[INFO] cloning repository https://github.com/brain0/cowbench
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/brain0/cowbench" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbrain0%2Fcowbench", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbrain0%2Fcowbench'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 6a114c3645e39d61d916258537325903a3fbfbdb
[INFO] testing brain0/cowbench against master#432e145bd5a974c5b6f4dd9b352891bd7502b69d for pr-87041
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbrain0%2Fcowbench" "/workspace/builds/worker-11/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-11/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/brain0/cowbench on toolchain 432e145bd5a974c5b6f4dd9b352891bd7502b69d
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/brain0/cowbench
[INFO] finished tweaking git repo https://github.com/brain0/cowbench
[INFO] tweaked toml for git repo https://github.com/brain0/cowbench written to /workspace/builds/worker-11/source/Cargo.toml
[INFO] crate git repo https://github.com/brain0/cowbench already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "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" "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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "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] 1388f1f0f2458512b2644c416a6ea06acfae21cf12a2e3792c3a5bdbbc0dcc3c
[INFO] running `Command { std: "docker" "start" "-a" "1388f1f0f2458512b2644c416a6ea06acfae21cf12a2e3792c3a5bdbbc0dcc3c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1388f1f0f2458512b2644c416a6ea06acfae21cf12a2e3792c3a5bdbbc0dcc3c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1388f1f0f2458512b2644c416a6ea06acfae21cf12a2e3792c3a5bdbbc0dcc3c", kill_on_drop: false }`
[INFO] [stdout] 1388f1f0f2458512b2644c416a6ea06acfae21cf12a2e3792c3a5bdbbc0dcc3c
[INFO] running `Command { std: "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" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "build" "--frozen" "--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] 9c1d051118863ab6fa1afd7fe7c55508fc72799aedb426a39f851f672f79e02e
[INFO] running `Command { std: "docker" "start" "-a" "9c1d051118863ab6fa1afd7fe7c55508fc72799aedb426a39f851f672f79e02e", kill_on_drop: false }`
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]    Compiling cfg-if v0.1.10
[INFO] [stderr]    Compiling ppv-lite86 v0.2.6
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling rand_chacha v0.2.2
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling cowbench v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0658]: use of unstable library feature 'bench_black_box'
[INFO] [stdout]   --> src/main.rs:48:5
[INFO] [stdout]    |
[INFO] [stdout] 48 |     std::hint::black_box(s);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: see issue #64102 <https://github.com/rust-lang/rust/issues/64102> for more information
[INFO] [stdout]    = help: add `#![feature(bench_black_box)]` to the crate attributes to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0658]: use of unstable library feature 'bench_black_box'
[INFO] [stdout]   --> src/main.rs:52:5
[INFO] [stdout]    |
[INFO] [stdout] 52 |     std::hint::black_box(s);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: see issue #64102 <https://github.com/rust-lang/rust/issues/64102> for more information
[INFO] [stdout]    = help: add `#![feature(bench_black_box)]` to the crate attributes to enable
[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 E0658`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `cowbench`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "9c1d051118863ab6fa1afd7fe7c55508fc72799aedb426a39f851f672f79e02e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9c1d051118863ab6fa1afd7fe7c55508fc72799aedb426a39f851f672f79e02e", kill_on_drop: false }`
[INFO] [stdout] 9c1d051118863ab6fa1afd7fe7c55508fc72799aedb426a39f851f672f79e02e