[INFO] fetching crate tree-automata 0.1.2...
[INFO] documenting tree-automata-0.1.2 against 1.61.0 for beta-1.62-rustdoc-1
[INFO] extracting crate tree-automata 0.1.2 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate tree-automata 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 tree-automata 0.1.2
[INFO] finished tweaking crates.io crate tree-automata 0.1.2
[INFO] tweaked toml for crates.io crate tree-automata 0.1.2 written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] crate crates.io crate tree-automata 0.1.2 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]  Downloading crates ...
[INFO] [stderr]   Downloaded terms v0.1.2
[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] 14dd78e0f24840d07c7080265add4f463d49418b12047d70ccea93176fb4f403
[INFO] running `Command { std: "docker" "start" "-a" "14dd78e0f24840d07c7080265add4f463d49418b12047d70ccea93176fb4f403", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "14dd78e0f24840d07c7080265add4f463d49418b12047d70ccea93176fb4f403", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "14dd78e0f24840d07c7080265add4f463d49418b12047d70ccea93176fb4f403", kill_on_drop: false }`
[INFO] [stdout] 14dd78e0f24840d07c7080265add4f463d49418b12047d70ccea93176fb4f403
[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] 4c29be6c58a5f016c1b6064e7b46919098a57415847527fd3b6507188adc2560
[INFO] running `Command { std: "docker" "start" "-a" "4c29be6c58a5f016c1b6064e7b46919098a57415847527fd3b6507188adc2560", kill_on_drop: false }`
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]    Compiling libc v0.2.76
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]     Checking ppv-lite86 v0.2.9
[INFO] [stderr]     Checking lazy_static v1.4.0
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[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 crossbeam-channel v0.4.3
[INFO] [stderr]     Checking terms v0.1.2
[INFO] [stderr]  Documenting tree-automata v0.1.2 (/opt/rustwide/workdir)
[INFO] [stderr] error: could not document `tree-automata`
[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(trait_alias)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^
[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
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name tree_automata src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --document-private-items -C metadata=8cc4a10d3f95dcfc -L dependency=/opt/rustwide/target/debug/deps --extern crossbeam_channel=/opt/rustwide/target/debug/deps/libcrossbeam_channel-69664f3c2a35f936.rmeta --extern terms=/opt/rustwide/target/debug/deps/libterms-fc4cdf1c3ed97254.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" "4c29be6c58a5f016c1b6064e7b46919098a57415847527fd3b6507188adc2560", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4c29be6c58a5f016c1b6064e7b46919098a57415847527fd3b6507188adc2560", kill_on_drop: false }`
[INFO] [stdout] 4c29be6c58a5f016c1b6064e7b46919098a57415847527fd3b6507188adc2560