bwhetherington/rust-2048
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/bwhetherington/rust-2048" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbwhetherington%2Frust-2048", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbwhetherington%2Frust-2048'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] c80aad95941ca1f8797613d73ab44044c3178f40
[INFO] testing bwhetherington/rust-2048 against master#62efba8a050c64249dab942951bb28f710208bc8 for pr-90799
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbwhetherington%2Frust-2048" "/workspace/builds/worker-14/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-14/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/bwhetherington/rust-2048 on toolchain 62efba8a050c64249dab942951bb28f710208bc8
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/bwhetherington/rust-2048
[INFO] finished tweaking git repo https://github.com/bwhetherington/rust-2048
[INFO] tweaked toml for git repo https://github.com/bwhetherington/rust-2048 written to /workspace/builds/worker-14/source/Cargo.toml
[INFO] crate git repo https://github.com/bwhetherington/rust-2048 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] c4d9f64a8a7dca3a1474a4d53a3ca09d0fb948bd4d9e9abe852a34f2b0a35628
[INFO] running `Command { std: "docker" "start" "-a" "c4d9f64a8a7dca3a1474a4d53a3ca09d0fb948bd4d9e9abe852a34f2b0a35628", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c4d9f64a8a7dca3a1474a4d53a3ca09d0fb948bd4d9e9abe852a34f2b0a35628", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c4d9f64a8a7dca3a1474a4d53a3ca09d0fb948bd4d9e9abe852a34f2b0a35628", kill_on_drop: false }`
[INFO] [stdout] c4d9f64a8a7dca3a1474a4d53a3ca09d0fb948bd4d9e9abe852a34f2b0a35628
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7ce29c0ab9dbb2fae57287ef28a4cb0ff2391a3e6310b057a0e1b9b1ecfb2c97
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "7ce29c0ab9dbb2fae57287ef28a4cb0ff2391a3e6310b057a0e1b9b1ecfb2c97", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-2048-2 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `game::*`
[INFO] [stdout]  --> src/main.rs:8:5
[INFO] [stdout]   |
[INFO] [stdout] 8 | use game::*;
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `d`
[INFO] [stdout]   --> src/main.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let d: Matrix<_> = m.diag().into();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_d`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `j`
[INFO] [stdout]   --> src/game/mod.rs:74:13
[INFO] [stdout]    |
[INFO] [stdout] 74 |         for j in 0..source.cols() {
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_j`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:70:37
[INFO] [stdout]    |
[INFO] [stdout] 70 | fn slide_left(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                     ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `source`
[INFO] [stdout]   --> src/game/mod.rs:82:16
[INFO] [stdout]    |
[INFO] [stdout] 82 | fn slide_right(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:82:38
[INFO] [stdout]    |
[INFO] [stdout] 82 | fn slide_right(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                      ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `source`
[INFO] [stdout]   --> src/game/mod.rs:88:13
[INFO] [stdout]    |
[INFO] [stdout] 88 | fn slide_up(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:88:35
[INFO] [stdout]    |
[INFO] [stdout] 88 | fn slide_up(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                   ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `source`
[INFO] [stdout]   --> src/game/mod.rs:94:15
[INFO] [stdout]    |
[INFO] [stdout] 94 | fn slide_down(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |               ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:94:37
[INFO] [stdout]    |
[INFO] [stdout] 94 | fn slide_down(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                     ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 10 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 1.22s
[INFO] running `Command { std: "docker" "inspect" "7ce29c0ab9dbb2fae57287ef28a4cb0ff2391a3e6310b057a0e1b9b1ecfb2c97", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7ce29c0ab9dbb2fae57287ef28a4cb0ff2391a3e6310b057a0e1b9b1ecfb2c97", kill_on_drop: false }`
[INFO] [stdout] 7ce29c0ab9dbb2fae57287ef28a4cb0ff2391a3e6310b057a0e1b9b1ecfb2c97
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 0ae262b26c55f26f957933217e8bfdb92057c269ec562d75c098b6ccbc0e332e
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "0ae262b26c55f26f957933217e8bfdb92057c269ec562d75c098b6ccbc0e332e", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-2048-2 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `game::*`
[INFO] [stdout]  --> src/main.rs:8:5
[INFO] [stdout]   |
[INFO] [stdout] 8 | use game::*;
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `d`
[INFO] [stdout]   --> src/main.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let d: Matrix<_> = m.diag().into();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_d`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `j`
[INFO] [stdout]   --> src/game/mod.rs:74:13
[INFO] [stdout]    |
[INFO] [stdout] 74 |         for j in 0..source.cols() {
