[INFO] fetching crate stream_buffer 0.2.0...
[INFO] documenting stream_buffer-0.2.0 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate stream_buffer 0.2.0 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate stream_buffer 0.2.0 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 stream_buffer 0.2.0
[INFO] finished tweaking crates.io crate stream_buffer 0.2.0
[INFO] tweaked toml for crates.io crate stream_buffer 0.2.0 written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate crates.io crate stream_buffer 0.2.0 already has a lockfile, it will not be regenerated
[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-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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] 8e4b15b34119b8e06467c25e0d9be9b4d776b267a98bbfcbecd4bcec10b68411
[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" "8e4b15b34119b8e06467c25e0d9be9b4d776b267a98bbfcbecd4bcec10b68411", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8e4b15b34119b8e06467c25e0d9be9b4d776b267a98bbfcbecd4bcec10b68411", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8e4b15b34119b8e06467c25e0d9be9b4d776b267a98bbfcbecd4bcec10b68411", kill_on_drop: false }`
[INFO] [stdout] 8e4b15b34119b8e06467c25e0d9be9b4d776b267a98bbfcbecd4bcec10b68411
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 5e1328f90647ef78e599411b61b27e394240140a555ca60adf33c001677a58c6
[INFO] running `Command { std: "docker" "start" "-a" "5e1328f90647ef78e599411b61b27e394240140a555ca60adf33c001677a58c6", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.74
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking ppv-lite86 v0.2.8
[INFO] [stderr]     Checking either v1.6.0
[INFO] [stderr]     Checking remove_dir_all v0.5.3
[INFO] [stderr]     Checking itertools v0.9.0
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking tempfile v3.1.0
[INFO] [stderr]  Documenting stream_buffer v0.2.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(type_alias_impl_trait)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(trait_alias)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(extend_one)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 4 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 `stream_buffer`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name stream_buffer src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern itertools=/opt/rustwide/target/debug/deps/libitertools-2a87993ac53204c8.rmeta --extern tempfile=/opt/rustwide/target/debug/deps/libtempfile-9455542fcc867a76.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "5e1328f90647ef78e599411b61b27e394240140a555ca60adf33c001677a58c6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5e1328f90647ef78e599411b61b27e394240140a555ca60adf33c001677a58c6", kill_on_drop: false }`
[INFO] [stdout] 5e1328f90647ef78e599411b61b27e394240140a555ca60adf33c001677a58c6