[INFO] cloning repository https://github.com/PaulGrandperrin/playground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/PaulGrandperrin/playground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FPaulGrandperrin%2Fplayground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FPaulGrandperrin%2Fplayground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 572ff41ccdfa72771a37fd9ab89f37e9b5451041
[INFO] documenting PaulGrandperrin/playground against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FPaulGrandperrin%2Fplayground" "/workspace/builds/worker-8/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-8/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/PaulGrandperrin/playground on toolchain beta-2020-08-29
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/PaulGrandperrin/playground
[INFO] finished tweaking git repo https://github.com/PaulGrandperrin/playground
[INFO] tweaked toml for git repo https://github.com/PaulGrandperrin/playground written to /workspace/builds/worker-8/source/Cargo.toml
[INFO] crate git repo https://github.com/PaulGrandperrin/playground already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded color-backtrace v0.1.3
[INFO] [stderr]   Downloaded libc v0.2.55
[INFO] [stderr]   Downloaded num-bigint v0.2.2
[INFO] [stderr]   Downloaded backtrace v0.3.26
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/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" "+beta-2020-08-29" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 33c8bd35528a5a7827ced86ef67fbad3b862d09c94e21c7ecc5dd16d8b132a91
[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" "33c8bd35528a5a7827ced86ef67fbad3b862d09c94e21c7ecc5dd16d8b132a91", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "33c8bd35528a5a7827ced86ef67fbad3b862d09c94e21c7ecc5dd16d8b132a91", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "33c8bd35528a5a7827ced86ef67fbad3b862d09c94e21c7ecc5dd16d8b132a91", kill_on_drop: false }`
[INFO] [stdout] 33c8bd35528a5a7827ced86ef67fbad3b862d09c94e21c7ecc5dd16d8b132a91
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/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" "+beta-2020-08-29" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 8d0f2bc4fc6339a2efcfa8c8c962bb9c88c6a79dc30759daace0259af4fd07f2
[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" "8d0f2bc4fc6339a2efcfa8c8c962bb9c88c6a79dc30759daace0259af4fd07f2", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.55
[INFO] [stderr]    Compiling syn v0.15.34
[INFO] [stderr]     Checking rustc-demangle v0.1.14
[INFO] [stderr]    Compiling serde v1.0.91
[INFO] [stderr]    Compiling num-traits v0.2.8
[INFO] [stderr]    Compiling num-integer v0.1.41
[INFO] [stderr]    Compiling backtrace v0.3.26
[INFO] [stderr]    Compiling num-iter v0.1.39
[INFO] [stderr]    Compiling backtrace-sys v0.1.28
[INFO] [stderr]     Checking itertools v0.8.0
[INFO] [stderr]     Checking dirs v1.0.5
[INFO] [stderr]     Checking iovec v0.1.2
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking term v0.5.2
[INFO] [stderr]     Checking num-complex v0.2.1
[INFO] [stderr]     Checking num-bigint v0.2.2
[INFO] [stderr]     Checking color-backtrace v0.1.3
[INFO] [stderr]     Checking num-rational v0.2.1
[INFO] [stderr]    Compiling synstructure v0.10.2
[INFO] [stderr]     Checking num v0.2.0
[INFO] [stderr]    Compiling serde_derive v1.0.91
[INFO] [stderr]    Compiling failure_derive v0.1.5
[INFO] [stderr]     Checking failure v0.1.5
[INFO] [stderr]     Checking exitfailure v0.5.1
[INFO] [stderr]     Checking bincode v1.1.4
[INFO] [stderr]  Documenting playground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/main.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | / #![feature(
[INFO] [stdout] 2 | |     trivial_bounds,
[INFO] [stdout] 3 | |     try_from,
[INFO] [stdout] 4 | |     non_exhaustive,
[INFO] [stdout] ... |
[INFO] [stdout] 8 | |     never_type
[INFO] [stdout] 9 | | )]
[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 `playground`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type bin --crate-name playground 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 bincode=/opt/rustwide/target/debug/deps/libbincode-a641971cfe037a43.rmeta --extern bytes=/opt/rustwide/target/debug/deps/libbytes-01854486f7be8305.rmeta --extern color_backtrace=/opt/rustwide/target/debug/deps/libcolor_backtrace-090e3d5b97a2566f.rmeta --extern exitfailure=/opt/rustwide/target/debug/deps/libexitfailure-2ca20a80b11c47b1.rmeta --extern failure=/opt/rustwide/target/debug/deps/libfailure-a350cdebc31095cd.rmeta --extern itertools=/opt/rustwide/target/debug/deps/libitertools-d317d4d8cc9ecda0.rmeta --extern num=/opt/rustwide/target/debug/deps/libnum-284ebadc1fb76f03.rmeta --extern serde=/opt/rustwide/target/debug/deps/libserde-8d62d7da4e0c4853.rmeta --cap-lints=warn --crate-version 0.1.0` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "8d0f2bc4fc6339a2efcfa8c8c962bb9c88c6a79dc30759daace0259af4fd07f2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8d0f2bc4fc6339a2efcfa8c8c962bb9c88c6a79dc30759daace0259af4fd07f2", kill_on_drop: false }`
[INFO] [stdout] 8d0f2bc4fc6339a2efcfa8c8c962bb9c88c6a79dc30759daace0259af4fd07f2