[INFO] cloning repository https://github.com/wa7sa34cx/rust-book-repeat
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/wa7sa34cx/rust-book-repeat" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fwa7sa34cx%2Frust-book-repeat", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fwa7sa34cx%2Frust-book-repeat'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 58ec64c7c5a1e42319c9ae0ceee35cb077aa937f
[INFO] testing wa7sa34cx/rust-book-repeat against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fwa7sa34cx%2Frust-book-repeat" "/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/wa7sa34cx/rust-book-repeat on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/wa7sa34cx/rust-book-repeat
[INFO] finished tweaking git repo https://github.com/wa7sa34cx/rust-book-repeat
[INFO] tweaked toml for git repo https://github.com/wa7sa34cx/rust-book-repeat written to /workspace/builds/worker-24/source/Cargo.toml
[INFO] crate git repo https://github.com/wa7sa34cx/rust-book-repeat already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 1f2bf741bd3a987c974ff6d6e736f931b8c5dbfccfcefb165cb3f24f8f674b02
[INFO] running `Command { std: "docker" "start" "-a" "1f2bf741bd3a987c974ff6d6e736f931b8c5dbfccfcefb165cb3f24f8f674b02", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1f2bf741bd3a987c974ff6d6e736f931b8c5dbfccfcefb165cb3f24f8f674b02", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1f2bf741bd3a987c974ff6d6e736f931b8c5dbfccfcefb165cb3f24f8f674b02", kill_on_drop: false }`
[INFO] [stdout] 1f2bf741bd3a987c974ff6d6e736f931b8c5dbfccfcefb165cb3f24f8f674b02
[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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 2a4469283d99fdbc9fe35f098f3d3c64f47d5ef0225dbce435f2da67132fe0ae
[INFO] running `Command { std: "docker" "start" "-a" "2a4469283d99fdbc9fe35f098f3d3c64f47d5ef0225dbce435f2da67132fe0ae", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.97
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling rust-book-repeat v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]   --> src/ch04_01_ownership/mod.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let s2 = s1; // value MOVED here
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `black`
[INFO] [stdout]   --> src/ch05_structs/mod.rs:43:9
[INFO] [stdout]    |
[INFO] [stdout] 43 |     let black = Color(0, 0, 0);
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_black`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `origin`
[INFO] [stdout]   --> src/ch05_structs/mod.rs:44:9
[INFO] [stdout]    |
[INFO] [stdout] 44 |     let origin = Point(0, 0, 0);
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_origin`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `four`
[INFO] [stdout]  --> src/ch06_enums/mod.rs:2:9
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let four = IpAddrKind::V4;
[INFO] [stdout]   |         ^^^^ help: if this is intentional, prefix it with an underscore: `_four`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `six`
[INFO] [stdout]  --> src/ch06_enums/mod.rs:3:9
[INFO] [stdout]   |
[INFO] [stdout] 3 |     let six = IpAddrKind::V6;
[INFO] [stdout]   |         ^^^ help: if this is intentional, prefix it with an underscore: `_six`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `home`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let home = IpAddr::V4(127, 0, 0, 1);
[INFO] [stdout]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_home`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `loopback`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:16:9
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let loopback = IpAddr::V6(String::from("::1"));
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_loopback`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `some_number`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let some_number = Some(5);
[INFO] [stdout]    |         ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_some_number`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `absent_number`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:28:9
[INFO] [stdout]    |
[INFO] [stdout] 28 |     let absent_number: Option<i32> = None;
[INFO] [stdout]    |         ^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_absent_number`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `count` is assigned to, but never used
[INFO] [stdout]   --> src/ch06_enums/mod.rs:64:13
[INFO] [stdout]    |
[INFO] [stdout] 64 |     let mut count = 0;
[INFO] [stdout]    |             ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_count` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `count` is never read
[INFO] [stdout]   --> src/ch06_enums/mod.rs:70:9
[INFO] [stdout]    |
[INFO] [stdout] 70 |         count += 1;
[INFO] [stdout]    |         ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `integer`
[INFO] [stdout]   --> src/ch10_01_generics/mod.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let integer = Point { x: 5, y: 10 };
