[INFO] updating cached repository https://github.com/link-a/learning-rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune", kill_on_drop: false }`
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4ca745beb79cd03273a21b0a662399decbee808d
[INFO] checking link-a/learning-rust against try#0ab79c4b48ad19260fa46623f452c1b403a360e8 for pr-74315
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flink-a%2Flearning-rust" "/workspace/builds/worker-3/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/link-a/learning-rust on toolchain 0ab79c4b48ad19260fa46623f452c1b403a360e8
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0ab79c4b48ad19260fa46623f452c1b403a360e8" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/link-a/learning-rust
[INFO] finished tweaking git repo https://github.com/link-a/learning-rust
[INFO] tweaked toml for git repo https://github.com/link-a/learning-rust written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/link-a/learning-rust already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0ab79c4b48ad19260fa46623f452c1b403a360e8" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+0ab79c4b48ad19260fa46623f452c1b403a360e8" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c6ca5bf34c46f82d47d91e598d97a15e044276e3b980de90b84c5746b52b8d63
[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" "c6ca5bf34c46f82d47d91e598d97a15e044276e3b980de90b84c5746b52b8d63", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c6ca5bf34c46f82d47d91e598d97a15e044276e3b980de90b84c5746b52b8d63", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c6ca5bf34c46f82d47d91e598d97a15e044276e3b980de90b84c5746b52b8d63", kill_on_drop: false }`
[INFO] [stdout] c6ca5bf34c46f82d47d91e598d97a15e044276e3b980de90b84c5746b52b8d63
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+0ab79c4b48ad19260fa46623f452c1b403a360e8" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 45893a5e757132a9000899e6b1ce93c8ac4e511ff3474a58ef4d8433547f2aa7
[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" "45893a5e757132a9000899e6b1ce93c8ac4e511ff3474a58ef4d8433547f2aa7", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.66
[INFO] [stderr]     Checking bloom v0.3.2
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking clap v2.33.0
[INFO] [stderr]     Checking ctci v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `cell_1`
[INFO] [stdout]  --> src/bin/unsafe.rs:7:9
[INFO] [stdout]   |
[INFO] [stdout] 7 |     let cell_1 = Cell {
[INFO] [stdout]   |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_cell_1`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary `unsafe` block
[INFO] [stdout]   --> src/bin/unsafe.rs:11:5
[INFO] [stdout]    |
[INFO] [stdout] 11 |     unsafe {
[INFO] [stdout]    |     ^^^^^^ unnecessary `unsafe` block
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_unsafe)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `val`
[INFO] [stdout]  --> src/bin/unsafe.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 |     val: i32,
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `next`
[INFO] [stdout]  --> src/bin/unsafe.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 |     next: Option<Box<Cell>>,
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::borrow::Borrow`
[INFO] [stdout]  --> src/bin/ref_cells.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::borrow::Borrow;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::cell::RefCell`
[INFO] [stdout]  --> src/bin/ref_cells.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::cell::RefCell;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::mem`
[INFO] [stdout]  --> src/bin/ref_cells.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::mem;
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::rc::Rc`
[INFO] [stdout]  --> src/bin/ref_cells.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use std::rc::Rc;
[INFO] [stdout]   |     ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::mem`
[INFO] [stdout]    --> src/bin/ref_cells.rs:228:9
[INFO] [stdout]     |
[INFO] [stdout] 228 |     use std::mem;
[INFO] [stdout]     |         ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::borrow::Borrow`
[INFO] [stdout]  --> src/bin/ref_cells.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::borrow::Borrow;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::cell::RefCell`
[INFO] [stdout]  --> src/bin/ref_cells.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use std::cell::RefCell;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::mem`
[INFO] [stdout]  --> src/bin/ref_cells.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::mem;
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::rc::Rc`
[INFO] [stdout]  --> src/bin/ref_cells.rs:4:5
[INFO] [stdout]   |
[INFO] [stdout] 4 | use std::rc::Rc;
[INFO] [stdout]   |     ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::mem`
[INFO] [stdout]    --> src/bin/ref_cells.rs:228:9
[INFO] [stdout]     |
[INFO] [stdout] 228 |     use std::mem;
[INFO] [stdout]     |         ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `cell_1`
[INFO] [stdout]  --> src/bin/unsafe.rs:7:9
[INFO] [stdout]   |
[INFO] [stdout] 7 |     let cell_1 = Cell {
[INFO] [stdout]   |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_cell_1`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary `unsafe` block
[INFO] [stdout]   --> src/bin/unsafe.rs:11:5
[INFO] [stdout]    |
[INFO] [stdout] 11 |     unsafe {
[INFO] [stdout]    |     ^^^^^^ unnecessary `unsafe` block
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_unsafe)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `val`
[INFO] [stdout]  --> src/bin/unsafe.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 |     val: i32,
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `next`
[INFO] [stdout]  --> src/bin/unsafe.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 |     next: Option<Box<Cell>>,
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 15.84s
[INFO] running `Command { std: "docker" "inspect" "45893a5e757132a9000899e6b1ce93c8ac4e511ff3474a58ef4d8433547f2aa7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "45893a5e757132a9000899e6b1ce93c8ac4e511ff3474a58ef4d8433547f2aa7", kill_on_drop: false }`
[INFO] [stdout] 45893a5e757132a9000899e6b1ce93c8ac4e511ff3474a58ef4d8433547f2aa7