[INFO] cloning repository https://github.com/mufenqwq/linkedlist
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/mufenqwq/linkedlist" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmufenqwq%2Flinkedlist", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmufenqwq%2Flinkedlist'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] b7ddb832292a8d6b3348bdbd03958e59fee6a590
[INFO] checking mufenqwq/linkedlist against try#48c9d93cf65d550d124c40108859fd993778c157 for pr-153692-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmufenqwq%2Flinkedlist" "/workspace/builds/worker-5-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/mufenqwq/linkedlist
[INFO] finished tweaking git repo https://github.com/mufenqwq/linkedlist
[INFO] tweaked toml for git repo https://github.com/mufenqwq/linkedlist written to /workspace/builds/worker-5-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/mufenqwq/linkedlist on toolchain 48c9d93cf65d550d124c40108859fd993778c157
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+48c9d93cf65d550d124c40108859fd993778c157" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/mufenqwq/linkedlist 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" "+48c9d93cf65d550d124c40108859fd993778c157" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+48c9d93cf65d550d124c40108859fd993778c157" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] d61176e833a520c728d9a1b9668ad12c38eebcbb1cfcd70fcab221928839652c
[INFO] running `Command { std: "docker" "start" "-a" "d61176e833a520c728d9a1b9668ad12c38eebcbb1cfcd70fcab221928839652c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d61176e833a520c728d9a1b9668ad12c38eebcbb1cfcd70fcab221928839652c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d61176e833a520c728d9a1b9668ad12c38eebcbb1cfcd70fcab221928839652c", kill_on_drop: false }`
[INFO] [stdout] d61176e833a520c728d9a1b9668ad12c38eebcbb1cfcd70fcab221928839652c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+48c9d93cf65d550d124c40108859fd993778c157" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f3fcf4fad8bc175252537626322a9e5ee0fff9f063d4d699a46b64af702fe037
[INFO] running `Command { std: "docker" "start" "-a" "f3fcf4fad8bc175252537626322a9e5ee0fff9f063d4d699a46b64af702fe037", kill_on_drop: false }`
[INFO] [stderr]     Checking linkelist v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: type `first::Node` is more private than the item `first::Link::More::0`
[INFO] [stdout]   --> src/first.rs:7:10
[INFO] [stdout]    |
[INFO] [stdout]  7 |     More(Box<Node>),
[INFO] [stdout]    |          ^^^^^^^^^ field `first::Link::More::0` is reachable at visibility `pub`
[INFO] [stdout]    |
[INFO] [stdout] note: but type `first::Node` is only usable at visibility `pub(self)`
[INFO] [stdout]   --> src/first.rs:11:1
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Node {
[INFO] [stdout]    | ^^^^^^^^^^^
[INFO] [stdout]    = note: `#[warn(private_interfaces)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> src/fourth.rs:95:23
[INFO] [stdout]    |
[INFO] [stdout] 95 |     pub fn peek_front(&self) -> Option<Ref<T>> {
[INFO] [stdout]    |                       ^^^^^            ^^^^^^ the same lifetime is hidden here
[INFO] [stdout]    |                       |
[INFO] [stdout]    |                       the lifetime is elided here
[INFO] [stdout]    |
[INFO] [stdout]    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout]    = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]    |
[INFO] [stdout] 95 |     pub fn peek_front(&self) -> Option<Ref<'_, T>> {
[INFO] [stdout]    |                                            +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/fourth.rs:102:27
[INFO] [stdout]     |
[INFO] [stdout] 102 |     pub fn peek_front_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |                           ^^^^^^^^^            ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                           |
[INFO] [stdout]     |                           the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 102 |     pub fn peek_front_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                       +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/fourth.rs:108:22
[INFO] [stdout]     |
[INFO] [stdout] 108 |     pub fn peek_back(&self) -> Option<Ref<T>> {
[INFO] [stdout]     |                      ^^^^^            ^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                      |
[INFO] [stdout]     |                      the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 108 |     pub fn peek_back(&self) -> Option<Ref<'_, T>> {
[INFO] [stdout]     |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/fourth.rs:114:26
[INFO] [stdout]     |
[INFO] [stdout] 114 |     pub fn peek_back_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |                          ^^^^^^^^^            ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                          |
[INFO] [stdout]     |                          the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 114 |     pub fn peek_back_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type `first::Node` is more private than the item `first::Link::More::0`
[INFO] [stdout]   --> src/first.rs:7:10
[INFO] [stdout]    |
[INFO] [stdout]  7 |     More(Box<Node>),
[INFO] [stdout]    |          ^^^^^^^^^ field `first::Link::More::0` is reachable at visibility `pub`
[INFO] [stdout]    |
[INFO] [stdout] note: but type `first::Node` is only usable at visibility `pub(self)`
[INFO] [stdout]   --> src/first.rs:11:1
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Node {
