[INFO] cloning repository https://github.com/Lakret/backtrack_rs
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Lakret/backtrack_rs" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLakret%2Fbacktrack_rs", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLakret%2Fbacktrack_rs'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 21a7dfdaf0c1a79561b1e3182f90e30563868603
[INFO] testing Lakret/backtrack_rs against beta-2021-01-01 for beta-1.50-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLakret%2Fbacktrack_rs" "/workspace/builds/worker-5/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/Lakret/backtrack_rs on toolchain beta-2021-01-01
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-01-01" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/Lakret/backtrack_rs
[INFO] finished tweaking git repo https://github.com/Lakret/backtrack_rs
[INFO] tweaked toml for git repo https://github.com/Lakret/backtrack_rs written to /workspace/builds/worker-5/source/Cargo.toml
[INFO] crate git repo https://github.com/Lakret/backtrack_rs already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-01-01" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-01-01" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 7fbbc57da8e03ac827c7bb9c14a34618e3052879e0ac40f873b718ef9510dcec
[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" "7fbbc57da8e03ac827c7bb9c14a34618e3052879e0ac40f873b718ef9510dcec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7fbbc57da8e03ac827c7bb9c14a34618e3052879e0ac40f873b718ef9510dcec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7fbbc57da8e03ac827c7bb9c14a34618e3052879e0ac40f873b718ef9510dcec", kill_on_drop: false }`
[INFO] [stdout] 7fbbc57da8e03ac827c7bb9c14a34618e3052879e0ac40f873b718ef9510dcec
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-01-01" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9099e972acd2e40d3bde56a8aaa1ddcb28615fd24b44b8bfa90f32048f2eea49
[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" "9099e972acd2e40d3bde56a8aaa1ddcb28615fd24b44b8bfa90f32048f2eea49", kill_on_drop: false }`
[INFO] [stderr]    Compiling backtrack_rs v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `std::thread::JoinHandle`
[INFO] [stdout]    --> src/lib.rs:210:5
[INFO] [stdout]     |
[INFO] [stdout] 210 | use std::thread::JoinHandle;
[INFO] [stdout]     |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `iteration`
[INFO] [stdout]    --> src/lib.rs:284:3
[INFO] [stdout]     |
[INFO] [stdout] 284 |   iteration: u32,
[INFO] [stdout]     |   ^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_iteration`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `reduced_domain`
[INFO] [stdout]   --> src/ac3.rs:19:13
[INFO] [stdout]    |
[INFO] [stdout] 19 |         let reduced_domain = csp
[INFO] [stdout]    |             ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_reduced_domain`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ac3.rs:33:8
[INFO] [stdout]    |
[INFO] [stdout] 33 |       [x, y] => {}
[INFO] [stdout]    |        ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]   --> src/ac3.rs:33:11
[INFO] [stdout]    |
[INFO] [stdout] 33 |       [x, y] => {}
[INFO] [stdout]    |           ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/ac3.rs:15:7
[INFO] [stdout]    |
[INFO] [stdout] 15 |   let mut constraint_refs = csp.constraints.iter().collect::<Vec<_>>();
[INFO] [stdout]    |       ----^^^^^^^^^^^^^^^
[INFO] [stdout]    |       |
[INFO] [stdout]    |       help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 6 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `lazy_static::lazy_static`
[INFO] [stdout]  --> src/main.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use lazy_static::lazy_static;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 3.42s
[INFO] running `Command { std: "docker" "inspect" "9099e972acd2e40d3bde56a8aaa1ddcb28615fd24b44b8bfa90f32048f2eea49", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9099e972acd2e40d3bde56a8aaa1ddcb28615fd24b44b8bfa90f32048f2eea49", kill_on_drop: false }`
[INFO] [stdout] 9099e972acd2e40d3bde56a8aaa1ddcb28615fd24b44b8bfa90f32048f2eea49
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-01-01" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f26c5ff803b004eb01c63bbaf7c426014222aef7ee841279681f96ae01411c10
[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" "f26c5ff803b004eb01c63bbaf7c426014222aef7ee841279681f96ae01411c10", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.70
