[INFO] cloning repository https://github.com/ryota-sakamoto/rust_study
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/ryota-sakamoto/rust_study" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fryota-sakamoto%2Frust_study", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fryota-sakamoto%2Frust_study'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 5eb4f8bec1711983c25dcc199f9e5c1cb2a2aa47
[INFO] checking ryota-sakamoto/rust_study against try#f47dd4da3ae8c32c9e65d307bfe640b143e674df for pr-77526
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fryota-sakamoto%2Frust_study" "/workspace/builds/worker-14/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-14/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/ryota-sakamoto/rust_study on toolchain f47dd4da3ae8c32c9e65d307bfe640b143e674df
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/ryota-sakamoto/rust_study
[INFO] finished tweaking git repo https://github.com/ryota-sakamoto/rust_study
[INFO] tweaked toml for git repo https://github.com/ryota-sakamoto/rust_study written to /workspace/builds/worker-14/source/Cargo.toml
[INFO] crate git repo https://github.com/ryota-sakamoto/rust_study already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 7b57d0937ed627e19ec0aed61a03024395278137d2c070095e8e8067bc9fd6bf
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "7b57d0937ed627e19ec0aed61a03024395278137d2c070095e8e8067bc9fd6bf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7b57d0937ed627e19ec0aed61a03024395278137d2c070095e8e8067bc9fd6bf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7b57d0937ed627e19ec0aed61a03024395278137d2c070095e8e8067bc9fd6bf", kill_on_drop: false }`
[INFO] [stdout] 7b57d0937ed627e19ec0aed61a03024395278137d2c070095e8e8067bc9fd6bf
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] bed3f168e0eeaf592dac307a6b89382c354943f16070b33988321f4cc833e76f
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "bed3f168e0eeaf592dac307a6b89382c354943f16070b33988321f4cc833e76f", kill_on_drop: false }`
[INFO] [stderr]     Checking rand v0.4.2
[INFO] [stderr]     Checking rust_test v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused macro definition
[INFO] [stdout]   --> src/list.rs:53:1
[INFO] [stdout]    |
[INFO] [stdout] 53 | / macro_rules! list {
[INFO] [stdout] 54 | |     ($($n: expr),*) => {
[INFO] [stdout] 55 | |         {
[INFO] [stdout] 56 | |             let mut list = List::empty_list();
[INFO] [stdout] ...  |
[INFO] [stdout] 74 | |     };
[INFO] [stdout] 75 | | }
[INFO] [stdout]    | |_^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_macros)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused macro definition
[INFO] [stdout]   --> src/list.rs:53:1
[INFO] [stdout]    |
[INFO] [stdout] 53 | / macro_rules! list {
[INFO] [stdout] 54 | |     ($($n: expr),*) => {
[INFO] [stdout] 55 | |         {
[INFO] [stdout] 56 | |             let mut list = List::empty_list();
[INFO] [stdout] ...  |
[INFO] [stdout] 74 | |     };
[INFO] [stdout] 75 | | }
[INFO] [stdout]    | |_^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_macros)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `call`
[INFO] [stdout]  --> src/module.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn call() {
[INFO] [stdout]   |        ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Nil`
[INFO] [stdout]  --> src/list.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 |     Nil,
[INFO] [stdout]   |     ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `List`
[INFO] [stdout]  --> src/list.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | /     List {
[INFO] [stdout] 7 | |         head: T,
[INFO] [stdout] 8 | |         tail: Box<List<T>>,
[INFO] [stdout] 9 | |     }
[INFO] [stdout]   | |_____^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `empty_list`
[INFO] [stdout]   --> src/list.rs:13:12
[INFO] [stdout]    |
[INFO] [stdout] 13 |     pub fn empty_list() -> List<T> {
[INFO] [stdout]    |            ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `prepend`
[INFO] [stdout]   --> src/list.rs:17:12
[INFO] [stdout]    |
[INFO] [stdout] 17 |     pub fn prepend(self, t: T) -> Self {
[INFO] [stdout]    |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `head`
[INFO] [stdout]   --> src/list.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 |     pub fn head(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `last`
[INFO] [stdout]   --> src/list.rs:31:12
[INFO] [stdout]    |
[INFO] [stdout] 31 |     pub fn last(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `is_empty`
[INFO] [stdout]   --> src/list.rs:44:8
[INFO] [stdout]    |
[INFO] [stdout] 44 |     fn is_empty(&self) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `tailrec`
[INFO] [stdout]   --> src/list.rs:87:4
[INFO] [stdout]    |
[INFO] [stdout] 87 | fn tailrec<T: Debug>(list: &List<T>) {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:27:26
[INFO] [stdout]    |
[INFO] [stdout] 27 |             &List::List {head: ref head, tail: _} => head,
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_shorthand_field_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:26
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:42
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:22
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:38
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `call`
[INFO] [stdout]  --> src/module.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn call() {
[INFO] [stdout]   |        ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Nil`
[INFO] [stdout]  --> src/list.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 |     Nil,
[INFO] [stdout]   |     ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `List`
[INFO] [stdout]  --> src/list.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | /     List {
[INFO] [stdout] 7 | |         head: T,
[INFO] [stdout] 8 | |         tail: Box<List<T>>,
[INFO] [stdout] 9 | |     }
[INFO] [stdout]   | |_____^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `empty_list`
[INFO] [stdout]   --> src/list.rs:13:12
[INFO] [stdout]    |
[INFO] [stdout] 13 |     pub fn empty_list() -> List<T> {
[INFO] [stdout]    |            ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `prepend`
[INFO] [stdout]   --> src/list.rs:17:12
