[INFO] fetching crate dgunther2001-linked_list 1.0.8...
[INFO] checking dgunther2001-linked_list-1.0.8 against master#cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c for pr-143170
[INFO] extracting crate dgunther2001-linked_list 1.0.8 into /workspace/builds/worker-1-tc1/source
[INFO] started tweaking crates.io crate dgunther2001-linked_list 1.0.8
[INFO] finished tweaking crates.io crate dgunther2001-linked_list 1.0.8
[INFO] tweaked toml for crates.io crate dgunther2001-linked_list 1.0.8 written to /workspace/builds/worker-1-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate dgunther2001-linked_list 1.0.8 on toolchain cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/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@sha256:90999bfc7ae267e83380e433d8e61a7c072ca6729e92edbae886d3423b3a6f4c" "/opt/rustwide/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 22bbc2aabfe4460a401cc8cb7a35688078feb4250d48cf9426fb53e3068b24cd
[INFO] running `Command { std: "docker" "start" "-a" "22bbc2aabfe4460a401cc8cb7a35688078feb4250d48cf9426fb53e3068b24cd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "22bbc2aabfe4460a401cc8cb7a35688078feb4250d48cf9426fb53e3068b24cd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "22bbc2aabfe4460a401cc8cb7a35688078feb4250d48cf9426fb53e3068b24cd", kill_on_drop: false }`
[INFO] [stdout] 22bbc2aabfe4460a401cc8cb7a35688078feb4250d48cf9426fb53e3068b24cd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/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@sha256:90999bfc7ae267e83380e433d8e61a7c072ca6729e92edbae886d3423b3a6f4c" "/opt/rustwide/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b2c32bff78fb7a03dec47ce30a9d57ef0b41d4d6f514686e0e37e173d103e42a
[INFO] running `Command { std: "docker" "start" "-a" "b2c32bff78fb7a03dec47ce30a9d57ef0b41d4d6f514686e0e37e173d103e42a", kill_on_drop: false }`
[INFO] [stderr]     Checking dgunther2001-linked_list v1.0.8 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `crate::linked_list::LinkedList`
[INFO] [stdout]  --> src/lib.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use crate::linked_list::LinkedList;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `n`
[INFO] [stdout]   --> src/linked_list.rs:89:18
[INFO] [stdout]    |
[INFO] [stdout] 89 |             Some(n) => {
[INFO] [stdout]    |                  ^ help: if this is intentional, prefix it with an underscore: `_n`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/linked_list.rs:221:33
[INFO] [stdout]     |
[INFO] [stdout] 221 | ...   self.head.as_mut().map(|mut n| &mut n.el) // if the mutable reference to self.head is None, return None, otherwise return a mutable...
[INFO] [stdout]     |                               ----^
[INFO] [stdout]     |                               |
[INFO] [stdout]     |                               help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: methods `next` and `iter` are never used
[INFO] [stdout]   --> src/linked_list.rs:29:8
[INFO] [stdout]    |
[INFO] [stdout] 21 | / impl <T> ListNode<T> 
[INFO] [stdout] 22 | | where T: Debug {
[INFO] [stdout]    | |______________- methods in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 29 |       fn next(&self) -> &Link<T> { // implementation of a next function
[INFO] [stdout]    |          ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 33 |       fn iter(&self) {
[INFO] [stdout]    |          ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `get_head_ref` is never used
[INFO] [stdout]    --> src/linked_list.rs:229:8
[INFO] [stdout]     |
[INFO] [stdout] 46  | / impl <T> LinkedList<T> 
[INFO] [stdout] 47  | | where T: Debug + Clone {
[INFO] [stdout]     | |______________________- method in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 229 |       fn get_head_ref(&self) -> Option<&ListNode<T>> {
[INFO] [stdout]     |          ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/linked_list.rs:388:17
[INFO] [stdout]     |
[INFO] [stdout] 388 |                 write!(f, "{} ", n.el);
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `n`
[INFO] [stdout]   --> src/linked_list.rs:89:18
[INFO] [stdout]    |
[INFO] [stdout] 89 |             Some(n) => {
[INFO] [stdout]    |                  ^ help: if this is intentional, prefix it with an underscore: `_n`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/linked_list.rs:221:33
[INFO] [stdout]     |
[INFO] [stdout] 221 | ...   self.head.as_mut().map(|mut n| &mut n.el) // if the mutable reference to self.head is None, return None, otherwise return a mutable...
[INFO] [stdout]     |                               ----^
[INFO] [stdout]     |                               |
[INFO] [stdout]     |                               help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: methods `next` and `iter` are never used
[INFO] [stdout]   --> src/linked_list.rs:29:8
[INFO] [stdout]    |
[INFO] [stdout] 21 | / impl <T> ListNode<T> 
[INFO] [stdout] 22 | | where T: Debug {
[INFO] [stdout]    | |______________- methods in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 29 |       fn next(&self) -> &Link<T> { // implementation of a next function
[INFO] [stdout]    |          ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 33 |       fn iter(&self) {
[INFO] [stdout]    |          ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `get_head_ref` is never used
[INFO] [stdout]    --> src/linked_list.rs:229:8
[INFO] [stdout]     |
[INFO] [stdout] 46  | / impl <T> LinkedList<T> 
[INFO] [stdout] 47  | | where T: Debug + Clone {
[INFO] [stdout]     | |______________________- method in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 229 |       fn get_head_ref(&self) -> Option<&ListNode<T>> {
[INFO] [stdout]     |          ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/linked_list.rs:388:17
[INFO] [stdout]     |
[INFO] [stdout] 388 |                 write!(f, "{} ", n.el);
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.30s
[INFO] running `Command { std: "docker" "inspect" "b2c32bff78fb7a03dec47ce30a9d57ef0b41d4d6f514686e0e37e173d103e42a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b2c32bff78fb7a03dec47ce30a9d57ef0b41d4d6f514686e0e37e173d103e42a", kill_on_drop: false }`
[INFO] [stdout] b2c32bff78fb7a03dec47ce30a9d57ef0b41d4d6f514686e0e37e173d103e42a