[INFO] updating cached repository arashout/rust_linkedlist
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/arashout/rust_linkedlist
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/arashout/rust_linkedlist" "work/ex/pr-63376/sources/master#60960a260f7b5c695fd0717311d72ce62dd4eb43/gh/arashout/rust_linkedlist"`
[INFO] [stderr] Cloning into 'work/ex/pr-63376/sources/master#60960a260f7b5c695fd0717311d72ce62dd4eb43/gh/arashout/rust_linkedlist'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/arashout/rust_linkedlist" "work/ex/pr-63376/sources/try#266783e4e09e4e9d5307c1c8e695659c58bbcac7/gh/arashout/rust_linkedlist"`
[INFO] [stderr] Cloning into 'work/ex/pr-63376/sources/try#266783e4e09e4e9d5307c1c8e695659c58bbcac7/gh/arashout/rust_linkedlist'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 1e6015ad0ec7684f3091ed0f40001734934354c9
[INFO] sha for GitHub repo arashout/rust_linkedlist: 1e6015ad0ec7684f3091ed0f40001734934354c9
[INFO] validating manifest of arashout/rust_linkedlist on toolchain master#60960a260f7b5c695fd0717311d72ce62dd4eb43
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+60960a260f7b5c695fd0717311d72ce62dd4eb43-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of arashout/rust_linkedlist on toolchain try#266783e4e09e4e9d5307c1c8e695659c58bbcac7
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+266783e4e09e4e9d5307c1c8e695659c58bbcac7-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing arashout/rust_linkedlist
[INFO] finished frobbing arashout/rust_linkedlist
[INFO] frobbed toml for arashout/rust_linkedlist written to work/ex/pr-63376/sources/master#60960a260f7b5c695fd0717311d72ce62dd4eb43/gh/arashout/rust_linkedlist/Cargo.toml
[INFO] started frobbing arashout/rust_linkedlist
[INFO] finished frobbing arashout/rust_linkedlist
[INFO] frobbed toml for arashout/rust_linkedlist written to work/ex/pr-63376/sources/try#266783e4e09e4e9d5307c1c8e695659c58bbcac7/gh/arashout/rust_linkedlist/Cargo.toml
[INFO] crate arashout/rust_linkedlist already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+60960a260f7b5c695fd0717311d72ce62dd4eb43-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+266783e4e09e4e9d5307c1c8e695659c58bbcac7-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] checking arashout/rust_linkedlist against try#266783e4e09e4e9d5307c1c8e695659c58bbcac7 for pr-63376
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/pr-63376/worker-2/try#266783e4e09e4e9d5307c1c8e695659c58bbcac7:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/pr-63376/sources/try#266783e4e09e4e9d5307c1c8e695659c58bbcac7/gh/arashout/rust_linkedlist:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+266783e4e09e4e9d5307c1c8e695659c58bbcac7-alt" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stdout] 44cb2209ce3f869e7d0a483d4a2b6a66a25ee2e70c06362e13c0ac02cd628685
[INFO] running `"docker" "start" "-a" "44cb2209ce3f869e7d0a483d4a2b6a66a25ee2e70c06362e13c0ac02cd628685"`
[INFO] [stderr]     Checking linkedlist v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused variable: `old_tail`
[INFO] [stderr]   --> src/fourth.rs:67:18
[INFO] [stderr]    |
[INFO] [stderr] 67 |             Some(old_tail) => {
[INFO] [stderr]    |                  ^^^^^^^^ help: consider prefixing with an underscore: `_old_tail`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `List`
[INFO] [stderr]  --> src/first.rs:4:1
[INFO] [stderr]   |
[INFO] [stderr] 4 | pub struct List {
[INFO] [stderr]   | ^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variant is never constructed: `More`
[INFO] [stderr]   --> src/first.rs:11:5
[INFO] [stderr]    |
[INFO] [stderr] 11 |     More(Box<Node>),
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/first.rs:21:5
[INFO] [stderr]    |
[INFO] [stderr] 21 |     pub fn new()-> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push`
[INFO] [stderr]   --> src/first.rs:25:5
[INFO] [stderr]    |
[INFO] [stderr] 25 |     pub fn push(&mut self, elem: i32) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `pop`
[INFO] [stderr]   --> src/first.rs:33:5
[INFO] [stderr]    |
[INFO] [stderr] 33 |     pub fn pop(&mut self) -> Option<i32> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/second.rs:13:5
[INFO] [stderr]    |
[INFO] [stderr] 13 |     pub fn new() -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push`
[INFO] [stderr]   --> src/second.rs:17:5
[INFO] [stderr]    |
[INFO] [stderr] 17 |     pub fn push(&mut self, elem: T) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `peek`
