[INFO] cloning repository https://github.com/illegalhex/adventofcode_2020
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/illegalhex/adventofcode_2020" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fillegalhex%2Fadventofcode_2020", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fillegalhex%2Fadventofcode_2020'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d83863d208f48f0ea23916b8ff48c7de935bf62f
[INFO] documenting illegalhex/adventofcode_2020 against 1.61.0 for beta-1.62-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fillegalhex%2Fadventofcode_2020" "/workspace/builds/worker-3/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/illegalhex/adventofcode_2020 on toolchain 1.61.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.61.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] removed /workspace/builds/worker-3/source/rust-toolchain
[INFO] started tweaking git repo https://github.com/illegalhex/adventofcode_2020
[INFO] finished tweaking git repo https://github.com/illegalhex/adventofcode_2020
[INFO] tweaked toml for git repo https://github.com/illegalhex/adventofcode_2020 written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/illegalhex/adventofcode_2020 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.61.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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:d190cb871061d98bc6d0581d85cb2ecb09a0f8a142ba5463de30be9999fc3251" "/opt/rustwide/cargo-home/bin/cargo" "+1.61.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 470c44e0452241ae906b665df330bcf57d947fcae39976ba45a1af23b3390043
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "470c44e0452241ae906b665df330bcf57d947fcae39976ba45a1af23b3390043", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "470c44e0452241ae906b665df330bcf57d947fcae39976ba45a1af23b3390043", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "470c44e0452241ae906b665df330bcf57d947fcae39976ba45a1af23b3390043", kill_on_drop: false }`
[INFO] [stdout] 470c44e0452241ae906b665df330bcf57d947fcae39976ba45a1af23b3390043
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "RUSTDOCFLAGS=--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:d190cb871061d98bc6d0581d85cb2ecb09a0f8a142ba5463de30be9999fc3251" "/opt/rustwide/cargo-home/bin/cargo" "+1.61.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 189302cb10523eddf4b9652ecd9e0677b27fae09aa046c7335f6469668a68c6d
[INFO] running `Command { std: "docker" "start" "-a" "189302cb10523eddf4b9652ecd9e0677b27fae09aa046c7335f6469668a68c6d", kill_on_drop: false }`
[INFO] [stderr]     Checking either v1.6.1
[INFO] [stderr]     Checking itertools v0.9.0
[INFO] [stderr]  Documenting adventofcode_2020 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(iterator_fold_self)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not document `adventofcode_2020`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name adventofcode_2020 src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=8bd392eb253494dc -L dependency=/opt/rustwide/target/debug/deps --extern itertools=/opt/rustwide/target/debug/deps/libitertools-31732f101c7334d9.rmeta --cap-lints=warn --crate-version 0.1.0` (exit status: 1)
[INFO] running `Command { std: "docker" "inspect" "189302cb10523eddf4b9652ecd9e0677b27fae09aa046c7335f6469668a68c6d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "189302cb10523eddf4b9652ecd9e0677b27fae09aa046c7335f6469668a68c6d", kill_on_drop: false }`
[INFO] [stdout] 189302cb10523eddf4b9652ecd9e0677b27fae09aa046c7335f6469668a68c6d