[INFO] fetching crate nrf52840 0.2.0...
[INFO] documenting nrf52840-0.2.0 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate nrf52840 0.2.0 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate nrf52840 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 nrf52840 0.2.0
[INFO] finished tweaking crates.io crate nrf52840 0.2.0
[INFO] tweaked toml for crates.io crate nrf52840 0.2.0 written to /workspace/builds/worker-4/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] 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] 9c6355ed933a73b4e283aae42672f26f8d45aad839e2379b23594b9ae912b5db
[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" "9c6355ed933a73b4e283aae42672f26f8d45aad839e2379b23594b9ae912b5db", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "9c6355ed933a73b4e283aae42672f26f8d45aad839e2379b23594b9ae912b5db", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9c6355ed933a73b4e283aae42672f26f8d45aad839e2379b23594b9ae912b5db", kill_on_drop: false }`
[INFO] [stdout] 9c6355ed933a73b4e283aae42672f26f8d45aad839e2379b23594b9ae912b5db
[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] [stdout] 1083943a51d922dd687989fbaf21ba164f62e7907e46b879202d571b5c719dbf
[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" "1083943a51d922dd687989fbaf21ba164f62e7907e46b879202d571b5c719dbf", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Checking stable_deref_trait v1.2.0
[INFO] [stderr]    Compiling cortex-m v0.6.3
[INFO] [stderr]     Checking vcell v0.1.2
[INFO] [stderr]    Compiling cortex-m v0.5.10
[INFO] [stderr]     Checking bitfield v0.13.2
[INFO] [stderr]    Compiling nrf52840 v0.2.0 (/opt/rustwide/workdir)
[INFO] [stderr]     Checking aligned v0.2.0
[INFO] [stderr]    Compiling bare-metal v0.2.5
[INFO] [stderr]     Checking volatile-register v0.2.0
[INFO] [stderr]     Checking as-slice v0.1.3
[INFO] [stderr]     Checking aligned v0.3.4
[INFO] [stderr]  Documenting nrf52840 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:6:1
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![feature(untagged_unions)]
[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 `nrf52840`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --crate-type lib --crate-name nrf52840 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 bare_metal=/opt/rustwide/target/debug/deps/libbare_metal-f1e4959e24c8e643.rmeta --extern cortex_m=/opt/rustwide/target/debug/deps/libcortex_m-e2524b63e15d93a3.rmeta --extern vcell=/opt/rustwide/target/debug/deps/libvcell-2f371df3cd1ada44.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "1083943a51d922dd687989fbaf21ba164f62e7907e46b879202d571b5c719dbf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1083943a51d922dd687989fbaf21ba164f62e7907e46b879202d571b5c719dbf", kill_on_drop: false }`
[INFO] [stdout] 1083943a51d922dd687989fbaf21ba164f62e7907e46b879202d571b5c719dbf