[INFO] fetching crate doku-derive 0.9.0...
[INFO] testing doku-derive-0.9.0 against 1.54.0 for beta-1.55-1
[INFO] extracting crate doku-derive 0.9.0 into /workspace/builds/worker-21/source
[INFO] validating manifest of crates.io crate doku-derive 0.9.0 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 doku-derive 0.9.0
[INFO] finished tweaking crates.io crate doku-derive 0.9.0
[INFO] tweaked toml for crates.io crate doku-derive 0.9.0 written to /workspace/builds/worker-21/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] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-21/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-21/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] 57d686ca6c4771b072a38d5c01a9234b86f4363b82802458ead3398ad353d42e
[INFO] running `Command { std: "docker" "start" "-a" "57d686ca6c4771b072a38d5c01a9234b86f4363b82802458ead3398ad353d42e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "57d686ca6c4771b072a38d5c01a9234b86f4363b82802458ead3398ad353d42e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "57d686ca6c4771b072a38d5c01a9234b86f4363b82802458ead3398ad353d42e", kill_on_drop: false }`
[INFO] [stdout] 57d686ca6c4771b072a38d5c01a9234b86f4363b82802458ead3398ad353d42e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-21/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-21/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] f125600eb7122efcb66195dcf852beb6e76e1bc291d4f5a10e9d833e031a1cee
[INFO] running `Command { std: "docker" "start" "-a" "f125600eb7122efcb66195dcf852beb6e76e1bc291d4f5a10e9d833e031a1cee", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro-error-attr v1.0.4
[INFO] [stderr]    Compiling proc-macro-error v1.0.4
[INFO] [stderr]    Compiling darling_core v0.13.0
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/darling_core-0.13.0/src/lib.rs:2:38
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![cfg_attr(feature = "diagnostics", feature(proc_macro_diagnostic))]
[INFO] [stdout]   |                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `darling_core`
[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" "f125600eb7122efcb66195dcf852beb6e76e1bc291d4f5a10e9d833e031a1cee", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f125600eb7122efcb66195dcf852beb6e76e1bc291d4f5a10e9d833e031a1cee", kill_on_drop: false }`
[INFO] [stdout] f125600eb7122efcb66195dcf852beb6e76e1bc291d4f5a10e9d833e031a1cee
