[INFO] cloning repository https://github.com/elderhammer/rust-by-example
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/elderhammer/rust-by-example" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felderhammer%2Frust-by-example", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felderhammer%2Frust-by-example'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 9e957cb35410683879987ffa9a1c47ad03f8f7cb
[INFO] checking elderhammer/rust-by-example against master#a42d94ebb883116f2867cbe3016d9bde9ca6d3f7 for pr-117593
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felderhammer%2Frust-by-example" "/workspace/builds/worker-1-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/elderhammer/rust-by-example on toolchain a42d94ebb883116f2867cbe3016d9bde9ca6d3f7
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+a42d94ebb883116f2867cbe3016d9bde9ca6d3f7" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/elderhammer/rust-by-example
[INFO] finished tweaking git repo https://github.com/elderhammer/rust-by-example
[INFO] tweaked toml for git repo https://github.com/elderhammer/rust-by-example written to /workspace/builds/worker-1-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/elderhammer/rust-by-example 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" "+a42d94ebb883116f2867cbe3016d9bde9ca6d3f7" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[ERROR] this task or one of its parent failed!
[ERROR] no output for 300 seconds
[ERROR] note: run with `RUST_BACKTRACE=1` to display a backtrace.
[INFO] checking elderhammer/rust-by-example against try#031b389f0c31c0f91c9464d26313ae513dbe8d36 for pr-117593
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felderhammer%2Frust-by-example" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/elderhammer/rust-by-example on toolchain 031b389f0c31c0f91c9464d26313ae513dbe8d36
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+031b389f0c31c0f91c9464d26313ae513dbe8d36" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/elderhammer/rust-by-example
[INFO] finished tweaking git repo https://github.com/elderhammer/rust-by-example
[INFO] tweaked toml for git repo https://github.com/elderhammer/rust-by-example written to /workspace/builds/worker-1-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/elderhammer/rust-by-example 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" "+031b389f0c31c0f91c9464d26313ae513dbe8d36" "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
[ERROR] error running command: no output for 300 seconds
[INFO] checking elderhammer/rust-by-example against try#031b389f0c31c0f91c9464d26313ae513dbe8d36 for pr-117593
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Felderhammer%2Frust-by-example" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/elderhammer/rust-by-example on toolchain 031b389f0c31c0f91c9464d26313ae513dbe8d36
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+031b389f0c31c0f91c9464d26313ae513dbe8d36" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/elderhammer/rust-by-example
[INFO] finished tweaking git repo https://github.com/elderhammer/rust-by-example
[INFO] tweaked toml for git repo https://github.com/elderhammer/rust-by-example written to /workspace/builds/worker-1-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/elderhammer/rust-by-example 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" "+031b389f0c31c0f91c9464d26313ae513dbe8d36" "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-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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@sha256:0c7e0e8312ad82a1bed3696438480b7da990d348377d3754e1cd95b06a8a36c7" "/opt/rustwide/cargo-home/bin/cargo" "+031b389f0c31c0f91c9464d26313ae513dbe8d36" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 702d2498ac0049be68c93207aaf50eb2841e4d92a902e8e262082acfc6e35d05
[INFO] running `Command { std: "docker" "start" "-a" "702d2498ac0049be68c93207aaf50eb2841e4d92a902e8e262082acfc6e35d05", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "702d2498ac0049be68c93207aaf50eb2841e4d92a902e8e262082acfc6e35d05", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "702d2498ac0049be68c93207aaf50eb2841e4d92a902e8e262082acfc6e35d05", kill_on_drop: false }`
[INFO] [stdout] 702d2498ac0049be68c93207aaf50eb2841e4d92a902e8e262082acfc6e35d05