[INFO] [stdout]    | ^^^^^^^^^^^
[INFO] [stdout]    = note: `#[warn(private_interfaces)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> src/fourth.rs:95:23
[INFO] [stdout]    |
[INFO] [stdout] 95 |     pub fn peek_front(&self) -> Option<Ref<T>> {
[INFO] [stdout]    |                       ^^^^^            ^^^^^^ the same lifetime is hidden here
[INFO] [stdout]    |                       |
[INFO] [stdout]    |                       the lifetime is elided here
[INFO] [stdout]    |
[INFO] [stdout]    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout]    = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]    |
[INFO] [stdout] 95 |     pub fn peek_front(&self) -> Option<Ref<'_, T>> {
[INFO] [stdout]    |                                            +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/fourth.rs:102:27
[INFO] [stdout]     |
[INFO] [stdout] 102 |     pub fn peek_front_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |                           ^^^^^^^^^            ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                           |
[INFO] [stdout]     |                           the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 102 |     pub fn peek_front_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                       +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/fourth.rs:108:22
[INFO] [stdout]     |
[INFO] [stdout] 108 |     pub fn peek_back(&self) -> Option<Ref<T>> {
[INFO] [stdout]     |                      ^^^^^            ^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                      |
[INFO] [stdout]     |                      the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 108 |     pub fn peek_back(&self) -> Option<Ref<'_, T>> {
[INFO] [stdout]     |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/fourth.rs:114:26
[INFO] [stdout]     |
[INFO] [stdout] 114 |     pub fn peek_back_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |                          ^^^^^^^^^            ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                          |
[INFO] [stdout]     |                          the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 114 |     pub fn peek_back_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                      +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `option`
[INFO] [stdout]   --> src/main.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let option = option_name.as_ref();
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_option`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `option1`
[INFO] [stdout]   --> src/main.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let option1 = option_name.as_deref();
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_option1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s1`
[INFO] [stdout]   --> src/main.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let s1 = &s;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]   --> src/main.rs:35:9
[INFO] [stdout]    |
[INFO] [stdout] 35 |     let s2 = s.to_string();
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/main.rs:38:9
[INFO] [stdout]    |
[INFO] [stdout] 38 |     let b = Rc::clone(&a);
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `handle`
[INFO] [stdout]   --> src/main.rs:42:13
[INFO] [stdout]    |
[INFO] [stdout] 42 |         let handle = thread::spawn(move || {
[INFO] [stdout]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_handle`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `age`
[INFO] [stdout]   --> src/main.rs:99:35
[INFO] [stdout]    |
[INFO] [stdout] 99 |     fn display(self: &mut Person, age: u8) {
[INFO] [stdout]    |                                   ^^^ help: if this is intentional, prefix it with an underscore: `_age`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `name`
[INFO] [stdout]    --> src/main.rs:100:22
[INFO] [stdout]     |
[INFO] [stdout] 100 |         let Person { name, age } = &self;
[INFO] [stdout]     |                      ^^^^ help: try ignoring the field: `name: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `age`
[INFO] [stdout]    --> src/main.rs:100:28
[INFO] [stdout]     |
[INFO] [stdout] 100 |         let Person { name, age } = &self;
[INFO] [stdout]     |                            ^^^ help: try ignoring the field: `age: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type `first::Node` is more private than the item `first::Link::More::0`
[INFO] [stdout]   --> src/first.rs:7:10
[INFO] [stdout]    |
[INFO] [stdout]  7 |     More(Box<Node>),
[INFO] [stdout]    |          ^^^^^^^^^ field `first::Link::More::0` is reachable at visibility `pub(crate)`
[INFO] [stdout]    |
[INFO] [stdout] note: but type `first::Node` is only usable at visibility `pub(self)`
[INFO] [stdout]   --> src/first.rs:11:1
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Node {
[INFO] [stdout]    | ^^^^^^^^^^^
[INFO] [stdout]    = note: `#[warn(private_interfaces)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Person` is never constructed
[INFO] [stdout]   --> src/main.rs:90:8
[INFO] [stdout]    |
[INFO] [stdout] 90 | struct Person {
[INFO] [stdout]    |        ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated items `new` and `display` are never used
[INFO] [stdout]   --> src/main.rs:96:8
[INFO] [stdout]    |
[INFO] [stdout] 95 | impl Person {
[INFO] [stdout]    | ----------- associated items in this implementation
[INFO] [stdout] 96 |     fn new(name: String, age: u8) -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] ...