[INFO] [stderr]   --> src/second.rs:33:5
[INFO] [stderr]    |
[INFO] [stderr] 33 |     pub fn peek(&self) -> Option<&T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `peek_mut`
[INFO] [stderr]   --> src/second.rs:37:5
[INFO] [stderr]    |
[INFO] [stderr] 37 |     pub fn peek_mut(&mut self) -> Option<&mut T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `IntoIter`
[INFO] [stderr]   --> src/second.rs:47:1
[INFO] [stderr]    |
[INFO] [stderr] 47 | pub struct IntoIter<T> {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `into_iter`
[INFO] [stderr]   --> src/second.rs:52:5
[INFO] [stderr]    |
[INFO] [stderr] 52 |     pub fn into_iter(self) -> IntoIter<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `Iter`
[INFO] [stderr]   --> src/second.rs:65:1
[INFO] [stderr]    |
[INFO] [stderr] 65 | pub struct Iter<'a, T> {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `iter`
[INFO] [stderr]   --> src/second.rs:70:5
[INFO] [stderr]    |
[INFO] [stderr] 70 |     pub fn iter<'a>(&'a self) -> Iter<'a, T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `IterMut`
[INFO] [stderr]   --> src/second.rs:87:1
[INFO] [stderr]    |
[INFO] [stderr] 87 | pub struct IterMut<'a, T> {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `iter_mut`
[INFO] [stderr]   --> src/second.rs:92:5
[INFO] [stderr]    |
[INFO] [stderr] 92 |     pub fn iter_mut(&mut self) -> IterMut<'_, T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `List`
[INFO] [stderr]  --> src/third.rs:3:1
[INFO] [stderr]   |
[INFO] [stderr] 3 | pub struct List<T> {
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/third.rs:15:5
[INFO] [stderr]    |
[INFO] [stderr] 15 |     pub fn new() -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `append`
[INFO] [stderr]   --> src/third.rs:18:5
[INFO] [stderr]    |
[INFO] [stderr] 18 |     pub fn append(&self, elem: T) -> List<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `tail`
[INFO] [stderr]   --> src/third.rs:26:5
[INFO] [stderr]    |
[INFO] [stderr] 26 |     pub fn tail(&self) -> List<T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `head`
[INFO] [stderr]   --> src/third.rs:31:5
[INFO] [stderr]    |
[INFO] [stderr] 31 |     pub fn head(&self) -> Option<&T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: struct is never constructed: `Iter`
[INFO] [stderr]   --> src/third.rs:36:1
[INFO] [stderr]    |
[INFO] [stderr] 36 | pub struct Iter<'a, T> {
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `iter`
[INFO] [stderr]   --> src/third.rs:41:5
[INFO] [stderr]    |
[INFO] [stderr] 41 |     pub fn iter(&self) -> Iter<'_, T> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: type alias is never used: `Link`
[INFO] [stderr]  --> src/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/fourth.rs:11:1
[INFO] [stderr]    |
[INFO] [stderr] 11 | struct Node<T> {
[INFO] [stderr]    | ^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `new`
[INFO] [stderr]   --> src/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/fourth.rs:28:5
[INFO] [stderr]    |
[INFO] [stderr] 28 |     pub fn new() -> Self {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push_front`
[INFO] [stderr]   --> src/fourth.rs:34:5
[INFO] [stderr]    |
[INFO] [stderr] 34 |     pub fn push_front(&mut self, elem: T) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push_back`
[INFO] [stderr]   --> src/fourth.rs:64:5
[INFO] [stderr]    |
[INFO] [stderr] 64 |     pub fn push_back(&mut self, elem: T) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `peek_front`
[INFO] [stderr]   --> src/fourth.rs:76:5
[INFO] [stderr]    |
[INFO] [stderr] 76 |     pub fn peek_front(&self) -> Option<Ref<T>> {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `old_tail`
[INFO] [stderr]   --> src/fourth.rs:67:18
[INFO] [stderr]    |
[INFO] [stderr] 67 |             Some(old_tail) => {
[INFO] [stderr]    |                  ^^^^^^^^ help: consider prefixing with an underscore: `_old_tail`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: method is never used: `push_back`
[INFO] [stderr]   --> src/fourth.rs:64:5
[INFO] [stderr]    |
[INFO] [stderr] 64 |     pub fn push_back(&mut self, elem: T) {
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.53s
[INFO] running `"docker" "inspect" "44cb2209ce3f869e7d0a483d4a2b6a66a25ee2e70c06362e13c0ac02cd628685"`
[INFO] running `"docker" "rm" "-f" "44cb2209ce3f869e7d0a483d4a2b6a66a25ee2e70c06362e13c0ac02cd628685"`
[INFO] [stdout] 44cb2209ce3f869e7d0a483d4a2b6a66a25ee2e70c06362e13c0ac02cd628685