[INFO] cloning repository https://github.com/aklk1ng/rust_data_structure
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/aklk1ng/rust_data_structure" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Faklk1ng%2Frust_data_structure", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Faklk1ng%2Frust_data_structure'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a8f80594b1a64c650ba90cc59ab0fbe9954a471f
[INFO] checking aklk1ng/rust_data_structure against try#0611f7de057c584b8771102fde7aed6c70c71d3b for pr-146440
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Faklk1ng%2Frust_data_structure" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/aklk1ng/rust_data_structure
[INFO] finished tweaking git repo https://github.com/aklk1ng/rust_data_structure
[INFO] tweaked toml for git repo https://github.com/aklk1ng/rust_data_structure written to /workspace/builds/worker-1-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/aklk1ng/rust_data_structure on toolchain 0611f7de057c584b8771102fde7aed6c70c71d3b
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+0611f7de057c584b8771102fde7aed6c70c71d3b" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/aklk1ng/rust_data_structure 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" "+0611f7de057c584b8771102fde7aed6c70c71d3b" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr] warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"`
[INFO] [stderr]   |
[INFO] [stderr]   = note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
[INFO] [stderr]   = note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
[INFO] [stderr]   = note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions
[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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+0611f7de057c584b8771102fde7aed6c70c71d3b" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e55f748ef616ce83c907919743143f3bba87f05eda5889b612a14ccd1601c43d
[INFO] running `Command { std: "docker" "start" "-a" "e55f748ef616ce83c907919743143f3bba87f05eda5889b612a14ccd1601c43d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e55f748ef616ce83c907919743143f3bba87f05eda5889b612a14ccd1601c43d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e55f748ef616ce83c907919743143f3bba87f05eda5889b612a14ccd1601c43d", kill_on_drop: false }`
[INFO] [stdout] e55f748ef616ce83c907919743143f3bba87f05eda5889b612a14ccd1601c43d
[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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+0611f7de057c584b8771102fde7aed6c70c71d3b" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5a30e654d9480fa01733a30b268ff54e4e6d06d0a6f330f5b4d95ce437c38f1e
[INFO] running `Command { std: "docker" "start" "-a" "5a30e654d9480fa01733a30b268ff54e4e6d06d0a6f330f5b4d95ce437c38f1e", kill_on_drop: false }`
[INFO] [stderr] warning: virtual workspace defaulting to `resolver = "1"` despite one or more workspace members being on edition 2021 which implies `resolver = "2"`
[INFO] [stderr]   |
[INFO] [stderr]   = note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
[INFO] [stderr]   = note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
[INFO] [stderr]   = note: for more details see https://doc.rust-lang.org/cargo/reference/resolver.html#resolver-versions
[INFO] [stderr]     Checking DoubleList v0.1.0 (/opt/rustwide/workdir/DoubleList)
[INFO] [stderr]     Checking Queue v0.1.0 (/opt/rustwide/workdir/Queue)
[INFO] [stderr]     Checking Linked_List v0.1.0 (/opt/rustwide/workdir/Linked_List)
[INFO] [stderr]     Checking ListNode v0.1.0 (/opt/rustwide/workdir/ListNode)
[INFO] [stderr]     Checking Binary_Tree v0.1.0 (/opt/rustwide/workdir/Binary_Tree)
[INFO] [stderr]     Checking Stack v0.1.0 (/opt/rustwide/workdir/Stack)
[INFO] [stdout] warning: unused import: `std::borrow::Borrow`
[INFO] [stdout]  --> Binary_Tree/src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::borrow::Borrow;
[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::fmt::Error`
[INFO] [stdout]  --> Binary_Tree/src/main.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::fmt::Error;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type alias `Link` is never used
[INFO] [stdout]  --> DoubleList/src/lib.rs:4:6
[INFO] [stdout]   |
[INFO] [stdout] 4 | type Link<T> = Option<Rc<RefCell<Node<T>>>>;
[INFO] [stdout]   |      ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Node` is never constructed
[INFO] [stdout]  --> DoubleList/src/lib.rs:6:8
[INFO] [stdout]   |
[INFO] [stdout] 6 | struct Node<T> {
[INFO] [stdout]   |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new` is never used
[INFO] [stdout]   --> DoubleList/src/lib.rs:13:8
[INFO] [stdout]    |
[INFO] [stdout] 12 | impl<T> Node<T> {
[INFO] [stdout]    | --------------- associated function in this implementation
[INFO] [stdout] 13 |     fn new(val: T) -> Rc<RefCell<Self>> {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `List` is never constructed
[INFO] [stdout]   --> DoubleList/src/lib.rs:22:8
[INFO] [stdout]    |
[INFO] [stdout] 22 | struct List<T> {
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: multiple associated items are never used
[INFO] [stdout]    --> DoubleList/src/lib.rs:28:8
[INFO] [stdout]     |
[INFO] [stdout]  27 | impl<T> List<T> {
[INFO] [stdout]     | --------------- associated items in this implementation
[INFO] [stdout]  28 |     fn new() -> Self {
[INFO] [stdout]     |        ^^^
[INFO] [stdout] ...