[INFO] [stdout] 99 |     fn display(self: &mut Person, age: u8) {
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `List` is never constructed
[INFO] [stdout]  --> src/first.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub struct List {
[INFO] [stdout]   |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Link` is never used
[INFO] [stdout]  --> src/first.rs:5:10
[INFO] [stdout]   |
[INFO] [stdout] 5 | pub enum Link {
[INFO] [stdout]   |          ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Node` is never constructed
[INFO] [stdout]   --> src/first.rs:11:8
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Node {
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated items `new`, `push`, and `pop` are never used
[INFO] [stdout]   --> src/first.rs:17:12
[INFO] [stdout]    |
[INFO] [stdout] 16 | impl List {
[INFO] [stdout]    | --------- associated items in this implementation
[INFO] [stdout] 17 |     pub fn new() -> Self {
[INFO] [stdout]    |            ^^^
[INFO] [stdout] ...
[INFO] [stdout] 20 |     pub fn push(&mut self, elem: i32) {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 28 |     pub fn pop(&mut self) -> Option<i32> {
[INFO] [stdout]    |            ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `List` is never constructed
[INFO] [stdout]  --> src/second.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub struct List<T> {
[INFO] [stdout]   |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type alias `Link` is never used
[INFO] [stdout]  --> src/second.rs:4:6
[INFO] [stdout]   |
[INFO] [stdout] 4 | type Link<T> = Option<Box<Node<T>>>;
[INFO] [stdout]   |      ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Node` is never constructed
[INFO] [stdout]  --> src/second.rs:6:8
[INFO] [stdout]   |
[INFO] [stdout] 6 | struct Node<T> {
[INFO] [stdout]   |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated items `new`, `push`, `pop`, `peek`, and `peek_mut` are never used
[INFO] [stdout]   --> src/second.rs:12:12
[INFO] [stdout]    |
[INFO] [stdout] 11 | impl<T> List<T> {
[INFO] [stdout]    | --------------- associated items in this implementation
[INFO] [stdout] 12 |     pub fn new() -> Self {
[INFO] [stdout]    |            ^^^
[INFO] [stdout] ...
[INFO] [stdout] 15 |     pub fn push(&mut self, elem: T) {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 23 |     pub fn pop(&mut self) -> Option<T> {
[INFO] [stdout]    |            ^^^
[INFO] [stdout] ...
[INFO] [stdout] 30 |     pub fn peek(&self) -> Option<&T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 36 |     pub fn peek_mut(&mut self) -> Option<&mut T> {
[INFO] [stdout]    |            ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `IntoIter` is never constructed
[INFO] [stdout]   --> src/second.rs:51:12
[INFO] [stdout]    |
[INFO] [stdout] 51 | pub struct IntoIter<T> (List<T>);
[INFO] [stdout]    |            ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `into_iter` is never used
[INFO] [stdout]   --> src/second.rs:54:12
[INFO] [stdout]    |
[INFO] [stdout] 53 | impl<T> List<T> {
[INFO] [stdout]    | --------------- method in this implementation
[INFO] [stdout] 54 |     pub fn into_iter(self) -> IntoIter<T> {
[INFO] [stdout]    |            ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Iter` is never constructed
[INFO] [stdout]   --> src/second.rs:66:12
[INFO] [stdout]    |
[INFO] [stdout] 66 | pub struct Iter<'a, T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `iter` is never used
[INFO] [stdout]   --> src/second.rs:71:12
[INFO] [stdout]    |
[INFO] [stdout] 70 | impl<T> List<T> {
[INFO] [stdout]    | --------------- method in this implementation
[INFO] [stdout] 71 |     pub fn iter<'a>(&'a self) -> Iter<'a, T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `IterMut` is never constructed
[INFO] [stdout]   --> src/second.rs:87:12
[INFO] [stdout]    |
[INFO] [stdout] 87 | pub struct IterMut<'a, T> {
[INFO] [stdout]    |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `iter_mut` is never used
[INFO] [stdout]   --> src/second.rs:92:12
[INFO] [stdout]    |
[INFO] [stdout] 91 | impl<T> List<T> {
[INFO] [stdout]    | --------------- method in this implementation
[INFO] [stdout] 92 |     pub fn iter_mut(&mut self) -> IterMut<'_, T> {
