[INFO] crate rx 0.0.1 is already in cache
[INFO] testing rx-0.0.1 against 1.44.0 for beta-1.45-1
[INFO] extracting crate rx 0.0.1 into /workspace/builds/worker-5/source
[INFO] validating manifest of crates.io crate rx 0.0.1 on toolchain 1.44.0
[INFO] running `"/workspace/cargo-home/bin/cargo" "+1.44.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate rx 0.0.1
[INFO] finished tweaking crates.io crate rx 0.0.1
[INFO] tweaked toml for crates.io crate rx 0.0.1 written to /workspace/builds/worker-5/source/Cargo.toml
[INFO] running `"/workspace/cargo-home/bin/cargo" "+1.44.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/workspace/cargo-home/bin/cargo" "+1.44.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "/opt/rustwide/cargo-home/bin/cargo" "+1.44.0" "build" "--frozen"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] acf050ba0c2967bd44f364506e497eb16c2fdd40918a6376bfc1ddd8ad0d32d4
[INFO] running `"docker" "start" "-a" "acf050ba0c2967bd44f364506e497eb16c2fdd40918a6376bfc1ddd8ad0d32d4"`
[INFO] [stderr] sudo: setrlimit(RLIMIT_CORE): Operation not permitted
[INFO] [stderr]    Compiling rx v0.0.1 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:16:1
[INFO] [stderr]    |
[INFO] [stderr] 16 | #![feature(fn_traits, unboxed_closures)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stderr]   --> src/subject.rs:17:24
[INFO] [stderr]    |
[INFO] [stderr] 17 |     observers: Vec<Box<BoxedObserver<T, E>>>,
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn BoxedObserver<T, E>`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error; 1 warning emitted
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: could not compile `rx`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "acf050ba0c2967bd44f364506e497eb16c2fdd40918a6376bfc1ddd8ad0d32d4"`
[INFO] running `"docker" "rm" "-f" "acf050ba0c2967bd44f364506e497eb16c2fdd40918a6376bfc1ddd8ad0d32d4"`
[INFO] [stdout] acf050ba0c2967bd44f364506e497eb16c2fdd40918a6376bfc1ddd8ad0d32d4