[INFO] cloning repository https://github.com/zgblog/rust-study
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/zgblog/rust-study" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzgblog%2Frust-study", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzgblog%2Frust-study'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 979810785a1ae2349cfb7e0529b386adef18ccd9
[INFO] testing zgblog/rust-study against try#c2e32f1c9652b13ed99608599c1e855462f421f3 for pr-146098-7
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzgblog%2Frust-study" "/workspace/builds/worker-0-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/zgblog/rust-study
[INFO] finished tweaking git repo https://github.com/zgblog/rust-study
[INFO] tweaked toml for git repo https://github.com/zgblog/rust-study written to /workspace/builds/worker-0-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/zgblog/rust-study on toolchain c2e32f1c9652b13ed99608599c1e855462f421f3
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c2e32f1c9652b13ed99608599c1e855462f421f3" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/zgblog/rust-study 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" "+c2e32f1c9652b13ed99608599c1e855462f421f3" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+c2e32f1c9652b13ed99608599c1e855462f421f3" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 6f1de6104c2f1dc30726ab485f6021b165639bd4d2fad3d3977c8e1de5b46edd
[INFO] running `Command { std: "docker" "start" "-a" "6f1de6104c2f1dc30726ab485f6021b165639bd4d2fad3d3977c8e1de5b46edd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "6f1de6104c2f1dc30726ab485f6021b165639bd4d2fad3d3977c8e1de5b46edd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6f1de6104c2f1dc30726ab485f6021b165639bd4d2fad3d3977c8e1de5b46edd", kill_on_drop: false }`
[INFO] [stdout] 6f1de6104c2f1dc30726ab485f6021b165639bd4d2fad3d3977c8e1de5b46edd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+c2e32f1c9652b13ed99608599c1e855462f421f3" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 0aacbb8f13e6bfcd3350d35ee50db44f9a11c381f36ad87acdd7bb7cd83e62f2
[INFO] running `Command { std: "docker" "start" "-a" "0aacbb8f13e6bfcd3350d35ee50db44f9a11c381f36ad87acdd7bb7cd83e62f2", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.155
[INFO] [stderr]    Compiling getrandom v0.2.15
[INFO] [stderr]    Compiling rand_core v0.6.4
[INFO] [stderr]    Compiling rand_chacha v0.3.1
[INFO] [stderr]    Compiling rand v0.8.5
[INFO] [stderr]    Compiling study v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: field `seasonal_fruit` is never read
[INFO] [stdout]  --> src/lib.rs:4:9
[INFO] [stdout]   |
[INFO] [stdout] 2 |     pub struct Breakfast{
[INFO] [stdout]   |                --------- field in this struct
[INFO] [stdout] 3 |         pub toast: String,
[INFO] [stdout] 4 |         seasonal_fruit: String
[INFO] [stdout]   |         ^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Appetizer` is never used
[INFO] [stdout]   --> src/lib.rs:16:14
[INFO] [stdout]    |
[INFO] [stdout] 16 |     pub enum Appetizer {}
[INFO] [stdout]    |              ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `seat_at_table` is never used
[INFO] [stdout]   --> src/lib.rs:23:12
[INFO] [stdout]    |
[INFO] [stdout] 23 |         fn seat_at_table() {}
[INFO] [stdout]    |            ^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `take_order` is never used
[INFO] [stdout]   --> src/lib.rs:27:12
[INFO] [stdout]    |
[INFO] [stdout] 27 |         fn take_order() {}
[INFO] [stdout]    |            ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `take_payment` is never used
[INFO] [stdout]   --> src/lib.rs:29:12
[INFO] [stdout]    |
[INFO] [stdout] 29 |         fn take_payment() {}
[INFO] [stdout]    |            ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `todo` is never used
[INFO] [stdout]  --> src/back_of_house/hosting.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn todo() {}
[INFO] [stdout]   |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0615]: attempted to take value of method `len` on type `&'a str`
[INFO] [stdout]   --> src/bin/generics/lifetime_test.rs:58:20
[INFO] [stdout]    |
[INFO] [stdout] 58 |     if x.len() > y.len {
[INFO] [stdout]    |                    ^^^ method, not a field
[INFO] [stdout]    |
[INFO] [stdout] help: use parentheses to call the method
[INFO] [stdout]    |
[INFO] [stdout] 58 |     if x.len() > y.len() {
[INFO] [stdout]    |                       ++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> src/bin/collect/string_test.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 9 |     let mut s = String::new();
[INFO] [stdout]   |         ----^
[INFO] [stdout]   |         |
[INFO] [stdout]   |         help: remove this `mut`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]  --> src/bin/collect/string_test.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 9 |     let mut s = String::new();
[INFO] [stdout]   |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let s = data.to_string();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let s = "initial contents".to_string();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let s = String::from("initial contents");
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:20:9
