[INFO] cloning repository https://github.com/Emerentius/advent_of_code_2021
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Emerentius/advent_of_code_2021" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEmerentius%2Fadvent_of_code_2021", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEmerentius%2Fadvent_of_code_2021'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] ba09a2f27392ee31215a9875586731066e235d7c
[INFO] documenting Emerentius/advent_of_code_2021 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%2FEmerentius%2Fadvent_of_code_2021" "/workspace/builds/worker-1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/Emerentius/advent_of_code_2021 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] started tweaking git repo https://github.com/Emerentius/advent_of_code_2021
[INFO] finished tweaking git repo https://github.com/Emerentius/advent_of_code_2021
[INFO] tweaked toml for git repo https://github.com/Emerentius/advent_of_code_2021 written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] crate git repo https://github.com/Emerentius/advent_of_code_2021 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] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded lazy-regex-proc_macros v2.2.2
[INFO] [stderr]   Downloaded wide v0.7.3
[INFO] [stderr]   Downloaded lazy-regex v2.2.2
[INFO] [stderr]   Downloaded simba v0.6.0
[INFO] [stderr]   Downloaded nalgebra v0.29.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] ed90246c60e977cfd5e3f6458cd2c824e116c591d12009cc41faf41ab501ad3f
[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" "ed90246c60e977cfd5e3f6458cd2c824e116c591d12009cc41faf41ab501ad3f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ed90246c60e977cfd5e3f6458cd2c824e116c591d12009cc41faf41ab501ad3f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ed90246c60e977cfd5e3f6458cd2c824e116c591d12009cc41faf41ab501ad3f", kill_on_drop: false }`
[INFO] [stdout] ed90246c60e977cfd5e3f6458cd2c824e116c591d12009cc41faf41ab501ad3f
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] 7408321e44db8f58b43349efbb8cc1912461ce79e852f9fe75831a81201308dd
[INFO] running `Command { std: "docker" "start" "-a" "7408321e44db8f58b43349efbb8cc1912461ce79e852f9fe75831a81201308dd", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.33
[INFO] [stderr]    Compiling unicode-xid v0.2.2
[INFO] [stderr]    Compiling version_check v0.9.3
[INFO] [stderr]    Compiling libc v0.2.112
[INFO] [stderr]    Compiling regex-syntax v0.6.25
[INFO] [stderr]     Checking vec_map v0.8.2
[INFO] [stderr]     Checking minimal-lexical v0.2.1
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling num-integer v0.1.44
[INFO] [stderr]    Compiling num-rational v0.4.0
[INFO] [stderr]     Checking safe_arch v0.6.0
[INFO] [stderr]     Checking textwrap v0.11.0
[INFO] [stderr]     Checking memchr v2.4.1
[INFO] [stderr]     Checking itertools v0.10.1
[INFO] [stderr]    Compiling proc-macro-error-attr v1.0.4
[INFO] [stderr]    Compiling proc-macro-error v1.0.4
[INFO] [stderr]    Compiling nom v7.1.0
[INFO] [stderr]     Checking wide v0.7.3
[INFO] [stderr]     Checking aho-corasick v0.7.18
[INFO] [stderr]    Compiling quote v1.0.10
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]    Compiling syn v1.0.82
[INFO] [stderr]     Checking clap v2.34.0
[INFO] [stderr]     Checking regex v1.5.4
[INFO] [stderr]     Checking num-complex v0.4.0
[INFO] [stderr]     Checking approx v0.5.0
[INFO] [stderr]     Checking simba v0.6.0
[INFO] [stderr]    Compiling nalgebra-macros v0.1.0
[INFO] [stderr]    Compiling lazy-regex-proc_macros v2.2.2
[INFO] [stderr]    Compiling structopt-derive v0.4.18
[INFO] [stderr]     Checking lazy-regex v2.2.2
[INFO] [stderr]     Checking structopt v0.3.25
[INFO] [stderr]     Checking nalgebra v0.29.0
[INFO] [stderr]  Documenting advent_of_code_2021 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(drain_filter)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(stmt_expr_attributes)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not document `advent_of_code_2021`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2021 --crate-type bin --crate-name advent_of_code_2021 src/main.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=ffcb301a9f7063b5 -L dependency=/opt/rustwide/target/debug/deps --extern fnv=/opt/rustwide/target/debug/deps/libfnv-5eaa67ceb9d9bb54.rmeta --extern itertools=/opt/rustwide/target/debug/deps/libitertools-768244cffa2ddad5.rmeta --extern lazy_regex=/opt/rustwide/target/debug/deps/liblazy_regex-d7da44b0792793ca.rmeta --extern nalgebra=/opt/rustwide/target/debug/deps/libnalgebra-1bf57c9a81f9e7f0.rmeta --extern nom=/opt/rustwide/target/debug/deps/libnom-b97916a12d79a983.rmeta --extern once_cell=/opt/rustwide/target/debug/deps/libonce_cell-e7a72559679d7976.rmeta --extern structopt=/opt/rustwide/target/debug/deps/libstructopt-aabc52eb729e89f5.rmeta --cap-lints=warn --crate-version 0.1.0` (exit status: 1)
[INFO] running `Command { std: "docker" "inspect" "7408321e44db8f58b43349efbb8cc1912461ce79e852f9fe75831a81201308dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7408321e44db8f58b43349efbb8cc1912461ce79e852f9fe75831a81201308dd", kill_on_drop: false }`
[INFO] [stdout] 7408321e44db8f58b43349efbb8cc1912461ce79e852f9fe75831a81201308dd