[INFO] cloning repository https://github.com/clD11/rust-katas
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/clD11/rust-katas" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FclD11%2Frust-katas", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FclD11%2Frust-katas'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 815b661c7a29d4dfeb7b2111be737ca450b237c3
[INFO] checking clD11/rust-katas against master#33fdb797f59421c7bbecaa4588ed5d7a31a9494a for pr-87190-3
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FclD11%2Frust-katas" "/workspace/builds/worker-107/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-107/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/clD11/rust-katas on toolchain 33fdb797f59421c7bbecaa4588ed5d7a31a9494a
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/clD11/rust-katas
[INFO] finished tweaking git repo https://github.com/clD11/rust-katas
[INFO] tweaked toml for git repo https://github.com/clD11/rust-katas written to /workspace/builds/worker-107/source/Cargo.toml
[INFO] crate git repo https://github.com/clD11/rust-katas already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "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-107/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-107/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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 1e6573c39007b82c77c37ea4a4d987ae50f7314e3c29179fa451266c3faeaeaf
[INFO] running `Command { std: "docker" "start" "-a" "1e6573c39007b82c77c37ea4a4d987ae50f7314e3c29179fa451266c3faeaeaf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1e6573c39007b82c77c37ea4a4d987ae50f7314e3c29179fa451266c3faeaeaf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1e6573c39007b82c77c37ea4a4d987ae50f7314e3c29179fa451266c3faeaeaf", kill_on_drop: false }`
[INFO] [stdout] 1e6573c39007b82c77c37ea4a4d987ae50f7314e3c29179fa451266c3faeaeaf
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-107/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-107/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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 2f4b1e9d5c02562ffe229216a6f34ee62fdfe5cace67c85558ddc01455922667
[INFO] running `Command { std: "docker" "start" "-a" "2f4b1e9d5c02562ffe229216a6f34ee62fdfe5cace67c85558ddc01455922667", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.68
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking ppv-lite86 v0.2.6
[INFO] [stderr]     Checking lazy_static v1.4.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking rust-katas v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `std::io`
[INFO] [stdout]  --> src/hackerrank/problem_solving/ice_cream_parlor.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::io;
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io`
[INFO] [stdout]  --> src/hackerrank/problem_solving/missing_numbers.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io;
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::string::String`
[INFO] [stdout]  --> src/rust_book/slice.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use std::string::String;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io`
[INFO] [stdout]  --> src/hackerrank/problem_solving/ice_cream_parlor.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::io;
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io`
[INFO] [stdout]  --> src/hackerrank/problem_solving/missing_numbers.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io;
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `n`
[INFO] [stdout]   --> src/hackerrank/utils.rs:50:9
[INFO] [stdout]    |
[INFO] [stdout] 50 |     let n: u8 = num.trim().parse().unwrap();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_n`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `count_number_deletions`
[INFO] [stdout]  --> src/hackerrank/problem_solving/alternating_characters.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn count_number_deletions(input: String) -> u32 {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `append_and_delete`
[INFO] [stdout]  --> src/hackerrank/problem_solving/append_and_delete.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn append_and_delete(initial: &str, desired: &str, operation: usize) -> &'static str {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `build`
[INFO] [stdout]  --> src/hackerrank/problem_solving/breadth_first_search_shortest_reach.rs:7:8
[INFO] [stdout]   |
[INFO] [stdout] 7 |     fn build(v: usize) -> Graph {
[INFO] [stdout]   |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `add_edge`
[INFO] [stdout]   --> src/hackerrank/problem_solving/breadth_first_search_shortest_reach.rs:14:8
[INFO] [stdout]    |
[INFO] [stdout] 14 |     fn add_edge(&mut self, v: usize, w: usize) {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `adj`
[INFO] [stdout]   --> src/hackerrank/problem_solving/breadth_first_search_shortest_reach.rs:19:8
[INFO] [stdout]    |
[INFO] [stdout] 19 |     fn adj(&mut self, v: usize) -> &Vec<usize> {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `encrypt`
[INFO] [stdout]  --> src/hackerrank/problem_solving/caesar_cipher.rs:2:4
[INFO] [stdout]   |
[INFO] [stdout] 2 | fn encrypt(message: &str, rotate: u8) -> String {
