[INFO] cloning repository https://github.com/lao-dongxi/Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/lao-dongxi/Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flao-dongxi%2FRust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flao-dongxi%2FRust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 2585d39b52666d7bef86c31802f08a596e3abb30
[INFO] checking lao-dongxi/Rust against master#ecb170afc878648c3ae355dbd596c8e4b6f7ebdc for pr-139022
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flao-dongxi%2FRust" "/workspace/builds/worker-7-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/lao-dongxi/Rust on toolchain ecb170afc878648c3ae355dbd596c8e4b6f7ebdc
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+ecb170afc878648c3ae355dbd596c8e4b6f7ebdc" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/lao-dongxi/Rust
[INFO] finished tweaking git repo https://github.com/lao-dongxi/Rust
[INFO] tweaked toml for git repo https://github.com/lao-dongxi/Rust written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/lao-dongxi/Rust 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" "+ecb170afc878648c3ae355dbd596c8e4b6f7ebdc" "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-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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@sha256:4b26683ee3c49f365255c425c23003cbf4366de097804722c29c5bbbee3624d2" "/opt/rustwide/cargo-home/bin/cargo" "+ecb170afc878648c3ae355dbd596c8e4b6f7ebdc" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 1fa2aa646985898b42bfa82e5a27ff8cb6d20f9a009b7e35a44927e3354887d7
[INFO] running `Command { std: "docker" "start" "-a" "1fa2aa646985898b42bfa82e5a27ff8cb6d20f9a009b7e35a44927e3354887d7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1fa2aa646985898b42bfa82e5a27ff8cb6d20f9a009b7e35a44927e3354887d7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1fa2aa646985898b42bfa82e5a27ff8cb6d20f9a009b7e35a44927e3354887d7", kill_on_drop: false }`
[INFO] [stdout] 1fa2aa646985898b42bfa82e5a27ff8cb6d20f9a009b7e35a44927e3354887d7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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@sha256:4b26683ee3c49f365255c425c23003cbf4366de097804722c29c5bbbee3624d2" "/opt/rustwide/cargo-home/bin/cargo" "+ecb170afc878648c3ae355dbd596c8e4b6f7ebdc" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5a354c62ec745f830afd3e5a9651ef0c08e375ff44e825833af67ac210b6ff2a
[INFO] running `Command { std: "docker" "start" "-a" "5a354c62ec745f830afd3e5a9651ef0c08e375ff44e825833af67ac210b6ff2a", kill_on_drop: false }`
[INFO] [stderr]     Checking Playground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `clone`
[INFO] [stdout]  --> src/lib.rs:1:11
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::{clone, fmt::{Debug, Display}};
[INFO] [stdout]   |           ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]   --> src/lib.rs:63:16
[INFO] [stdout]    |
[INFO] [stdout] 63 | pub fn notify7(s:&str)->impl Summary{
[INFO] [stdout]    |                ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `clone`
[INFO] [stdout]  --> src/lib.rs:1:11
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::{clone, fmt::{Debug, Display}};
[INFO] [stdout]   |           ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item2`
[INFO] [stdout]   --> src/lib.rs:41:34
[INFO] [stdout]    |
[INFO] [stdout] 41 | pub fn notify(item1:impl Summary,item2:impl Summary){ 
[INFO] [stdout]    |                                  ^^^^^ help: if this is intentional, prefix it with an underscore: `_item2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item2`
[INFO] [stdout]   --> src/lib.rs:44:34
[INFO] [stdout]    |
[INFO] [stdout] 44 | pub fn notify2<T:Summary>(item:T,item2:T){
[INFO] [stdout]    |                                  ^^^^^ help: if this is intentional, prefix it with an underscore: `_item2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/lib.rs:53:53
[INFO] [stdout]    |
[INFO] [stdout] 53 | pub fn notify5<T:Summary+Display,U:Clone+Debug>(a:T,b:U)->String{
[INFO] [stdout]    |                                                     ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/lib.rs:56:25
[INFO] [stdout]    |
[INFO] [stdout] 56 | pub fn notify6<T,U>(a:T,b:U)->String
[INFO] [stdout]    |                         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: crate `Playground` should have a snake case name
[INFO] [stdout]   |
[INFO] [stdout]   = help: convert the identifier to snake case: `playground`
