[INFO] fetching crate arc_ast 0.4.2...
[INFO] testing arc_ast-0.4.2 against 1.55.0 for beta-1.56-1
[INFO] extracting crate arc_ast 0.4.2 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate arc_ast 0.4.2 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "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-1/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "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-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] a020b543ec86f20ce8ad882a2ed708104ad7a5019e4281a9850550e3f9f02815
[INFO] running `Command { std: "docker" "start" "-a" "a020b543ec86f20ce8ad882a2ed708104ad7a5019e4281a9850550e3f9f02815", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a020b543ec86f20ce8ad882a2ed708104ad7a5019e4281a9850550e3f9f02815", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a020b543ec86f20ce8ad882a2ed708104ad7a5019e4281a9850550e3f9f02815", kill_on_drop: false }`
[INFO] [stdout] a020b543ec86f20ce8ad882a2ed708104ad7a5019e4281a9850550e3f9f02815
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 6a77a7ae78e26219fd7ebf71af5927e6f5f53e13ac37d654d174a9e4a65efb8e
[INFO] running `Command { std: "docker" "start" "-a" "6a77a7ae78e26219fd7ebf71af5927e6f5f53e13ac37d654d174a9e4a65efb8e", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.130
[INFO] [stderr]    Compiling num-integer v0.1.44
[INFO] [stderr]    Compiling num-bigint v0.3.3
[INFO] [stderr]    Compiling num-iter v0.1.42
[INFO] [stderr]    Compiling num-rational v0.3.2
[INFO] [stderr]    Compiling yaml-rust v0.4.5
[INFO] [stderr]    Compiling num-complex v0.3.1
[INFO] [stderr]    Compiling bigdecimal v0.2.2
[INFO] [stderr]    Compiling num v0.3.1
[INFO] [stderr]    Compiling serde_json v1.0.67
[INFO] [stderr]    Compiling toml v0.5.8
[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` due to 2 previous errors; 1 warning emitted
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "6a77a7ae78e26219fd7ebf71af5927e6f5f53e13ac37d654d174a9e4a65efb8e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6a77a7ae78e26219fd7ebf71af5927e6f5f53e13ac37d654d174a9e4a65efb8e", kill_on_drop: false }`
[INFO] [stdout] 6a77a7ae78e26219fd7ebf71af5927e6f5f53e13ac37d654d174a9e4a65efb8e