[INFO] cloning repository https://github.com/YuankaiZhu/RustDemoWeek4
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/YuankaiZhu/RustDemoWeek4" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FYuankaiZhu%2FRustDemoWeek4", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FYuankaiZhu%2FRustDemoWeek4'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d09db9636b418294b14790cca5f9fccbf3c4a60d
[INFO] checking YuankaiZhu/RustDemoWeek4 against try#3fada14ee01d755dc8076e611f11bf65b28ffd21 for pr-154971
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FYuankaiZhu%2FRustDemoWeek4" "/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/YuankaiZhu/RustDemoWeek4
[INFO] finished tweaking git repo https://github.com/YuankaiZhu/RustDemoWeek4
[INFO] tweaked toml for git repo https://github.com/YuankaiZhu/RustDemoWeek4 written to /workspace/builds/worker-4-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/YuankaiZhu/RustDemoWeek4 on toolchain 3fada14ee01d755dc8076e611f11bf65b28ffd21
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+3fada14ee01d755dc8076e611f11bf65b28ffd21" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/YuankaiZhu/RustDemoWeek4 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" "+3fada14ee01d755dc8076e611f11bf65b28ffd21" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+3fada14ee01d755dc8076e611f11bf65b28ffd21" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c514cf06ff34f750b55796fa0e7f4a521bf7e7cdb06e99deab23090cdafe4f92
[INFO] running `Command { std: "docker" "start" "-a" "c514cf06ff34f750b55796fa0e7f4a521bf7e7cdb06e99deab23090cdafe4f92", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c514cf06ff34f750b55796fa0e7f4a521bf7e7cdb06e99deab23090cdafe4f92", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c514cf06ff34f750b55796fa0e7f4a521bf7e7cdb06e99deab23090cdafe4f92", kill_on_drop: false }`
[INFO] [stdout] c514cf06ff34f750b55796fa0e7f4a521bf7e7cdb06e99deab23090cdafe4f92
[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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+3fada14ee01d755dc8076e611f11bf65b28ffd21" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] da6ebea78cbafc7bce4e5ad03c01ba54ae58c29c66a40b776392508a3b46811d
[INFO] running `Command { std: "docker" "start" "-a" "da6ebea78cbafc7bce4e5ad03c01ba54ae58c29c66a40b776392508a3b46811d", kill_on_drop: false }`
[INFO] [stderr]     Checking Week4 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/main.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let mut result = parse_expression(&mut tokens)?;
[INFO] [stdout]    |         ----^^^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/main.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let mut result = parse_expression(&mut tokens)?;
[INFO] [stdout]    |         ----^^^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.08s
[INFO] running `Command { std: "docker" "inspect" "da6ebea78cbafc7bce4e5ad03c01ba54ae58c29c66a40b776392508a3b46811d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "da6ebea78cbafc7bce4e5ad03c01ba54ae58c29c66a40b776392508a3b46811d", kill_on_drop: false }`
[INFO] [stdout] da6ebea78cbafc7bce4e5ad03c01ba54ae58c29c66a40b776392508a3b46811d