[INFO] [stdout]   = note: `#[warn(non_snake_case)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]   --> src/lib.rs:63:16
[INFO] [stdout]    |
[INFO] [stdout] 63 | pub fn notify7(s:&str)->impl Summary{
[INFO] [stdout]    |                ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item2`
[INFO] [stdout]   --> src/lib.rs:41:34
[INFO] [stdout]    |
[INFO] [stdout] 41 | pub fn notify(item1:impl Summary,item2:impl Summary){ 
[INFO] [stdout]    |                                  ^^^^^ help: if this is intentional, prefix it with an underscore: `_item2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `item2`
[INFO] [stdout]   --> src/lib.rs:44:34
[INFO] [stdout]    |
[INFO] [stdout] 44 | pub fn notify2<T:Summary>(item:T,item2:T){
[INFO] [stdout]    |                                  ^^^^^ help: if this is intentional, prefix it with an underscore: `_item2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/lib.rs:53:53
[INFO] [stdout]    |
[INFO] [stdout] 53 | pub fn notify5<T:Summary+Display,U:Clone+Debug>(a:T,b:U)->String{
[INFO] [stdout]    |                                                     ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `b`
[INFO] [stdout]   --> src/lib.rs:56:25
[INFO] [stdout]    |
[INFO] [stdout] 56 | pub fn notify6<T,U>(a:T,b:U)->String
[INFO] [stdout]    |                         ^ help: if this is intentional, prefix it with an underscore: `_b`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `res`
[INFO] [stdout]  --> src/bin/result_test2.rs:7:9
[INFO] [stdout]   |
[INFO] [stdout] 7 |     let res=read_username_from_file();
[INFO] [stdout]   |         ^^^ help: if this is intentional, prefix it with an underscore: `_res`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `e`
[INFO] [stdout]  --> src/bin/result_test.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 |    let e=match v {
[INFO] [stdout]   |        ^ help: if this is intentional, prefix it with an underscore: `_e`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `q`
[INFO] [stdout]   --> src/bin/result_test.rs:20:9
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let q=File::open("china.txt").expect("找不到指定文件");
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_q`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type `user` should have an upper camel case name
[INFO] [stdout]   --> src/bin/lifetime_test.rs:25:8
[INFO] [stdout]    |
[INFO] [stdout] 25 | struct user<'a>{
[INFO] [stdout]    |        ^^^^ help: convert the identifier to upper camel case (notice the capitalization): `User`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_camel_case_types)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `u`
[INFO] [stdout]  --> src/bin/lifetime_test.rs:4:9
[INFO] [stdout]   |
[INFO] [stdout] 4 |     let u=user{
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_u`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `scor`
[INFO] [stdout]   --> src/bin/hashmap_test.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let scor:HashMap<_,_>=teams.iter().zip(initalscores.iter()).collect();
[INFO] [stdout]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_scor`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: methods `level` and `annouce_and_return_part` are never used
[INFO] [stdout]   --> src/bin/lifetime_test.rs:9:8
[INFO] [stdout]    |
[INFO] [stdout] 8  | impl <'a> user <'a>{
[INFO] [stdout]    | ------------------- methods in this implementation
[INFO] [stdout] 9  |     fn level(&self)->i32 {
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 12 |     fn annouce_and_return_part(&self,announcement:&str)->&str {
[INFO] [stdout]    |        ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `longest` is never used
[INFO] [stdout]   --> src/bin/lifetime_test.rs:17:4
[INFO] [stdout]    |
[INFO] [stdout] 17 | fn longest<'a>(x:&'a str,y:&'a str)->&'a str {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `part` is never read
[INFO] [stdout]   --> src/bin/lifetime_test.rs:26:5
[INFO] [stdout]    |
[INFO] [stdout] 25 | struct user<'a>{
[INFO] [stdout]    |        ---- field in this struct
[INFO] [stdout] 26 |     part:&'a str,
[INFO] [stdout]    |     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `longest_with_an_annoucement` is never used
[INFO] [stdout]   --> src/bin/lifetime_test.rs:29:4
[INFO] [stdout]    |
[INFO] [stdout] 29 | fn longest_with_an_annoucement<'a,T>(x:&'a str,y:&'a str,ann:T)->&'a str 
[INFO] [stdout]    |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `core::fmt`
[INFO] [stdout]  --> src/bin/string_test.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use core::fmt;
