[INFO] cloning repository https://github.com/twissel/bench-locks
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/twissel/bench-locks" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftwissel%2Fbench-locks", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftwissel%2Fbench-locks'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 984b1c6832478652efbbdc3cc3bc9a1f842cfd10
[INFO] documenting twissel/bench-locks against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftwissel%2Fbench-locks" "/workspace/builds/worker-5/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/twissel/bench-locks on toolchain beta-2020-08-29
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/twissel/bench-locks
[INFO] finished tweaking git repo https://github.com/twissel/bench-locks
[INFO] tweaked toml for git repo https://github.com/twissel/bench-locks written to /workspace/builds/worker-5/source/Cargo.toml
[INFO] crate git repo https://github.com/twissel/bench-locks already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating git repository `https://github.com/tokio-rs/tokio`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded proc-macro-hack v0.5.9
[INFO] [stderr]   Downloaded tracing-attributes v0.1.2
[INFO] [stderr]   Downloaded futures-channel-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded tracing v0.1.7
[INFO] [stderr]   Downloaded tracing-core v0.1.5
[INFO] [stderr]   Downloaded futures-sink-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded proc-macro2 v1.0.2
[INFO] [stderr]   Downloaded futures-timer v0.3.0
[INFO] [stderr]   Downloaded futures-util-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded futures-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded async-std v0.99.4
[INFO] [stderr]   Downloaded futures-executor-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded futures-select-macro-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded futures-join-macro-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded async-trait v0.1.11
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "+beta-2020-08-29" "metadata" "--no-deps" "--format-version=1", 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] 9e5daaf8df5b8c3558e3d503a60a9f4d673b22418e2ca0dcc522785458c3e1c7
[INFO] running `Command { std: "docker" "start" "-a" "9e5daaf8df5b8c3558e3d503a60a9f4d673b22418e2ca0dcc522785458c3e1c7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "9e5daaf8df5b8c3558e3d503a60a9f4d673b22418e2ca0dcc522785458c3e1c7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9e5daaf8df5b8c3558e3d503a60a9f4d673b22418e2ca0dcc522785458c3e1c7", kill_on_drop: false }`
[INFO] [stdout] 9e5daaf8df5b8c3558e3d503a60a9f4d673b22418e2ca0dcc522785458c3e1c7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "+beta-2020-08-29" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 3ad73eb9ce8edbf24f36f1f14042d38a5a3ce0c8b10a18e41a26f1fa04ea2a82
[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" "3ad73eb9ce8edbf24f36f1f14042d38a5a3ce0c8b10a18e41a26f1fa04ea2a82", kill_on_drop: false }`
[INFO] [stderr]     Checking spin v0.5.2
[INFO] [stderr]    Compiling proc-macro2 v1.0.2
[INFO] [stderr]    Compiling syn v1.0.5
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling proc-macro-nested v0.1.3
[INFO] [stderr]     Checking futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling arrayvec v0.4.11
[INFO] [stderr]     Checking log v0.4.8
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking lazy_static v1.4.0
[INFO] [stderr]     Checking futures-sink-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking c2-chacha v0.2.2
[INFO] [stderr]     Checking crossbeam-utils v0.6.6
[INFO] [stderr]     Checking tracing-core v0.1.5
[INFO] [stderr]     Checking futures-channel-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking mio v0.6.19
[INFO] [stderr]     Checking rand_chacha v0.2.1
[INFO] [stderr]     Checking tokio-io v0.2.0-alpha.4 (https://github.com/tokio-rs/tokio#9766cd64)
[INFO] [stderr]     Checking crossbeam-channel v0.3.9
[INFO] [stderr]     Checking crossbeam-queue v0.1.2
[INFO] [stderr]     Checking async-task v1.0.0
[INFO] [stderr]     Checking rand v0.7.0
[INFO] [stderr]     Checking crossbeam-epoch v0.7.2
[INFO] [stderr]     Checking tokio-codec v0.2.0-alpha.4 (https://github.com/tokio-rs/tokio#9766cd64)
[INFO] [stderr]    Compiling quote v1.0.2
[INFO] [stderr]     Checking crossbeam-deque v0.7.1
[INFO] [stderr]     Checking mio-uds v0.6.7
[INFO] [stderr]    Compiling proc-macro-hack v0.5.9
[INFO] [stderr]    Compiling tracing-attributes v0.1.2
[INFO] [stderr]    Compiling tokio-macros v0.2.0-alpha.4 (https://github.com/tokio-rs/tokio#9766cd64)
[INFO] [stderr]    Compiling async-trait v0.1.11
[INFO] [stderr]     Checking tracing v0.1.7
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling futures-join-macro-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking futures-util-preview v0.3.0-alpha.18
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/futures-util-preview-0.3.0-alpha.18/src/lib.rs:4:38
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![cfg_attr(feature = "async-await", feature(async_await))]
[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 compile `futures-util-preview`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "3ad73eb9ce8edbf24f36f1f14042d38a5a3ce0c8b10a18e41a26f1fa04ea2a82", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3ad73eb9ce8edbf24f36f1f14042d38a5a3ce0c8b10a18e41a26f1fa04ea2a82", kill_on_drop: false }`
[INFO] [stdout] 3ad73eb9ce8edbf24f36f1f14042d38a5a3ce0c8b10a18e41a26f1fa04ea2a82