[INFO] fetching crate letsgo 0.0.1...
[INFO] documenting letsgo-0.0.1 against 1.75.0 for beta-1.76-rustdoc-1
[INFO] extracting crate letsgo 0.0.1 into /workspace/builds/worker-4-tc1/source
[INFO] validating manifest of crates.io crate letsgo 0.0.1 on toolchain 1.75.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate letsgo 0.0.1
[INFO] finished tweaking crates.io crate letsgo 0.0.1
[INFO] tweaked toml for crates.io crate letsgo 0.0.1 written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.75.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded async-ready v3.0.0
[INFO] [stderr]   Downloaded enum-as-inner v0.2.1
[INFO] [stderr]   Downloaded romio v0.3.0-alpha.10
[INFO] [stderr]   Downloaded async-datagram v3.0.0
[INFO] [stderr]   Downloaded trust-dns-resolver v0.11.1
[INFO] [stderr]   Downloaded futures-select-macro-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded trust-dns-proto v0.7.4
[INFO] [stderr]   Downloaded futures-join-macro-preview v0.3.0-alpha.18
[INFO] [stderr]   Downloaded runtime-attributes v0.3.0-alpha.6
[INFO] [stderr]   Downloaded juliex v0.3.0-alpha.8
[INFO] [stderr]   Downloaded runtime-native v0.3.0-alpha.6
[INFO] [stderr]   Downloaded runtime v0.3.0-alpha.7
[INFO] [stderr]   Downloaded wasm-bindgen-futures v0.3.27
[INFO] [stderr]   Downloaded runtime-tokio v0.3.0-alpha.6
[INFO] [stderr]   Downloaded runtime-raw v0.3.0-alpha.5
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.75.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c20d5e5ced99104d9eb1b53acaaf552d1174a4a2eb6654861dff3e57a493fffc
[INFO] running `Command { std: "docker" "start" "-a" "c20d5e5ced99104d9eb1b53acaaf552d1174a4a2eb6654861dff3e57a493fffc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c20d5e5ced99104d9eb1b53acaaf552d1174a4a2eb6654861dff3e57a493fffc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c20d5e5ced99104d9eb1b53acaaf552d1174a4a2eb6654861dff3e57a493fffc", kill_on_drop: false }`
[INFO] [stdout] c20d5e5ced99104d9eb1b53acaaf552d1174a4a2eb6654861dff3e57a493fffc
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/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" "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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+1.75.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 87760a2977a6d8b9e246eff268697e43b092cb2c0ab8f5c7c788658099474798
[INFO] running `Command { std: "docker" "start" "-a" "87760a2977a6d8b9e246eff268697e43b092cb2c0ab8f5c7c788658099474798", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.151
[INFO] [stderr]     Checking futures v0.1.31
[INFO] [stderr]    Compiling maybe-uninit v2.0.0
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling memoffset v0.5.6
[INFO] [stderr]     Checking lock_api v0.3.4
[INFO] [stderr]    Compiling crossbeam-epoch v0.8.2
[INFO] [stderr]    Compiling proc-macro-nested v0.1.7
[INFO] [stderr]    Compiling getrandom v0.1.16
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling parking_lot_core v0.6.3
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]    Compiling autocfg v0.1.8
[INFO] [stderr]    Compiling proc-macro2 v1.0.76
[INFO] [stderr]     Checking rand_core v0.4.2
[INFO] [stderr]     Checking futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]     Checking futures-sink-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking rand_core v0.3.1
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling failure_derive v0.1.8
[INFO] [stderr]     Checking futures-channel-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking gimli v0.28.1
[INFO] [stderr]     Checking smallvec v0.6.14
[INFO] [stderr]     Checking miniz_oxide v0.7.1
[INFO] [stderr]     Checking unicode-normalization v0.1.22
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]     Checking object v0.32.2
[INFO] [stderr]     Checking rustc-demangle v0.1.23
[INFO] [stderr]     Checking rand_hc v0.1.0
[INFO] [stderr]     Checking rand_isaac v0.1.1
[INFO] [stderr]     Checking rand_xorshift v0.1.1
[INFO] [stderr]     Checking rand_jitter v0.1.4
[INFO] [stderr]     Checking crossbeam-utils v0.6.6
[INFO] [stderr]     Checking async-datagram v3.0.0
[INFO] [stderr]     Checking async-ready v3.0.0
[INFO] [stderr]     Checking percent-encoding v1.0.1
[INFO] [stderr]     Checking match_cfg v0.1.0
[INFO] [stderr]     Checking linked-hash-map v0.5.6
[INFO] [stderr]     Checking quick-error v1.2.3
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling quote v1.0.35
[INFO] [stderr]     Checking crossbeam-queue v0.2.3
[INFO] [stderr]     Checking crossbeam-channel v0.4.4
[INFO] [stderr]     Checking idna v0.1.5