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_integer`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/ch15_04_rc/mod.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let b = Cons(3, Rc::clone(&a));
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]   --> src/ch15_04_rc/mod.rs:17:13
[INFO] [stdout]    |
[INFO] [stdout] 17 |         let c = Cons(4, Rc::clone(&a));
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/ch19_03_adv_types/mod.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let f: Thunk = Box::new(|| println!("hi"));
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `text_length`
[INFO] [stdout]   --> src/options/mod.rs:33:9
[INFO] [stdout]    |
[INFO] [stdout] 33 |     let text_length: Option<usize> = text.as_ref().map(|s| s.len());
[INFO] [stdout]    |         ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_text_length`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/options/mod.rs:42:9
[INFO] [stdout]    |
[INFO] [stdout] 42 |     let x: Option<&str> = None;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1010:47
[INFO] [stdout]      |
[INFO] [stdout] 1010 |     assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
[INFO] [stdout]      |                                               ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1011:46
[INFO] [stdout]      |
[INFO] [stdout] 1011 |     assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
[INFO] [stdout]      |                                              ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1012:48
[INFO] [stdout]      |
[INFO] [stdout] 1012 |     assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
[INFO] [stdout]      |                                                ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1013:43
[INFO] [stdout]      |
[INFO] [stdout] 1013 |     let r = s.binary_search_by_key(&1, |&(a, b)| b);
[INFO] [stdout]      |                                           ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/iterator/mod.rs:73:9
[INFO] [stdout]    |
[INFO] [stdout] 73 |     let mut iter = a1.iter().chain(a2.iter());
[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: 22 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 26.17s
[INFO] running `Command { std: "docker" "inspect" "2a4469283d99fdbc9fe35f098f3d3c64f47d5ef0225dbce435f2da67132fe0ae", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2a4469283d99fdbc9fe35f098f3d3c64f47d5ef0225dbce435f2da67132fe0ae", kill_on_drop: false }`
[INFO] [stdout] 2a4469283d99fdbc9fe35f098f3d3c64f47d5ef0225dbce435f2da67132fe0ae
[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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 97f7af6cfb29910131956f8ec5894f877ac80cf26da6c4c584cb05ecb509840a
[INFO] running `Command { std: "docker" "start" "-a" "97f7af6cfb29910131956f8ec5894f877ac80cf26da6c4c584cb05ecb509840a", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-book-repeat v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]   --> src/ch04_01_ownership/mod.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let s2 = s1; // value MOVED here
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `black`
[INFO] [stdout]   --> src/ch05_structs/mod.rs:43:9
[INFO] [stdout]    |
[INFO] [stdout] 43 |     let black = Color(0, 0, 0);
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_black`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `origin`
[INFO] [stdout]   --> src/ch05_structs/mod.rs:44:9
[INFO] [stdout]    |
[INFO] [stdout] 44 |     let origin = Point(0, 0, 0);
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_origin`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `four`
[INFO] [stdout]  --> src/ch06_enums/mod.rs:2:9
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let four = IpAddrKind::V4;
[INFO] [stdout]   |         ^^^^ help: if this is intentional, prefix it with an underscore: `_four`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `six`
[INFO] [stdout]  --> src/ch06_enums/mod.rs:3:9
[INFO] [stdout]   |
[INFO] [stdout] 3 |     let six = IpAddrKind::V6;
[INFO] [stdout]   |         ^^^ help: if this is intentional, prefix it with an underscore: `_six`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `home`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let home = IpAddr::V4(127, 0, 0, 1);
[INFO] [stdout]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_home`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `loopback`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:16:9
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let loopback = IpAddr::V6(String::from("::1"));
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_loopback`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `some_number`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let some_number = Some(5);
[INFO] [stdout]    |         ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_some_number`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `absent_number`
[INFO] [stdout]   --> src/ch06_enums/mod.rs:28:9
