[INFO] cloning repository https://github.com/ricardopieper/rust-concurrency-tests
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/ricardopieper/rust-concurrency-tests" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fricardopieper%2Frust-concurrency-tests", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fricardopieper%2Frust-concurrency-tests'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] bf5d96403af158bfc1ad58a705530c2211efde87
[INFO] testing ricardopieper/rust-concurrency-tests against beta-2021-09-08 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fricardopieper%2Frust-concurrency-tests" "/workspace/builds/worker-2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/ricardopieper/rust-concurrency-tests on toolchain beta-2021-09-08
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-09-08" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/ricardopieper/rust-concurrency-tests
[INFO] finished tweaking git repo https://github.com/ricardopieper/rust-concurrency-tests
[INFO] tweaked toml for git repo https://github.com/ricardopieper/rust-concurrency-tests written to /workspace/builds/worker-2/source/Cargo.toml
[INFO] crate git repo https://github.com/ricardopieper/rust-concurrency-tests already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-09-08" "fetch" "--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-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-09-08" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 7eb94539752b5a5f6664c06e46e34760c58964c5151309a34420535f4825f095
[INFO] running `Command { std: "docker" "start" "-a" "7eb94539752b5a5f6664c06e46e34760c58964c5151309a34420535f4825f095", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7eb94539752b5a5f6664c06e46e34760c58964c5151309a34420535f4825f095", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7eb94539752b5a5f6664c06e46e34760c58964c5151309a34420535f4825f095", kill_on_drop: false }`
[INFO] [stdout] 7eb94539752b5a5f6664c06e46e34760c58964c5151309a34420535f4825f095
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-09-08" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] e1a0a6fbd9779a4ba8a426db4478fb7c313a2aad65ee56e09f568fd2ae59ac56
[INFO] running `Command { std: "docker" "start" "-a" "e1a0a6fbd9779a4ba8a426db4478fb7c313a2aad65ee56e09f568fd2ae59ac56", kill_on_drop: false }`
[INFO] [stderr]    Compiling autocfg v0.1.2
[INFO] [stderr]    Compiling rand_core v0.4.0
[INFO] [stderr]    Compiling libc v0.2.51
[INFO] [stderr]    Compiling rand_core v0.3.1
[INFO] [stderr]    Compiling rand_jitter v0.1.3
[INFO] [stderr]    Compiling rand_isaac v0.1.1
[INFO] [stderr]    Compiling rand_xorshift v0.1.1
[INFO] [stderr]    Compiling rand_hc v0.1.0
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]    Compiling rand_os v0.1.3
[INFO] [stderr]    Compiling rust-concurrency-tests v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stdout]    |
[INFO] [stdout] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stdout]     |
[INFO] [stdout] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stdout]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stdout]     |
[INFO] [stdout] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stdout]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stdout]    |
[INFO] [stdout] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stdout]     |
[INFO] [stdout] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stdout]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stdout]     |
[INFO] [stdout] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stdout]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 5.85s
[INFO] running `Command { std: "docker" "inspect" "e1a0a6fbd9779a4ba8a426db4478fb7c313a2aad65ee56e09f568fd2ae59ac56", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e1a0a6fbd9779a4ba8a426db4478fb7c313a2aad65ee56e09f568fd2ae59ac56", kill_on_drop: false }`
[INFO] [stdout] e1a0a6fbd9779a4ba8a426db4478fb7c313a2aad65ee56e09f568fd2ae59ac56
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-09-08" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] a6f20ac6a6aad4501dabb14a9effe6b8268d8075f07721cdcb7e0b246e00603f
[INFO] running `Command { std: "docker" "start" "-a" "a6f20ac6a6aad4501dabb14a9effe6b8268d8075f07721cdcb7e0b246e00603f", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-concurrency-tests v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stdout]    |
[INFO] [stdout] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stdout]     |
[INFO] [stdout] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stdout]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stdout]     |
[INFO] [stdout] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stdout]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stdout]    |
[INFO] [stdout] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stdout]     |
[INFO] [stdout] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stdout]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stdout]     |
[INFO] [stdout] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stdout]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> tests/linked_set_tests.rs:5:9
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[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: variable does not need to be mutable
[INFO] [stdout]   --> tests/linked_set_tests.rs:24:9
[INFO] [stdout]    |
[INFO] [stdout] 24 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout]    |         ----^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> tests/linked_set_tests.rs:40:9
[INFO] [stdout]    |
[INFO] [stdout] 40 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout]    |         ----^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> tests/linked_set_tests.rs:49:9
[INFO] [stdout]    |
[INFO] [stdout] 49 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout]    |         ----^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> tests/linked_set_tests.rs:58:9
[INFO] [stdout]    |
[INFO] [stdout] 58 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout]    |         ----^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> tests/linked_set_tests.rs:83:9
[INFO] [stdout]    |
[INFO] [stdout] 83 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout]    |         ----^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> tests/linked_set_tests.rs:108:9
[INFO] [stdout]     |
[INFO] [stdout] 108 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout]     |         ----^^^
[INFO] [stdout]     |         |
[INFO] [stdout]     |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stdout]    |