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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@sha256:0c7e0e8312ad82a1bed3696438480b7da990d348377d3754e1cd95b06a8a36c7" "/opt/rustwide/cargo-home/bin/cargo" "+031b389f0c31c0f91c9464d26313ae513dbe8d36" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 768f2b672652fdbc4265812d9a92356f0a098e55364b80860f39f0264e2a6593
[INFO] running `Command { std: "docker" "start" "-a" "768f2b672652fdbc4265812d9a92356f0a098e55364b80860f39f0264e2a6593", kill_on_drop: false }`
[INFO] [stderr]     Checking rust-by-example v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused label
[INFO] [stdout]   --> src/bin/flow_of_control.rs:77:13
[INFO] [stdout]    |
[INFO] [stdout] 77 |             'inner: loop {
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_labels)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused label
[INFO] [stdout]   --> src/bin/flow_of_control.rs:77:13
[INFO] [stdout]    |
[INFO] [stdout] 77 |             'inner: loop {
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_labels)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `reverse` is never used
[INFO] [stdout]   --> src/bin/primitives.rs:43:8
[INFO] [stdout]    |
[INFO] [stdout] 43 |     fn reverse(pair: (i32, bool)) -> (bool, i32) {
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `square`
[INFO] [stdout]   --> src/bin/custom_types.rs:87:13
[INFO] [stdout]    |
[INFO] [stdout] 87 |         let square = square(point, edge);
[INFO] [stdout]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_square`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dec`
[INFO] [stdout]    --> src/bin/functions.rs:188:17
[INFO] [stdout]     |
[INFO] [stdout] 188 |         let mut dec = || {
[INFO] [stdout]     |                 ^^^ help: if this is intentional, prefix it with an underscore: `_dec`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/bin/functions.rs:188:13
[INFO] [stdout]     |
[INFO] [stdout] 188 |         let mut dec = || {
[INFO] [stdout]     |             ----^^^
[INFO] [stdout]     |             |
[INFO] [stdout]     |             help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/bin/functions.rs:258:13
[INFO] [stdout]     |
[INFO] [stdout] 258 |         let mut count = 1;
[INFO] [stdout]     |             ----^^^^^
[INFO] [stdout]     |             |
[INFO] [stdout]     |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `arr1`
[INFO] [stdout]    --> src/bin/functions.rs:351:17
[INFO] [stdout]     |
[INFO] [stdout] 351 |             let arr1 = [1, 2, 3];
[INFO] [stdout]     |                 ^^^^ help: if this is intentional, prefix it with an underscore: `_arr1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `arr2`
[INFO] [stdout]    --> src/bin/functions.rs:352:17
[INFO] [stdout]     |
[INFO] [stdout] 352 |             let arr2 = [4, 5, 6];
[INFO] [stdout]     |                 ^^^^ help: if this is intentional, prefix it with an underscore: `_arr2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `print`
[INFO] [stdout]    --> src/bin/functions.rs:367:17
[INFO] [stdout]     |
[INFO] [stdout] 367 |             let print = || {
[INFO] [stdout]     |                 ^^^^^ help: if this is intentional, prefix it with an underscore: `_print`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `bar`
[INFO] [stdout]    --> src/bin/functions.rs:371:21
[INFO] [stdout]     |
[INFO] [stdout] 371 |             let mut bar = || {
[INFO] [stdout]     |                     ^^^ help: if this is intentional, prefix it with an underscore: `_bar`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `nothing`
[INFO] [stdout]   --> src/bin/error_handling.rs:51:9
[INFO] [stdout]    |
[INFO] [stdout] 51 |     let nothing: Option<&str> = None;
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_nothing`
[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/bin/functions.rs:371:17
[INFO] [stdout]     |
[INFO] [stdout] 371 |             let mut bar = || {
[INFO] [stdout]     |                 ----^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing
[INFO] [stdout]    --> src/bin/functions.rs:261:13
[INFO] [stdout]     |
[INFO] [stdout] 261 |             mem::drop(count);
[INFO] [stdout]     |             ^^^^^^^^^^-----^
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       argument has type `i32`
[INFO] [stdout]     |
[INFO] [stdout]     = note: use `let _ = ...` to ignore the expression or result
[INFO] [stdout]     = note: `#[warn(dropping_copy_types)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing
[INFO] [stdout]    --> src/bin/functions.rs:262:13
[INFO] [stdout]     |
[INFO] [stdout] 262 |             mem::drop(x);