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let hello = String::from("السلام عليكم");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:21:9
[INFO] [stdout]    |
[INFO] [stdout] 21 |     let hello = String::from("Dobrý den");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:22:9
[INFO] [stdout]    |
[INFO] [stdout] 22 |     let hello = String::from("Hello");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:23:9
[INFO] [stdout]    |
[INFO] [stdout] 23 |     let hello = String::from("שָׁלוֹם");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:24:9
[INFO] [stdout]    |
[INFO] [stdout] 24 |     let hello = String::from("नमस्ते");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:25:9
[INFO] [stdout]    |
[INFO] [stdout] 25 |     let hello = String::from("こんにちは");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:26:9
[INFO] [stdout]    |
[INFO] [stdout] 26 |     let hello = String::from("안녕하세요");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let hello = String::from("你好");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:28:9
[INFO] [stdout]    |
[INFO] [stdout] 28 |     let hello = String::from("Olá");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:29:9
[INFO] [stdout]    |
[INFO] [stdout] 29 |     let hello = String::from("Здравствуйте");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]   --> src/bin/collect/string_test.rs:30:9
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let hello = String::from("Hola");
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0308]: mismatched types
[INFO] [stdout]   --> src/bin/generics/lifetime_test.rs:59:9
[INFO] [stdout]    |
[INFO] [stdout] 56 | fn longest_with_an_announcement<'a, T> (x: &'a str, y: &'a str, ann: T) where T: Display {
[INFO] [stdout]    |                                                                        - help: try adding a return type: `-> &'a str`
[INFO] [stdout] ...
[INFO] [stdout] 59 |         x
[INFO] [stdout]    |         ^ expected `()`, found `&str`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `scores`
[INFO] [stdout]   --> src/bin/collect/map_test.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let scores: HashMap<_, _> = teams.iter().zip(init_scores.iter()).collect();
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_scores`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `study` (bin "lifetime") due to 3 previous errors; 1 warning emitted
[INFO] [stdout] error[E0308]: mismatched types
[INFO] [stdout]   --> src/bin/generics/lifetime_test.rs:61:9
[INFO] [stdout]    |
[INFO] [stdout] 56 | fn longest_with_an_announcement<'a, T> (x: &'a str, y: &'a str, ann: T) where T: Display {
[INFO] [stdout]    |                                                                        - help: try adding a return type: `-> &'a str`
[INFO] [stdout] ...
[INFO] [stdout] 61 |         y
[INFO] [stdout]    |         ^ expected `()`, found `&str`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] warning: unused variable: `i`
[INFO] [stdout]   --> src/bin/generics/lifetime_test.rs:53:9
[INFO] [stdout]    |
[INFO] [stdout] 53 |     let i = ImportantExcerpt {part: first_sentence};
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_i`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0308, E0615.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0308`.
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]  --> src/bin/error/result_test.rs:7:9
[INFO] [stdout]   |
[INFO] [stdout] 7 |     let f = match f {
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around `if` condition
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:90:11
[INFO] [stdout]    |
[INFO] [stdout] 90 |         if(self.x >= self.y) {
[INFO] [stdout]    |           ^                ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_parens)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 90 -         if(self.x >= self.y) {
[INFO] [stdout] 90 +         if self.x >= self.y  {
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/bin/error/result_test.rs:22:9
[INFO] [stdout]    |
[INFO] [stdout] 22 |     let f = File::open("hello.txt").unwrap_or_else(|error| {
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/bin/error/result_test.rs:35:9
[INFO] [stdout]    |
[INFO] [stdout] 35 |     let f = File::open("hello.txt").unwrap();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/bin/error/result_test.rs:40:9
[INFO] [stdout]    |
[INFO] [stdout] 40 |     let f = File::open("hello.txt").expect("Failed to open hello.txt");
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `p3`
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:12:9
[INFO] [stdout]    |
[INFO] [stdout] 12 |     let p3 = p1.mixup(p2);
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_p3`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `largest_i32` is never used
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:16:4
[INFO] [stdout]    |
[INFO] [stdout] 16 | fn largest_i32(list: &[i32]) -> i32 {
[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 `largest_char` is never used
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:26:4
[INFO] [stdout]    |
[INFO] [stdout] 26 | fn largest_char(list: &[char]) -> char {
[INFO] [stdout]    |    ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `x` is never used
