[INFO] fetching crate arc_ast 0.4.2...
[INFO] testing arc_ast-0.4.2 against 1.54.0 for beta-1.55-1
[INFO] extracting crate arc_ast 0.4.2 into /workspace/builds/worker-44/source
[INFO] validating manifest of crates.io crate arc_ast 0.4.2 on toolchain 1.54.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.54.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate arc_ast 0.4.2
[INFO] finished tweaking crates.io crate arc_ast 0.4.2
[INFO] tweaked toml for crates.io crate arc_ast 0.4.2 written to /workspace/builds/worker-44/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.54.0" "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" "+1.54.0" "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-44/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-44/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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+1.54.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] b9a5c2a26acf10ecb54ee7efca18f891b8f98d7995a7995715335c4badab5a16
[INFO] running `Command { std: "docker" "start" "-a" "b9a5c2a26acf10ecb54ee7efca18f891b8f98d7995a7995715335c4badab5a16", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b9a5c2a26acf10ecb54ee7efca18f891b8f98d7995a7995715335c4badab5a16", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b9a5c2a26acf10ecb54ee7efca18f891b8f98d7995a7995715335c4badab5a16", kill_on_drop: false }`
[INFO] [stdout] b9a5c2a26acf10ecb54ee7efca18f891b8f98d7995a7995715335c4badab5a16
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-44/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-44/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" "RUSTFLAGS=--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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+1.54.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9fec69f5ba7b8ec1f11babb4acd327496a1c9896074d3d32ffa982f66c824253
[INFO] running `Command { std: "docker" "start" "-a" "9fec69f5ba7b8ec1f11babb4acd327496a1c9896074d3d32ffa982f66c824253", kill_on_drop: false }`
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]    Compiling serde v1.0.127
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling hashbrown v0.11.2
[INFO] [stderr]    Compiling serde_json v1.0.66
[INFO] [stderr]    Compiling linked-hash-map v0.5.4
[INFO] [stderr]    Compiling itoa v0.4.7
[INFO] [stderr]    Compiling yaml-rust v0.4.5
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling num-integer v0.1.44
[INFO] [stderr]    Compiling num-bigint v0.3.2
[INFO] [stderr]    Compiling indexmap v1.7.0
[INFO] [stderr]    Compiling num-iter v0.1.42
[INFO] [stderr]    Compiling num-rational v0.3.2
[INFO] [stderr]    Compiling num-complex v0.3.1
[INFO] [stderr]    Compiling bigdecimal v0.2.0
[INFO] [stderr]    Compiling toml v0.5.8
[INFO] [stderr]    Compiling num v0.3.1
[INFO] [stderr]    Compiling arc_ast v0.4.2 (/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(box_syntax)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `crate::utils::parse_format`
[INFO] [stdout]  --> src/ast/statements/mod.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use crate::utils::parse_format;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `arc_ast`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "9fec69f5ba7b8ec1f11babb4acd327496a1c9896074d3d32ffa982f66c824253", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9fec69f5ba7b8ec1f11babb4acd327496a1c9896074d3d32ffa982f66c824253", kill_on_drop: false }`
[INFO] [stdout] 9fec69f5ba7b8ec1f11babb4acd327496a1c9896074d3d32ffa982f66c824253