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_j`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:70:37
[INFO] [stdout]    |
[INFO] [stdout] 70 | fn slide_left(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                     ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `source`
[INFO] [stdout]   --> src/game/mod.rs:82:16
[INFO] [stdout]    |
[INFO] [stdout] 82 | fn slide_right(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:82:38
[INFO] [stdout]    |
[INFO] [stdout] 82 | fn slide_right(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                      ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `source`
[INFO] [stdout]   --> src/game/mod.rs:88:13
[INFO] [stdout]    |
[INFO] [stdout] 88 | fn slide_up(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:88:35
[INFO] [stdout]    |
[INFO] [stdout] 88 | fn slide_up(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                   ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `source`
[INFO] [stdout]   --> src/game/mod.rs:94:15
[INFO] [stdout]    |
[INFO] [stdout] 94 | fn slide_down(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |               ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dest`
[INFO] [stdout]   --> src/game/mod.rs:94:37
[INFO] [stdout]    |
[INFO] [stdout] 94 | fn slide_down(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stdout]    |                                     ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 10 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.81s
[INFO] running `Command { std: "docker" "inspect" "0ae262b26c55f26f957933217e8bfdb92057c269ec562d75c098b6ccbc0e332e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0ae262b26c55f26f957933217e8bfdb92057c269ec562d75c098b6ccbc0e332e", kill_on_drop: false }`
[INFO] [stdout] 0ae262b26c55f26f957933217e8bfdb92057c269ec562d75c098b6ccbc0e332e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 4104cf2824b91996eabba5dab9674d912beca541d1df42f9be3382c33d889619
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "4104cf2824b91996eabba5dab9674d912beca541d1df42f9be3382c33d889619", kill_on_drop: false }`
[INFO] [stdout] 
[INFO] [stderr] warning: unused import: `game::*`
[INFO] [stdout] running 0 tests
[INFO] [stderr]  --> src/main.rs:8:5
[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] 8 | use game::*;
[INFO] [stdout] 
[INFO] [stderr]   |     ^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `d`
[INFO] [stderr]   --> src/main.rs:15:9
[INFO] [stderr]    |
[INFO] [stderr] 15 |     let d: Matrix<_> = m.diag().into();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_d`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `j`
[INFO] [stderr]   --> src/game/mod.rs:74:13
[INFO] [stderr]    |
[INFO] [stderr] 74 |         for j in 0..source.cols() {
[INFO] [stderr]    |             ^ help: if this is intentional, prefix it with an underscore: `_j`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `dest`
[INFO] [stderr]   --> src/game/mod.rs:70:37
[INFO] [stderr]    |
[INFO] [stderr] 70 | fn slide_left(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |                                     ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `source`
[INFO] [stderr]   --> src/game/mod.rs:82:16
[INFO] [stderr]    |
[INFO] [stderr] 82 | fn slide_right(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |                ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `dest`
[INFO] [stderr]   --> src/game/mod.rs:82:38
[INFO] [stderr]    |
[INFO] [stderr] 82 | fn slide_right(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |                                      ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `source`
[INFO] [stderr]   --> src/game/mod.rs:88:13
[INFO] [stderr]    |
[INFO] [stderr] 88 | fn slide_up(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `dest`
[INFO] [stderr]   --> src/game/mod.rs:88:35
[INFO] [stderr]    |
[INFO] [stderr] 88 | fn slide_up(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |                                   ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `source`
[INFO] [stderr]   --> src/game/mod.rs:94:15
[INFO] [stderr]    |
[INFO] [stderr] 94 | fn slide_down(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |               ^^^^^^ help: if this is intentional, prefix it with an underscore: `_source`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `dest`
[INFO] [stderr]   --> src/game/mod.rs:94:37
[INFO] [stderr]    |
[INFO] [stderr] 94 | fn slide_down(source: &Matrix<u32>, dest: &mut Matrix<u32>) {
[INFO] [stderr]    |                                     ^^^^ help: if this is intentional, prefix it with an underscore: `_dest`
[INFO] [stderr] 
[INFO] [stderr] warning: `rust-2048-2` (bin "rust-2048-2" test) generated 10 warnings
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.03s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/rust_2048_2-cb8f1903fc306fb7)
[INFO] running `Command { std: "docker" "inspect" "4104cf2824b91996eabba5dab9674d912beca541d1df42f9be3382c33d889619", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4104cf2824b91996eabba5dab9674d912beca541d1df42f9be3382c33d889619", kill_on_drop: false }`
[INFO] [stdout] 4104cf2824b91996eabba5dab9674d912beca541d1df42f9be3382c33d889619