[INFO] cloning repository https://github.com/emmanuel2406/Rust_projects-reference_cycle
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/emmanuel2406/Rust_projects-reference_cycle" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Femmanuel2406%2FRust_projects-reference_cycle", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Femmanuel2406%2FRust_projects-reference_cycle'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] bf8760a50acc89aa02daac37accc964f78811a5e
[INFO] checking emmanuel2406/Rust_projects-reference_cycle against try#a2a6e871b05c7b8ecc9a3c8a20db1f39e995e399 for pr-145770
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Femmanuel2406%2FRust_projects-reference_cycle" "/workspace/builds/worker-4-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/emmanuel2406/Rust_projects-reference_cycle
[INFO] finished tweaking git repo https://github.com/emmanuel2406/Rust_projects-reference_cycle
[INFO] tweaked toml for git repo https://github.com/emmanuel2406/Rust_projects-reference_cycle written to /workspace/builds/worker-4-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/emmanuel2406/Rust_projects-reference_cycle on toolchain a2a6e871b05c7b8ecc9a3c8a20db1f39e995e399
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+a2a6e871b05c7b8ecc9a3c8a20db1f39e995e399" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/emmanuel2406/Rust_projects-reference_cycle already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+a2a6e871b05c7b8ecc9a3c8a20db1f39e995e399" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/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@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+a2a6e871b05c7b8ecc9a3c8a20db1f39e995e399" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 17814be3c7f17446e65fdef1abcf859f3125263e2975f0dd7369d29efc0cfeb2
[INFO] running `Command { std: "docker" "start" "-a" "17814be3c7f17446e65fdef1abcf859f3125263e2975f0dd7369d29efc0cfeb2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "17814be3c7f17446e65fdef1abcf859f3125263e2975f0dd7369d29efc0cfeb2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "17814be3c7f17446e65fdef1abcf859f3125263e2975f0dd7369d29efc0cfeb2", kill_on_drop: false }`
[INFO] [stdout] 17814be3c7f17446e65fdef1abcf859f3125263e2975f0dd7369d29efc0cfeb2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/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" "RUSTDOCFLAGS=--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@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+a2a6e871b05c7b8ecc9a3c8a20db1f39e995e399" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] c34a77ba977d6ba1ffcfa80447b59d49eabd3420c66846511431ded066ddf4d5
[INFO] running `Command { std: "docker" "start" "-a" "c34a77ba977d6ba1ffcfa80447b59d49eabd3420c66846511431ded066ddf4d5", kill_on_drop: false }`
[INFO] [stderr]     Checking reference_cycle v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/main.rs:7:10
[INFO] [stdout]   |
[INFO] [stdout] 7 |     Cons(i32, RefCell<Rc<List>>),
[INFO] [stdout]   |     ---- ^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `List` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 7 -     Cons(i32, RefCell<Rc<List>>),
[INFO] [stdout] 7 +     Cons((), RefCell<Rc<List>>),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/main.rs:7:10
[INFO] [stdout]   |
[INFO] [stdout] 7 |     Cons(i32, RefCell<Rc<List>>),
[INFO] [stdout]   |     ---- ^^^
[INFO] [stdout]   |     |
[INFO] [stdout]   |     field in this variant
[INFO] [stdout]   |
[INFO] [stdout]   = note: `List` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]   |
[INFO] [stdout] 7 -     Cons(i32, RefCell<Rc<List>>),
[INFO] [stdout] 7 +     Cons((), RefCell<Rc<List>>),
[INFO] [stdout]   |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.16s
[INFO] running `Command { std: "docker" "inspect" "c34a77ba977d6ba1ffcfa80447b59d49eabd3420c66846511431ded066ddf4d5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c34a77ba977d6ba1ffcfa80447b59d49eabd3420c66846511431ded066ddf4d5", kill_on_drop: false }`
[INFO] [stdout] c34a77ba977d6ba1ffcfa80447b59d49eabd3420c66846511431ded066ddf4d5