[INFO] [stdout]    |
[INFO] [stdout] 28 |     let absent_number: Option<i32> = None;
[INFO] [stdout]    |         ^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_absent_number`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `count` is assigned to, but never used
[INFO] [stdout]   --> src/ch06_enums/mod.rs:64:13
[INFO] [stdout]    |
[INFO] [stdout] 64 |     let mut count = 0;
[INFO] [stdout]    |             ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_count` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `count` is never read
[INFO] [stdout]   --> src/ch06_enums/mod.rs:70:9
[INFO] [stdout]    |
[INFO] [stdout] 70 |         count += 1;
[INFO] [stdout]    |         ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `integer`
[INFO] [stdout]   --> src/ch10_01_generics/mod.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let integer = Point { x: 5, y: 10 };
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_integer`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/ch15_04_rc/mod.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let b = Cons(3, Rc::clone(&a));
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]   --> src/ch15_04_rc/mod.rs:17:13
[INFO] [stdout]    |
[INFO] [stdout] 17 |         let c = Cons(4, Rc::clone(&a));
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/ch19_03_adv_types/mod.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let f: Thunk = Box::new(|| println!("hi"));
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `text_length`
[INFO] [stdout]   --> src/options/mod.rs:33:9
[INFO] [stdout]    |
[INFO] [stdout] 33 |     let text_length: Option<usize> = text.as_ref().map(|s| s.len());
[INFO] [stdout]    |         ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_text_length`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/options/mod.rs:42:9
[INFO] [stdout]    |
[INFO] [stdout] 42 |     let x: Option<&str> = None;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1010:47
[INFO] [stdout]      |
[INFO] [stdout] 1010 |     assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
[INFO] [stdout]      |                                               ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1011:46
[INFO] [stdout]      |
[INFO] [stdout] 1011 |     assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
[INFO] [stdout]      |                                              ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1012:48
[INFO] [stdout]      |
[INFO] [stdout] 1012 |     assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
[INFO] [stdout]      |                                                ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]     --> src/vectors/mod.rs:1013:43
[INFO] [stdout]      |
[INFO] [stdout] 1013 |     let r = s.binary_search_by_key(&1, |&(a, b)| b);
[INFO] [stdout]      |                                           ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/iterator/mod.rs:73:9
[INFO] [stdout]    |
[INFO] [stdout] 73 |     let mut iter = a1.iter().chain(a2.iter());
[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: 22 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 2.15s
[INFO] running `Command { std: "docker" "inspect" "97f7af6cfb29910131956f8ec5894f877ac80cf26da6c4c584cb05ecb509840a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "97f7af6cfb29910131956f8ec5894f877ac80cf26da6c4c584cb05ecb509840a", kill_on_drop: false }`
[INFO] [stdout] 97f7af6cfb29910131956f8ec5894f877ac80cf26da6c4c584cb05ecb509840a
[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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] e18b7fae6673cedc8851c1c4c6ff6f5f867b4fc52c2feef83f60cae04f30fa06
[INFO] running `Command { std: "docker" "start" "-a" "e18b7fae6673cedc8851c1c4c6ff6f5f867b4fc52c2feef83f60cae04f30fa06", kill_on_drop: false }`
[INFO] [stderr] warning: unused variable: `s2`
[INFO] [stderr]   --> src/ch04_01_ownership/mod.rs:14:9
[INFO] [stderr]    |
[INFO] [stderr] 14 |     let s2 = s1; // value MOVED here
[INFO] [stderr]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `black`
[INFO] [stderr]   --> src/ch05_structs/mod.rs:43:9
[INFO] [stderr]    |
[INFO] [stderr] 43 |     let black = Color(0, 0, 0);
[INFO] [stderr]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_black`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `origin`
[INFO] [stderr]   --> src/ch05_structs/mod.rs:44:9
[INFO] [stderr]    |
[INFO] [stderr] 44 |     let origin = Point(0, 0, 0);
[INFO] [stderr]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_origin`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `four`
[INFO] [stderr]  --> src/ch06_enums/mod.rs:2:9
[INFO] [stderr]   |
[INFO] [stderr] 2 |     let four = IpAddrKind::V4;
[INFO] [stderr]   |         ^^^^ help: if this is intentional, prefix it with an underscore: `_four`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `six`
[INFO] [stderr]  --> src/ch06_enums/mod.rs:3:9
[INFO] [stderr]   |
[INFO] [stderr] 3 |     let six = IpAddrKind::V6;
