[INFO] cloning repository https://github.com/theduke/rust-serialization-benchmarks
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/theduke/rust-serialization-benchmarks" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftheduke%2Frust-serialization-benchmarks", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftheduke%2Frust-serialization-benchmarks'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4d24c6531d75942ef58ef4005e6dbb8f661b2225
[INFO] documenting theduke/rust-serialization-benchmarks against master#394e1b40d264aa6928811919c1124fa248e7d802 for pr-73566
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ftheduke%2Frust-serialization-benchmarks" "/workspace/builds/worker-0/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/theduke/rust-serialization-benchmarks on toolchain 394e1b40d264aa6928811919c1124fa248e7d802
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/theduke/rust-serialization-benchmarks
[INFO] finished tweaking git repo https://github.com/theduke/rust-serialization-benchmarks
[INFO] tweaked toml for git repo https://github.com/theduke/rust-serialization-benchmarks written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] crate git repo https://github.com/theduke/rust-serialization-benchmarks already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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@sha256:819119df93c0f5eca3f29186f14981ef29945a311854d7222af07488600a2584" "/opt/rustwide/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] ef569e4dbbedad700b972d6e3901e29335cb9b3a9ab935cf27ec99930deb5fae
[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" "ef569e4dbbedad700b972d6e3901e29335cb9b3a9ab935cf27ec99930deb5fae", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ef569e4dbbedad700b972d6e3901e29335cb9b3a9ab935cf27ec99930deb5fae", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ef569e4dbbedad700b972d6e3901e29335cb9b3a9ab935cf27ec99930deb5fae", kill_on_drop: false }`
[INFO] [stdout] ef569e4dbbedad700b972d6e3901e29335cb9b3a9ab935cf27ec99930deb5fae
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "RUSTDOCFLAGS=--cap-lints=forbid" "-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@sha256:819119df93c0f5eca3f29186f14981ef29945a311854d7222af07488600a2584" "/opt/rustwide/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ac18bb07c3c187cb9dc013488ac26739ccef15e18fe831af72d7dc29c5d9d7f4
[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" "ac18bb07c3c187cb9dc013488ac26739ccef15e18fe831af72d7dc29c5d9d7f4", kill_on_drop: false }`
[INFO] [stderr]     Checking libc v0.2.19
[INFO] [stderr]     Checking num-traits v0.1.36
[INFO] [stderr]     Checking serde v0.8.21
[INFO] [stderr]    Compiling winapi-build v0.1.1
[INFO] [stderr]     Checking winapi v0.2.8
[INFO] [stderr]     Checking rustc-serialize v0.3.22
[INFO] [stderr]    Compiling quote v0.3.10
[INFO] [stderr]    Compiling unicode-xid v0.0.3
[INFO] [stderr]    Compiling gcc v0.3.41
[INFO] [stderr]     Checking byteorder v1.0.0
[INFO] [stderr]     Checking byteorder v0.5.3
[INFO] [stderr]     Checking dtoa v0.2.2
[INFO] [stderr]     Checking regex-syntax v0.3.9
[INFO] [stderr]     Checking utf8-ranges v0.1.3
[INFO] [stderr]     Checking itoa v0.1.1
[INFO] [stderr]     Checking linked-hash-map v0.0.9
[INFO] [stderr]     Checking iter-read v0.1.0
[INFO] [stderr]     Checking lazy_static v0.2.2
[INFO] [stderr]     Checking byteorder v0.3.13
[INFO] [stderr]     Checking bencher v0.1.2 (https://github.com/theduke/bencher.git#59ee1f8f)
