[INFO] updating cached repository https://github.com/sanevillain/rust_intro
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] fd8a87eac661a6748b7abf2a65346421e1ce013a
[INFO] testing sanevillain/rust_intro against try#41997647ba6a77908f6ef64401414feb00bccf16 for pr-71274
[INFO] running `"git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsanevillain%2Frust_intro" "/workspace/builds/worker-13/source"`
[INFO] [stderr] Cloning into '/workspace/builds/worker-13/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/sanevillain/rust_intro on toolchain 41997647ba6a77908f6ef64401414feb00bccf16
[INFO] running `"/workspace/cargo-home/bin/cargo" "+41997647ba6a77908f6ef64401414feb00bccf16" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/sanevillain/rust_intro
[INFO] finished tweaking git repo https://github.com/sanevillain/rust_intro
[INFO] tweaked toml for git repo https://github.com/sanevillain/rust_intro written to /workspace/builds/worker-13/source/Cargo.toml
[INFO] crate git repo https://github.com/sanevillain/rust_intro already has a lockfile, it will not be regenerated
[INFO] running `"/workspace/cargo-home/bin/cargo" "+41997647ba6a77908f6ef64401414feb00bccf16" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+41997647ba6a77908f6ef64401414feb00bccf16" "build" "--frozen"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] d6e044ed9bf1a397b3689d4cd7367aeae50d68338388a3cc2ae937ee1596375f
[INFO] running `"docker" "start" "-a" "d6e044ed9bf1a397b3689d4cd7367aeae50d68338388a3cc2ae937ee1596375f"`
[INFO] [stderr]    Compiling play_ground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]  --> src/main.rs:3:9
[INFO] [stderr]   |
[INFO] [stderr] 3 |     let x = 5;
[INFO] [stderr]   |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable `y` is assigned to, but never used
[INFO] [stderr]  --> src/main.rs:6:9
[INFO] [stderr]   |
[INFO] [stderr] 6 |     let mut y = 10;
[INFO] [stderr]   |         ^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: consider using `_y` instead
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `y` is never read
[INFO] [stderr]  --> src/main.rs:7:5
[INFO] [stderr]   |
[INFO] [stderr] 7 |     y += 1;
[INFO] [stderr]   |     ^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr]   = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]   --> src/main.rs:15:9
[INFO] [stderr]    |
[INFO] [stderr] 15 |     let a = 1 + 21;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `s`
[INFO] [stderr]   --> src/main.rs:16:9
[INFO] [stderr]    |
[INFO] [stderr] 16 |     let s = 30 - 20;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `m`
[INFO] [stderr]   --> src/main.rs:17:9
[INFO] [stderr]    |
[INFO] [stderr] 17 |     let m = 5 * 10;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_m`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `d`
[INFO] [stderr]   --> src/main.rs:18:9
[INFO] [stderr]    |
[INFO] [stderr] 18 |     let d = 4 / 6;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_d`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `r`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let r = 49 % 2;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_r`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `t`
[INFO] [stderr]   --> src/main.rs:22:9
[INFO] [stderr]    |
[INFO] [stderr] 22 |     let t: bool = true;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_t`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `f`
[INFO] [stderr]   --> src/main.rs:23:9
[INFO] [stderr]    |
[INFO] [stderr] 23 |     let f: bool = false;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `c`
[INFO] [stderr]   --> src/main.rs:26:9
[INFO] [stderr]    |
[INFO] [stderr] 26 |     let c: char = 'z';
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `z`
[INFO] [stderr]   --> src/main.rs:32:10
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |          ^ help: if this is intentional, prefix it with an underscore: `_z`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/main.rs:32:13
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |             ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/main.rs:32:16
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |                ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x1`
[INFO] [stderr]   --> src/main.rs:35:16
[INFO] [stderr]    |
[INFO] [stderr] 35 |     let (_, _, x1) = t;
