[INFO] cloning repository https://github.com/zhenhuanlee/lists
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/zhenhuanlee/lists" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzhenhuanlee%2Flists"`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzhenhuanlee%2Flists'...
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 1843ceed34c5430df52e577ca11703f0eb01a3af
[INFO] checking zhenhuanlee/lists against try#e4dba30b9b475d8750370c4dfb49b6541990904d for pr-71393
[INFO] running `"git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzhenhuanlee%2Flists" "/workspace/builds/worker-3/source"`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zhenhuanlee/lists on toolchain e4dba30b9b475d8750370c4dfb49b6541990904d
[INFO] running `"/workspace/cargo-home/bin/cargo" "+e4dba30b9b475d8750370c4dfb49b6541990904d" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/zhenhuanlee/lists
[INFO] finished tweaking git repo https://github.com/zhenhuanlee/lists
[INFO] tweaked toml for git repo https://github.com/zhenhuanlee/lists written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/zhenhuanlee/lists already has a lockfile, it will not be regenerated
[INFO] running `"/workspace/cargo-home/bin/cargo" "+e4dba30b9b475d8750370c4dfb49b6541990904d" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+e4dba30b9b475d8750370c4dfb49b6541990904d" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] bdad75e43feb63e0d6668582e1a2ace740e2a43284ccd5b862611ea94a0a43fa
[INFO] running `"docker" "start" "-a" "bdad75e43feb63e0d6668582e1a2ace740e2a43284ccd5b862611ea94a0a43fa"`
[INFO] [stderr]     Checking lists v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] warning: unused import: `super::List`
[INFO] [stderr]   --> src/lib/first.rs:56:9
[INFO] [stderr]    |
[INFO] [stderr] 56 |     use super::List;
[INFO] [stderr]    |         ^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `super::List`
[INFO] [stderr]    --> src/lib/second.rs:121:9
[INFO] [stderr]     |
[INFO] [stderr] 121 |     use super::List;
[INFO] [stderr]     |         ^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `std::mem`
[INFO] [stderr]  --> src/main.rs:3:5
[INFO] [stderr]   |
[INFO] [stderr] 3 | use std::mem;
[INFO] [stderr]   |     ^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `std::mem`
[INFO] [stderr]  --> src/main.rs:3:5
[INFO] [stderr]   |
[INFO] [stderr] 3 | use std::mem;
[INFO] [stderr]   |     ^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/main.rs:18:9
[INFO] [stderr]    |
[INFO] [stderr] 18 |     let x = iter.next().unwrap();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let y = iter.next().unwrap();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `z`
[INFO] [stderr]   --> src/main.rs:20:9
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let z = iter.next().unwrap();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_z`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `elem`
[INFO] [stderr]   --> src/lib/fourth.rs:28:16
[INFO] [stderr]    |
[INFO] [stderr] 28 |     pub fn new(elem: T) -> Self {
[INFO] [stderr]    |                ^^^^ help: if this is intentional, prefix it with an underscore: `_elem`
[INFO] [stderr] 
[INFO] [stderr] warning: variant is never constructed: `More`
[INFO] [stderr]   --> src/lib/first.rs:11:5
[INFO] [stderr]    |
[INFO] [stderr] 11 |     More(Box<Node>),
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/first.rs:22:5
[INFO] [stderr]    |
[INFO] [stderr] 22 |     pub fn new() -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push`
[INFO] [stderr]   --> src/lib/first.rs:26:5
[INFO] [stderr]    |
[INFO] [stderr] 26 |     pub fn push(&mut self, elem: i32) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `pop`
[INFO] [stderr]   --> src/lib/first.rs:32:5
[INFO] [stderr]    |
[INFO] [stderr] 32 |     pub fn pop(&mut self) -> Option<i32> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/second.rs:26:5
[INFO] [stderr]    |
[INFO] [stderr] 26 |     pub fn new() -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push`
[INFO] [stderr]   --> src/lib/second.rs:30:5
[INFO] [stderr]    |
[INFO] [stderr] 30 |     pub fn push(&mut self, elem: T) -> &mut Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `peek`
[INFO] [stderr]   --> src/lib/second.rs:53:5
[INFO] [stderr]    |
[INFO] [stderr] 53 |     pub fn peek(&self) -> Option<&T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `mut_peek`
[INFO] [stderr]   --> src/lib/second.rs:59:5
[INFO] [stderr]    |
[INFO] [stderr] 59 |     pub fn mut_peek(&mut self) -> Option<&mut T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `into_iter`
[INFO] [stderr]   --> src/lib/second.rs:67:5
[INFO] [stderr]    |
[INFO] [stderr] 67 |     pub fn into_iter(self) -> IntoIter<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `iter`
[INFO] [stderr]   --> src/lib/second.rs:71:5
[INFO] [stderr]    |
[INFO] [stderr] 71 |     pub fn iter(&self) -> Iter<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `iter_mut`
[INFO] [stderr]   --> src/lib/second.rs:75:5
[INFO] [stderr]    |
[INFO] [stderr] 75 |     pub fn iter_mut(&mut self) -> IterMut<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `iter`
[INFO] [stderr]   --> src/lib/third.rs:21:5
[INFO] [stderr]    |