[INFO] [stderr]    Compiling syn v0.10.5
[INFO] [stderr]    Compiling kernel32-sys v0.2.2
[INFO] [stderr]     Checking rand v0.3.15
[INFO] [stderr]     Checking memchr v0.1.11
[INFO] [stderr]     Checking num-integer v0.1.32
[INFO] [stderr]     Checking rmp v0.8.1
[INFO] [stderr]     Checking aho-corasick v0.5.3
[INFO] [stderr]     Checking num-iter v0.1.32
[INFO] [stderr]     Checking thread-id v2.0.0
[INFO] [stderr]     Checking time v0.1.35
[INFO] [stderr]     Checking num v0.1.36
[INFO] [stderr]     Checking thread_local v0.2.7
[INFO] [stderr]    Compiling rust-crypto v0.2.36
[INFO] [stderr]     Checking chrono v0.2.25
[INFO] [stderr]     Checking regex v0.1.80
[INFO] [stderr]    Compiling serde_codegen_internals v0.11.3
[INFO] [stderr]     Checking num-bigint v0.1.35
[INFO] [stderr]     Checking cbor v0.4.0
[INFO] [stderr]    Compiling serde_codegen v0.8.21
[INFO] [stderr]     Checking serde_test v0.8.21
[INFO] [stderr]     Checking rmp-serde v0.11.0
[INFO] [stderr]     Checking serde_cbor v0.4.0
[INFO] [stderr]     Checking toml v0.2.1
[INFO] [stderr]     Checking serde_json v0.8.4
[INFO] [stderr]     Checking bincode v0.6.1
[INFO] [stderr]     Checking serde-pickle v0.2.0
[INFO] [stderr]     Checking linked-hash-map v0.3.0
[INFO] [stderr]    Compiling serde_derive v0.8.21
[INFO] [stderr]     Checking yaml-rust v0.3.5
[INFO] [stderr]     Checking serde-hjson v0.8.1
[INFO] [stderr]     Checking serde_yaml v0.5.0
[INFO] [stderr]     Checking bson v0.3.2
[INFO] [stderr]  Documenting rust_serialization_benchmark v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0635]: unknown feature `step_by`
[INFO] [stdout]  --> src/main.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(step_by)]
[INFO] [stdout]   |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0635`.
[INFO] [stdout] 
[INFO] [stderr] error: Could not document `rust_serialization_benchmark`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --crate-type bin --crate-name rust_serialization_benchmark src/main.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern bencher=/opt/rustwide/target/debug/deps/libbencher-a9968d71a6fed027.rmeta --extern bincode=/opt/rustwide/target/debug/deps/libbincode-94ca0dcc5302cfd2.rmeta --extern bson=/opt/rustwide/target/debug/deps/libbson-082a19094a894b88.rmeta --extern cbor=/opt/rustwide/target/debug/deps/libcbor-8008d4bf44031724.rmeta --extern rmp_serde=/opt/rustwide/target/debug/deps/librmp_serde-c309527a8ca6fc2b.rmeta --extern serde=/opt/rustwide/target/debug/deps/libserde-feb67df99d0ceefa.rmeta --extern serde_hjson=/opt/rustwide/target/debug/deps/libserde_hjson-9d4725a2bc2ce87e.rmeta --extern serde_pickle=/opt/rustwide/target/debug/deps/libserde_pickle-101b512d2cffecee.rmeta --extern serde_cbor=/opt/rustwide/target/debug/deps/libserde_cbor-61df49dc73f7cb23.rmeta --extern serde_derive=/opt/rustwide/target/debug/deps/libserde_derive-920330324a383143.so --extern serde_json=/opt/rustwide/target/debug/deps/libserde_json-67c9122957501d27.rmeta --extern serde_yaml=/opt/rustwide/target/debug/deps/libserde_yaml-661cbc9977cc15d8.rmeta --extern toml=/opt/rustwide/target/debug/deps/libtoml-c2ced15bc28fa1af.rmeta --cap-lints=forbid` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "ac18bb07c3c187cb9dc013488ac26739ccef15e18fe831af72d7dc29c5d9d7f4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ac18bb07c3c187cb9dc013488ac26739ccef15e18fe831af72d7dc29c5d9d7f4", kill_on_drop: false }`
[INFO] [stdout] ac18bb07c3c187cb9dc013488ac26739ccef15e18fe831af72d7dc29c5d9d7f4