[INFO] [stderr]     Checking lru-cache v0.1.2
[INFO] [stderr]     Checking crossbeam-deque v0.7.4
[INFO] [stderr]    Compiling syn v1.0.109
[INFO] [stderr]     Checking tokio-executor v0.1.10
[INFO] [stderr]     Checking tokio-sync v0.1.8
[INFO] [stderr]     Checking crossbeam v0.7.3
[INFO] [stderr]     Checking tokio-timer v0.2.13
[INFO] [stderr]     Checking tokio-current-thread v0.1.7
[INFO] [stderr]     Checking url v1.7.2
[INFO] [stderr]    Compiling cc v1.0.83
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking num_cpus v1.16.0
[INFO] [stderr]     Checking net2 v0.2.39
[INFO] [stderr]     Checking rand_os v0.1.3
[INFO] [stderr]     Checking hostname v0.3.1
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking socket2 v0.3.19
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking mio v0.6.23
[INFO] [stderr]     Checking resolv-conf v0.6.3
[INFO] [stderr]     Checking tokio-threadpool v0.1.18
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking tokio-io v0.1.13
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking mio-uds v0.6.8
[INFO] [stderr]     Checking tokio-reactor v0.1.12
[INFO] [stderr]     Checking tokio-codec v0.1.2
[INFO] [stderr]     Checking tokio-fs v0.1.7
[INFO] [stderr]    Compiling backtrace v0.3.69
[INFO] [stderr]     Checking tokio-udp v0.1.6
[INFO] [stderr]     Checking tokio-tcp v0.1.4
[INFO] [stderr]     Checking tokio-uds v0.2.7
[INFO] [stderr]     Checking addr2line v0.21.0
[INFO] [stderr]     Checking tokio v0.1.22
[INFO] [stderr]    Compiling futures-join-macro-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling enum-as-inner v0.2.1
[INFO] [stderr]     Checking futures-util-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling synstructure v0.12.6
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/futures-util-preview-0.3.0-alpha.18/src/lib.rs:4:38
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![cfg_attr(feature = "async-await", feature(async_await))]
[INFO] [stdout]   |                                      ^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `async_await` has been stable since `1.39.0` and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling runtime-attributes v0.3.0-alpha.6
[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 `futures-util-preview` (lib) due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "87760a2977a6d8b9e246eff268697e43b092cb2c0ab8f5c7c788658099474798", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "87760a2977a6d8b9e246eff268697e43b092cb2c0ab8f5c7c788658099474798", kill_on_drop: false }`
[INFO] [stdout] 87760a2977a6d8b9e246eff268697e43b092cb2c0ab8f5c7c788658099474798
[INFO] documenting letsgo-0.0.1 against beta-2023-12-22 for beta-1.76-rustdoc-1
[INFO] extracting crate letsgo 0.0.1 into /workspace/builds/worker-4-tc2/source
[INFO] validating manifest of crates.io crate letsgo 0.0.1 on toolchain beta-2023-12-22
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-12-22" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate letsgo 0.0.1
[INFO] finished tweaking crates.io crate letsgo 0.0.1
[INFO] tweaked toml for crates.io crate letsgo 0.0.1 written to /workspace/builds/worker-4-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-12-22" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2023-12-22" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2023-12-22" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 6dc41be1e4f4aff7732b05deca8ad55ac04151694e27bb7e5d12861f02743157
[INFO] running `Command { std: "docker" "start" "-a" "6dc41be1e4f4aff7732b05deca8ad55ac04151694e27bb7e5d12861f02743157", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "6dc41be1e4f4aff7732b05deca8ad55ac04151694e27bb7e5d12861f02743157", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6dc41be1e4f4aff7732b05deca8ad55ac04151694e27bb7e5d12861f02743157", kill_on_drop: false }`
[INFO] [stdout] 6dc41be1e4f4aff7732b05deca8ad55ac04151694e27bb7e5d12861f02743157
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/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" "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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2023-12-22" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9a56b1f24e07f13659fcb159e492c622fbbd9ff4c19f947cb373c41dd948ad3d
[INFO] running `Command { std: "docker" "start" "-a" "9a56b1f24e07f13659fcb159e492c622fbbd9ff4c19f947cb373c41dd948ad3d", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.151
[INFO] [stderr]     Checking futures v0.1.31
[INFO] [stderr]    Compiling maybe-uninit v2.0.0
