[INFO] cloning repository https://github.com/DerDoni/rust_book
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/DerDoni/rust_book" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FDerDoni%2Frust_book", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FDerDoni%2Frust_book'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 3340e580a3ca6f4999621d79bb705cce7b735d60
[INFO] testing DerDoni/rust_book against master#b70888601af92f6cdc0364abab3446e418b91d36 for pr-86479
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FDerDoni%2Frust_book" "/workspace/builds/worker-12/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-12/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/DerDoni/rust_book on toolchain b70888601af92f6cdc0364abab3446e418b91d36
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+b70888601af92f6cdc0364abab3446e418b91d36" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/DerDoni/rust_book
[INFO] finished tweaking git repo https://github.com/DerDoni/rust_book
[INFO] tweaked toml for git repo https://github.com/DerDoni/rust_book written to /workspace/builds/worker-12/source/Cargo.toml
[INFO] crate git repo https://github.com/DerDoni/rust_book already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+b70888601af92f6cdc0364abab3446e418b91d36" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "+b70888601af92f6cdc0364abab3446e418b91d36" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 762dd7d49f9c4a93f4769fbd0ebd43d1abfe8859b81f591ccd5fb99b1cb2972a
[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" "762dd7d49f9c4a93f4769fbd0ebd43d1abfe8859b81f591ccd5fb99b1cb2972a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "762dd7d49f9c4a93f4769fbd0ebd43d1abfe8859b81f591ccd5fb99b1cb2972a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "762dd7d49f9c4a93f4769fbd0ebd43d1abfe8859b81f591ccd5fb99b1cb2972a", kill_on_drop: false }`
[INFO] [stdout] 762dd7d49f9c4a93f4769fbd0ebd43d1abfe8859b81f591ccd5fb99b1cb2972a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "+b70888601af92f6cdc0364abab3446e418b91d36" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 3efb32cf2c93240c482713c605dbb7ba1054d6455e1f16f95927ad82e800b1f5
[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" "3efb32cf2c93240c482713c605dbb7ba1054d6455e1f16f95927ad82e800b1f5", kill_on_drop: false }`
[INFO] [stderr]    Compiling exercise v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0308]: mismatched types
[INFO] [stdout]   --> src/main.rs:33:5
[INFO] [stdout]    |
[INFO] [stdout] 31 |   fn mode(ints: &Vec<i32>) -> i32 {
[INFO] [stdout]    |                               --- expected `i32` because of return type
[INFO] [stdout] 32 |       let mut map = HashMap::new();
[INFO] [stdout] 33 | /     for number in ints {
[INFO] [stdout] 34 | |         let count = map.entry(number).or_insert(0);
[INFO] [stdout] 35 | |         *count += 1;
[INFO] [stdout] 36 | |     }
[INFO] [stdout]    | |_____^ expected `i32`, found `()`
[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 E0308`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `exercise` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "3efb32cf2c93240c482713c605dbb7ba1054d6455e1f16f95927ad82e800b1f5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3efb32cf2c93240c482713c605dbb7ba1054d6455e1f16f95927ad82e800b1f5", kill_on_drop: false }`
[INFO] [stdout] 3efb32cf2c93240c482713c605dbb7ba1054d6455e1f16f95927ad82e800b1f5