[INFO] fetching crate nbits_vec 0.1.1...
[INFO] documenting nbits_vec-0.1.1 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate nbits_vec 0.1.1 into /workspace/builds/worker-2/source
[INFO] validating manifest of crates.io crate nbits_vec 0.1.1 on toolchain 1.46.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate nbits_vec 0.1.1
[INFO] finished tweaking crates.io crate nbits_vec 0.1.1
[INFO] tweaked toml for crates.io crate nbits_vec 0.1.1 written to /workspace/builds/worker-2/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 1fe811bff4f7dc5fbfc4cc7384f3b3670bac1881aab32eeabd1d1eb0d316d69b
[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" "1fe811bff4f7dc5fbfc4cc7384f3b3670bac1881aab32eeabd1d1eb0d316d69b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1fe811bff4f7dc5fbfc4cc7384f3b3670bac1881aab32eeabd1d1eb0d316d69b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1fe811bff4f7dc5fbfc4cc7384f3b3670bac1881aab32eeabd1d1eb0d316d69b", kill_on_drop: false }`
[INFO] [stdout] 1fe811bff4f7dc5fbfc4cc7384f3b3670bac1881aab32eeabd1d1eb0d316d69b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] dab5e221f0f87e983d214bbcde72b0654504eefe854ff0e401fa5adf9fe7e9f7
[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" "dab5e221f0f87e983d214bbcde72b0654504eefe854ff0e401fa5adf9fe7e9f7", kill_on_drop: false }`
[INFO] [stderr]     Checking num-bigint v0.1.44
[INFO] [stderr]     Checking num-iter v0.1.41
[INFO] [stderr]     Checking num-rational v0.1.42
[INFO] [stderr]     Checking num v0.1.42
[INFO] [stderr]  Documenting nbits_vec v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:28:1
[INFO] [stdout]    |
[INFO] [stdout] 28 | #![feature(alloc)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 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 `nbits_vec`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --crate-type lib --crate-name nbits_vec src/lib.rs -o /opt/rustwide/target/doc --cfg 'feature="default"' --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern num=/opt/rustwide/target/debug/deps/libnum-c67ca3189b1bb84f.rmeta --extern typenum=/opt/rustwide/target/debug/deps/libtypenum-546f462e1e0cb138.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "dab5e221f0f87e983d214bbcde72b0654504eefe854ff0e401fa5adf9fe7e9f7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "dab5e221f0f87e983d214bbcde72b0654504eefe854ff0e401fa5adf9fe7e9f7", kill_on_drop: false }`
[INFO] [stdout] dab5e221f0f87e983d214bbcde72b0654504eefe854ff0e401fa5adf9fe7e9f7