[INFO] fetching crate combinatorics 0.0.1...
[INFO] checking combinatorics-0.0.1 against master#0a8629bff642c3c3b84bb644c0099194f063b627 for pr-86231
[INFO] extracting crate combinatorics 0.0.1 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate combinatorics 0.0.1 on toolchain 0a8629bff642c3c3b84bb644c0099194f063b627
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0a8629bff642c3c3b84bb644c0099194f063b627" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate combinatorics 0.0.1
[INFO] finished tweaking crates.io crate combinatorics 0.0.1
[INFO] tweaked toml for crates.io crate combinatorics 0.0.1 written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0a8629bff642c3c3b84bb644c0099194f063b627" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0a8629bff642c3c3b84bb644c0099194f063b627" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+0a8629bff642c3c3b84bb644c0099194f063b627" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 528bcbf6972dbc397fcb916ca8c63e2b9c839f2a7f5c6b07787b24506f727b78
[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" "528bcbf6972dbc397fcb916ca8c63e2b9c839f2a7f5c6b07787b24506f727b78", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "528bcbf6972dbc397fcb916ca8c63e2b9c839f2a7f5c6b07787b24506f727b78", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "528bcbf6972dbc397fcb916ca8c63e2b9c839f2a7f5c6b07787b24506f727b78", kill_on_drop: false }`
[INFO] [stdout] 528bcbf6972dbc397fcb916ca8c63e2b9c839f2a7f5c6b07787b24506f727b78
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+0a8629bff642c3c3b84bb644c0099194f063b627" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ee863d84466ffa6fc47730e7692c12900221490f45f58b6ad956201e91421cf8
[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" "ee863d84466ffa6fc47730e7692c12900221490f45f58b6ad956201e91421cf8", kill_on_drop: false }`
[INFO] [stderr]     Checking combinatorics v0.0.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
[INFO] [stdout]   --> src/lib.rs:29:1
[INFO] [stdout]    |
[INFO] [stdout] 29 | extern crate libc;
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: see issue #27812 <https://github.com/rust-lang/rust/issues/27812> for more information
[INFO] [stdout]    = help: add `#![feature(rustc_private)]` to the crate attributes to enable
[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 E0658`.
[INFO] [stdout] 
[INFO] [stdout] error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
[INFO] [stdout]   --> src/lib.rs:29:1
[INFO] [stdout]    |
[INFO] [stdout] 29 | extern crate libc;
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: see issue #27812 <https://github.com/rust-lang/rust/issues/27812> for more information
[INFO] [stdout]    = help: add `#![feature(rustc_private)]` to the crate attributes to enable
[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 E0658`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `combinatorics`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "ee863d84466ffa6fc47730e7692c12900221490f45f58b6ad956201e91421cf8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ee863d84466ffa6fc47730e7692c12900221490f45f58b6ad956201e91421cf8", kill_on_drop: false }`
[INFO] [stdout] ee863d84466ffa6fc47730e7692c12900221490f45f58b6ad956201e91421cf8