[INFO] [stdout]    |            ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `option`
[INFO] [stdout]   --> src/main.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let option = option_name.as_ref();
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_option`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `option1`
[INFO] [stdout]   --> src/main.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let option1 = option_name.as_deref();
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_option1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s1`
[INFO] [stdout]   --> src/main.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let s1 = &s;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]   --> src/main.rs:35:9
[INFO] [stdout]    |
[INFO] [stdout] 35 |     let s2 = s.to_string();
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/main.rs:38:9
[INFO] [stdout]    |
[INFO] [stdout] 38 |     let b = Rc::clone(&a);
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `handle`
[INFO] [stdout]   --> src/main.rs:42:13
[INFO] [stdout]    |
[INFO] [stdout] 42 |         let handle = thread::spawn(move || {
[INFO] [stdout]    |             ^^^^^^ help: if this is intentional, prefix it with an underscore: `_handle`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `age`
[INFO] [stdout]   --> src/main.rs:99:35
[INFO] [stdout]    |
[INFO] [stdout] 99 |     fn display(self: &mut Person, age: u8) {
[INFO] [stdout]    |                                   ^^^ help: if this is intentional, prefix it with an underscore: `_age`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `name`
[INFO] [stdout]    --> src/main.rs:100:22
[INFO] [stdout]     |
[INFO] [stdout] 100 |         let Person { name, age } = &self;
[INFO] [stdout]     |                      ^^^^ help: try ignoring the field: `name: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `age`
[INFO] [stdout]    --> src/main.rs:100:28
[INFO] [stdout]     |
[INFO] [stdout] 100 |         let Person { name, age } = &self;
[INFO] [stdout]     |                            ^^^ help: try ignoring the field: `age: _`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type `first::Node` is more private than the item `first::Link::More::0`
[INFO] [stdout]   --> src/first.rs:7:10
[INFO] [stdout]    |
[INFO] [stdout]  7 |     More(Box<Node>),
[INFO] [stdout]    |          ^^^^^^^^^ field `first::Link::More::0` is reachable at visibility `pub(crate)`
[INFO] [stdout]    |
[INFO] [stdout] note: but type `first::Node` is only usable at visibility `pub(self)`
[INFO] [stdout]   --> src/first.rs:11:1
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Node {
[INFO] [stdout]    | ^^^^^^^^^^^
[INFO] [stdout]    = note: `#[warn(private_interfaces)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Person` is never constructed
[INFO] [stdout]   --> src/main.rs:90:8
[INFO] [stdout]    |
[INFO] [stdout] 90 | struct Person {
[INFO] [stdout]    |        ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated items `new` and `display` are never used
[INFO] [stdout]   --> src/main.rs:96:8
[INFO] [stdout]    |
[INFO] [stdout] 95 | impl Person {
[INFO] [stdout]    | ----------- associated items in this implementation
[INFO] [stdout] 96 |     fn new(name: String, age: u8) -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] ...
[INFO] [stdout] 99 |     fn display(self: &mut Person, age: u8) {
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Iter` is never constructed
[INFO] [stdout]   --> src/second.rs:66:12
[INFO] [stdout]    |
[INFO] [stdout] 66 | pub struct Iter<'a, T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `iter` is never used
[INFO] [stdout]   --> src/second.rs:71:12
[INFO] [stdout]    |
[INFO] [stdout] 70 | impl<T> List<T> {
[INFO] [stdout]    | --------------- method in this implementation
[INFO] [stdout] 71 |     pub fn iter<'a>(&'a self) -> Iter<'a, T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.64s
[INFO] running `Command { std: "docker" "inspect" "f3fcf4fad8bc175252537626322a9e5ee0fff9f063d4d699a46b64af702fe037", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f3fcf4fad8bc175252537626322a9e5ee0fff9f063d4d699a46b64af702fe037", kill_on_drop: false }`
[INFO] [stdout] f3fcf4fad8bc175252537626322a9e5ee0fff9f063d4d699a46b64af702fe037