[INFO] [stdout]   |     ^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Playground::NewsArticle`
[INFO] [stdout]  --> src/bin/trait_test.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use Playground::NewsArticle;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `scor`
[INFO] [stdout]   --> src/bin/hashmap_test.rs:10:9
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let scor:HashMap<_,_>=teams.iter().zip(initalscores.iter()).collect();
[INFO] [stdout]    |         ^^^^ help: if this is intentional, prefix it with an underscore: `_scor`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `e`
[INFO] [stdout]  --> src/bin/result_test.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 |    let e=match v {
[INFO] [stdout]   |        ^ help: if this is intentional, prefix it with an underscore: `_e`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `q`
[INFO] [stdout]   --> src/bin/result_test.rs:20:9
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let q=File::open("china.txt").expect("找不到指定文件");
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_q`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Playground::NewsArticle`
[INFO] [stdout]  --> src/bin/trait_test.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use Playground::NewsArticle;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type `user` should have an upper camel case name
[INFO] [stdout]   --> src/bin/lifetime_test.rs:25:8
[INFO] [stdout]    |
[INFO] [stdout] 25 | struct user<'a>{
[INFO] [stdout]    |        ^^^^ help: convert the identifier to upper camel case (notice the capitalization): `User`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_camel_case_types)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `core::fmt`
[INFO] [stdout]  --> src/bin/string_test.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use core::fmt;
[INFO] [stdout]   |     ^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `res`
[INFO] [stdout]  --> src/bin/result_test2.rs:7:9
[INFO] [stdout]   |
[INFO] [stdout] 7 |     let res=read_username_from_file();
[INFO] [stdout]   |         ^^^ help: if this is intentional, prefix it with an underscore: `_res`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `u`
[INFO] [stdout]  --> src/bin/lifetime_test.rs:4:9
[INFO] [stdout]   |
[INFO] [stdout] 4 |     let u=user{
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_u`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: methods `level` and `annouce_and_return_part` are never used
[INFO] [stdout]   --> src/bin/lifetime_test.rs:9:8
[INFO] [stdout]    |
[INFO] [stdout] 8  | impl <'a> user <'a>{
[INFO] [stdout]    | ------------------- methods in this implementation
[INFO] [stdout] 9  |     fn level(&self)->i32 {
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 12 |     fn annouce_and_return_part(&self,announcement:&str)->&str {
[INFO] [stdout]    |        ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `longest` is never used
[INFO] [stdout]   --> src/bin/lifetime_test.rs:17:4
[INFO] [stdout]    |
[INFO] [stdout] 17 | fn longest<'a>(x:&'a str,y:&'a str)->&'a str {
[INFO] [stdout]    |    ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `part` is never read
[INFO] [stdout]   --> src/bin/lifetime_test.rs:26:5
[INFO] [stdout]    |
[INFO] [stdout] 25 | struct user<'a>{
[INFO] [stdout]    |        ---- field in this struct
[INFO] [stdout] 26 |     part:&'a str,
[INFO] [stdout]    |     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `longest_with_an_annoucement` is never used
[INFO] [stdout]   --> src/bin/lifetime_test.rs:29:4
[INFO] [stdout]    |
[INFO] [stdout] 29 | fn longest_with_an_annoucement<'a,T>(x:&'a str,y:&'a str,ann:T)->&'a str 
[INFO] [stdout]    |    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `first`
[INFO] [stdout]   --> src/bin/vec_test.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let first=&v[0];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_first`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `first`
[INFO] [stdout]   --> src/bin/vec_test.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let first=&v[0];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_first`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.45s
[INFO] running `Command { std: "docker" "inspect" "5a354c62ec745f830afd3e5a9651ef0c08e375ff44e825833af67ac210b6ff2a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5a354c62ec745f830afd3e5a9651ef0c08e375ff44e825833af67ac210b6ff2a", kill_on_drop: false }`
[INFO] [stdout] 5a354c62ec745f830afd3e5a9651ef0c08e375ff44e825833af67ac210b6ff2a