[INFO] fetching crate fumio 0.1.0...
[INFO] documenting fumio-0.1.0 against 1.75.0 for beta-1.76-rustdoc-1
[INFO] extracting crate fumio 0.1.0 into /workspace/builds/worker-6-tc1/source
[INFO] validating manifest of crates.io crate fumio 0.1.0 on toolchain 1.75.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate fumio 0.1.0
[INFO] finished tweaking crates.io crate fumio 0.1.0
[INFO] tweaked toml for crates.io crate fumio 0.1.0 written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[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 crossbeam-utils v0.6.6
[INFO] [stderr]   Downloaded fumio-utils v0.1.0
[INFO] [stderr]   Downloaded fumio-reactor v0.1.0
[INFO] [stderr]   Downloaded tokio-sync v0.2.0-alpha.5
[INFO] [stderr]   Downloaded fumio-pool v0.1.0
[INFO] [stderr]   Downloaded tokio-timer v0.3.0-alpha.5
[INFO] [stderr]   Downloaded tokio-executor v0.2.0-alpha.5
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.75.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e57d92f8f167c8cad7790d2ec284d944dd3816c909df424b3f91aebd35c073ed
[INFO] running `Command { std: "docker" "start" "-a" "e57d92f8f167c8cad7790d2ec284d944dd3816c909df424b3f91aebd35c073ed", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e57d92f8f167c8cad7790d2ec284d944dd3816c909df424b3f91aebd35c073ed", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e57d92f8f167c8cad7790d2ec284d944dd3816c909df424b3f91aebd35c073ed", kill_on_drop: false }`
[INFO] [stdout] e57d92f8f167c8cad7790d2ec284d944dd3816c909df424b3f91aebd35c073ed
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/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" "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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.75.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 38cdcf4368265324505480d8ffc384eff40b4d7e79f7d2defa1a67c532cce463
[INFO] running `Command { std: "docker" "start" "-a" "38cdcf4368265324505480d8ffc384eff40b4d7e79f7d2defa1a67c532cce463", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro-hack v0.5.20+deprecated
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling proc-macro-nested v0.1.7
[INFO] [stderr]     Checking getrandom v0.1.16
[INFO] [stderr]     Checking futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking num_cpus v1.16.0
[INFO] [stderr]     Checking net2 v0.2.39
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking futures-sink-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking log v0.4.20
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking crossbeam-utils v0.6.6
[INFO] [stderr]     Checking futures-channel-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking mio v0.6.23
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]    Compiling futures-join-macro-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling futures-select-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 stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/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]   |                                      ^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `async_await` has been stable since `1.39.0` and no longer requires an attribute to enable
[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` (lib) due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "38cdcf4368265324505480d8ffc384eff40b4d7e79f7d2defa1a67c532cce463", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "38cdcf4368265324505480d8ffc384eff40b4d7e79f7d2defa1a67c532cce463", kill_on_drop: false }`
[INFO] [stdout] 38cdcf4368265324505480d8ffc384eff40b4d7e79f7d2defa1a67c532cce463