[INFO] [stdout]   |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `cat_and_mouse`
[INFO] [stdout]  --> src/hackerrank/problem_solving/cat_mouse.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn cat_and_mouse(x: i32, y: i32, z: i32) -> &'static str {
[INFO] [stdout]   |        ^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `sum`
[INFO] [stdout]  --> src/hackerrank/problem_solving/distinct_pairs.rs:4:8
[INFO] [stdout]   |
[INFO] [stdout] 4 | pub fn sum(nums: &[u32], target: u32) -> u32 {
[INFO] [stdout]   |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `divisible_sum_pairs`
[INFO] [stdout]  --> src/hackerrank/problem_solving/divisible_sum_pairs.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn divisible_sum_pairs(n: usize, k: u32, ar: &[u32]) -> u32 {
[INFO] [stdout]   |        ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `fair_rations`
[INFO] [stdout]  --> src/hackerrank/problem_solving/fair_rations.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn fair_rations(arr: &[u32]) -> &'static str {
[INFO] [stdout]   |        ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `find_digits`
[INFO] [stdout]  --> src/hackerrank/problem_solving/find_digits.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn find_digits(n: u32) -> u32 {
[INFO] [stdout]   |        ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `is_divisible_by`
[INFO] [stdout]  --> src/hackerrank/problem_solving/fizz_buzz.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn is_divisible_by(lhs: u32, rhs: u32) -> bool {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `fizzbuzz`
[INFO] [stdout]  --> src/hackerrank/problem_solving/fizz_buzz.rs:8:4
[INFO] [stdout]   |
[INFO] [stdout] 8 | fn fizzbuzz(n: u32) {
[INFO] [stdout]   |    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `fizzbuzz_to`
[INFO] [stdout]   --> src/hackerrank/problem_solving/fizz_buzz.rs:20:4
[INFO] [stdout]    |
[INFO] [stdout] 20 | fn fizzbuzz_to(n: u32) {
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `fizzbuzz_two`
[INFO] [stdout]  --> src/hackerrank/problem_solving/fizz_buzz_two.rs:3:4
[INFO] [stdout]   |
[INFO] [stdout] 3 | fn fizzbuzz_two() {
[INFO] [stdout]   |    ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `funny_string`
[INFO] [stdout]  --> src/hackerrank/problem_solving/funny_string.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn funny_string(input: &str) -> &'static str {
[INFO] [stdout]   |    ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `has_hackerrank`
[INFO] [stdout]  --> src/hackerrank/problem_solving/hackerrank_string.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn has_hackerrank(input: &str) -> &'static str {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `what_flavours`
[INFO] [stdout]  --> src/hackerrank/problem_solving/ice_cream_parlor.rs:5:4
[INFO] [stdout]   |
[INFO] [stdout] 5 | fn what_flavours(flavours: &Vec<u32>, money: &u32) -> [u32; 2] {
[INFO] [stdout]   |    ^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `make_anagram`
[INFO] [stdout]  --> src/hackerrank/problem_solving/making_anagrams.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn make_anagram(a: &str, b: &str) -> u32 {
[INFO] [stdout]   |    ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `count_difference`
[INFO] [stdout]  --> src/hackerrank/problem_solving/mars_exploration.rs:2:4
[INFO] [stdout]   |
[INFO] [stdout] 2 | fn count_difference(input: &str) -> u32 {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `missing_numbers`
[INFO] [stdout]  --> src/hackerrank/problem_solving/missing_numbers.rs:6:4
[INFO] [stdout]   |
[INFO] [stdout] 6 | fn missing_numbers(arr: &Vec<u32>, brr: &Vec<u32>) -> Vec<u32> {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `to_roman_numeral`
[INFO] [stdout]   --> src/hackerrank/problem_solving/number_converter.rs:29:8
[INFO] [stdout]    |
[INFO] [stdout] 29 | pub fn to_roman_numeral(number: u32) -> String {
[INFO] [stdout]    |        ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `find_pairs_to_target`
[INFO] [stdout]  --> src/hackerrank/problem_solving/pairs.rs:3:8
[INFO] [stdout]   |
[INFO] [stdout] 3 | pub fn find_pairs_to_target(input: Vec<u32>, target: u32) -> u32 {
[INFO] [stdout]   |        ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `pairs_boxed`
[INFO] [stdout]   --> src/hackerrank/problem_solving/pairs.rs:21:4
[INFO] [stdout]    |
[INFO] [stdout] 21 | fn pairs_boxed() -> Box<[u32; 2]> {
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `pairs_vec`
[INFO] [stdout]   --> src/hackerrank/problem_solving/pairs.rs:27:4
[INFO] [stdout]    |
[INFO] [stdout] 27 | fn pairs_vec() -> Vec<[u32; 2]> {
[INFO] [stdout]    |    ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `balanced_sums_count`
[INFO] [stdout]  --> src/hackerrank/problem_solving/sherlock_and_array.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn balanced_sums_count(arr: &Vec<u32>) -> &str {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `balanced_sums`
[INFO] [stdout]   --> src/hackerrank/problem_solving/sherlock_and_array.rs:13:4
[INFO] [stdout]    |
[INFO] [stdout] 13 | fn balanced_sums(arr: &Vec<u32>) -> &str {
[INFO] [stdout]    |    ^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `two_characters`