[INFO] [stderr]    Compiling serde v1.0.110
[INFO] [stderr]    Compiling byteorder v1.3.4
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling syn v1.0.21
[INFO] [stderr]    Compiling regex-syntax v0.6.17
[INFO] [stderr]    Compiling oorandom v11.1.1
[INFO] [stderr]    Compiling quote v1.0.5
[INFO] [stderr]    Compiling clap v2.33.1
[INFO] [stderr]    Compiling plotters v0.2.14
[INFO] [stderr]    Compiling criterion-plot v0.4.2
[INFO] [stdout] warning: unused import: `std::thread::JoinHandle`
[INFO] [stdout]    --> src/lib.rs:210:5
[INFO] [stdout]     |
[INFO] [stdout] 210 | use std::thread::JoinHandle;
[INFO] [stdout]     |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `iteration`
[INFO] [stdout]    --> src/lib.rs:284:3
[INFO] [stdout]     |
[INFO] [stdout] 284 |   iteration: u32,
[INFO] [stdout]     |   ^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_iteration`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `reduced_domain`
[INFO] [stdout]   --> src/ac3.rs:19:13
[INFO] [stdout]    |
[INFO] [stdout] 19 |         let reduced_domain = csp
[INFO] [stdout]    |             ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_reduced_domain`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ac3.rs:33:8
[INFO] [stdout]    |
[INFO] [stdout] 33 |       [x, y] => {}
[INFO] [stdout]    |        ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]   --> src/ac3.rs:33:11
[INFO] [stdout]    |
[INFO] [stdout] 33 |       [x, y] => {}
[INFO] [stdout]    |           ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/ac3.rs:15:7
[INFO] [stdout]    |
[INFO] [stdout] 15 |   let mut constraint_refs = csp.constraints.iter().collect::<Vec<_>>();
[INFO] [stdout]    |       ----^^^^^^^^^^^^^^^
[INFO] [stdout]    |       |
[INFO] [stdout]    |       help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 6 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling csv-core v0.1.10
[INFO] [stderr]    Compiling regex-automata v0.1.9
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling atty v0.2.14
[INFO] [stderr]    Compiling rayon-core v1.7.0
[INFO] [stderr]    Compiling regex v1.3.7
[INFO] [stderr]    Compiling rayon v1.3.0
[INFO] [stderr]    Compiling bstr v0.2.13
[INFO] [stderr]    Compiling serde_json v1.0.53
[INFO] [stderr]    Compiling csv v1.1.3
[INFO] [stderr]    Compiling tinytemplate v1.0.4
[INFO] [stderr]    Compiling serde_derive v1.0.110
[INFO] [stderr]    Compiling criterion v0.3.2
[INFO] [stderr]    Compiling backtrack_rs v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `lazy_static::lazy_static`
[INFO] [stdout]  --> src/main.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use lazy_static::lazy_static;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::thread::JoinHandle`
[INFO] [stdout]    --> src/lib.rs:210:5
[INFO] [stdout]     |
[INFO] [stdout] 210 | use std::thread::JoinHandle;
[INFO] [stdout]     |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `iteration`
[INFO] [stdout]    --> src/lib.rs:284:3
[INFO] [stdout]     |
[INFO] [stdout] 284 |   iteration: u32,
[INFO] [stdout]     |   ^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_iteration`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `reduced_domain`
[INFO] [stdout]   --> src/ac3.rs:19:13
[INFO] [stdout]    |
[INFO] [stdout] 19 |         let reduced_domain = csp
[INFO] [stdout]    |             ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_reduced_domain`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ac3.rs:33:8
[INFO] [stdout]    |
[INFO] [stdout] 33 |       [x, y] => {}
[INFO] [stdout]    |        ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]   --> src/ac3.rs:33:11
[INFO] [stdout]    |
[INFO] [stdout] 33 |       [x, y] => {}
[INFO] [stdout]    |           ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/ac3.rs:15:7
[INFO] [stdout]    |
[INFO] [stdout] 15 |   let mut constraint_refs = csp.constraints.iter().collect::<Vec<_>>();
[INFO] [stdout]    |       ----^^^^^^^^^^^^^^^
[INFO] [stdout]    |       |
[INFO] [stdout]    |       help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 6 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 1m 12s
[INFO] running `Command { std: "docker" "inspect" "f26c5ff803b004eb01c63bbaf7c426014222aef7ee841279681f96ae01411c10", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f26c5ff803b004eb01c63bbaf7c426014222aef7ee841279681f96ae01411c10", kill_on_drop: false }`
[INFO] [stdout] f26c5ff803b004eb01c63bbaf7c426014222aef7ee841279681f96ae01411c10