[INFO] [stdout]  35 |     fn push_front(&mut self, val: T) {
[INFO] [stdout]     |        ^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  50 |     fn pop_front(&mut self) -> Option<T> {
[INFO] [stdout]     |        ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  65 |     fn push_back(&mut self, val: T) {
[INFO] [stdout]     |        ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  80 |     fn pop_back(&mut self) -> Option<T> {
[INFO] [stdout]     |        ^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  95 |     fn peek_front(&self) -> Option<Ref<T>> {
[INFO] [stdout]     |        ^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 101 |     fn peek_back(&self) -> Option<Ref<T>> {
[INFO] [stdout]     |        ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 107 |     fn peek_back_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |        ^^^^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 113 |     fn peek_front_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |        ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `IntoIter` is never constructed
[INFO] [stdout]    --> DoubleList/src/lib.rs:126:8
[INFO] [stdout]     |
[INFO] [stdout] 126 | struct IntoIter<T>(List<T>);
[INFO] [stdout]     |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `into_iter` is never used
[INFO] [stdout]    --> DoubleList/src/lib.rs:129:8
[INFO] [stdout]     |
[INFO] [stdout] 128 | impl<T> List<T> {
[INFO] [stdout]     | --------------- method in this implementation
[INFO] [stdout] 129 |     fn into_iter(self) -> IntoIter<T> {
[INFO] [stdout]     |        ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: crate `DoubleList` should have a snake case name
[INFO] [stdout]   |
[INFO] [stdout]   = help: convert the identifier to snake case: `double_list`
[INFO] [stdout]   = note: `#[warn(non_snake_case)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> DoubleList/src/lib.rs:95:19
[INFO] [stdout]    |
[INFO] [stdout] 95 |     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 |     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]    --> DoubleList/src/lib.rs:101:18
[INFO] [stdout]     |
[INFO] [stdout] 101 |     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] 101 |     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]    --> DoubleList/src/lib.rs:107:22
[INFO] [stdout]     |
[INFO] [stdout] 107 |     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] 107 |     fn peek_back_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]    --> DoubleList/src/lib.rs:113:23
[INFO] [stdout]     |
[INFO] [stdout] 113 |     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] 113 |     fn peek_front_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                   +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: struct `List` is never constructed
[INFO] [stdout]   --> ListNode/src/main.rs:30:12
[INFO] [stdout]    |
[INFO] [stdout] 30 | pub struct List<T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `pub` struct has private fields, no public constructor, and is not otherwise reachable through the external API, so consider providing a public constructor or removing it
[INFO] [stdout]    = note: `#[deny(unused_unconstructable_pub_struct)]` (part of `#[deny(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `head` is never read
[INFO] [stdout]   --> ListNode/src/main.rs:31:5
[INFO] [stdout]    |
[INFO] [stdout] 30 | pub struct List<T> {
[INFO] [stdout]    |            ---- field in this struct
[INFO] [stdout] 31 |     head: Option<Box<Node<T>>>,
[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`, `push_front`, `pop_front`, and `is_empty` are never used
[INFO] [stdout]   --> ListNode/src/main.rs:35:8
[INFO] [stdout]    |
[INFO] [stdout] 34 | impl<T> List<T> {
[INFO] [stdout]    | --------------- associated items in this implementation
[INFO] [stdout] 35 |     fn new() -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] ...
