[INFO] cloning repository https://github.com/Sieciechu/rust-test
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Sieciechu/rust-test" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FSieciechu%2Frust-test", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FSieciechu%2Frust-test'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 49952d34665dec33b6a5eacec6c23918c6795805
[INFO] checking Sieciechu/rust-test against master#af4a5a13a15fa0c60e06321077ef452f769b42fd for pr-122960-3
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FSieciechu%2Frust-test" "/workspace/builds/worker-4-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/Sieciechu/rust-test on toolchain af4a5a13a15fa0c60e06321077ef452f769b42fd
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/Sieciechu/rust-test
[INFO] finished tweaking git repo https://github.com/Sieciechu/rust-test
[INFO] tweaked toml for git repo https://github.com/Sieciechu/rust-test written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/Sieciechu/rust-test 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" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded rand_os v0.1.1
[INFO] [stderr]   Downloaded rand_jitter v0.1.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 9076d1f81a4a64e304c27b4ded30af23781d1b5054d50c0acd0caeaab4b2d754
[INFO] running `Command { std: "docker" "start" "-a" "9076d1f81a4a64e304c27b4ded30af23781d1b5054d50c0acd0caeaab4b2d754", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "9076d1f81a4a64e304c27b4ded30af23781d1b5054d50c0acd0caeaab4b2d754", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9076d1f81a4a64e304c27b4ded30af23781d1b5054d50c0acd0caeaab4b2d754", kill_on_drop: false }`
[INFO] [stdout] 9076d1f81a4a64e304c27b4ded30af23781d1b5054d50c0acd0caeaab4b2d754
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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" "-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f57477ba4768c310542f5d6f61a11970d4cd27103fb09bdd9153447a482d8cb6
[INFO] running `Command { std: "docker" "start" "-a" "f57477ba4768c310542f5d6f61a11970d4cd27103fb09bdd9153447a482d8cb6", kill_on_drop: false }`
[INFO] [stderr]     Checking rand_core v0.4.0
[INFO] [stderr]    Compiling autocfg v0.1.2
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling libc v0.2.48
[INFO] [stderr]     Checking rand_core v0.3.1
[INFO] [stderr]     Checking rand_jitter v0.1.0
[INFO] [stderr]    Compiling semver v0.9.0
[INFO] [stderr]     Checking rand_xorshift v0.1.1
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]     Checking rand_hc v0.1.0
[INFO] [stderr]     Checking rand_isaac v0.1.1
[INFO] [stderr]    Compiling rustc_version v0.2.3
[INFO] [stderr]    Compiling rand_pcg v0.1.1
[INFO] [stderr]     Checking rand_os v0.1.1
[INFO] [stderr]     Checking add_one v0.1.0 (/opt/rustwide/workdir/add_one)
[INFO] [stdout] error[E0594]: cannot assign to `head.next`, which is behind a `&` reference
[INFO] [stdout]   --> add_one/src/lib.rs:26:9
[INFO] [stdout]    |
[INFO] [stdout] 26 |         head.next = Some(n); // does not work
[INFO] [stdout]    |         ^^^^^^^^^ `head` is a `&` reference, so the data it refers to cannot be written
[INFO] [stdout]    |
[INFO] [stdout] help: consider changing this to be a mutable reference
[INFO] [stdout]    |
[INFO] [stdout] 20 |         let mut head: &Self = &mut self;
[INFO] [stdout]    |                                +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0594`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `add_one` (lib) due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error[E0594]: cannot assign to `head.next`, which is behind a `&` reference
[INFO] [stdout]   --> add_one/src/lib.rs:26:9
[INFO] [stdout]    |
[INFO] [stdout] 26 |         head.next = Some(n); // does not work
[INFO] [stdout]    |         ^^^^^^^^^ `head` is a `&` reference, so the data it refers to cannot be written
[INFO] [stdout]    |
[INFO] [stdout] help: consider changing this to be a mutable reference
[INFO] [stdout]    |
[INFO] [stdout] 20 |         let mut head: &Self = &mut self;
[INFO] [stdout]    |                                +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 1 previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0594`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `add_one` (lib test) due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "f57477ba4768c310542f5d6f61a11970d4cd27103fb09bdd9153447a482d8cb6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f57477ba4768c310542f5d6f61a11970d4cd27103fb09bdd9153447a482d8cb6", kill_on_drop: false }`
[INFO] [stdout] f57477ba4768c310542f5d6f61a11970d4cd27103fb09bdd9153447a482d8cb6