[INFO] cloning repository https://github.com/valekar/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/valekar/rust-book" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvalekar%2Frust-book", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvalekar%2Frust-book'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 2eeae0ed967ea63e698198235aa39cf767ba7851
[INFO] building valekar/rust-book against master#11663cd3bfefef7d34e8f0892c250bf698049392+rustflags=-Dtail-expr-drop-order for pr-134523
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvalekar%2Frust-book" "/workspace/builds/worker-6-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/valekar/rust-book on toolchain 11663cd3bfefef7d34e8f0892c250bf698049392
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+11663cd3bfefef7d34e8f0892c250bf698049392" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/valekar/rust-book
[INFO] finished tweaking git repo https://github.com/valekar/rust-book
[INFO] tweaked toml for git repo https://github.com/valekar/rust-book written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/valekar/rust-book 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" "+11663cd3bfefef7d34e8f0892c250bf698049392" "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-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/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:f3a9d4ad9d972b27faf3965f35b62e55ba32bbce8f20bc8fe909558a86702fde" "/opt/rustwide/cargo-home/bin/cargo" "+11663cd3bfefef7d34e8f0892c250bf698049392" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 18a0f6d66d7b9f54b48a0720e66f9ed343221b264d191e39158b91dc6668b979
[INFO] running `Command { std: "docker" "start" "-a" "18a0f6d66d7b9f54b48a0720e66f9ed343221b264d191e39158b91dc6668b979", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "18a0f6d66d7b9f54b48a0720e66f9ed343221b264d191e39158b91dc6668b979", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "18a0f6d66d7b9f54b48a0720e66f9ed343221b264d191e39158b91dc6668b979", kill_on_drop: false }`
[INFO] [stdout] 18a0f6d66d7b9f54b48a0720e66f9ed343221b264d191e39158b91dc6668b979
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/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 -Dtail-expr-drop-order" "-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:f3a9d4ad9d972b27faf3965f35b62e55ba32bbce8f20bc8fe909558a86702fde" "/opt/rustwide/cargo-home/bin/cargo" "+11663cd3bfefef7d34e8f0892c250bf698049392" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 497ead1b43282d417d7eebaee5a56ad36a4098c99f01061295e8eb6bb2dbbec9
[INFO] running `Command { std: "docker" "start" "-a" "497ead1b43282d417d7eebaee5a56ad36a4098c99f01061295e8eb6bb2dbbec9", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.98
[INFO] [stderr]    Compiling ppv-lite86 v0.2.10
[INFO] [stderr]    Compiling chap-3 v0.1.0 (/opt/rustwide/workdir/chap-3)
[INFO] [stderr]    Compiling chap-4 v0.1.0 (/opt/rustwide/workdir/chap-4)
[INFO] [stderr]    Compiling chap-1 v0.1.0 (/opt/rustwide/workdir/chap-1)
[INFO] [stdout] warning: unused variable: `s3`
[INFO] [stdout]   --> chap-4/src/main.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let s3 = &mut s1;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s3`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s4`
[INFO] [stdout]   --> chap-4/src/main.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let s4 = &mut s1;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s4`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling getrandom v0.2.3
[INFO] [stderr]    Compiling rand_core v0.6.3
[INFO] [stderr]    Compiling rand_chacha v0.3.1
[INFO] [stderr]    Compiling rand v0.8.4
[INFO] [stderr]    Compiling chap-2 v0.1.0 (/opt/rustwide/workdir/chap-2)
[INFO] [stdout] warning: unused import: `std::error::Error`
[INFO] [stdout]  --> chap-2/src/main.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::error::Error;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.70s
[INFO] running `Command { std: "docker" "inspect" "497ead1b43282d417d7eebaee5a56ad36a4098c99f01061295e8eb6bb2dbbec9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "497ead1b43282d417d7eebaee5a56ad36a4098c99f01061295e8eb6bb2dbbec9", kill_on_drop: false }`
[INFO] [stdout] 497ead1b43282d417d7eebaee5a56ad36a4098c99f01061295e8eb6bb2dbbec9
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/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 -Dtail-expr-drop-order" "-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:f3a9d4ad9d972b27faf3965f35b62e55ba32bbce8f20bc8fe909558a86702fde" "/opt/rustwide/cargo-home/bin/cargo" "+11663cd3bfefef7d34e8f0892c250bf698049392" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 40eb43fa318d55211fdd5b37eb55a83ff73dfc8e9e80b9a427128fa4f4fc584f
[INFO] running `Command { std: "docker" "start" "-a" "40eb43fa318d55211fdd5b37eb55a83ff73dfc8e9e80b9a427128fa4f4fc584f", kill_on_drop: false }`
[INFO] [stderr]    Compiling chap-3 v0.1.0 (/opt/rustwide/workdir/chap-3)
[INFO] [stderr]    Compiling chap-4 v0.1.0 (/opt/rustwide/workdir/chap-4)
[INFO] [stderr]    Compiling chap-1 v0.1.0 (/opt/rustwide/workdir/chap-1)
[INFO] [stderr]    Compiling chap-2 v0.1.0 (/opt/rustwide/workdir/chap-2)
[INFO] [stdout] warning: unused variable: `s3`
[INFO] [stdout]   --> chap-4/src/main.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let s3 = &mut s1;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s3`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s4`
[INFO] [stdout]   --> chap-4/src/main.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let s4 = &mut s1;
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_s4`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::error::Error`
[INFO] [stdout]  --> chap-2/src/main.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use std::error::Error;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.18s
[INFO] running `Command { std: "docker" "inspect" "40eb43fa318d55211fdd5b37eb55a83ff73dfc8e9e80b9a427128fa4f4fc584f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "40eb43fa318d55211fdd5b37eb55a83ff73dfc8e9e80b9a427128fa4f4fc584f", kill_on_drop: false }`
[INFO] [stdout] 40eb43fa318d55211fdd5b37eb55a83ff73dfc8e9e80b9a427128fa4f4fc584f