[INFO] fetching crate json-trait-rs 0.11.0...
[INFO] testing json-trait-rs-0.11.0 against 1.49.0 for beta-1.50-1
[INFO] extracting crate json-trait-rs 0.11.0 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate json-trait-rs 0.11.0 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate json-trait-rs 0.11.0
[INFO] finished tweaking crates.io crate json-trait-rs 0.11.0
[INFO] tweaked toml for crates.io crate json-trait-rs 0.11.0 written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 23a66ff7458483df65d30c79c7778d4a92d5a19dd1ba6f78d991f01cd8409fb4
[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" "23a66ff7458483df65d30c79c7778d4a92d5a19dd1ba6f78d991f01cd8409fb4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "23a66ff7458483df65d30c79c7778d4a92d5a19dd1ba6f78d991f01cd8409fb4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "23a66ff7458483df65d30c79c7778d4a92d5a19dd1ba6f78d991f01cd8409fb4", kill_on_drop: false }`
[INFO] [stdout] 23a66ff7458483df65d30c79c7778d4a92d5a19dd1ba6f78d991f01cd8409fb4
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] c629bdd631b5f0eefdef674610db585b977c3c8e5d89445d5237d496fd26b626
[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" "c629bdd631b5f0eefdef674610db585b977c3c8e5d89445d5237d496fd26b626", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.57
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]    Compiling libc v0.2.81
[INFO] [stderr]    Compiling failure_derive v0.1.8
[INFO] [stderr]    Compiling gimli v0.23.0
[INFO] [stderr]    Compiling adler v0.2.3
[INFO] [stderr]    Compiling cfg-if v1.0.0
[INFO] [stderr]    Compiling object v0.22.0
[INFO] [stderr]    Compiling rustc-demangle v0.1.18
[INFO] [stderr]    Compiling strum v0.20.0
[INFO] [stderr]    Compiling join-lazy-fmt v0.9.2
[INFO] [stderr]    Compiling miniz_oxide v0.4.3
[INFO] [stderr]    Compiling addr2line v0.14.1
[INFO] [stderr]    Compiling backtrace v0.3.55
[INFO] [stderr]    Compiling synstructure v0.12.4
[INFO] [stderr]    Compiling strum_macros v0.20.1
[INFO] [stderr]    Compiling failure v0.1.8
[INFO] [stderr]    Compiling json-trait-rs v0.11.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:43:1
[INFO] [stdout]    |
[INFO] [stdout] 43 | #![feature(specialization)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]   --> src/lib.rs:43:12
[INFO] [stdout]    |
[INFO] [stdout] 43 | #![feature(specialization)]
[INFO] [stdout]    |            ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:37:5
[INFO] [stdout]    |
[INFO] [stdout] 37 |     warnings,
[INFO] [stdout]    |     ^^^^^^^^
[INFO] [stdout]    = note: `#[warn(incomplete_features)]` implied by `#[warn(warnings)]`
[INFO] [stdout]    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]    = help: consider using `min_specialization` instead, which is more stable and complete
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `json-trait-rs`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "c629bdd631b5f0eefdef674610db585b977c3c8e5d89445d5237d496fd26b626", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c629bdd631b5f0eefdef674610db585b977c3c8e5d89445d5237d496fd26b626", kill_on_drop: false }`
[INFO] [stdout] c629bdd631b5f0eefdef674610db585b977c3c8e5d89445d5237d496fd26b626