[INFO] [stdout]     |             ^^^^^^^^^^-^
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       argument has type `i32`
[INFO] [stdout]     |
[INFO] [stdout]     = note: use `let _ = ...` to ignore the expression or result
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 10 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `apple`
[INFO] [stdout]    --> src/bin/error_handling.rs:254:13
[INFO] [stdout]     |
[INFO] [stdout] 254 |         let apple = Some(Fruit::Apple);
[INFO] [stdout]     |             ^^^^^ help: if this is intentional, prefix it with an underscore: `_apple`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `square`
[INFO] [stdout]   --> src/bin/custom_types.rs:87:13
[INFO] [stdout]    |
[INFO] [stdout] 87 |         let square = square(point, edge);
[INFO] [stdout]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_square`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `reverse` is never used
[INFO] [stdout]   --> src/bin/primitives.rs:43:8
[INFO] [stdout]    |
[INFO] [stdout] 43 |     fn reverse(pair: (i32, bool)) -> (bool, i32) {
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `number` is never read
[INFO] [stdout]   --> src/bin/error_handling.rs:93:13
[INFO] [stdout]    |
[INFO] [stdout] 91 |         struct PhoneNumber {
[INFO] [stdout]    |                ----------- field in this struct
[INFO] [stdout] 92 |             area_code: Option<u8>,
[INFO] [stdout] 93 |             number: u32,
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `PhoneNumber` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `Potato` is never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:123:53
[INFO] [stdout]     |
[INFO] [stdout] 123 |         #[derive(Debug)] enum Food { Apple, Carrot, Potato }
[INFO] [stdout]     |                               ----                  ^^^^^^
[INFO] [stdout]     |                               |
[INFO] [stdout]     |                               variant in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Food` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `cookable_v1` is never used
[INFO] [stdout]    --> src/bin/error_handling.rs:201:12
[INFO] [stdout]     |
[INFO] [stdout] 201 |         fn cookable_v1(food: Food) -> Option<Food> {
[INFO] [stdout]     |            ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Banana`, `Kiwi`, and `Lemon` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:235:37
[INFO] [stdout]     |
[INFO] [stdout] 235 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----                  ^^^^^^  ^^^^  ^^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Orange` and `Banana` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:252:29
[INFO] [stdout]     |
[INFO] [stdout] 252 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----          ^^^^^^  ^^^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Orange`, `Banana`, `Kiwi`, and `Lemon` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:282:29
[INFO] [stdout]     |
[INFO] [stdout] 282 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----          ^^^^^^  ^^^^^^  ^^^^  ^^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Apple`, `Orange`, `Banana`, and `Kiwi` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:298:22
[INFO] [stdout]     |
[INFO] [stdout] 298 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----   ^^^^^  ^^^^^^  ^^^^^^  ^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 9 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:35:9
[INFO] [stdout]    |
[INFO] [stdout] 35 |     let b = a;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `name`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:71:22
[INFO] [stdout]    |
[INFO] [stdout] 71 |         let Person { name, ref age } = person;
[INFO] [stdout]    |                      ^^^^ help: try ignoring the field: `name: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `age`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:71:28
[INFO] [stdout]    |
[INFO] [stdout] 71 |         let Person { name, ref age } = person;
[INFO] [stdout]    |                            ^^^^^^^ help: try ignoring the field: `age: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:89:13
[INFO] [stdout]    |
[INFO] [stdout] 89 |         let a = what(&foo);
[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/bin/scoping_rules.rs:101:13
[INFO] [stdout]     |
[INFO] [stdout] 101 |         let mut name = (
[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: function `get_first` is never used
