[INFO] fetching crate mantle-rpc 0.1.1...
[INFO] documenting mantle-rpc-0.1.1 against 1.61.0 for beta-1.62-rustdoc-1
[INFO] extracting crate mantle-rpc 0.1.1 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate mantle-rpc 0.1.1 on toolchain 1.61.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.61.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mantle-rpc 0.1.1
[INFO] finished tweaking crates.io crate mantle-rpc 0.1.1
[INFO] tweaked toml for crates.io crate mantle-rpc 0.1.1 written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.61.0" "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" "+1.61.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded wasmparser v0.30.0
[INFO] [stderr]   Downloaded walrus v0.8.0
[INFO] [stderr]   Downloaded walrus-macro v0.8.0
[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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:d190cb871061d98bc6d0581d85cb2ecb09a0f8a142ba5463de30be9999fc3251" "/opt/rustwide/cargo-home/bin/cargo" "+1.61.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e4d91bb84b30895ded4f585780e0a3af26085536f55fffb7915de5f5e4226b8b
[INFO] running `Command { std: "docker" "start" "-a" "e4d91bb84b30895ded4f585780e0a3af26085536f55fffb7915de5f5e4226b8b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e4d91bb84b30895ded4f585780e0a3af26085536f55fffb7915de5f5e4226b8b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e4d91bb84b30895ded4f585780e0a3af26085536f55fffb7915de5f5e4226b8b", kill_on_drop: false }`
[INFO] [stdout] e4d91bb84b30895ded4f585780e0a3af26085536f55fffb7915de5f5e4226b8b
[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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:d190cb871061d98bc6d0581d85cb2ecb09a0f8a142ba5463de30be9999fc3251" "/opt/rustwide/cargo-home/bin/cargo" "+1.61.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 60de358a04383d74e0a747b3633aad586623b319c2384827603ce173fab99b0d
[INFO] running `Command { std: "docker" "start" "-a" "60de358a04383d74e0a747b3633aad586623b319c2384827603ce173fab99b0d", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.39
[INFO] [stderr]    Compiling unicode-ident v1.0.0
[INFO] [stderr]    Compiling syn v1.0.95
[INFO] [stderr]    Compiling serde_derive v1.0.137
[INFO] [stderr]    Compiling serde v1.0.137
[INFO] [stderr]    Compiling quote v1.0.18
[INFO] [stderr]  Documenting mantle-rpc 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:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(box_syntax)]
[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 `mantle-rpc`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name mantle_rpc src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=e2a4261b95b06ecc -L dependency=/opt/rustwide/target/debug/deps --extern serde=/opt/rustwide/target/debug/deps/libserde-69a2bcf8b67d1cdf.rmeta --cap-lints=warn --crate-version 0.1.1` (exit status: 1)
[INFO] running `Command { std: "docker" "inspect" "60de358a04383d74e0a747b3633aad586623b319c2384827603ce173fab99b0d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "60de358a04383d74e0a747b3633aad586623b319c2384827603ce173fab99b0d", kill_on_drop: false }`
[INFO] [stdout] 60de358a04383d74e0a747b3633aad586623b319c2384827603ce173fab99b0d