[INFO] cloning repository https://github.com/Eson-Jia/rust-play-ground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Eson-Jia/rust-play-ground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEson-Jia%2Frust-play-ground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEson-Jia%2Frust-play-ground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] dd185b73c3e92aa42d4c73412360dff9e16f1e7c
[INFO] checking Eson-Jia/rust-play-ground against try#2b39fe756f52bc2825bf5b2bfc385cab922dae10 for pr-143011
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEson-Jia%2Frust-play-ground" "/workspace/builds/worker-1-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/Eson-Jia/rust-play-ground
[INFO] finished tweaking git repo https://github.com/Eson-Jia/rust-play-ground
[INFO] tweaked toml for git repo https://github.com/Eson-Jia/rust-play-ground written to /workspace/builds/worker-1-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/Eson-Jia/rust-play-ground on toolchain 2b39fe756f52bc2825bf5b2bfc385cab922dae10
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+2b39fe756f52bc2825bf5b2bfc385cab922dae10" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/Eson-Jia/rust-play-ground 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" "+2b39fe756f52bc2825bf5b2bfc385cab922dae10" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/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" "+2b39fe756f52bc2825bf5b2bfc385cab922dae10" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c3745821e777944c2ebc339ea26d9ff2f5196a671da6f8091a23534a6065cd69
[INFO] running `Command { std: "docker" "start" "-a" "c3745821e777944c2ebc339ea26d9ff2f5196a671da6f8091a23534a6065cd69", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c3745821e777944c2ebc339ea26d9ff2f5196a671da6f8091a23534a6065cd69", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c3745821e777944c2ebc339ea26d9ff2f5196a671da6f8091a23534a6065cd69", kill_on_drop: false }`
[INFO] [stdout] c3745821e777944c2ebc339ea26d9ff2f5196a671da6f8091a23534a6065cd69
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc2/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" "+2b39fe756f52bc2825bf5b2bfc385cab922dae10" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] a48ce949e3fad8d767f3ec35747939f1ab033a140f5bc6c299ca22b5340fb5ea
[INFO] running `Command { std: "docker" "start" "-a" "a48ce949e3fad8d767f3ec35747939f1ab033a140f5bc6c299ca22b5340fb5ea", kill_on_drop: false }`
[INFO] [stderr]    Compiling autocfg v0.1.7
[INFO] [stderr]     Checking rand_core v0.4.2
[INFO] [stderr]    Compiling libc v0.2.71
[INFO] [stderr]     Checking rand_core v0.3.1
[INFO] [stderr]     Checking rand_jitter v0.1.4
[INFO] [stderr]     Checking rand_isaac v0.1.1
[INFO] [stderr]     Checking rand_xorshift v0.1.1
[INFO] [stderr]     Checking rand_hc v0.1.0
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]     Checking rand_os v0.1.3
[INFO] [stderr]     Checking play-ground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: function `test` is never used
[INFO] [stdout]   --> src/bin/functions.rs:11:4
[INFO] [stdout]    |
[INFO] [stdout] 11 | fn test(){
[INFO] [stdout]    |    ^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `other_error`
[INFO] [stdout]   --> src/bin/match_result.rs:12:14
[INFO] [stdout]    |
[INFO] [stdout] 12 |              other_error =>panic!(""),
[INFO] [stdout]    |              ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_other_error`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `v`
[INFO] [stdout]  --> src/bin/vector.rs:3:9
[INFO] [stdout]   |
[INFO] [stdout] 3 |     let v: Vec<i32> = Vec::new();
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_v`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `v`
[INFO] [stdout]  --> src/bin/vector.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |     let v = vec![123,12];
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_v`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `first`
[INFO] [stdout]   --> src/bin/vector.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let first = v[0];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_first`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `second`
[INFO] [stdout]   --> src/bin/vector.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let second  = v.get(1);
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_second`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `does_not_exist`
[INFO] [stdout]   --> src/bin/vector.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let does_not_exist  = v[100];
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_does_not_exist`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `does_not_exist`
[INFO] [stdout]   --> src/bin/vector.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let does_not_exist= v.get(100);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_does_not_exist`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]  --> src/bin/data_type.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |     let c = 'a';
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `five_hundred`
[INFO] [stdout]   --> src/bin/data_type.rs:16:9
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let five_hundred = tup.0;
[INFO] [stdout]    |         ^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_five_hundred`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `six_point_four`
[INFO] [stdout]   --> src/bin/data_type.rs:17:9
[INFO] [stdout]    |
[INFO] [stdout] 17 |     let six_point_four = tup.1;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_six_point_four`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `one`
