[INFO] cloning repository https://github.com/francis8991/clrs-rust-challenge
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/francis8991/clrs-rust-challenge" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffrancis8991%2Fclrs-rust-challenge", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffrancis8991%2Fclrs-rust-challenge'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d31d15c46244b202c3bff4215df99623bd8f838f
[INFO] checking francis8991/clrs-rust-challenge against 615014f15745532730b9ce7a1d9309f8b4756f93 for pr-160491
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffrancis8991%2Fclrs-rust-challenge" "/workspace/builds/worker-2-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/francis8991/clrs-rust-challenge
[INFO] finished tweaking git repo https://github.com/francis8991/clrs-rust-challenge
[INFO] tweaked toml for git repo https://github.com/francis8991/clrs-rust-challenge written to /workspace/builds/worker-2-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/francis8991/clrs-rust-challenge on toolchain 615014f15745532730b9ce7a1d9309f8b4756f93
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+615014f15745532730b9ce7a1d9309f8b4756f93" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/francis8991/clrs-rust-challenge 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" "+615014f15745532730b9ce7a1d9309f8b4756f93" "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-2-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,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" "-m" "1610612736" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:00c5645b54fe3ce5dae1417175e3c7fb6a6646c021d554ecd63a097b8b9f3602" "sleep" "infinity", kill_on_drop: false }`
[INFO] [stdout] 047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b
[INFO] running `Command { std: "docker" "start" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "exec" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-w" "/opt/rustwide/workdir" "--user" "0:0" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b" "/opt/rustwide/cargo-home/bin/cargo" "+615014f15745532730b9ce7a1d9309f8b4756f93" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "exec" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-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" "-w" "/opt/rustwide/workdir" "--user" "0:0" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b" "/opt/rustwide/cargo-home/bin/cargo" "+615014f15745532730b9ce7a1d9309f8b4756f93" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr]     Checking CLRS-rust-challenge v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: struct `List` is never constructed
[INFO] [stdout]  --> src/double_list.rs:4:12
[INFO] [stdout]   |
[INFO] [stdout] 4 | pub struct List<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: type alias `Link` is never used
[INFO] [stdout]  --> src/double_list.rs:9:6
[INFO] [stdout]   |
[INFO] [stdout] 9 | type Link<T> = Option<Rc<RefCell<Node<T>>>>;
[INFO] [stdout]   |      ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Node` is never constructed
[INFO] [stdout]   --> src/double_list.rs:11:8
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Node<T> {
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `new` is never used
[INFO] [stdout]   --> src/double_list.rs:18:8
[INFO] [stdout]    |
[INFO] [stdout] 17 | impl<T> Node<T> {
[INFO] [stdout]    | --------------- associated function in this implementation
[INFO] [stdout] 18 |     fn new(elem: T) -> Rc<RefCell<Self>> {
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: multiple associated items are never used
[INFO] [stdout]    --> src/double_list.rs:28:12
[INFO] [stdout]     |
[INFO] [stdout]  27 | impl<T> List<T> {
[INFO] [stdout]     | --------------- associated items in this implementation
[INFO] [stdout]  28 |     pub fn new() -> Self {
[INFO] [stdout]     |            ^^^
[INFO] [stdout] ...
[INFO] [stdout]  35 |     pub fn push_front(&mut self, elem: T) {
[INFO] [stdout]     |            ^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  50 |     pub fn push_back(&mut self, elem: T) {
[INFO] [stdout]     |            ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  65 |     pub fn pop_back(&mut self) -> Option<T> {
[INFO] [stdout]     |            ^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  80 |     pub fn pop_front(&mut self) -> Option<T> {
[INFO] [stdout]     |            ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout]  95 |     pub fn peek_front(&self) -> Option<Ref<T>> {
[INFO] [stdout]     |            ^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 101 |     pub fn peek_back(&self) -> Option<Ref<T>> {
[INFO] [stdout]     |            ^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 107 |     pub fn peek_back_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |            ^^^^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 113 |     pub fn peek_front_mut(&mut self) -> Option<RefMut<T>> {
[INFO] [stdout]     |            ^^^^^^^^^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 119 |     pub fn into_iter(self) -> IntoIter<T> {
[INFO] [stdout]     |            ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `IntoIter` is never constructed
[INFO] [stdout]    --> src/double_list.rs:130:12
[INFO] [stdout]     |
[INFO] [stdout] 130 | pub struct IntoIter<T>(List<T>);
[INFO] [stdout]     |            ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: crate `CLRS_rust_challenge` should have a snake case name
[INFO] [stdout]   |
[INFO] [stdout]   = help: convert the identifier to snake case: `clrs_rust_challenge`
[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]   --> src/double_list.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/double_list.rs:101:22
[INFO] [stdout]     |
[INFO] [stdout] 101 |     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] 101 |     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/double_list.rs:107:26
[INFO] [stdout]     |
[INFO] [stdout] 107 |     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] 107 |     pub 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]    --> src/double_list.rs:113:27
[INFO] [stdout]     |
[INFO] [stdout] 113 |     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] 113 |     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/double_list.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/double_list.rs:101:22
[INFO] [stdout]     |
[INFO] [stdout] 101 |     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] 101 |     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/double_list.rs:107:26
[INFO] [stdout]     |
[INFO] [stdout] 107 |     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] 107 |     pub 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]    --> src/double_list.rs:113:27
[INFO] [stdout]     |
[INFO] [stdout] 113 |     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] 113 |     pub fn peek_front_mut(&mut self) -> Option<RefMut<'_, T>> {
[INFO] [stdout]     |                                                       +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.07s
[INFO] running `Command { std: "docker" "inspect" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b", kill_on_drop: false }`
[INFO] [stdout] 047765b4526158a7f5044c054f3e9aa62b7e1a207dd9a377f8568ba11299bf8b