[INFO] [stdout] 39 |     fn push_front(&mut self, val: T) {
[INFO] [stdout]    |        ^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 45 |     fn pop_front(&mut self) -> Option<T> {
[INFO] [stdout]    |        ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 52 |     fn is_empty(&self) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> Binary_Tree/src/main.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let mut root = Tree::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: `root`
[INFO] [stdout]   --> Binary_Tree/src/main.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let mut root = Tree::new();
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_root`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new` is never used
[INFO] [stdout]   --> Binary_Tree/src/main.rs:14:8
[INFO] [stdout]    |
[INFO] [stdout] 13 | impl Node {
[INFO] [stdout]    | --------- associated function in this implementation
[INFO] [stdout] 14 |     fn new(val: i32) -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `root` is never read
[INFO] [stdout]   --> Binary_Tree/src/main.rs:24:5
[INFO] [stdout]    |
[INFO] [stdout] 23 | struct Tree {
[INFO] [stdout]    |        ---- field in this struct
[INFO] [stdout] 24 |     root: Option<Rc<RefCell<Node>>>,
[INFO] [stdout]    |     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::borrow::Borrow`
[INFO] [stdout]  --> Binary_Tree/src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::borrow::Borrow;
[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::fmt::Error`
[INFO] [stdout]  --> Binary_Tree/src/main.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::fmt::Error;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `ListNode` (bin "ListNode") due to 1 previous error; 2 warnings emitted
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> Binary_Tree/src/main.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let mut root = Tree::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: `root`
[INFO] [stdout]   --> Binary_Tree/src/main.rs:34:9
[INFO] [stdout]    |
[INFO] [stdout] 34 |     let mut root = Tree::new();
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_root`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new` is never used
[INFO] [stdout]   --> Binary_Tree/src/main.rs:14:8
[INFO] [stdout]    |
[INFO] [stdout] 13 | impl Node {
[INFO] [stdout]    | --------- associated function in this implementation
[INFO] [stdout] 14 |     fn new(val: i32) -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `root` is never read
[INFO] [stdout]   --> Binary_Tree/src/main.rs:24:5
[INFO] [stdout]    |
[INFO] [stdout] 23 | struct Tree {
[INFO] [stdout]    |        ---- field in this struct
[INFO] [stdout] 24 |     root: Option<Rc<RefCell<Node>>>,
[INFO] [stdout]    |     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> DoubleList/src/lib.rs:95:19
[INFO] [stdout]    |
[INFO] [stdout] 95 |     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 |     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]    --> DoubleList/src/lib.rs:101:18
[INFO] [stdout]     |
[INFO] [stdout] 101 |     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] 101 |     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]    --> DoubleList/src/lib.rs:107:22
[INFO] [stdout]     |
[INFO] [stdout] 107 |     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] 107 |     fn peek_back_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]    --> DoubleList/src/lib.rs:113:23
[INFO] [stdout]     |
[INFO] [stdout] 113 |     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] 113 |     fn peek_front_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                   +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> ListNode/src/main.rs:71:13
[INFO] [stdout]    |
[INFO] [stdout] 71 |         let mut list = Node::new(-1);
[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: `list`
[INFO] [stdout]   --> ListNode/src/main.rs:71:13
[INFO] [stdout]    |
[INFO] [stdout] 71 |         let mut list = Node::new(-1);
[INFO] [stdout]    |             ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_list`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: struct `List` is never constructed
[INFO] [stdout]   --> ListNode/src/main.rs:30:12
[INFO] [stdout]    |
[INFO] [stdout] 30 | pub struct List<T> {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `pub` struct has private fields, no public constructor, and is not otherwise reachable through the external API, so consider providing a public constructor or removing it
[INFO] [stdout]    = note: `#[deny(unused_unconstructable_pub_struct)]` (part of `#[deny(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `head` is never read
[INFO] [stdout]   --> ListNode/src/main.rs:31:5
[INFO] [stdout]    |
[INFO] [stdout] 30 | pub struct List<T> {
[INFO] [stdout]    |            ---- field in this struct
[INFO] [stdout] 31 |     head: Option<Box<Node<T>>>,
[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`, `push_front`, `pop_front`, and `is_empty` are never used
[INFO] [stdout]   --> ListNode/src/main.rs:35:8
[INFO] [stdout]    |
[INFO] [stdout] 34 | impl<T> List<T> {
[INFO] [stdout]    | --------------- associated items in this implementation
[INFO] [stdout] 35 |     fn new() -> Self {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] ...
[INFO] [stdout] 39 |     fn push_front(&mut self, val: T) {
[INFO] [stdout]    |        ^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 45 |     fn pop_front(&mut self) -> Option<T> {
[INFO] [stdout]    |        ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 52 |     fn is_empty(&self) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `ListNode` (bin "ListNode" test) due to 1 previous error; 4 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "5a30e654d9480fa01733a30b268ff54e4e6d06d0a6f330f5b4d95ce437c38f1e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5a30e654d9480fa01733a30b268ff54e4e6d06d0a6f330f5b4d95ce437c38f1e", kill_on_drop: false }`
[INFO] [stdout] 5a30e654d9480fa01733a30b268ff54e4e6d06d0a6f330f5b4d95ce437c38f1e