[INFO] [stdout]   --> src/bin/data_type.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let one = tup.2;
[INFO] [stdout]    |         ^^^ help: if this is intentional, prefix it with an underscore: `_one`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/data_type.rs:21:9
[INFO] [stdout]    |
[INFO] [stdout] 21 |     let a =[1,2,3,4,5];
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/data_type.rs:23:9
[INFO] [stdout]    |
[INFO] [stdout] 23 |     let a:[i32;5]= [1,2,3,4,5];
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `first`
[INFO] [stdout]   --> src/bin/data_type.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let first = a[0];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_first`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `second`
[INFO] [stdout]   --> src/bin/data_type.rs:28:9
[INFO] [stdout]    |
[INFO] [stdout] 28 |     let second  = a[1];
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_second`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a2`
[INFO] [stdout]   --> src/bin/data_type.rs:30:15
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let[a0,a1,a2,a3,a4] = a;
[INFO] [stdout]    |               ^^ help: if this is intentional, prefix it with an underscore: `_a2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a3`
[INFO] [stdout]   --> src/bin/data_type.rs:30:18
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let[a0,a1,a2,a3,a4] = a;
[INFO] [stdout]    |                  ^^ help: if this is intentional, prefix it with an underscore: `_a3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a4`
[INFO] [stdout]   --> src/bin/data_type.rs:30:21
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let[a0,a1,a2,a3,a4] = a;
[INFO] [stdout]    |                     ^^ help: if this is intentional, prefix it with an underscore: `_a4`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/vector.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let mut v = vec![1,2,3,4,5];
[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] error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
[INFO] [stdout]   --> src/bin/vector.rs:26:5
[INFO] [stdout]    |
[INFO] [stdout] 25 |     let first =  &v[0];
[INFO] [stdout]    |                   - immutable borrow occurs here
[INFO] [stdout] 26 |     v.push(6);
[INFO] [stdout]    |     ^^^^^^^^^ mutable borrow occurs here
[INFO] [stdout] 27 |     println!("the first element is :{}",first);
[INFO] [stdout]    |                                         ----- immutable borrow later used here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `other_error`
[INFO] [stdout]   --> src/bin/match_result.rs:12:14
[INFO] [stdout]    |
[INFO] [stdout] 12 |              other_error =>panic!(""),
[INFO] [stdout]    |              ^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_other_error`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0502`.
[INFO] [stdout] 
[INFO] [stdout] warning: function `test1` is never used
[INFO] [stdout]  --> src/bin/functions.rs:5:8
[INFO] [stdout]   |
[INFO] [stdout] 5 |     fn test1(a:String){
[INFO] [stdout]   |        ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `play-ground` (bin "vector" test) due to 1 previous error; 7 warnings emitted
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] warning: function `test` is never used
[INFO] [stdout]   --> src/bin/functions.rs:11:4
[INFO] [stdout]    |
[INFO] [stdout] 11 | fn test(){
[INFO] [stdout]    |    ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/match_result.rs:16:5
[INFO] [stdout]    |
[INFO] [stdout] 16 |     f.write(b"hello,world");
[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] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let _ = f.write(b"hello,world");
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/match_result.rs:17:5
[INFO] [stdout]    |
[INFO] [stdout] 17 |     f.read_to_string( & mut buff);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 17 |     let _ = f.read_to_string( & mut buff);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]  --> src/bin/data_type.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |     let c = 'a';
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `five_hundred`
[INFO] [stdout]   --> src/bin/data_type.rs:16:9
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let five_hundred = tup.0;
[INFO] [stdout]    |         ^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_five_hundred`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `six_point_four`
[INFO] [stdout]   --> src/bin/data_type.rs:17:9
[INFO] [stdout]    |
[INFO] [stdout] 17 |     let six_point_four = tup.1;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_six_point_four`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `one`
[INFO] [stdout]   --> src/bin/data_type.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let one = tup.2;
[INFO] [stdout]    |         ^^^ help: if this is intentional, prefix it with an underscore: `_one`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/data_type.rs:21:9
[INFO] [stdout]    |
[INFO] [stdout] 21 |     let a =[1,2,3,4,5];
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/bin/data_type.rs:23:9
[INFO] [stdout]    |
[INFO] [stdout] 23 |     let a:[i32;5]= [1,2,3,4,5];
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `first`
[INFO] [stdout]   --> src/bin/data_type.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let first = a[0];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_first`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `second`