[INFO] [stdout]    |
[INFO] [stdout] 17 |     pub fn prepend(self, t: T) -> Self {
[INFO] [stdout]    |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `head`
[INFO] [stdout]   --> src/list.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 |     pub fn head(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `last`
[INFO] [stdout]   --> src/list.rs:31:12
[INFO] [stdout]    |
[INFO] [stdout] 31 |     pub fn last(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `is_empty`
[INFO] [stdout]   --> src/list.rs:44:8
[INFO] [stdout]    |
[INFO] [stdout] 44 |     fn is_empty(&self) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `tailrec`
[INFO] [stdout]   --> src/list.rs:87:4
[INFO] [stdout]    |
[INFO] [stdout] 87 | fn tailrec<T: Debug>(list: &List<T>) {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:27:26
[INFO] [stdout]    |
[INFO] [stdout] 27 |             &List::List {head: ref head, tail: _} => head,
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_shorthand_field_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:26
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:42
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:22
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:38
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 15 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 15 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused macro definition
[INFO] [stdout]   --> src/list.rs:53:1
[INFO] [stdout]    |
[INFO] [stdout] 53 | / macro_rules! list {
[INFO] [stdout] 54 | |     ($($n: expr),*) => {
[INFO] [stdout] 55 | |         {
[INFO] [stdout] 56 | |             let mut list = List::empty_list();
[INFO] [stdout] ...  |
[INFO] [stdout] 74 | |     };
[INFO] [stdout] 75 | | }
[INFO] [stdout]    | |_^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_macros)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/main.rs:78:19
[INFO] [stdout]    |
[INFO] [stdout] 78 |     let func: Box<Fn(u64) -> u64> = Box::new(|a| a.pow(2));
[INFO] [stdout]    |                   ^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(u64) -> u64`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused macro definition
[INFO] [stdout]   --> src/list.rs:53:1
[INFO] [stdout]    |
[INFO] [stdout] 53 | / macro_rules! list {
[INFO] [stdout] 54 | |     ($($n: expr),*) => {
[INFO] [stdout] 55 | |         {
[INFO] [stdout] 56 | |             let mut list = List::empty_list();
[INFO] [stdout] ...  |
[INFO] [stdout] 74 | |     };
[INFO] [stdout] 75 | | }
[INFO] [stdout]    | |_^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_macros)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/main.rs:78:19
[INFO] [stdout]    |
[INFO] [stdout] 78 |     let func: Box<Fn(u64) -> u64> = Box::new(|a| a.pow(2));
[INFO] [stdout]    |                   ^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(u64) -> u64`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `head`
[INFO] [stdout]   --> src/list.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 |     pub fn head(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `last`
[INFO] [stdout]   --> src/list.rs:31:12
[INFO] [stdout]    |
[INFO] [stdout] 31 |     pub fn last(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `is_empty`
[INFO] [stdout]   --> src/list.rs:44:8
[INFO] [stdout]    |
[INFO] [stdout] 44 |     fn is_empty(&self) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `tailrec`
[INFO] [stdout]   --> src/list.rs:87:4
[INFO] [stdout]    |
[INFO] [stdout] 87 | fn tailrec<T: Debug>(list: &List<T>) {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:27:26
[INFO] [stdout]    |
[INFO] [stdout] 27 |             &List::List {head: ref head, tail: _} => head,
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_shorthand_field_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:26
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:42
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:22
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:38
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `head`
[INFO] [stdout]   --> src/list.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 |     pub fn head(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `last`
[INFO] [stdout]   --> src/list.rs:31:12
[INFO] [stdout]    |
[INFO] [stdout] 31 |     pub fn last(&self) -> &T {
[INFO] [stdout]    |            ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `is_empty`
[INFO] [stdout]   --> src/list.rs:44:8
[INFO] [stdout]    |
[INFO] [stdout] 44 |     fn is_empty(&self) -> bool {
[INFO] [stdout]    |        ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `tailrec`
[INFO] [stdout]   --> src/list.rs:87:4
[INFO] [stdout]    |
[INFO] [stdout] 87 | fn tailrec<T: Debug>(list: &List<T>) {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:27:26
[INFO] [stdout]    |
[INFO] [stdout] 27 |             &List::List {head: ref head, tail: _} => head,
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_shorthand_field_patterns)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:26
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:34:42
[INFO] [stdout]    |
[INFO] [stdout] 34 |             &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                          ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `head:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:22
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref head`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the `tail:` in this pattern is redundant
[INFO] [stdout]   --> src/list.rs:90:38
[INFO] [stdout]    |
[INFO] [stdout] 90 |         &List::List {head: ref head, tail: ref tail} => {
[INFO] [stdout]    |                                      ^^^^^^^^^^^^^^ help: use shorthand field pattern: `ref tail`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 11 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 11 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 2.41s
[INFO] running `Command { std: "docker" "inspect" "bed3f168e0eeaf592dac307a6b89382c354943f16070b33988321f4cc833e76f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bed3f168e0eeaf592dac307a6b89382c354943f16070b33988321f4cc833e76f", kill_on_drop: false }`
[INFO] [stdout] bed3f168e0eeaf592dac307a6b89382c354943f16070b33988321f4cc833e76f