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:58:8
[INFO] [stdout]    |
[INFO] [stdout] 57 | impl<T, U> Point<T, U> {
[INFO] [stdout]    | ---------------------- method in this implementation
[INFO] [stdout] 58 |     fn x(&self) -> &T {
[INFO] [stdout]    |        ^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Pair` is never constructed
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:75:8
[INFO] [stdout]    |
[INFO] [stdout] 75 | struct Pair<T> {
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new` is never used
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:81:8
[INFO] [stdout]    |
[INFO] [stdout] 80 | impl<T> Pair<T> {
[INFO] [stdout]    | --------------- associated function in this implementation
[INFO] [stdout] 81 |     fn new(x: T, y: T) -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `cmp_display` is never used
[INFO] [stdout]   --> src/bin/generics/gen_test.rs:89:8
[INFO] [stdout]    |
[INFO] [stdout] 88 | impl<T: Display + PartialOrd> Pair<T> {
[INFO] [stdout]    | ------------------------------------- method in this implementation
[INFO] [stdout] 89 |     fn cmp_display(&self) {
[INFO] [stdout]    |        ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `result_2` is never used
[INFO] [stdout]   --> src/bin/error/result_test.rs:20:4
[INFO] [stdout]    |
[INFO] [stdout] 20 | fn result_2() {
[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 `result_3` is never used
[INFO] [stdout]   --> src/bin/error/result_test.rs:33:4
[INFO] [stdout]    |
[INFO] [stdout] 33 | fn result_3() {
[INFO] [stdout]    |    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `result_4` is never used
[INFO] [stdout]   --> src/bin/error/result_test.rs:38:4
[INFO] [stdout]    |
[INFO] [stdout] 38 | fn result_4() {
[INFO] [stdout]    |    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `result_5` is never used
[INFO] [stdout]   --> src/bin/error/result_test.rs:46:4
[INFO] [stdout]    |
[INFO] [stdout] 46 | fn result_5() -> Result<String, io::Error> {
[INFO] [stdout]    |    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `result_6` is never used
[INFO] [stdout]   --> src/bin/error/result_test.rs:64:4
[INFO] [stdout]    |
[INFO] [stdout] 64 | fn result_6() -> Result<String, io::Error> {
[INFO] [stdout]    |    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> src/bin/slice.rs:2:9
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let mut s = String::from("Hello world!");
[INFO] [stdout]   |         ----^
[INFO] [stdout]   |         |
[INFO] [stdout]   |         help: remove this `mut`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `hello`
[INFO] [stdout]  --> src/bin/slice.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 9 |     let hello = &s[..5];
[INFO] [stdout]   |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_hello`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `world`
[INFO] [stdout]   --> src/bin/slice.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let world = &s[6..];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_world`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `whold`
[INFO] [stdout]   --> src/bin/slice.rs:12:9
[INFO] [stdout]    |
[INFO] [stdout] 12 |     let whold = &s[..];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_whold`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `slice`
[INFO] [stdout]   --> src/bin/slice.rs:37:9
[INFO] [stdout]    |
[INFO] [stdout] 37 |     let slice = &a[1..3];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_slice`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `first_world2` is never used
[INFO] [stdout]   --> src/bin/slice.rs:25:4
[INFO] [stdout]    |
[INFO] [stdout] 25 | fn first_world2(s: &str) -> &str {  // 字符串切片作为函数参数
[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 `array_slice` is never used
[INFO] [stdout]   --> src/bin/slice.rs:35:4
[INFO] [stdout]    |
[INFO] [stdout] 35 | fn array_slice() {
[INFO] [stdout]    |    ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::fmt::Result`
[INFO] [stdout]  --> src/main.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::fmt::Result;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io::Result as IoResult`
[INFO] [stdout]  --> src/main.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::io::Result as IoResult;    // as 关键字，起别名
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `cmp::Ordering` and `io::Empty`
[INFO] [stdout]  --> src/main.rs:4:11
[INFO] [stdout]   |
[INFO] [stdout] 4 | use std::{cmp::Ordering, io::Empty};   // {,}
[INFO] [stdout]   |           ^^^^^^^^^^^^^  ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `Write` and `self`
[INFO] [stdout]  --> src/main.rs:5:15
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::io::{self, Write}; // {自身 , }
[INFO] [stdout]   |               ^^^^  ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::collections::*`
[INFO] [stdout]  --> src/main.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use std::collections::*;    // 通配符
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s1`
[INFO] [stdout]   --> src/bin/owner.rs:22:9
[INFO] [stdout]    |
[INFO] [stdout] 22 |     let s1 = gives_ownership(); // 从函数结果中获取返回所有权
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s1`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s3`