[INFO] [stderr]    |                ^^ help: if this is intentional, prefix it with an underscore: `_x1`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]   --> src/main.rs:41:9
[INFO] [stderr]    |
[INFO] [stderr] 41 |     let a = [1, 2, 3, 4, 5, 6, 7, 8];
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: 16 warnings emitted
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 1.00s
[INFO] running `"docker" "inspect" "d6e044ed9bf1a397b3689d4cd7367aeae50d68338388a3cc2ae937ee1596375f"`
[INFO] running `"docker" "rm" "-f" "d6e044ed9bf1a397b3689d4cd7367aeae50d68338388a3cc2ae937ee1596375f"`
[INFO] [stdout] d6e044ed9bf1a397b3689d4cd7367aeae50d68338388a3cc2ae937ee1596375f
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+41997647ba6a77908f6ef64401414feb00bccf16" "test" "--frozen" "--no-run"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 21cf681fd1aaf2667126d6bffa95c9553808fca054f512f7c828a58a8d7ee2a3
[INFO] running `"docker" "start" "-a" "21cf681fd1aaf2667126d6bffa95c9553808fca054f512f7c828a58a8d7ee2a3"`
[INFO] [stderr]    Compiling play_ground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]  --> src/main.rs:3:9
[INFO] [stderr]   |
[INFO] [stderr] 3 |     let x = 5;
[INFO] [stderr]   |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable `y` is assigned to, but never used
[INFO] [stderr]  --> src/main.rs:6:9
[INFO] [stderr]   |
[INFO] [stderr] 6 |     let mut y = 10;
[INFO] [stderr]   |         ^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: consider using `_y` instead
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `y` is never read
[INFO] [stderr]  --> src/main.rs:7:5
[INFO] [stderr]   |
[INFO] [stderr] 7 |     y += 1;
[INFO] [stderr]   |     ^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr]   = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]   --> src/main.rs:15:9
[INFO] [stderr]    |
[INFO] [stderr] 15 |     let a = 1 + 21;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `s`
[INFO] [stderr]   --> src/main.rs:16:9
[INFO] [stderr]    |
[INFO] [stderr] 16 |     let s = 30 - 20;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `m`
[INFO] [stderr]   --> src/main.rs:17:9
[INFO] [stderr]    |
[INFO] [stderr] 17 |     let m = 5 * 10;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_m`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `d`
[INFO] [stderr]   --> src/main.rs:18:9
[INFO] [stderr]    |
[INFO] [stderr] 18 |     let d = 4 / 6;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_d`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `r`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let r = 49 % 2;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_r`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `t`
[INFO] [stderr]   --> src/main.rs:22:9
[INFO] [stderr]    |
[INFO] [stderr] 22 |     let t: bool = true;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_t`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `f`
[INFO] [stderr]   --> src/main.rs:23:9
[INFO] [stderr]    |
[INFO] [stderr] 23 |     let f: bool = false;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `c`
[INFO] [stderr]   --> src/main.rs:26:9
[INFO] [stderr]    |
[INFO] [stderr] 26 |     let c: char = 'z';
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `z`
[INFO] [stderr]   --> src/main.rs:32:10
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |          ^ help: if this is intentional, prefix it with an underscore: `_z`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/main.rs:32:13
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |             ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/main.rs:32:16
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |                ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x1`
[INFO] [stderr]   --> src/main.rs:35:16
[INFO] [stderr]    |
[INFO] [stderr] 35 |     let (_, _, x1) = t;
[INFO] [stderr]    |                ^^ help: if this is intentional, prefix it with an underscore: `_x1`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]   --> src/main.rs:41:9
[INFO] [stderr]    |
[INFO] [stderr] 41 |     let a = [1, 2, 3, 4, 5, 6, 7, 8];
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: 16 warnings emitted
[INFO] [stderr] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.84s
[INFO] running `"docker" "inspect" "21cf681fd1aaf2667126d6bffa95c9553808fca054f512f7c828a58a8d7ee2a3"`