[INFO] [stderr]   |         ^^^ help: if this is intentional, prefix it with an underscore: `_six`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `home`
[INFO] [stderr]   --> src/ch06_enums/mod.rs:15:9
[INFO] [stderr]    |
[INFO] [stderr] 15 |     let home = IpAddr::V4(127, 0, 0, 1);
[INFO] [stderr]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_home`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `loopback`
[INFO] [stderr]   --> src/ch06_enums/mod.rs:16:9
[INFO] [stderr]    |
[INFO] [stderr] 16 |     let loopback = IpAddr::V6(String::from("::1"));
[INFO] [stderr]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_loopback`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `some_number`
[INFO] [stderr]   --> src/ch06_enums/mod.rs:27:9
[INFO] [stderr]    |
[INFO] [stderr] 27 |     let some_number = Some(5);
[INFO] [stderr]    |         ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_some_number`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `absent_number`
[INFO] [stderr]   --> src/ch06_enums/mod.rs:28:9
[INFO] [stderr]    |
[INFO] [stderr] 28 |     let absent_number: Option<i32> = None;
[INFO] [stderr]    |         ^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_absent_number`
[INFO] [stderr] 
[INFO] [stderr] warning: variable `count` is assigned to, but never used
[INFO] [stderr]   --> src/ch06_enums/mod.rs:64:13
[INFO] [stderr]    |
[INFO] [stderr] 64 |     let mut count = 0;
[INFO] [stderr]    |             ^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: consider using `_count` instead
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `count` is never read
[INFO] [stderr]   --> src/ch06_enums/mod.rs:70:9
[INFO] [stderr]    |
[INFO] [stderr] 70 |         count += 1;
[INFO] [stderr]    |         ^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr]    = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `integer`
[INFO] [stderr]   --> src/ch10_01_generics/mod.rs:13:9
[INFO] [stderr]    |
[INFO] [stderr] 13 |     let integer = Point { x: 5, y: 10 };
[INFO] [stderr]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_integer`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `b`
[INFO] [stderr]   --> src/ch15_04_rc/mod.rs:14:9
[INFO] [stderr]    |
[INFO] [stderr] 14 |     let b = Cons(3, Rc::clone(&a));
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `c`
[INFO] [stderr]   --> src/ch15_04_rc/mod.rs:17:13
[INFO] [stderr]    |
[INFO] [stderr] 17 |         let c = Cons(4, Rc::clone(&a));
[INFO] [stderr]    |             ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `f`
[INFO] [stderr]   --> src/ch19_03_adv_types/mod.rs:10:9
[INFO] [stderr]    |
[INFO] [stderr] 10 |     let f: Thunk = Box::new(|| println!("hi"));
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `text_length`
[INFO] [stderr]   --> src/options/mod.rs:33:9
[INFO] [stderr]    |
[INFO] [stderr] 33 |     let text_length: Option<usize> = text.as_ref().map(|s| s.len());
[INFO] [stderr]    |         ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_text_length`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/options/mod.rs:42:9
[INFO] [stderr]    |
[INFO] [stderr] 42 |     let x: Option<&str> = None;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]     --> src/vectors/mod.rs:1010:47
[INFO] [stderr]      |
[INFO] [stderr] 1010 |     assert_eq!(s.binary_search_by_key(&13, |&(a, b)| b), Ok(9));
[INFO] [stderr]      |                                               ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]     --> src/vectors/mod.rs:1011:46
[INFO] [stderr]      |
[INFO] [stderr] 1011 |     assert_eq!(s.binary_search_by_key(&4, |&(a, b)| b), Err(7));
[INFO] [stderr]      |                                              ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]     --> src/vectors/mod.rs:1012:48
[INFO] [stderr]      |
[INFO] [stderr] 1012 |     assert_eq!(s.binary_search_by_key(&100, |&(a, b)| b), Err(13));
[INFO] [stderr]      |                                                ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]     --> src/vectors/mod.rs:1013:43
[INFO] [stderr]      |
[INFO] [stderr] 1013 |     let r = s.binary_search_by_key(&1, |&(a, b)| b);
[INFO] [stderr]      |                                           ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/iterator/mod.rs:73:9
[INFO] [stderr]    |
[INFO] [stderr] 73 |     let mut iter = a1.iter().chain(a2.iter());
[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: `rust-book-repeat` (bin "rust-book-repeat" test) generated 22 warnings
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.02s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/rust_book_repeat-120bd275c8110c8f)
[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" "e18b7fae6673cedc8851c1c4c6ff6f5f867b4fc52c2feef83f60cae04f30fa06", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e18b7fae6673cedc8851c1c4c6ff6f5f867b4fc52c2feef83f60cae04f30fa06", kill_on_drop: false }`
[INFO] [stdout] e18b7fae6673cedc8851c1c4c6ff6f5f867b4fc52c2feef83f60cae04f30fa06