[INFO] cloning repository https://github.com/matklad/group-by-challenge
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matklad/group-by-challenge" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatklad%2Fgroup-by-challenge", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatklad%2Fgroup-by-challenge'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 297c95d461427a61f621767443897c37bef43f0f
[INFO] checking matklad/group-by-challenge against try#45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4 for pr-83744
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatklad%2Fgroup-by-challenge" "/workspace/builds/worker-4/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/matklad/group-by-challenge on toolchain 45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/matklad/group-by-challenge
[INFO] finished tweaking git repo https://github.com/matklad/group-by-challenge
[INFO] tweaked toml for git repo https://github.com/matklad/group-by-challenge written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/matklad/group-by-challenge already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "fetch" "--locked" "--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" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 0b90175c768d0935e0b4eaf327e4ddd14f299e4f4c136373e5c93152d6f27794
[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" "0b90175c768d0935e0b4eaf327e4ddd14f299e4f4c136373e5c93152d6f27794", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "0b90175c768d0935e0b4eaf327e4ddd14f299e4f4c136373e5c93152d6f27794", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0b90175c768d0935e0b4eaf327e4ddd14f299e4f4c136373e5c93152d6f27794", kill_on_drop: false }`
[INFO] [stdout] 0b90175c768d0935e0b4eaf327e4ddd14f299e4f4c136373e5c93152d6f27794
[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" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] fe999e24580291973af6b5833006644fc0ca4762cc2e6754036fe9052c187580
[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" "fe999e24580291973af6b5833006644fc0ca4762cc2e6754036fe9052c187580", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Checking group-by-challenge v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `xs`
[INFO] [stdout]  --> src/lib.rs:1:29
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                             ^^ help: if this is intentional, prefix it with an underscore: `_xs`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `key_fn`
[INFO] [stdout]  --> src/lib.rs:1:36
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                                    ^^^^^^ help: if this is intentional, prefix it with an underscore: `_key_fn`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `xs`
[INFO] [stdout]  --> src/lib.rs:1:29
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                             ^^ help: if this is intentional, prefix it with an underscore: `_xs`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `key_fn`
[INFO] [stdout]  --> src/lib.rs:1:36
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                                    ^^^^^^ help: if this is intentional, prefix it with an underscore: `_key_fn`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 1.17s
[INFO] running `Command { std: "docker" "inspect" "fe999e24580291973af6b5833006644fc0ca4762cc2e6754036fe9052c187580", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fe999e24580291973af6b5833006644fc0ca4762cc2e6754036fe9052c187580", kill_on_drop: false }`
[INFO] [stdout] fe999e24580291973af6b5833006644fc0ca4762cc2e6754036fe9052c187580