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling memoffset v0.5.6
[INFO] [stderr]     Checking lock_api v0.3.4
[INFO] [stderr]    Compiling crossbeam-epoch v0.8.2
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling getrandom v0.1.16
[INFO] [stderr]    Compiling proc-macro-nested v0.1.7
[INFO] [stderr]    Compiling parking_lot_core v0.6.3
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]    Compiling autocfg v0.1.8
[INFO] [stderr]    Compiling proc-macro2 v1.0.76
[INFO] [stderr]     Checking rand_core v0.4.2
[INFO] [stderr]     Checking futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking futures-sink-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]     Checking futures-channel-preview v0.3.0-alpha.18
[INFO] [stderr]     Checking rand_core v0.3.1
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling failure_derive v0.1.8
[INFO] [stderr]     Checking gimli v0.28.1
[INFO] [stderr]     Checking smallvec v0.6.14
[INFO] [stderr]     Checking miniz_oxide v0.7.1
[INFO] [stderr]     Checking unicode-normalization v0.1.22
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]     Checking object v0.32.2
[INFO] [stderr]     Checking rustc-demangle v0.1.23
[INFO] [stderr]     Checking rand_xorshift v0.1.1
[INFO] [stderr]     Checking rand_isaac v0.1.1
[INFO] [stderr]     Checking rand_hc v0.1.0
[INFO] [stderr]     Checking rand_jitter v0.1.4
[INFO] [stderr]     Checking crossbeam-utils v0.6.6
[INFO] [stderr]     Checking async-ready v3.0.0
[INFO] [stderr]     Checking percent-encoding v1.0.1
[INFO] [stderr]     Checking async-datagram v3.0.0
[INFO] [stderr]     Checking match_cfg v0.1.0
[INFO] [stderr]     Checking linked-hash-map v0.5.6
[INFO] [stderr]     Checking crossbeam-queue v0.2.3
[INFO] [stderr]     Checking crossbeam-channel v0.4.4
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]     Checking quick-error v1.2.3
[INFO] [stderr]     Checking idna v0.1.5
[INFO] [stderr]    Compiling quote v1.0.35
[INFO] [stderr]     Checking lru-cache v0.1.2
[INFO] [stderr]     Checking crossbeam-deque v0.7.4
[INFO] [stderr]    Compiling syn v1.0.109
[INFO] [stderr]     Checking tokio-executor v0.1.10
[INFO] [stderr]     Checking tokio-sync v0.1.8
[INFO] [stderr]     Checking crossbeam v0.7.3
[INFO] [stderr]     Checking url v1.7.2
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking num_cpus v1.16.0
[INFO] [stderr]     Checking net2 v0.2.39
[INFO] [stderr]     Checking rand_os v0.1.3
[INFO] [stderr]     Checking socket2 v0.3.19
[INFO] [stderr]     Checking hostname v0.3.1
[INFO] [stderr]     Checking tokio-timer v0.2.13
[INFO] [stderr]    Compiling cc v1.0.83
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking tokio-current-thread v0.1.7
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking tokio-threadpool v0.1.18
[INFO] [stderr]     Checking mio v0.6.23
[INFO] [stderr]     Checking resolv-conf v0.6.3
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking tokio-io v0.1.13
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking mio-uds v0.6.8
[INFO] [stderr]     Checking tokio-reactor v0.1.12
[INFO] [stderr]     Checking tokio-codec v0.1.2
[INFO] [stderr]     Checking tokio-fs v0.1.7
[INFO] [stderr]    Compiling backtrace v0.3.69
[INFO] [stderr]     Checking tokio-udp v0.1.6
[INFO] [stderr]     Checking tokio-tcp v0.1.4
[INFO] [stderr]     Checking tokio-uds v0.2.7
[INFO] [stderr]     Checking tokio v0.1.22
[INFO] [stderr]     Checking addr2line v0.21.0
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling futures-join-macro-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling enum-as-inner v0.2.1
[INFO] [stderr]     Checking futures-util-preview v0.3.0-alpha.18
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/futures-util-preview-0.3.0-alpha.18/src/lib.rs:4:38
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![cfg_attr(feature = "async-await", feature(async_await))]
[INFO] [stdout]   |                                      ^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `async_await` has been stable since `1.39.0` and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling synstructure v0.12.6
[INFO] [stdout] error: aborting due to 1 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 `futures-util-preview` (lib) due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "9a56b1f24e07f13659fcb159e492c622fbbd9ff4c19f947cb373c41dd948ad3d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9a56b1f24e07f13659fcb159e492c622fbbd9ff4c19f947cb373c41dd948ad3d", kill_on_drop: false }`
[INFO] [stdout] 9a56b1f24e07f13659fcb159e492c622fbbd9ff4c19f947cb373c41dd948ad3d