[INFO] [stdout]   --> src/bin/owner.rs:25:9
[INFO] [stdout]    |
[INFO] [stdout] 25 |     let s3 = takes_and_gives_back(s2);
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `calculate_length` is never used
[INFO] [stdout]   --> src/bin/owner.rs:60:4
[INFO] [stdout]    |
[INFO] [stdout] 60 | fn calculate_length(s: String) -> (String, usize) {
[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: `user1`
[INFO] [stdout]   --> src/bin/struct_test.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let user1 = User {
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_user1`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `Alabama` is never constructed
[INFO] [stdout]  --> src/bin/match_test.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | enum UsState {
[INFO] [stdout]   |      ------- variant in this enum
[INFO] [stdout] 3 |     Alabama,
[INFO] [stdout]   |     ^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `UsState` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Penny`, `Nickel`, and `Dime` are never constructed
[INFO] [stdout]  --> src/bin/match_test.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | enum Coin {
[INFO] [stdout]   |      ---- variants in this enum
[INFO] [stdout] 7 |     Penny,
[INFO] [stdout]   |     ^^^^^
[INFO] [stdout] 8 |     Nickel,
[INFO] [stdout]   |     ^^^^^^
[INFO] [stdout] 9 |     Dime,
[INFO] [stdout]   |     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `w`
[INFO] [stdout]   --> src/bin/struct_test.rs:41:9
[INFO] [stdout]    |
[INFO] [stdout] 41 |     let w = 30;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_w`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `l`
[INFO] [stdout]   --> src/bin/struct_test.rs:42:9
[INFO] [stdout]    |
[INFO] [stdout] 42 |     let l = 50;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_l`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/struct_test.rs:53:9
[INFO] [stdout]    |
[INFO] [stdout] 53 |     let a = Rectangle::square(32);
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `username`, `email`, `sign_in_count`, and `active` are never read
[INFO] [stdout]  --> src/bin/struct_test.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | struct User {
[INFO] [stdout]   |        ---- fields in this struct
[INFO] [stdout] 2 |     username: String,
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout] 3 |     email: String,
[INFO] [stdout]   |     ^^^^^
[INFO] [stdout] 4 |     sign_in_count: u64,
[INFO] [stdout]   |     ^^^^^^^^^^^^^
[INFO] [stdout] 5 |     active: bool
[INFO] [stdout]   |     ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `can_hold` is never used
[INFO] [stdout]   --> src/bin/struct_test.rs:17:8
[INFO] [stdout]    |
[INFO] [stdout] 13 | impl Rectangle {
[INFO] [stdout]    | -------------- method in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 17 |     fn can_hold(&self, other: &Rectangle) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Color` is never constructed
[INFO] [stdout]   --> src/bin/struct_test.rs:29:8
[INFO] [stdout]    |
[INFO] [stdout] 29 | struct Color(i32, i32, i32);    // tuple struct
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `build_user` is never used
[INFO] [stdout]   --> src/bin/struct_test.rs:58:4
[INFO] [stdout]    |
[INFO] [stdout] 58 | fn build_user(email: String, username: String) -> User {
[INFO] [stdout]    |    ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `update` is never used
[INFO] [stdout]   --> src/bin/struct_test.rs:67:4
[INFO] [stdout]    |
[INFO] [stdout] 67 | fn update(user: User) -> User {
[INFO] [stdout]    |    ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `area` is never used
[INFO] [stdout]   --> src/bin/struct_test.rs:75:4
[INFO] [stdout]    |
[INFO] [stdout] 75 | fn area(width: u32, length: u32) -> u32 {
[INFO] [stdout]    |    ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `area2` is never used
[INFO] [stdout]   --> src/bin/struct_test.rs:79:4
[INFO] [stdout]    |
[INFO] [stdout] 79 | fn area2(dim: &Rectangle) -> u32 {
[INFO] [stdout]    |    ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/bin/smartpointer/mem_leak.rs:7:10
[INFO] [stdout]   |
[INFO] [stdout] 7 |     Cons(i32, RefCell<Rc<List>>),
[INFO] [stdout]   |     ---- ^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `List` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 7 -     Cons(i32, RefCell<Rc<List>>),
[INFO] [stdout] 7 +     Cons((), RefCell<Rc<List>>),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `value` and `children` are never read
[INFO] [stdout]   --> src/bin/smartpointer/mem_leak.rs:47:5
[INFO] [stdout]    |
[INFO] [stdout] 46 | struct Node {
[INFO] [stdout]    |        ---- fields in this struct
[INFO] [stdout] 47 |     value: i32,
[INFO] [stdout]    |     ^^^^^
[INFO] [stdout] 48 |     children: RefCell<Vec<Rc<Node>>>,
[INFO] [stdout]    |     ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Node` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "0aacbb8f13e6bfcd3350d35ee50db44f9a11c381f36ad87acdd7bb7cd83e62f2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0aacbb8f13e6bfcd3350d35ee50db44f9a11c381f36ad87acdd7bb7cd83e62f2", kill_on_drop: false }`
[INFO] [stdout] 0aacbb8f13e6bfcd3350d35ee50db44f9a11c381f36ad87acdd7bb7cd83e62f2