[INFO] fetching crate lain 0.5.2...
[INFO] documenting lain-0.5.2 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate lain 0.5.2 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate lain 0.5.2 on toolchain 1.46.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate lain 0.5.2
[INFO] finished tweaking crates.io crate lain 0.5.2
[INFO] tweaked toml for crates.io crate lain 0.5.2 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] b132ff2046f678d6305ef74b9c61125a2d36444ed01ed5111ce6a12d03179731
[INFO] running `Command { std: "docker" "start" "-a" "b132ff2046f678d6305ef74b9c61125a2d36444ed01ed5111ce6a12d03179731", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b132ff2046f678d6305ef74b9c61125a2d36444ed01ed5111ce6a12d03179731", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b132ff2046f678d6305ef74b9c61125a2d36444ed01ed5111ce6a12d03179731", kill_on_drop: false }`
[INFO] [stdout] b132ff2046f678d6305ef74b9c61125a2d36444ed01ed5111ce6a12d03179731
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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" "RUSTDOCFLAGS=--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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] e6d3f698048ec029f517a80b0545a5ed3acf143a42cf1a6a253bc83bfb81dcfc
[INFO] running `Command { std: "docker" "start" "-a" "e6d3f698048ec029f517a80b0545a5ed3acf143a42cf1a6a253bc83bfb81dcfc", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro-hack-impl v0.4.2
[INFO] [stderr]    Compiling num-integer v0.1.43
[INFO] [stderr]    Compiling num-bigint v0.2.6
[INFO] [stderr]    Compiling num-iter v0.1.41
[INFO] [stderr]    Compiling num-rational v0.2.4
[INFO] [stderr]    Compiling num-complex v0.2.4
[INFO] [stderr]    Compiling field-offset v0.3.2
[INFO] [stderr]     Checking getrandom v0.1.14
[INFO] [stderr]    Compiling num-derive v0.2.5
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking rand_pcg v0.2.1
[INFO] [stderr]    Compiling proc-macro-hack v0.4.2
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]    Compiling mashup-impl v0.1.12
[INFO] [stderr]    Compiling mashup v0.1.12
[INFO] [stderr]    Compiling lain_derive v0.5.2
[INFO] [stderr]     Checking num v0.2.1
[INFO] [stderr]  Documenting lain v0.5.2 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]    --> src/lib.rs:101:1
[INFO] [stdout]     |
[INFO] [stdout] 101 | #![feature(specialization)]
[INFO] [stdout]     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 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 document `lain`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name lain src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern byteorder=/opt/rustwide/target/debug/deps/libbyteorder-cdbbc07100f440a1.rmeta --extern field_offset=/opt/rustwide/target/debug/deps/libfield_offset-dcae7ca98780dc7c.rmeta --extern lain_derive=/opt/rustwide/target/debug/deps/liblain_derive-b62229f61c3cf046.so --extern lazy_static=/opt/rustwide/target/debug/deps/liblazy_static-57a7edc7f441d44c.rmeta --extern log=/opt/rustwide/target/debug/deps/liblog-75d540134d633bf3.rmeta --extern mashup=/opt/rustwide/target/debug/deps/libmashup-cca2a5f41242926f.rmeta --extern num=/opt/rustwide/target/debug/deps/libnum-097ddf5ac34c7cfa.rmeta --extern num_derive=/opt/rustwide/target/debug/deps/libnum_derive-c0546b5c2729e533.so --extern num_traits=/opt/rustwide/target/debug/deps/libnum_traits-705f46f124ac753d.rmeta --extern rand=/opt/rustwide/target/debug/deps/librand-01a1d0a621b64ff4.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "e6d3f698048ec029f517a80b0545a5ed3acf143a42cf1a6a253bc83bfb81dcfc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e6d3f698048ec029f517a80b0545a5ed3acf143a42cf1a6a253bc83bfb81dcfc", kill_on_drop: false }`
[INFO] [stdout] e6d3f698048ec029f517a80b0545a5ed3acf143a42cf1a6a253bc83bfb81dcfc