[INFO] cloning repository https://github.com/funbringer/rust-hkt-playground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/funbringer/rust-hkt-playground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffunbringer%2Frust-hkt-playground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffunbringer%2Frust-hkt-playground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 7c295a70108b4cb0becf5710c93f82575999a52d
[INFO] testing funbringer/rust-hkt-playground against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffunbringer%2Frust-hkt-playground" "/workspace/builds/worker-15/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-15/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/funbringer/rust-hkt-playground 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] removed /workspace/builds/worker-15/source/rust-toolchain
[INFO] started tweaking git repo https://github.com/funbringer/rust-hkt-playground
[INFO] finished tweaking git repo https://github.com/funbringer/rust-hkt-playground
[INFO] tweaked toml for git repo https://github.com/funbringer/rust-hkt-playground written to /workspace/builds/worker-15/source/Cargo.toml
[INFO] crate git repo https://github.com/funbringer/rust-hkt-playground already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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] 4f2d5448d84330a2dea1b69604fbfb56e7b9848ba23946bcaa1d0128541fae91
[INFO] running `Command { std: "docker" "start" "-a" "4f2d5448d84330a2dea1b69604fbfb56e7b9848ba23946bcaa1d0128541fae91", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "4f2d5448d84330a2dea1b69604fbfb56e7b9848ba23946bcaa1d0128541fae91", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4f2d5448d84330a2dea1b69604fbfb56e7b9848ba23946bcaa1d0128541fae91", kill_on_drop: false }`
[INFO] [stdout] 4f2d5448d84330a2dea1b69604fbfb56e7b9848ba23946bcaa1d0128541fae91
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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] 65a1eaa09121e1d29c0719ef70ab9006874afe45538d47afe342af7c3fbca805
[INFO] running `Command { std: "docker" "start" "-a" "65a1eaa09121e1d29c0719ef70ab9006874afe45538d47afe342af7c3fbca805", 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] [stderr]    Compiling demo v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(assert_matches)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(generic_associated_types)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![feature(maybe_uninit_array_assume_init)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:5:1
[INFO] [stdout]   |
[INFO] [stdout] 5 | #![feature(maybe_uninit_uninit_array)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:6:1
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![feature(never_type)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 5 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `demo` due to 6 previous errors
[INFO] running `Command { std: "docker" "inspect" "65a1eaa09121e1d29c0719ef70ab9006874afe45538d47afe342af7c3fbca805", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "65a1eaa09121e1d29c0719ef70ab9006874afe45538d47afe342af7c3fbca805", kill_on_drop: false }`
[INFO] [stdout] 65a1eaa09121e1d29c0719ef70ab9006874afe45538d47afe342af7c3fbca805