[INFO] fetching crate karsher 0.1.1...
[INFO] documenting karsher-0.1.1 against 1.61.0 for beta-1.62-rustdoc-1
[INFO] extracting crate karsher 0.1.1 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate karsher 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 karsher 0.1.1
[INFO] finished tweaking crates.io crate karsher 0.1.1
[INFO] tweaked toml for crates.io crate karsher 0.1.1 written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] crate crates.io crate karsher 0.1.1 already has a lockfile, it will not be regenerated
[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] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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] 0360d97c3f6c1dbc7d30c1bf8fdbf28e8585c8dd8a8dd6eafe9b5f7b0c7b19b9
[INFO] running `Command { std: "docker" "start" "-a" "0360d97c3f6c1dbc7d30c1bf8fdbf28e8585c8dd8a8dd6eafe9b5f7b0c7b19b9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "0360d97c3f6c1dbc7d30c1bf8fdbf28e8585c8dd8a8dd6eafe9b5f7b0c7b19b9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0360d97c3f6c1dbc7d30c1bf8fdbf28e8585c8dd8a8dd6eafe9b5f7b0c7b19b9", kill_on_drop: false }`
[INFO] [stdout] 0360d97c3f6c1dbc7d30c1bf8fdbf28e8585c8dd8a8dd6eafe9b5f7b0c7b19b9
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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] 48a53639d1ae86d4f6301b5244a6a19a2e9de2fb7d91581591e63fb51674789d
[INFO] running `Command { std: "docker" "start" "-a" "48a53639d1ae86d4f6301b5244a6a19a2e9de2fb7d91581591e63fb51674789d", 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 memchr v2.5.0
[INFO] [stderr]    Compiling serde v1.0.137
[INFO] [stderr]    Compiling anyhow v1.0.57
[INFO] [stderr]    Compiling serde_json v1.0.81
[INFO] [stderr]     Checking minimal-lexical v0.2.1
[INFO] [stderr]     Checking ryu v1.0.10
[INFO] [stderr]     Checking itoa v1.0.2
[INFO] [stderr]     Checking nom v7.1.1
[INFO] [stderr]    Compiling quote v1.0.18
[INFO] [stderr]  Documenting karsher v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(let_chains, btree_drain_filter)]
[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 `karsher`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2021 --crate-type bin --crate-name karsher src/main.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=45791a290f76a0ae -L dependency=/opt/rustwide/target/debug/deps --extern anyhow=/opt/rustwide/target/debug/deps/libanyhow-a2ad8fa07e0781ab.rmeta --extern nom=/opt/rustwide/target/debug/deps/libnom-248cc023f84d1e2a.rmeta --extern serde=/opt/rustwide/target/debug/deps/libserde-361aefd8ea33a964.rmeta --extern serde_json=/opt/rustwide/target/debug/deps/libserde_json-e465a967752ca58a.rmeta --cap-lints=warn --crate-version 0.1.1` (exit status: 1)
[INFO] running `Command { std: "docker" "inspect" "48a53639d1ae86d4f6301b5244a6a19a2e9de2fb7d91581591e63fb51674789d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "48a53639d1ae86d4f6301b5244a6a19a2e9de2fb7d91581591e63fb51674789d", kill_on_drop: false }`
[INFO] [stdout] 48a53639d1ae86d4f6301b5244a6a19a2e9de2fb7d91581591e63fb51674789d