[INFO] [stderr] 21 |     fn iter(&self) -> Iter<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/third.rs:38:5
[INFO] [stderr]    |
[INFO] [stderr] 38 |     pub fn new() -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `append`
[INFO] [stderr]   --> src/lib/third.rs:42:5
[INFO] [stderr]    |
[INFO] [stderr] 42 |     pub fn append(&self, elem: T) -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `tail`
[INFO] [stderr]   --> src/lib/third.rs:56:5
[INFO] [stderr]    |
[INFO] [stderr] 56 |     pub fn tail(&self) -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `head`
[INFO] [stderr]   --> src/lib/third.rs:60:5
[INFO] [stderr]    |
[INFO] [stderr] 60 |     pub fn head(&self) -> Option<&T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `List`
[INFO] [stderr]  --> src/lib/fourth.rs:4:8
[INFO] [stderr]   |
[INFO] [stderr] 4 | struct List<T> {
[INFO] [stderr]   |        ^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: type alias is never used: `Link`
[INFO] [stderr]  --> src/lib/fourth.rs:9:1
[INFO] [stderr]   |
[INFO] [stderr] 9 | type Link<T> = Option<Rc<RefCell<Node<T>>>>;
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `Node`
[INFO] [stderr]   --> src/lib/fourth.rs:11:8
[INFO] [stderr]    |
[INFO] [stderr] 11 | struct Node<T> {
[INFO] [stderr]    |        ^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/fourth.rs:18:5
[INFO] [stderr]    |
[INFO] [stderr] 18 |     fn new(elem: T) -> Rc<RefCell<Self>> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/fourth.rs:28:5
[INFO] [stderr]    |
[INFO] [stderr] 28 |     pub fn new(elem: T) -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push_front`
[INFO] [stderr]   --> src/lib/fourth.rs:32:5
[INFO] [stderr]    |
[INFO] [stderr] 32 |     pub fn push_front(&mut self, elem: T) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `second`
[INFO] [stderr]   --> src/main.rs:13:4
[INFO] [stderr]    |
[INFO] [stderr] 13 | fn second() {
[INFO] [stderr]    |    ^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `first`
[INFO] [stderr]   --> src/main.rs:23:4
[INFO] [stderr]    |
[INFO] [stderr] 23 | fn first() {
[INFO] [stderr]    |    ^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `test_ref`
[INFO] [stderr]   --> src/main.rs:39:4
[INFO] [stderr]    |
[INFO] [stderr] 39 | fn test_ref() {
[INFO] [stderr]    |    ^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: 32 warnings emitted
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/main.rs:18:9
[INFO] [stderr]    |
[INFO] [stderr] 18 |     let x = iter.next().unwrap();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let y = iter.next().unwrap();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `z`
[INFO] [stderr]   --> src/main.rs:20:9
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let z = iter.next().unwrap();
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_z`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `elem`
[INFO] [stderr]   --> src/lib/fourth.rs:28:16
[INFO] [stderr]    |
[INFO] [stderr] 28 |     pub fn new(elem: T) -> Self {
[INFO] [stderr]    |                ^^^^ help: if this is intentional, prefix it with an underscore: `_elem`
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `List`
[INFO] [stderr]  --> src/lib/fourth.rs:4:8
[INFO] [stderr]   |
[INFO] [stderr] 4 | struct List<T> {
[INFO] [stderr]   |        ^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: type alias is never used: `Link`
[INFO] [stderr]  --> src/lib/fourth.rs:9:1
[INFO] [stderr]   |
[INFO] [stderr] 9 | type Link<T> = Option<Rc<RefCell<Node<T>>>>;
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `Node`
[INFO] [stderr]   --> src/lib/fourth.rs:11:8
[INFO] [stderr]    |
[INFO] [stderr] 11 | struct Node<T> {
[INFO] [stderr]    |        ^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/fourth.rs:18:5
[INFO] [stderr]    |
[INFO] [stderr] 18 |     fn new(elem: T) -> Rc<RefCell<Self>> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/lib/fourth.rs:28:5
[INFO] [stderr]    |
[INFO] [stderr] 28 |     pub fn new(elem: T) -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push_front`
[INFO] [stderr]   --> src/lib/fourth.rs:32:5
[INFO] [stderr]    |
[INFO] [stderr] 32 |     pub fn push_front(&mut self, elem: T) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `second`
[INFO] [stderr]   --> src/main.rs:13:4
[INFO] [stderr]    |
[INFO] [stderr] 13 | fn second() {
[INFO] [stderr]    |    ^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `first`
[INFO] [stderr]   --> src/main.rs:23:4
[INFO] [stderr]    |
[INFO] [stderr] 23 | fn first() {
[INFO] [stderr]    |    ^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: function is never used: `test_ref`
[INFO] [stderr]   --> src/main.rs:39:4
[INFO] [stderr]    |
[INFO] [stderr] 39 | fn test_ref() {
[INFO] [stderr]    |    ^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: 14 warnings emitted
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.61s
[INFO] running `"docker" "inspect" "bdad75e43feb63e0d6668582e1a2ace740e2a43284ccd5b862611ea94a0a43fa"`
[INFO] running `"docker" "rm" "-f" "bdad75e43feb63e0d6668582e1a2ace740e2a43284ccd5b862611ea94a0a43fa"`
[INFO] [stdout] bdad75e43feb63e0d6668582e1a2ace740e2a43284ccd5b862611ea94a0a43fa