[INFO] cloning repository https://github.com/johnharris85/ardan_rust [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/johnharris85/ardan_rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjohnharris85%2Fardan_rust", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjohnharris85%2Fardan_rust'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] 581f83845c2bcb97fea6cf3f3c7a08bd479f51b1 [INFO] checking johnharris85/ardan_rust against try#c8085cfed34c45021fc8f66d073f6394b3e35431 for pr-148939 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjohnharris85%2Fardan_rust" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'... [INFO] [stderr] done. [INFO] started tweaking git repo https://github.com/johnharris85/ardan_rust [INFO] finished tweaking git repo https://github.com/johnharris85/ardan_rust [INFO] tweaked toml for git repo https://github.com/johnharris85/ardan_rust written to /workspace/builds/worker-3-tc2/source/Cargo.toml [INFO] validating manifest of git repo https://github.com/johnharris85/ardan_rust on toolchain c8085cfed34c45021fc8f66d073f6394b3e35431 [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c8085cfed34c45021fc8f66d073f6394b3e35431" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] crate git repo https://github.com/johnharris85/ardan_rust already has a lockfile, it will not be regenerated [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c8085cfed34c45021fc8f66d073f6394b3e35431" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/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@sha256:94a0c148923f5b2b52a63ef0eeb1882ad339ab61bce784c8077cbe41c61feb6c" "/opt/rustwide/cargo-home/bin/cargo" "+c8085cfed34c45021fc8f66d073f6394b3e35431" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] d2890a0f84de4f7edbd7c7910039ecbdbf2affd05643509b998b4a2e3dfd739d [INFO] running `Command { std: "docker" "start" "-a" "d2890a0f84de4f7edbd7c7910039ecbdbf2affd05643509b998b4a2e3dfd739d", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "d2890a0f84de4f7edbd7c7910039ecbdbf2affd05643509b998b4a2e3dfd739d", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "d2890a0f84de4f7edbd7c7910039ecbdbf2affd05643509b998b4a2e3dfd739d", kill_on_drop: false }` [INFO] [stdout] d2890a0f84de4f7edbd7c7910039ecbdbf2affd05643509b998b4a2e3dfd739d [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/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" "RUSTDOCFLAGS=--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@sha256:94a0c148923f5b2b52a63ef0eeb1882ad339ab61bce784c8077cbe41c61feb6c" "/opt/rustwide/cargo-home/bin/cargo" "+c8085cfed34c45021fc8f66d073f6394b3e35431" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] f55c1fb8c101db0e673297549c48f13bb65f4f9a2e4a2150e27b54a0a169f4cb [INFO] running `Command { std: "docker" "start" "-a" "f55c1fb8c101db0e673297549c48f13bb65f4f9a2e4a2150e27b54a0a169f4cb", kill_on_drop: false }` [INFO] [stderr] Compiling proc-macro2 v1.0.95 [INFO] [stderr] Compiling cc v1.2.19 [INFO] [stderr] Checking signal-hook-registry v1.4.2 [INFO] [stderr] Checking hashbrown v0.15.2 [INFO] [stderr] Compiling foldhash v0.1.5 [INFO] [stderr] Compiling num-traits v0.2.19 [INFO] [stderr] Compiling litemap v0.7.5 [INFO] [stderr] Compiling writeable v0.5.5 [INFO] [stderr] Compiling icu_locid_transform_data v1.5.1 [INFO] [stderr] Compiling icu_properties_data v1.5.1 [INFO] [stderr] Compiling crossbeam-utils v0.8.21 [INFO] [stderr] Compiling icu_normalizer_data v1.5.1 [INFO] [stderr] Compiling bitflags v2.9.0 [INFO] [stderr] Compiling write16 v1.0.0 [INFO] [stderr] Compiling utf16_iter v1.0.5 [INFO] [stderr] Compiling schemars v0.8.22 [INFO] [stderr] Compiling foreign-types-shared v0.1.1 [INFO] [stderr] Checking spin v0.9.8 [INFO] [stderr] Compiling tokio v1.44.2 [INFO] [stderr] Compiling openssl-probe v0.1.6 [INFO] [stderr] Compiling foreign-types v0.3.2 [INFO] [stderr] Compiling rustix v1.0.5 [INFO] [stderr] Compiling parking v2.2.1 [INFO] [stderr] Compiling semver v1.0.26 [INFO] [stderr] Compiling getrandom v0.3.2 [INFO] [stderr] Compiling dyn-clone v1.0.19 [INFO] [stderr] Compiling uuid v1.16.0 [INFO] [stderr] Compiling base64 v0.22.1 [INFO] [stderr] Compiling futures-executor v0.3.31 [INFO] [stderr] Checking concurrent-queue v2.5.0 [INFO] [stderr] Checking crossbeam-queue v0.3.12 [INFO] [stderr] Compiling multer v3.1.0 [INFO] [stderr] Compiling flume v0.11.1 [INFO] [stderr] Checking unicode-ident v1.0.18 [INFO] [stderr] Checking atoi v2.0.0 [INFO] [stderr] Compiling virtue v0.0.18 [INFO] [stderr] Checking event-listener v5.4.0 [INFO] [stderr] Compiling quote v1.0.40 [INFO] [stderr] Checking hashlink v0.10.0 [INFO] [stderr] Checking miniz_oxide v0.8.8 [INFO] [stderr] Checking chrono v0.4.40 [INFO] [stderr] Checking unty v0.0.4 [INFO] [stderr] Compiling syn v2.0.100 [INFO] [stderr] Compiling regex-automata v0.4.9 [INFO] [stderr] Compiling regress v0.10.3 [INFO] [stderr] Checking sysinfo v0.34.2 [INFO] [stderr] Checking heck v0.5.0 [INFO] [stderr] Compiling simd_helpers v0.1.0 [INFO] [stderr] Checking av1-grain v0.2.3 [INFO] [stderr] Compiling http v1.3.1 [INFO] [stderr] Checking flate2 v1.1.1 [INFO] [stderr] Compiling bincode_derive v2.0.1 [INFO] [stderr] Compiling unsafe-libyaml v0.2.11 [INFO] [stderr] Checking half v2.6.0 [INFO] [stderr] Checking bytemuck v1.22.0 [INFO] [stderr] Checking clap_builder v4.5.36 [INFO] [stderr] Checking png v0.17.16 [INFO] [stderr] Checking qoi v0.4.1 [INFO] [stderr] Checking exr v1.73.0 [INFO] [stderr] Compiling openssl-sys v0.9.107 [INFO] [stderr] Compiling libsqlite3-sys v0.30.1 [INFO] [stderr] Checking tiff v0.9.1 [INFO] [stderr] Checking workqueue v0.1.0 (/opt/rustwide/workdir/workqueue) [INFO] [stderr] Checking rwlocks v0.1.0 (/opt/rustwide/workdir/rwlocks) [INFO] [stderr] Compiling openssl v0.10.72 [INFO] [stderr] Compiling native-tls v0.2.14 [INFO] [stderr] Checking deadlocks v0.1.0 (/opt/rustwide/workdir/deadlocks) [INFO] [stderr] Checking footgun v0.1.0 (/opt/rustwide/workdir/footgun) [INFO] [stdout] warning: unused variable: `lock` [INFO] [stdout] --> deadlocks/src/main.rs:6:9 [INFO] [stdout] | [INFO] [stdout] 6 | let lock = my_shared.lock().unwrap(); [INFO] [stdout] | ^^^^ help: if this is intentional, prefix it with an underscore: `_lock` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Compiling tempfile v3.19.1 [INFO] [stderr] Checking variables v0.1.0 (/opt/rustwide/workdir/variables) [INFO] [stderr] Checking scoped_threads v0.1.0 (/opt/rustwide/workdir/scoped_threads) [INFO] [stdout] warning: function `double` is never used [INFO] [stdout] --> variables/src/main.rs:9:4 [INFO] [stdout] | [INFO] [stdout] 9 | fn double(n: i32) -> i32 { [INFO] [stdout] | ^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking divide_work v0.1.0 (/opt/rustwide/workdir/divide_work) [INFO] [stderr] Checking channels v0.1.0 (/opt/rustwide/workdir/channels) [INFO] [stderr] Checking mutexes v0.1.0 (/opt/rustwide/workdir/mutexes) [INFO] [stderr] Checking thread_builder v0.1.0 (/opt/rustwide/workdir/thread_builder) [INFO] [stdout] warning: unused variable: `lock` [INFO] [stdout] --> deadlocks/src/main.rs:6:9 [INFO] [stdout] | [INFO] [stdout] 6 | let lock = my_shared.lock().unwrap(); [INFO] [stdout] | ^^^^ help: if this is intentional, prefix it with an underscore: `_lock` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking threads v0.1.0 (/opt/rustwide/workdir/threads) [INFO] [stderr] Checking workers v0.1.0 (/opt/rustwide/workdir/workers) [INFO] [stdout] warning: function `from_thread` is never used [INFO] [stdout] --> threads/src/main.rs:1:4 [INFO] [stdout] | [INFO] [stdout] 1 | fn from_thread(n: u32) { [INFO] [stdout] | ^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function `from_thread` is never used [INFO] [stdout] --> threads/src/main.rs:1:4 [INFO] [stdout] | [INFO] [stdout] 1 | fn from_thread(n: u32) { [INFO] [stdout] | ^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function `double` is never used [INFO] [stdout] --> variables/src/main.rs:9:4 [INFO] [stdout] | [INFO] [stdout] 9 | fn double(n: i32) -> i32 { [INFO] [stdout] | ^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Compiling regex v1.11.1 [INFO] [stderr] Compiling tokio-stream v0.1.17 [INFO] [stderr] Compiling synstructure v0.13.1 [INFO] [stderr] Compiling serde_derive_internals v0.29.1 [INFO] [stderr] Compiling darling_core v0.20.11 [INFO] [stderr] Compiling serde_derive v1.0.219 [INFO] [stderr] Compiling zerofrom-derive v0.1.6 [INFO] [stderr] Compiling yoke-derive v0.7.5 [INFO] [stderr] Compiling tokio-macros v2.5.0 [INFO] [stderr] Compiling zerovec-derive v0.10.3 [INFO] [stderr] Compiling displaydoc v0.2.5 [INFO] [stderr] Compiling icu_provider_macros v1.5.0 [INFO] [stderr] Compiling tracing-attributes v0.1.28 [INFO] [stderr] Compiling futures-macro v0.3.31 [INFO] [stderr] Compiling openssl-macros v0.1.1 [INFO] [stderr] Compiling thiserror-impl v2.0.12 [INFO] [stderr] Compiling profiling-procmacros v1.0.16 [INFO] [stderr] Compiling thiserror-impl v1.0.69 [INFO] [stderr] Checking profiling v1.0.16 [INFO] [stderr] Compiling arg_enum_proc_macro v0.3.4 [INFO] [stderr] Compiling num-derive v0.4.2 [INFO] [stderr] Compiling schemars_derive v0.8.22 [INFO] [stderr] Checking futures-util v0.3.31 [INFO] [stderr] Compiling serde_repr v0.1.20 [INFO] [stderr] Compiling clap_derive v4.5.32 [INFO] [stderr] Compiling thiserror v2.0.12 [INFO] [stderr] Checking thiserror v1.0.69 [INFO] [stderr] Checking tracing v0.1.41 [INFO] [stderr] Checking zerofrom v0.1.6 [INFO] [stderr] Compiling yoke v0.7.5 [INFO] [stderr] Compiling zerovec v0.10.4 [INFO] [stderr] Checking axum-core v0.5.2 [INFO] [stderr] Compiling darling_macro v0.20.11 [INFO] [stderr] Compiling darling v0.20.11 [INFO] [stderr] Compiling tinystr v0.7.6 [INFO] [stderr] Compiling icu_collections v1.5.0 [INFO] [stderr] Compiling serde_with_macros v3.12.0 [INFO] [stderr] Checking clap v4.5.36 [INFO] [stderr] Compiling icu_locid v1.5.0 [INFO] [stderr] Checking serde v1.0.219 [INFO] [stderr] Compiling icu_provider v1.5.0 [INFO] [stderr] Compiling icu_locid_transform v1.5.0 [INFO] [stderr] Checking futures v0.3.31 [INFO] [stderr] Checking asyncawait v0.1.0 (/opt/rustwide/workdir/asyncawait) [INFO] [stderr] Compiling icu_properties v1.5.1 [INFO] [stderr] Checking serde_json v1.0.140 [INFO] [stderr] Checking indexmap v2.9.0 [INFO] [stderr] Checking serde_urlencoded v0.7.1 [INFO] [stderr] Checking either v1.15.0 [INFO] [stderr] Checking serde_path_to_error v0.1.17 [INFO] [stderr] Checking bincode v2.0.1 [INFO] [stderr] Checking serde_with v3.12.0 [INFO] [stderr] Checking tracing-serde v0.2.0 [INFO] [stderr] Checking rayon v1.10.0 [INFO] [stderr] Checking itertools v0.12.1 [INFO] [stderr] Checking authentication v0.1.0 (/opt/rustwide/workdir/authentication) [INFO] [stderr] Checking tracing-subscriber v0.3.19 [INFO] [stderr] Checking openapiv3 v2.0.0 [INFO] [stderr] Checking login v0.1.0 (/opt/rustwide/workdir/login) [INFO] [stderr] Checking login_manager v0.1.0 (/opt/rustwide/workdir/login_manager) [INFO] [stderr] Checking shared_data v0.1.0 (/opt/rustwide/workdir/shared_data) [INFO] [stderr] Checking tokio-util v0.7.15 [INFO] [stderr] Checking tower v0.5.2 [INFO] [stderr] Checking tokio-native-tls v0.3.1 [INFO] [stderr] Checking collector v0.1.0 (/opt/rustwide/workdir/collector) [INFO] [stderr] Compiling icu_normalizer v1.5.0 [INFO] [stdout] warning: function `send_command` is never used [INFO] [stdout] --> collector/src/sender.rs:6:8 [INFO] [stdout] | [INFO] [stdout] 6 | pub fn send_command(bytes: &[u8]) -> Result<(), CollectorError> { [INFO] [stdout] | ^^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking tokio-blocking v0.1.0 (/opt/rustwide/workdir/tokio-blocking) [INFO] [stderr] Checking tcpserver v0.1.0 (/opt/rustwide/workdir/tcpserver) [INFO] [stderr] Checking tokio-testing v0.1.0 (/opt/rustwide/workdir/tokio-testing) [INFO] [stdout] warning: function `send_command` is never used [INFO] [stdout] --> collector/src/sender.rs:6:8 [INFO] [stdout] | [INFO] [stdout] 6 | pub fn send_command(bytes: &[u8]) -> Result<(), CollectorError> { [INFO] [stdout] | ^^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking tokio-intro v0.1.0 (/opt/rustwide/workdir/tokio-intro) [INFO] [stdout] warning: unreachable expression [INFO] [stdout] --> tcpserver/src/main.rs:53:5 [INFO] [stdout] | [INFO] [stdout] 31 | / loop { [INFO] [stdout] 32 | | let (mut socket, address) = listener.accept().await?; [INFO] [stdout] 33 | | spawn(async move { [INFO] [stdout] 34 | | println!("Connection from {address:?}"); [INFO] [stdout] ... | [INFO] [stdout] 51 | | }); [INFO] [stdout] 52 | | } [INFO] [stdout] | |_____- any code following this expression is unreachable [INFO] [stdout] 53 | Ok(()) [INFO] [stdout] | ^^^^^^ unreachable expression [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking tokio-tracing v0.1.0 (/opt/rustwide/workdir/tokio-tracing) [INFO] [stdout] warning: unreachable expression [INFO] [stdout] --> tcpserver/src/main.rs:53:5 [INFO] [stdout] | [INFO] [stdout] 31 | / loop { [INFO] [stdout] 32 | | let (mut socket, address) = listener.accept().await?; [INFO] [stdout] 33 | | spawn(async move { [INFO] [stdout] 34 | | println!("Connection from {address:?}"); [INFO] [stdout] ... | [INFO] [stdout] 51 | | }); [INFO] [stdout] 52 | | } [INFO] [stdout] | |_____- any code following this expression is unreachable [INFO] [stdout] 53 | Ok(()) [INFO] [stdout] | ^^^^^^ unreachable expression [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Checking typify-impl v0.4.0 (https://github.com/oxidecomputer/typify#7ecb1d2d) [INFO] [stdout] warning: function `hello2` is never used [INFO] [stdout] --> tokio-intro/src/main.rs:6:10 [INFO] [stdout] | [INFO] [stdout] 6 | async fn hello2() -> u32 { [INFO] [stdout] | ^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function `double` is never used [INFO] [stdout] --> tokio-testing/src/lib.rs:3:10 [INFO] [stdout] | [INFO] [stdout] 3 | async fn double(n: u32) -> u32 { [INFO] [stdout] | ^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Compiling serde_tokenstream v0.2.2 [INFO] [stderr] Checking tokiochannels v0.1.0 (/opt/rustwide/workdir/tokiochannels) [INFO] [stderr] Checking h2 v0.4.9 [INFO] [stderr] Checking fileio v0.1.0 (/opt/rustwide/workdir/fileio) [INFO] [stdout] warning: function `hello2` is never used [INFO] [stdout] --> tokio-intro/src/main.rs:6:10 [INFO] [stdout] | [INFO] [stdout] 6 | async fn hello2() -> u32 { [INFO] [stdout] | ^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused variable: `now` [INFO] [stdout] --> fileio/src/main.rs:29:9 [INFO] [stdout] | [INFO] [stdout] 29 | let now = Instant::now(); [INFO] [stdout] | ^^^ help: if this is intentional, prefix it with an underscore: `_now` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused variable: `now` [INFO] [stdout] --> fileio/src/main.rs:29:9 [INFO] [stdout] | [INFO] [stdout] 29 | let now = Instant::now(); [INFO] [stdout] | ^^^ help: if this is intentional, prefix it with an underscore: `_now` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: function `read_lines` is never used [INFO] [stdout] --> fileio/src/main.rs:3:4 [INFO] [stdout] | [INFO] [stdout] 3 | fn read_lines
(filename: P) -> io::Result (filename: P) -> io::Result