[INFO] cloning repository https://github.com/ghotiphud/rust-intro [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/ghotiphud/rust-intro" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fghotiphud%2Frust-intro", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fghotiphud%2Frust-intro'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] c72640c3eb4a803d29bd3eb29798bcb85e9b4054 [INFO] testing ghotiphud/rust-intro against master#62efba8a050c64249dab942951bb28f710208bc8 for pr-90799 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fghotiphud%2Frust-intro" "/workspace/builds/worker-81/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-81/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/ghotiphud/rust-intro 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/ghotiphud/rust-intro [INFO] finished tweaking git repo https://github.com/ghotiphud/rust-intro [INFO] tweaked toml for git repo https://github.com/ghotiphud/rust-intro written to /workspace/builds/worker-81/source/Cargo.toml [INFO] crate git repo https://github.com/ghotiphud/rust-intro 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] [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-81/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/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:e8397a04204aaf8b9f284182a6f9e27a3c2e67044d0943b4415b160bfc957681" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] 792e5fad26b3bf6940a554226158400029c3546e43b43b64fab0748d6b724605 [INFO] running `Command { std: "docker" "start" "-a" "792e5fad26b3bf6940a554226158400029c3546e43b43b64fab0748d6b724605", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "792e5fad26b3bf6940a554226158400029c3546e43b43b64fab0748d6b724605", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "792e5fad26b3bf6940a554226158400029c3546e43b43b64fab0748d6b724605", kill_on_drop: false }` [INFO] [stdout] 792e5fad26b3bf6940a554226158400029c3546e43b43b64fab0748d6b724605 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/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:e8397a04204aaf8b9f284182a6f9e27a3c2e67044d0943b4415b160bfc957681" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "build" "--frozen" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] dea2ae6c62dfc3f0c0e4a5038031bdfdfc43414253397ed4ee571e076f133397 [INFO] running `Command { std: "docker" "start" "-a" "dea2ae6c62dfc3f0c0e4a5038031bdfdfc43414253397ed4ee571e076f133397", kill_on_drop: false }` [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] Compiling rust_intro v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] warning: unused variable: `y` [INFO] [stdout] --> src/safety.rs:3:9 [INFO] [stdout] | [INFO] [stdout] 3 | let y = &x[0]; //Borrow(Reference) the first element of x [INFO] [stdout] | ^ help: if this is intentional, prefix it with an underscore: `_y` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variable does not need to be mutable [INFO] [stdout] --> src/safety.rs:2:9 [INFO] [stdout] | [INFO] [stdout] 2 | let mut x = vec![10, 20]; //Create vec owned by x [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: unused variable: `y` [INFO] [stdout] --> src/main.rs:5:9 [INFO] [stdout] | [INFO] [stdout] 5 | let y = &x[0]; //Borrow(Reference) the first element of x [INFO] [stdout] | ^ help: if this is intentional, prefix it with an underscore: `_y` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function is never used: `iterator` [INFO] [stdout] --> src/main.rs:9:4 [INFO] [stdout] | [INFO] [stdout] 9 | fn iterator() { [INFO] [stdout] | ^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function is never used: `sum_pos` [INFO] [stdout] --> src/main.rs:16:4 [INFO] [stdout] | [INFO] [stdout] 16 | fn sum_pos(v: &Vec) -> i32 { [INFO] [stdout] | ^^^^^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: value assigned to `y` is never read [INFO] [stdout] --> src/types.rs:17:13 [INFO] [stdout] | [INFO] [stdout] 17 | let mut y = x as i64; [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: unnecessary `unsafe` block [INFO] [stdout] --> src/types.rs:71:9 [INFO] [stdout] | [INFO] [stdout] 71 | unsafe { [INFO] [stdout] | ^^^^^^ unnecessary `unsafe` block [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_unsafe)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused return value of `collect` that must be used [INFO] [stdout] --> src/concurrent.rs:140:5 [INFO] [stdout] | [INFO] [stdout] 140 | handles.into_iter().map(|h| h.join().unwrap()).collect::>(); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] = note: if you really need to exhaust the iterator, consider `.for_each(drop)` instead [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variant is never constructed: `None` [INFO] [stdout] --> src/types.rs:54:16 [INFO] [stdout] | [INFO] [stdout] 54 | enum Options { None, One, Two, Three } [INFO] [stdout] | ^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variant is never constructed: `Two` [INFO] [stdout] --> src/types.rs:54:27 [INFO] [stdout] | [INFO] [stdout] 54 | enum Options { None, One, Two, Three } [INFO] [stdout] | ^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variant is never constructed: `Three` [INFO] [stdout] --> src/types.rs:54:32 [INFO] [stdout] | [INFO] [stdout] 54 | enum Options { None, One, Two, Three } [INFO] [stdout] | ^^^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 3 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 5 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 1 warning emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Finished dev [unoptimized + debuginfo] target(s) in 3.62s [INFO] running `Command { std: "docker" "inspect" "dea2ae6c62dfc3f0c0e4a5038031bdfdfc43414253397ed4ee571e076f133397", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "dea2ae6c62dfc3f0c0e4a5038031bdfdfc43414253397ed4ee571e076f133397", kill_on_drop: false }` [INFO] [stdout] dea2ae6c62dfc3f0c0e4a5038031bdfdfc43414253397ed4ee571e076f133397 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/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:e8397a04204aaf8b9f284182a6f9e27a3c2e67044d0943b4415b160bfc957681" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] e955a5f129fb079d3f5588b1633f666ce19c7a47b0288a0445c1e7ef30c274e7 [INFO] running `Command { std: "docker" "start" "-a" "e955a5f129fb079d3f5588b1633f666ce19c7a47b0288a0445c1e7ef30c274e7", kill_on_drop: false }` [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] Compiling rust_intro v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] warning: unused variable: `y` [INFO] [stdout] --> src/main.rs:5:9 [INFO] [stdout] | [INFO] [stdout] 5 | let y = &x[0]; //Borrow(Reference) the first element of x [INFO] [stdout] | ^ help: if this is intentional, prefix it with an underscore: `_y` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function is never used: `iterator` [INFO] [stdout] --> src/main.rs:9:4 [INFO] [stdout] | [INFO] [stdout] 9 | fn iterator() { [INFO] [stdout] | ^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function is never used: `sum_pos` [INFO] [stdout] --> src/main.rs:16:4 [INFO] [stdout] | [INFO] [stdout] 16 | fn sum_pos(v: &Vec) -> i32 { [INFO] [stdout] | ^^^^^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused variable: `y` [INFO] [stdout] --> src/safety.rs:3:9 [INFO] [stdout] | [INFO] [stdout] 3 | let y = &x[0]; //Borrow(Reference) the first element of x [INFO] [stdout] | ^ help: if this is intentional, prefix it with an underscore: `_y` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variable does not need to be mutable [INFO] [stdout] --> src/safety.rs:2:9 [INFO] [stdout] | [INFO] [stdout] 2 | let mut x = vec![10, 20]; //Create vec owned by x [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: unused return value of `collect` that must be used [INFO] [stdout] --> src/concurrent.rs:140:5 [INFO] [stdout] | [INFO] [stdout] 140 | handles.into_iter().map(|h| h.join().unwrap()).collect::>(); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] = note: if you really need to exhaust the iterator, consider `.for_each(drop)` instead [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: value assigned to `y` is never read [INFO] [stdout] --> src/types.rs:17:13 [INFO] [stdout] | [INFO] [stdout] 17 | let mut y = x as i64; [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: unnecessary `unsafe` block [INFO] [stdout] --> src/types.rs:71:9 [INFO] [stdout] | [INFO] [stdout] 71 | unsafe { [INFO] [stdout] | ^^^^^^ unnecessary `unsafe` block [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_unsafe)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variant is never constructed: `None` [INFO] [stdout] --> src/types.rs:54:16 [INFO] [stdout] | [INFO] [stdout] 54 | enum Options { None, One, Two, Three } [INFO] [stdout] | ^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variant is never constructed: `Two` [INFO] [stdout] --> src/types.rs:54:27 [INFO] [stdout] | [INFO] [stdout] 54 | enum Options { None, One, Two, Three } [INFO] [stdout] | ^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: variant is never constructed: `Three` [INFO] [stdout] --> src/types.rs:54:32 [INFO] [stdout] | [INFO] [stdout] 54 | enum Options { None, One, Two, Three } [INFO] [stdout] | ^^^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 1 warning emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 3 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 5 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 5.04s [INFO] running `Command { std: "docker" "inspect" "e955a5f129fb079d3f5588b1633f666ce19c7a47b0288a0445c1e7ef30c274e7", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "e955a5f129fb079d3f5588b1633f666ce19c7a47b0288a0445c1e7ef30c274e7", kill_on_drop: false }` [INFO] [stdout] e955a5f129fb079d3f5588b1633f666ce19c7a47b0288a0445c1e7ef30c274e7 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-81/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:e8397a04204aaf8b9f284182a6f9e27a3c2e67044d0943b4415b160bfc957681" "/opt/rustwide/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "test" "--frozen", kill_on_drop: false }` [INFO] [stdout] dead154f573fbece66268b28151cf27f05e228ba4a43c18c4090fbf83599f284 [INFO] running `Command { std: "docker" "start" "-a" "dead154f573fbece66268b28151cf27f05e228ba4a43c18c4090fbf83599f284", kill_on_drop: false }` [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] warning: unused variable: `y` [INFO] [stderr] --> src/main.rs:5:9 [INFO] [stderr] | [INFO] [stderr] 5 | let y = &x[0]; //Borrow(Reference) the first element of x [INFO] [stderr] | ^ help: if this is intentional, prefix it with an underscore: `_y` [INFO] [stderr] | [INFO] [stdout] [INFO] [stderr] = note: `#[warn(unused_variables)]` on by default [INFO] [stdout] running 0 tests [INFO] [stderr] [INFO] [stdout] [INFO] [stderr] warning: function is never used: `iterator` [INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s [INFO] [stderr] --> src/main.rs:9:4 [INFO] [stdout] [INFO] [stderr] | [INFO] [stderr] 9 | fn iterator() { [INFO] [stderr] | ^^^^^^^^ [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(dead_code)]` on by default [INFO] [stderr] [INFO] [stderr] warning: function is never used: `sum_pos` [INFO] [stderr] --> src/main.rs:16:4 [INFO] [stderr] | [INFO] [stderr] 16 | fn sum_pos(v: &Vec) -> i32 { [INFO] [stderr] | ^^^^^^^ [INFO] [stderr] [INFO] [stderr] warning: `rust_intro` (bin "main" test) generated 3 warnings [INFO] [stderr] warning: value assigned to `y` is never read [INFO] [stderr] --> src/types.rs:17:13 [INFO] [stderr] | [INFO] [stderr] 17 | let mut y = x as i64; [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: unnecessary `unsafe` block [INFO] [stderr] --> src/types.rs:71:9 [INFO] [stderr] | [INFO] [stderr] 71 | unsafe { [INFO] [stderr] | ^^^^^^ unnecessary `unsafe` block [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(unused_unsafe)]` on by default [INFO] [stderr] [INFO] [stderr] warning: variant is never constructed: `None` [INFO] [stderr] --> src/types.rs:54:16 [INFO] [stderr] | [INFO] [stderr] 54 | enum Options { None, One, Two, Three } [INFO] [stderr] | ^^^^ [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(dead_code)]` on by default [INFO] [stderr] [INFO] [stderr] warning: variant is never constructed: `Two` [INFO] [stderr] --> src/types.rs:54:27 [INFO] [stderr] | [INFO] [stderr] 54 | enum Options { None, One, Two, Three } [INFO] [stderr] | ^^^ [INFO] [stderr] [INFO] [stderr] warning: variant is never constructed: `Three` [INFO] [stderr] --> src/types.rs:54:32 [INFO] [stderr] | [INFO] [stderr] 54 | enum Options { None, One, Two, Three } [INFO] [stderr] | ^^^^^ [INFO] [stderr] [INFO] [stderr] warning: unused variable: `y` [INFO] [stderr] --> src/safety.rs:3:9 [INFO] [stderr] | [INFO] [stderr] 3 | let y = &x[0]; //Borrow(Reference) the first element of x [INFO] [stderr] | ^ help: if this is intentional, prefix it with an underscore: `_y` [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(unused_variables)]` on by default [INFO] [stderr] [INFO] [stderr] warning: variable does not need to be mutable [INFO] [stderr] --> src/safety.rs:2:9 [INFO] [stderr] | [INFO] [stderr] 2 | let mut x = vec![10, 20]; //Create vec owned by x [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: unused return value of `collect` that must be used [INFO] [stderr] --> src/concurrent.rs:140:5 [INFO] [stderr] | [INFO] [stderr] 140 | handles.into_iter().map(|h| h.join().unwrap()).collect::>(); [INFO] [stderr] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(unused_must_use)]` on by default [INFO] [stderr] = note: if you really need to exhaust the iterator, consider `.for_each(drop)` instead [INFO] [stderr] [INFO] [stderr] warning: `rust_intro` (bin "types" test) generated 5 warnings [INFO] [stderr] warning: `rust_intro` (bin "safety" test) generated 2 warnings [INFO] [stderr] warning: `rust_intro` (bin "concurrent" test) generated 1 warning [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 2.42s [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/concurrent-12159364ae617b47) [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/main-ef25ef171e5df68a) [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] [stderr] Running unittests (/opt/rustwide/target/debug/deps/memory-4c5bf7cb3f9a1961) [INFO] [stdout] [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/safety-7da9172da4ce9a46) [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 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] [stderr] Running unittests (/opt/rustwide/target/debug/deps/traits-6b2d2b3f9edb7e28) [INFO] [stdout] [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/types-6ed30188a72208f0) [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 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" "dead154f573fbece66268b28151cf27f05e228ba4a43c18c4090fbf83599f284", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "dead154f573fbece66268b28151cf27f05e228ba4a43c18c4090fbf83599f284", kill_on_drop: false }` [INFO] [stdout] dead154f573fbece66268b28151cf27f05e228ba4a43c18c4090fbf83599f284