[INFO] [stdout]  --> src/hackerrank/problem_solving/two_characters.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn two_characters(input: &str) -> i32 {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `find_beautiful_number`
[INFO] [stdout]  --> src/hackerrank/problem_solving/separate_numbers.rs:3:4
[INFO] [stdout]   |
[INFO] [stdout] 3 | fn find_beautiful_number(input: &str) -> String {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `useful`
[INFO] [stdout]  --> src/hackerrank/utils.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 | pub fn useful() {
[INFO] [stdout]   |        ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `remove_newline`
[INFO] [stdout]   --> src/hackerrank/utils.rs:21:4
[INFO] [stdout]    |
[INFO] [stdout] 21 | fn remove_newline(line: &str) -> String {
[INFO] [stdout]    |    ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_lines`
[INFO] [stdout]   --> src/hackerrank/utils.rs:36:4
[INFO] [stdout]    |
[INFO] [stdout] 36 | fn read_lines() {
[INFO] [stdout]    |    ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_u8`
[INFO] [stdout]   --> src/hackerrank/utils.rs:47:4
[INFO] [stdout]    |
[INFO] [stdout] 47 | fn read_u8() {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_vec`
[INFO] [stdout]   --> src/hackerrank/utils.rs:59:8
[INFO] [stdout]    |
[INFO] [stdout] 59 | pub fn read_vec() -> Vec<String> {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `mask_character`
[INFO] [stdout]  --> src/rust_book/char_strings.rs:1:4
[INFO] [stdout]   |
[INFO] [stdout] 1 | fn mask_character(target: &str, input: &str) -> String {
[INFO] [stdout]   |    ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum is never used: `IpAddrKind`
[INFO] [stdout]  --> src/rust_book/defining_enums.rs:1:6
[INFO] [stdout]   |
[INFO] [stdout] 1 | enum IpAddrKind {
[INFO] [stdout]   |      ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `guess`
[INFO] [stdout]  --> src/rust_book/guessing_game.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 | pub fn guess() {
[INFO] [stdout]   |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `square`
[INFO] [stdout]   --> src/rust_book/rectangle.rs:13:8
[INFO] [stdout]    |
[INFO] [stdout] 13 |     fn square(d: i32) -> Rectangle {
[INFO] [stdout]    |        ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `area`
[INFO] [stdout]   --> src/rust_book/rectangle.rs:20:8
[INFO] [stdout]    |
[INFO] [stdout] 20 |     fn area(&self) -> i32 {
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `can_hold`
[INFO] [stdout]   --> src/rust_book/rectangle.rs:24:8
[INFO] [stdout]    |
[INFO] [stdout] 24 |     fn can_hold(&self, rectangle: &Rectangle) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `find_first_word`
[INFO] [stdout]  --> src/rust_book/slice.rs:8:8
[INFO] [stdout]   |
[INFO] [stdout] 8 | pub fn find_first_word(s: &str) -> &str {
[INFO] [stdout]   |        ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: irrefutable `if let` pattern
[INFO] [stdout]  --> src/rust_book/defining_enums.rs:9:8
[INFO] [stdout]   |
[INFO] [stdout] 9 |     if let IpAddrKind::V4(actual) = v4 {
[INFO] [stdout]   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(irrefutable_let_patterns)]` on by default
[INFO] [stdout]   = note: this pattern will always match, so the `if let` is useless
[INFO] [stdout]   = help: consider replacing the `if let` with a `let`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 45 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `n`
[INFO] [stdout]   --> src/hackerrank/utils.rs:50:9
[INFO] [stdout]    |
[INFO] [stdout] 50 |     let n: u8 = num.trim().parse().unwrap();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_n`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `useful`
[INFO] [stdout]  --> src/hackerrank/utils.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 | pub fn useful() {
[INFO] [stdout]   |        ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `remove_newline`
[INFO] [stdout]   --> src/hackerrank/utils.rs:21:4
[INFO] [stdout]    |
[INFO] [stdout] 21 | fn remove_newline(line: &str) -> String {
[INFO] [stdout]    |    ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_lines`
[INFO] [stdout]   --> src/hackerrank/utils.rs:36:4
[INFO] [stdout]    |
[INFO] [stdout] 36 | fn read_lines() {
[INFO] [stdout]    |    ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_u8`
[INFO] [stdout]   --> src/hackerrank/utils.rs:47:4
[INFO] [stdout]    |
[INFO] [stdout] 47 | fn read_u8() {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_vec`
[INFO] [stdout]   --> src/hackerrank/utils.rs:59:8
[INFO] [stdout]    |
[INFO] [stdout] 59 | pub fn read_vec() -> Vec<String> {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `guess`
[INFO] [stdout]  --> src/rust_book/guessing_game.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 | pub fn guess() {
[INFO] [stdout]   |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 10 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 20.84s
[INFO] running `Command { std: "docker" "inspect" "2f4b1e9d5c02562ffe229216a6f34ee62fdfe5cace67c85558ddc01455922667", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2f4b1e9d5c02562ffe229216a6f34ee62fdfe5cace67c85558ddc01455922667", kill_on_drop: false }`
[INFO] [stdout] 2f4b1e9d5c02562ffe229216a6f34ee62fdfe5cace67c85558ddc01455922667