[INFO] running `"docker" "rm" "-f" "21cf681fd1aaf2667126d6bffa95c9553808fca054f512f7c828a58a8d7ee2a3"`
[INFO] [stdout] 21cf681fd1aaf2667126d6bffa95c9553808fca054f512f7c828a58a8d7ee2a3
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+41997647ba6a77908f6ef64401414feb00bccf16" "test" "--frozen"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 95b54e9cba22803f2aadb39a691279bc2fe101f2936b053cc1c06d31edf89ed1
[INFO] running `"docker" "start" "-a" "95b54e9cba22803f2aadb39a691279bc2fe101f2936b053cc1c06d31edf89ed1"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]  --> src/main.rs:3:9
[INFO] [stderr]   |
[INFO] [stderr] 3 |     let x = 5;
[INFO] [stderr]   |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable `y` is assigned to, but never used
[INFO] [stderr]  --> src/main.rs:6:9
[INFO] [stderr]   |
[INFO] [stderr] 6 |     let mut y = 10;
[INFO] [stderr]   |         ^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: consider using `_y` instead
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `y` is never read
[INFO] [stderr]  --> src/main.rs:7:5
[INFO] [stderr]   |
[INFO] [stderr] 7 |     y += 1;
[INFO] [stderr]   |     ^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr]   = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]   --> src/main.rs:15:9
[INFO] [stderr]    |
[INFO] [stderr] 15 |     let a = 1 + 21;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `s`
[INFO] [stderr]   --> src/main.rs:16:9
[INFO] [stderr]    |
[INFO] [stderr] 16 |     let s = 30 - 20;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `m`
[INFO] [stderr]   --> src/main.rs:17:9
[INFO] [stderr]    |
[INFO] [stderr] 17 |     let m = 5 * 10;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_m`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `d`
[INFO] [stderr]   --> src/main.rs:18:9
[INFO] [stderr]    |
[INFO] [stderr] 18 |     let d = 4 / 6;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_d`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `r`
[INFO] [stderr]   --> src/main.rs:19:9
[INFO] [stderr]    |
[INFO] [stderr] 19 |     let r = 49 % 2;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_r`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `t`
[INFO] [stderr]   --> src/main.rs:22:9
[INFO] [stderr]    |
[INFO] [stderr] 22 |     let t: bool = true;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_t`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `f`
[INFO] [stderr]   --> src/main.rs:23:9
[INFO] [stderr]    |
[INFO] [stderr] 23 |     let f: bool = false;
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `c`
[INFO] [stderr]   --> src/main.rs:26:9
[INFO] [stderr]    |
[INFO] [stderr] 26 |     let c: char = 'z';
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `z`
[INFO] [stderr]   --> src/main.rs:32:10
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |          ^ help: if this is intentional, prefix it with an underscore: `_z`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `y`
[INFO] [stderr]   --> src/main.rs:32:13
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |             ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x`
[INFO] [stderr]   --> src/main.rs:32:16
[INFO] [stderr]    |
[INFO] [stderr] 32 |     let (z, y, x) = t;
[INFO] [stderr]    |                ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `x1`
[INFO] [stderr]   --> src/main.rs:35:16
[INFO] [stderr]    |
[INFO] [stderr] 35 |     let (_, _, x1) = t;
[INFO] [stderr]    |                ^^ help: if this is intentional, prefix it with an underscore: `_x1`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `a`
[INFO] [stderr]   --> src/main.rs:41:9
[INFO] [stderr]    |
[INFO] [stderr] 41 |     let a = [1, 2, 3, 4, 5, 6, 7, 8];
[INFO] [stderr]    |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stderr] 
[INFO] [stderr] warning: 16 warnings emitted
[INFO] [stderr] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.46s
[INFO] [stderr]      Running /opt/rustwide/target/debug/deps/play_ground-eb3c6845ee3cb458
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
[INFO] [stdout] 
[INFO] running `"docker" "inspect" "95b54e9cba22803f2aadb39a691279bc2fe101f2936b053cc1c06d31edf89ed1"`
[INFO] running `"docker" "rm" "-f" "95b54e9cba22803f2aadb39a691279bc2fe101f2936b053cc1c06d31edf89ed1"`
[INFO] [stdout] 95b54e9cba22803f2aadb39a691279bc2fe101f2936b053cc1c06d31edf89ed1