[INFO] [stdout] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stdout]     |
[INFO] [stdout] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stdout]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stdout]     |
[INFO] [stdout] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stdout]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stdout]    |
[INFO] [stdout] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stdout]     |
[INFO] [stdout] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stdout]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stdout]     |
[INFO] [stdout] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stdout]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 1.16s
[INFO] running `Command { std: "docker" "inspect" "a6f20ac6a6aad4501dabb14a9effe6b8268d8075f07721cdcb7e0b246e00603f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a6f20ac6a6aad4501dabb14a9effe6b8268d8075f07721cdcb7e0b246e00603f", kill_on_drop: false }`
[INFO] [stdout] a6f20ac6a6aad4501dabb14a9effe6b8268d8075f07721cdcb7e0b246e00603f
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-09-08" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 8b139b71b8c30383537f467ad2413a41a26a1799cf2ae0f4ff921b4e6cb49531
[INFO] running `Command { std: "docker" "start" "-a" "8b139b71b8c30383537f467ad2413a41a26a1799cf2ae0f4ff921b4e6cb49531", kill_on_drop: false }`
[INFO] [stderr] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stderr]   --> src/coarse_grained_linked_set.rs:86:17
[INFO] [stderr]    |
[INFO] [stderr] 86 |                 mem::replace(&mut self.root, Some(Box::new(new_node)));
[INFO] [stderr]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stderr]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stderr] 
[INFO] [stderr] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stderr]    --> src/coarse_grained_linked_set.rs:137:29
[INFO] [stderr]     |
[INFO] [stderr] 137 | ...                   mem::replace(&mut prev_node.next, Some(current_node));
[INFO] [stderr]     |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stderr] 
[INFO] [stderr] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stderr]    --> src/coarse_grained_linked_set.rs:141:25
[INFO] [stderr]     |
[INFO] [stderr] 141 |                         mem::replace(&mut prev_node.next, current);
[INFO] [stderr]     |                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stderr] 
[INFO] [stderr] warning: `rust-concurrency-tests` (lib) generated 3 warnings
[INFO] [stderr] warning: `rust-concurrency-tests` (lib test) generated 3 warnings (3 duplicates)
[INFO] [stdout] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stdout] running 0 tests
[INFO] [stderr]  --> tests/linked_set_tests.rs:5:9
[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] 5 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stdout] 
[INFO] [stderr]   |         ----^^^
[INFO] [stdout] 
[INFO] [stderr]   |         |
[INFO] [stdout] running 0 tests
[INFO] [stderr]   |         help: remove this `mut`
[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]   = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stderr] 
[INFO] [stdout] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stdout] running 7 tests
[INFO] [stderr]   --> tests/linked_set_tests.rs:24:9
[INFO] [stderr]    |
[INFO] [stderr] 24 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stderr]    |         ----^^^
[INFO] [stderr]    |         |
[INFO] [stderr]    |         help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> tests/linked_set_tests.rs:40:9
[INFO] [stderr]    |
[INFO] [stderr] 40 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stderr]    |         ----^^^
[INFO] [stderr]    |         |
[INFO] [stderr]    |         help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> tests/linked_set_tests.rs:49:9
[INFO] [stderr]    |
[INFO] [stderr] 49 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stderr]    |         ----^^^
[INFO] [stderr]    |         |
[INFO] [stderr]    |         help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> tests/linked_set_tests.rs:58:9
[INFO] [stderr]    |
[INFO] [stderr] 58 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stderr]    |         ----^^^
[INFO] [stderr]    |         |
[INFO] [stderr]    |         help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> tests/linked_set_tests.rs:83:9
[INFO] [stderr]    |
[INFO] [stderr] 83 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stderr]    |         ----^^^
[INFO] [stderr]    |         |
[INFO] [stderr]    |         help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]    --> tests/linked_set_tests.rs:108:9
[INFO] [stderr]     |
[INFO] [stderr] 108 |     let mut set = CoarseLockLinkedSet::<i32>::new();
[INFO] [stderr]     |         ----^^^
[INFO] [stderr]     |         |
[INFO] [stderr]     |         help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: `rust-concurrency-tests` (bin "rust-concurrency-tests") generated 3 warnings (3 duplicates)
[INFO] [stderr] warning: `rust-concurrency-tests` (bin "rust-concurrency-tests" test) generated 3 warnings (3 duplicates)
[INFO] [stderr] warning: `rust-concurrency-tests` (test "linked_set_tests") generated 7 warnings
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.02s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/rust_concurrency_tests-6b7cfc27c80987da)
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/rust_concurrency_tests-e2f8ce45a138e49c)
[INFO] [stderr]      Running tests/linked_set_tests.rs (/opt/rustwide/target/debug/deps/linked_set_tests-264ee6f9da364a9e)
[INFO] [stdout] test adds_and_removes_root ... ok
[INFO] [stdout] test adds_multiple_items_and_removes_everything_back_to_front ... ok
[INFO] [stdout] test adds_item ... ok
[INFO] [stdout] test adding_same_item_has_no_effect ... ok
[INFO] [stdout] test adds_root_and_fails_to_remove ... ok
[INFO] [stderr]    Doc-tests rust-concurrency-tests
[INFO] [stdout] test adds_multiple_items_and_removes_everything_front_to_back ... ok
[INFO] [stdout] test adds_multiple_items_and_removes_everything_no_particular_order ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 7 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.04s
[INFO] [stdout] 
[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" "8b139b71b8c30383537f467ad2413a41a26a1799cf2ae0f4ff921b4e6cb49531", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8b139b71b8c30383537f467ad2413a41a26a1799cf2ae0f4ff921b4e6cb49531", kill_on_drop: false }`
[INFO] [stdout] 8b139b71b8c30383537f467ad2413a41a26a1799cf2ae0f4ff921b4e6cb49531