[INFO] [stdout]   --> src/bin/scoping_rules.rs:97:12
[INFO] [stdout]    |
[INFO] [stdout] 97 |         fn get_first(name: &(Box<i32>, Box<i32>, String)) -> &Box<i32> {
[INFO] [stdout]    |            ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `author` is never read
[INFO] [stdout]    --> src/bin/scoping_rules.rs:157:13
[INFO] [stdout]     |
[INFO] [stdout] 156 |         struct Book {
[INFO] [stdout]     |                ---- field in this struct
[INFO] [stdout] 157 |             author: &'static str,
[INFO] [stdout]     |             ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Book` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `dec`
[INFO] [stdout]    --> src/bin/functions.rs:188:17
[INFO] [stdout]     |
[INFO] [stdout] 188 |         let mut dec = || {
[INFO] [stdout]     |                 ^^^ help: if this is intentional, prefix it with an underscore: `_dec`
[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/bin/functions.rs:188:13
[INFO] [stdout]     |
[INFO] [stdout] 188 |         let mut dec = || {
[INFO] [stdout]     |             ----^^^
[INFO] [stdout]     |             |
[INFO] [stdout]     |             help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/bin/functions.rs:258:13
[INFO] [stdout]     |
[INFO] [stdout] 258 |         let mut count = 1;
[INFO] [stdout]     |             ----^^^^^
[INFO] [stdout]     |             |
[INFO] [stdout]     |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `arr1`
[INFO] [stdout]    --> src/bin/functions.rs:351:17
[INFO] [stdout]     |
[INFO] [stdout] 351 |             let arr1 = [1, 2, 3];
[INFO] [stdout]     |                 ^^^^ help: if this is intentional, prefix it with an underscore: `_arr1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `arr2`
[INFO] [stdout]    --> src/bin/functions.rs:352:17
[INFO] [stdout]     |
[INFO] [stdout] 352 |             let arr2 = [4, 5, 6];
[INFO] [stdout]     |                 ^^^^ help: if this is intentional, prefix it with an underscore: `_arr2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `print`
[INFO] [stdout]    --> src/bin/functions.rs:367:17
[INFO] [stdout]     |
[INFO] [stdout] 367 |             let print = || {
[INFO] [stdout]     |                 ^^^^^ help: if this is intentional, prefix it with an underscore: `_print`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `bar`
[INFO] [stdout]    --> src/bin/functions.rs:371:21
[INFO] [stdout]     |
[INFO] [stdout] 371 |             let mut bar = || {
[INFO] [stdout]     |                     ^^^ help: if this is intentional, prefix it with an underscore: `_bar`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:35:9
[INFO] [stdout]    |
[INFO] [stdout] 35 |     let b = a;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `name`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:71:22
[INFO] [stdout]    |
[INFO] [stdout] 71 |         let Person { name, ref age } = person;
[INFO] [stdout]    |                      ^^^^ help: try ignoring the field: `name: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `age`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:71:28
[INFO] [stdout]    |
[INFO] [stdout] 71 |         let Person { name, ref age } = person;
[INFO] [stdout]    |                            ^^^^^^^ help: try ignoring the field: `age: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/scoping_rules.rs:89:13
[INFO] [stdout]    |
[INFO] [stdout] 89 |         let a = what(&foo);
[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/bin/scoping_rules.rs:101:13
[INFO] [stdout]     |
[INFO] [stdout] 101 |         let mut name = (
[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: function `get_first` is never used
[INFO] [stdout]   --> src/bin/scoping_rules.rs:97:12
[INFO] [stdout]    |
[INFO] [stdout] 97 |         fn get_first(name: &(Box<i32>, Box<i32>, String)) -> &Box<i32> {
[INFO] [stdout]    |            ^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `author` is never read
[INFO] [stdout]    --> src/bin/scoping_rules.rs:157:13
[INFO] [stdout]     |
[INFO] [stdout] 156 |         struct Book {
[INFO] [stdout]     |                ---- field in this struct
[INFO] [stdout] 157 |             author: &'static str,
[INFO] [stdout]     |             ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Book` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/bin/functions.rs:371:17
[INFO] [stdout]     |
[INFO] [stdout] 371 |             let mut bar = || {