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-01-01" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 6a1befbf2b1f58714a1662a9d5b017fc43160812e708898bddf1a70f9f90e1b7
[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" "6a1befbf2b1f58714a1662a9d5b017fc43160812e708898bddf1a70f9f90e1b7", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr] warning: unused import: `std::thread::JoinHandle`
[INFO] [stderr]    --> src/lib.rs:210:5
[INFO] [stderr]     |
[INFO] [stderr] 210 | use std::thread::JoinHandle;
[INFO] [stderr]     |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `iteration`
[INFO] [stderr]    --> src/lib.rs:284:3
[INFO] [stderr]     |
[INFO] [stderr] 284 |   iteration: u32,
[INFO] [stderr]     |   ^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_iteration`
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `reduced_domain`
[INFO] [stderr]   --> src/ac3.rs:19:13
[INFO] [stderr]    |
[INFO] [stderr] 19 |         let reduced_domain = csp
[INFO] [stderr]    |             ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_reduced_domain`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/ac3.rs:33:8
[INFO] [stderr]    |
[INFO] [stderr] 33 |       [x, y] => {}
[INFO] [stderr]    |        ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/ac3.rs:33:11
[INFO] [stderr]    |
[INFO] [stderr] 33 |       [x, y] => {}
[INFO] [stderr]    |           ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/ac3.rs:15:7
[INFO] [stderr]    |
[INFO] [stderr] 15 |   let mut constraint_refs = csp.constraints.iter().collect::<Vec<_>>();
[INFO] [stderr]    |       ----^^^^^^^^^^^^^^^
[INFO] [stderr]    |       |
[INFO] [stderr]    |       help: remove this `mut`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: 6 warnings emitted
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `std::thread::JoinHandle`
[INFO] [stderr]    --> src/lib.rs:210:5
[INFO] [stderr]     |
[INFO] [stderr] 210 | use std::thread::JoinHandle;
[INFO] [stderr]     |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `iteration`
[INFO] [stderr]    --> src/lib.rs:284:3
[INFO] [stderr]     |
[INFO] [stderr] 284 |   iteration: u32,
[INFO] [stderr]     |   ^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_iteration`
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `reduced_domain`
[INFO] [stderr]   --> src/ac3.rs:19:13
[INFO] [stderr]    |
[INFO] [stderr] 19 |         let reduced_domain = csp
[INFO] [stderr]    |             ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_reduced_domain`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/ac3.rs:33:8
[INFO] [stderr]    |
[INFO] [stderr] 33 |       [x, y] => {}
[INFO] [stderr]    |        ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/ac3.rs:33:11
[INFO] [stderr]    |
[INFO] [stderr] 33 |       [x, y] => {}
[INFO] [stderr]    |           ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/ac3.rs:15:7
[INFO] [stderr]    |
[INFO] [stderr] 15 |   let mut constraint_refs = csp.constraints.iter().collect::<Vec<_>>();
[INFO] [stderr]    |       ----^^^^^^^^^^^^^^^
[INFO] [stderr]    |       |
[INFO] [stderr]    |       help: remove this `mut`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: 6 warnings emitted
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `lazy_static::lazy_static`
[INFO] [stderr]  --> src/main.rs:4:5
[INFO] [stderr]   |
[INFO] [stderr] 4 | use lazy_static::lazy_static;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: 1 warning emitted
[INFO] [stderr] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.12s
[INFO] [stderr]      Running /opt/rustwide/target/debug/deps/backtrack_rs-716558ef044d1226
[INFO] [stderr]      Running /opt/rustwide/target/debug/deps/backtrack_rs-b2074434a513624e
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] running 3 tests
[INFO] [stdout] test tests::non_present_in_both_cells_works ... ok
[INFO] [stdout] test tests::present_in_one_cell_works ... ok
[INFO] [stdout] test tests::is_consistent_and_is_solved_work ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 3 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stderr]    Doc-tests backtrack_rs
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "6a1befbf2b1f58714a1662a9d5b017fc43160812e708898bddf1a70f9f90e1b7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6a1befbf2b1f58714a1662a9d5b017fc43160812e708898bddf1a70f9f90e1b7", kill_on_drop: false }`
[INFO] [stdout] 6a1befbf2b1f58714a1662a9d5b017fc43160812e708898bddf1a70f9f90e1b7