[INFO] fetching crate xtra 0.2.8...
[INFO] testing xtra-0.2.8 against 1.44.0 for beta-1.45-1
[INFO] extracting crate xtra 0.2.8 into /workspace/builds/worker-11/source
[INFO] validating manifest of crates.io crate xtra 0.2.8 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 xtra 0.2.8
[INFO] removed 0 missing examples
[INFO] finished tweaking crates.io crate xtra 0.2.8
[INFO] tweaked toml for crates.io crate xtra 0.2.8 written to /workspace/builds/worker-11/source/Cargo.toml
[INFO] crate crates.io crate xtra 0.2.8 already has a lockfile, it will not be regenerated
[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-11/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-11/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] bbab80774a0c27ea8d0a212e21725797af80b228657b23ce082d40ed1381cc49
[INFO] running `"docker" "start" "-a" "bbab80774a0c27ea8d0a212e21725797af80b228657b23ce082d40ed1381cc49"`
[INFO] [stderr] sudo: setrlimit(RLIMIT_CORE): Operation not permitted
[INFO] [stderr]    Compiling syn v1.0.17
[INFO] [stderr]    Compiling futures-sink v0.3.4
[INFO] [stderr]    Compiling futures-core v0.3.4
[INFO] [stderr]    Compiling futures-channel v0.3.4
[INFO] [stderr]    Compiling futures-macro v0.3.4
[INFO] [stderr]    Compiling futures-util v0.3.4
[INFO] [stderr]    Compiling futures-executor v0.3.4
[INFO] [stderr]    Compiling futures v0.3.4
[INFO] [stderr]    Compiling xtra v0.2.8 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:3:1
[INFO] [stderr]   |
[INFO] [stderr] 3 | / #![feature(
[INFO] [stderr] 4 | |     generic_associated_types,
[INFO] [stderr] 5 | |     weak_counts,
[INFO] [stderr] 6 | |     specialization,
[INFO] [stderr] 7 | |     type_alias_impl_trait,
[INFO] [stderr] 8 | |     doc_cfg
[INFO] [stderr] 9 | | )]
[INFO] [stderr]   | |__^
[INFO] [stderr] 
[INFO] [stderr] warning: the feature `generic_associated_types` is incomplete and may cause the compiler to crash
[INFO] [stderr]  --> src/lib.rs:4:5
[INFO] [stderr]   |
[INFO] [stderr] 4 |     generic_associated_types,
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(incomplete_features)]` 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 `xtra`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "bbab80774a0c27ea8d0a212e21725797af80b228657b23ce082d40ed1381cc49"`
[INFO] running `"docker" "rm" "-f" "bbab80774a0c27ea8d0a212e21725797af80b228657b23ce082d40ed1381cc49"`
[INFO] [stdout] bbab80774a0c27ea8d0a212e21725797af80b228657b23ce082d40ed1381cc49