[INFO] crate slot 0.2.5 is already in cache
[INFO] testing slot-0.2.5 against beta-2020-07-24 for beta-1.46-1
[INFO] extracting crate slot 0.2.5 into /workspace/builds/worker-3/source
[INFO] validating manifest of crates.io crate slot 0.2.5 on toolchain beta-2020-07-24
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate slot 0.2.5
[INFO] finished tweaking crates.io crate slot 0.2.5
[INFO] tweaked toml for crates.io crate slot 0.2.5 written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-07-24" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 594ec0f4cea56b23f7d16a1c688f3a9b6a390e7ddfc3b43189654d7d262630ca
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "594ec0f4cea56b23f7d16a1c688f3a9b6a390e7ddfc3b43189654d7d262630ca", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "594ec0f4cea56b23f7d16a1c688f3a9b6a390e7ddfc3b43189654d7d262630ca", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "594ec0f4cea56b23f7d16a1c688f3a9b6a390e7ddfc3b43189654d7d262630ca", kill_on_drop: false }`
[INFO] [stdout] 594ec0f4cea56b23f7d16a1c688f3a9b6a390e7ddfc3b43189654d7d262630ca
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-07-24" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5c23ec23d4566cfe943c86c304962c34b28a4f96e5e004288658e5eb8753e028
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "5c23ec23d4566cfe943c86c304962c34b28a4f96e5e004288658e5eb8753e028", kill_on_drop: false }`
[INFO] [stderr]    Compiling slot v0.2.5 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unknown lint: `unions_with_drop_fields`
[INFO] [stdout]  --> src/lib.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 9 | #[allow(unions_with_drop_fields)]
[INFO] [stdout]   |         ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unknown_lints)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unknown lint: `unions_with_drop_fields`
[INFO] [stdout]   --> src/lib.rs:16:17
[INFO] [stdout]    |
[INFO] [stdout] 16 |         #[allow(unions_with_drop_fields)]
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(const_fn)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![feature(const_fn_union)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:5:1
[INFO] [stdout]   |
[INFO] [stdout] 5 | #![feature(untagged_unions)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0740]: unions may not contain fields that need dropping
[INFO] [stdout]   --> src/lib.rs:11:21
[INFO] [stdout]    |
[INFO] [stdout] 11 | pub union Slot<T> { pub x: T }
[INFO] [stdout]    |                     ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: `std::mem::ManuallyDrop` can be used to wrap the type
[INFO] [stdout]   --> src/lib.rs:11:21
[INFO] [stdout]    |
[INFO] [stdout] 11 | pub union Slot<T> { pub x: T }
[INFO] [stdout]    |                     ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 4 previous errors; 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0554, E0740.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `slot`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "5c23ec23d4566cfe943c86c304962c34b28a4f96e5e004288658e5eb8753e028", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5c23ec23d4566cfe943c86c304962c34b28a4f96e5e004288658e5eb8753e028", kill_on_drop: false }`
[INFO] [stdout] 5c23ec23d4566cfe943c86c304962c34b28a4f96e5e004288658e5eb8753e028