[INFO] fetching crate kf-protocol-core 0.1.2...
[INFO] documenting kf-protocol-core-0.1.2 against 1.61.0 for beta-1.62-rustdoc-1
[INFO] extracting crate kf-protocol-core 0.1.2 into /workspace/builds/worker-27/source
[INFO] validating manifest of crates.io crate kf-protocol-core 0.1.2 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 kf-protocol-core 0.1.2
[INFO] finished tweaking crates.io crate kf-protocol-core 0.1.2
[INFO] tweaked toml for crates.io crate kf-protocol-core 0.1.2 written to /workspace/builds/worker-27/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]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-27/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-27/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] f5cd50a033fae6da37a3b771bfe43e8cb54adacb7fea9626bb4087a49c8911dd
[INFO] running `Command { std: "docker" "start" "-a" "f5cd50a033fae6da37a3b771bfe43e8cb54adacb7fea9626bb4087a49c8911dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f5cd50a033fae6da37a3b771bfe43e8cb54adacb7fea9626bb4087a49c8911dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f5cd50a033fae6da37a3b771bfe43e8cb54adacb7fea9626bb4087a49c8911dd", kill_on_drop: false }`
[INFO] [stdout] f5cd50a033fae6da37a3b771bfe43e8cb54adacb7fea9626bb4087a49c8911dd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-27/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-27/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] bd85fa1e9df0c00c9503138a46a9741c24b417a5b151bc64ac3d55eda8c2f7d4
[INFO] running `Command { std: "docker" "start" "-a" "bd85fa1e9df0c00c9503138a46a9741c24b417a5b151bc64ac3d55eda8c2f7d4", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v1.0.39
[INFO] [stderr]    Compiling unicode-ident v1.0.0
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling syn v1.0.95
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling autocfg v1.1.0
[INFO] [stderr]    Compiling serde_derive v1.0.137
[INFO] [stderr]    Compiling serde v1.0.137
[INFO] [stderr]    Compiling log v0.4.17
[INFO] [stderr]    Compiling num-derive v0.2.5
[INFO] [stderr]     Checking cfg-if v1.0.0
[INFO] [stderr]     Checking bytes v0.5.6
[INFO] [stderr]    Compiling num-traits v0.2.15
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling quote v1.0.18
[INFO] [stderr]  Documenting kf-protocol-core v0.1.2 (/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(specialization)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not document `kf-protocol-core`
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(specialization)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(incomplete_features)]` on by default
[INFO] [stdout]   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]   = help: consider using `min_specialization` instead, which is more stable and complete
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] Caused by:
[INFO] [stdout] error: aborting due to 2 previous errors; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name kf_protocol_core src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=e4689ec38c6b629e -L dependency=/opt/rustwide/target/debug/deps --extern bytes=/opt/rustwide/target/debug/deps/libbytes-d2f9b88178ca7b9a.rmeta --extern log=/opt/rustwide/target/debug/deps/liblog-11fcf639aa746c8b.rmeta --extern num_derive=/opt/rustwide/target/debug/deps/libnum_derive-e97f7eecb109fbd7.so --extern num_traits=/opt/rustwide/target/debug/deps/libnum_traits-9d0fb7f65d2860a4.rmeta --extern serde=/opt/rustwide/target/debug/deps/libserde-69a2bcf8b67d1cdf.rmeta --cap-lints=warn --crate-version 0.1.2` (exit status: 1)
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "bd85fa1e9df0c00c9503138a46a9741c24b417a5b151bc64ac3d55eda8c2f7d4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bd85fa1e9df0c00c9503138a46a9741c24b417a5b151bc64ac3d55eda8c2f7d4", kill_on_drop: false }`
[INFO] [stdout] bd85fa1e9df0c00c9503138a46a9741c24b417a5b151bc64ac3d55eda8c2f7d4