[INFO] cloning repository https://github.com/Rasarex/hangman_hardest_word
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Rasarex/hangman_hardest_word" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FRasarex%2Fhangman_hardest_word", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FRasarex%2Fhangman_hardest_word'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 1bf971719b7eb6ef29a781915808e5dbb2f811ce
[INFO] testing Rasarex/hangman_hardest_word against 1.60.0 for beta-1.61-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FRasarex%2Fhangman_hardest_word" "/workspace/builds/worker-9/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-9/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/Rasarex/hangman_hardest_word on toolchain 1.60.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/Rasarex/hangman_hardest_word
[INFO] finished tweaking git repo https://github.com/Rasarex/hangman_hardest_word
[INFO] tweaked toml for git repo https://github.com/Rasarex/hangman_hardest_word written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] crate git repo https://github.com/Rasarex/hangman_hardest_word already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "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-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 6c1741ca39280dd96c40fcfd01d1e2a69ba6cb0c49593bf7bb88bae0b04d243d
[INFO] running `Command { std: "docker" "start" "-a" "6c1741ca39280dd96c40fcfd01d1e2a69ba6cb0c49593bf7bb88bae0b04d243d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "6c1741ca39280dd96c40fcfd01d1e2a69ba6cb0c49593bf7bb88bae0b04d243d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6c1741ca39280dd96c40fcfd01d1e2a69ba6cb0c49593bf7bb88bae0b04d243d", kill_on_drop: false }`
[INFO] [stdout] 6c1741ca39280dd96c40fcfd01d1e2a69ba6cb0c49593bf7bb88bae0b04d243d
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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=warn" "-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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5be2d0d493d9364722208274f4f7a40fbb02e2828c35bfee38ff43949cb2e36d
[INFO] running `Command { std: "docker" "start" "-a" "5be2d0d493d9364722208274f4f7a40fbb02e2828c35bfee38ff43949cb2e36d", kill_on_drop: false }`
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling libc v0.2.74
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling regex-syntax v0.6.18
[INFO] [stderr]    Compiling thread_local v1.0.1
[INFO] [stderr]    Compiling aho-corasick v0.7.13
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling threadpool v1.8.1
[INFO] [stderr]    Compiling regex v1.3.9
[INFO] [stderr]    Compiling hardest_word v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/main.rs:87:17
[INFO] [stdout]    |
[INFO] [stdout] 87 |             let mut sorted = freq.to_sorted_vec();
[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: function is never used: `to_static_slice`
[INFO] [stdout]    --> src/main.rs:261:4
[INFO] [stdout]     |
[INFO] [stdout] 261 | fn to_static_slice<T : 'static >(vector : Vec<T>) -> &'static [T]{
[INFO] [stdout]     |    ^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(drain_filter)]
[INFO] [stdout]   |            ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `hardest_word` due to 2 previous errors; 2 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "5be2d0d493d9364722208274f4f7a40fbb02e2828c35bfee38ff43949cb2e36d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5be2d0d493d9364722208274f4f7a40fbb02e2828c35bfee38ff43949cb2e36d", kill_on_drop: false }`
[INFO] [stdout] 5be2d0d493d9364722208274f4f7a40fbb02e2828c35bfee38ff43949cb2e36d