[INFO] [stdout]     |                 ----^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing
[INFO] [stdout]    --> src/bin/functions.rs:261:13
[INFO] [stdout]     |
[INFO] [stdout] 261 |             mem::drop(count);
[INFO] [stdout]     |             ^^^^^^^^^^-----^
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       argument has type `i32`
[INFO] [stdout]     |
[INFO] [stdout]     = note: use `let _ = ...` to ignore the expression or result
[INFO] [stdout]     = note: `#[warn(dropping_copy_types)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing
[INFO] [stdout]    --> src/bin/functions.rs:262:13
[INFO] [stdout]     |
[INFO] [stdout] 262 |             mem::drop(x);
[INFO] [stdout]     |             ^^^^^^^^^^-^
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       argument has type `i32`
[INFO] [stdout]     |
[INFO] [stdout]     = note: use `let _ = ...` to ignore the expression or result
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 10 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `nothing`
[INFO] [stdout]   --> src/bin/error_handling.rs:51:9
[INFO] [stdout]    |
[INFO] [stdout] 51 |     let nothing: Option<&str> = None;
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_nothing`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `apple`
[INFO] [stdout]    --> src/bin/error_handling.rs:254:13
[INFO] [stdout]     |
[INFO] [stdout] 254 |         let apple = Some(Fruit::Apple);
[INFO] [stdout]     |             ^^^^^ help: if this is intentional, prefix it with an underscore: `_apple`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `number` is never read
[INFO] [stdout]   --> src/bin/error_handling.rs:93:13
[INFO] [stdout]    |
[INFO] [stdout] 91 |         struct PhoneNumber {
[INFO] [stdout]    |                ----------- field in this struct
[INFO] [stdout] 92 |             area_code: Option<u8>,
[INFO] [stdout] 93 |             number: u32,
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `PhoneNumber` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `Potato` is never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:123:53
[INFO] [stdout]     |
[INFO] [stdout] 123 |         #[derive(Debug)] enum Food { Apple, Carrot, Potato }
[INFO] [stdout]     |                               ----                  ^^^^^^
[INFO] [stdout]     |                               |
[INFO] [stdout]     |                               variant in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Food` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `cookable_v1` is never used
[INFO] [stdout]    --> src/bin/error_handling.rs:201:12
[INFO] [stdout]     |
[INFO] [stdout] 201 |         fn cookable_v1(food: Food) -> Option<Food> {
[INFO] [stdout]     |            ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Banana`, `Kiwi`, and `Lemon` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:235:37
[INFO] [stdout]     |
[INFO] [stdout] 235 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----                  ^^^^^^  ^^^^  ^^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Orange` and `Banana` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:252:29
[INFO] [stdout]     |
[INFO] [stdout] 252 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----          ^^^^^^  ^^^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Orange`, `Banana`, `Kiwi`, and `Lemon` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:282:29
[INFO] [stdout]     |
[INFO] [stdout] 282 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----          ^^^^^^  ^^^^^^  ^^^^  ^^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Apple`, `Orange`, `Banana`, and `Kiwi` are never constructed
[INFO] [stdout]    --> src/bin/error_handling.rs:298:22
[INFO] [stdout]     |
[INFO] [stdout] 298 |         enum Fruit { Apple, Orange, Banana, Kiwi, Lemon }
[INFO] [stdout]     |              -----   ^^^^^  ^^^^^^  ^^^^^^  ^^^^
[INFO] [stdout]     |              |
[INFO] [stdout]     |              variants in this enum
[INFO] [stdout]     |
[INFO] [stdout]     = note: `Fruit` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 9 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.53s
[INFO] running `Command { std: "docker" "inspect" "768f2b672652fdbc4265812d9a92356f0a098e55364b80860f39f0264e2a6593", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "768f2b672652fdbc4265812d9a92356f0a098e55364b80860f39f0264e2a6593", kill_on_drop: false }`
[INFO] [stdout] 768f2b672652fdbc4265812d9a92356f0a098e55364b80860f39f0264e2a6593