[INFO] [stdout]   --> src/bin/data_type.rs:28:9
[INFO] [stdout]    |
[INFO] [stdout] 28 |     let second  = a[1];
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_second`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a2`
[INFO] [stdout]   --> src/bin/data_type.rs:30:15
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let[a0,a1,a2,a3,a4] = a;
[INFO] [stdout]    |               ^^ help: if this is intentional, prefix it with an underscore: `_a2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a3`
[INFO] [stdout]   --> src/bin/data_type.rs:30:18
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let[a0,a1,a2,a3,a4] = a;
[INFO] [stdout]    |                  ^^ help: if this is intentional, prefix it with an underscore: `_a3`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a4`
[INFO] [stdout]   --> src/bin/data_type.rs:30:21
[INFO] [stdout]    |
[INFO] [stdout] 30 |     let[a0,a1,a2,a3,a4] = a;
[INFO] [stdout]    |                     ^^ help: if this is intentional, prefix it with an underscore: `_a4`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/match_result.rs:16:5
[INFO] [stdout]    |
[INFO] [stdout] 16 |     f.write(b"hello,world");
[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] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let _ = f.write(b"hello,world");
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/match_result.rs:17:5
[INFO] [stdout]    |
[INFO] [stdout] 17 |     f.read_to_string( & mut buff);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 17 |     let _ = f.read_to_string( & mut buff);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `v`
[INFO] [stdout]  --> src/bin/vector.rs:3:9
[INFO] [stdout]   |
[INFO] [stdout] 3 |     let v: Vec<i32> = Vec::new();
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_v`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `v`
[INFO] [stdout]  --> src/bin/vector.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |     let v = vec![123,12];
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_v`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `first`
[INFO] [stdout]   --> src/bin/vector.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let first = v[0];
[INFO] [stdout]    |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_first`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `second`
[INFO] [stdout]   --> src/bin/vector.rs:15:9
[INFO] [stdout]    |
[INFO] [stdout] 15 |     let second  = v.get(1);
[INFO] [stdout]    |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_second`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `does_not_exist`
[INFO] [stdout]   --> src/bin/vector.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let does_not_exist  = v[100];
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_does_not_exist`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `does_not_exist`
[INFO] [stdout]   --> src/bin/vector.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let does_not_exist= v.get(100);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_does_not_exist`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/vector.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let mut v = vec![1,2,3,4,5];
[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] error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable
[INFO] [stdout]   --> src/bin/vector.rs:26:5
[INFO] [stdout]    |
[INFO] [stdout] 25 |     let first =  &v[0];
[INFO] [stdout]    |                   - immutable borrow occurs here
[INFO] [stdout] 26 |     v.push(6);
[INFO] [stdout]    |     ^^^^^^^^^ mutable borrow occurs here
[INFO] [stdout] 27 |     println!("the first element is :{}",first);
[INFO] [stdout]    |                                         ----- immutable borrow later used here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function `square` is never used
[INFO] [stdout]   --> src/bin/method.rs:18:8
[INFO] [stdout]    |
[INFO] [stdout] 7  | impl Rectangle {
[INFO] [stdout]    | -------------- associated function in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 18 |     fn square(size:u32) ->Rectangle{
[INFO] [stdout]    |        ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `size` is never used
[INFO] [stdout]   --> src/bin/method.rs:28:8
[INFO] [stdout]    |
[INFO] [stdout] 27 | impl Rectangle {
[INFO] [stdout]    | -------------- method in this implementation
[INFO] [stdout] 28 |     fn size(&self)->(u32,u32){
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0502`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `play-ground` (bin "vector") due to 1 previous error; 7 warnings emitted
[INFO] [stdout] warning: associated function `square` is never used
[INFO] [stdout]   --> src/bin/method.rs:18:8
[INFO] [stdout]    |
[INFO] [stdout] 7  | impl Rectangle {
[INFO] [stdout]    | -------------- associated function in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 18 |     fn square(size:u32) ->Rectangle{
[INFO] [stdout]    |        ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `size` is never used
[INFO] [stdout]   --> src/bin/method.rs:28:8
[INFO] [stdout]    |
[INFO] [stdout] 27 | impl Rectangle {
[INFO] [stdout]    | -------------- method in this implementation
[INFO] [stdout] 28 |     fn size(&self)->(u32,u32){
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "a48ce949e3fad8d767f3ec35747939f1ab033a140f5bc6c299ca22b5340fb5ea", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a48ce949e3fad8d767f3ec35747939f1ab033a140f5bc6c299ca22b5340fb5ea", kill_on_drop: false }`
[INFO] [stdout] a48ce949e3fad8d767f3ec35747939f1ab033a140f5bc6c299ca22b5340fb5ea
