[INFO] cloning 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" "clone" "--bare" "https://github.com/link-a/learning-rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flink-a%2Flearning-rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flink-a%2Flearning-rust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4ca745beb79cd03273a21b0a662399decbee808d
[INFO] checking link-a/learning-rust against master#0d37dca25a51fb900a402c94c8818ad1c2789e30 for pr-77526
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flink-a%2Flearning-rust" "/workspace/builds/worker-1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/link-a/learning-rust on toolchain 0d37dca25a51fb900a402c94c8818ad1c2789e30
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0d37dca25a51fb900a402c94c8818ad1c2789e30" "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-1/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" "+0d37dca25a51fb900a402c94c8818ad1c2789e30" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+0d37dca25a51fb900a402c94c8818ad1c2789e30" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 8292f9b49311ee157f049391007f4b836616e231d73aeb1518a1fb74b91d72ec
[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" "8292f9b49311ee157f049391007f4b836616e231d73aeb1518a1fb74b91d72ec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8292f9b49311ee157f049391007f4b836616e231d73aeb1518a1fb74b91d72ec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8292f9b49311ee157f049391007f4b836616e231d73aeb1518a1fb74b91d72ec", kill_on_drop: false }`
[INFO] [stdout] 8292f9b49311ee157f049391007f4b836616e231d73aeb1518a1fb74b91d72ec
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+0d37dca25a51fb900a402c94c8818ad1c2789e30" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 553b70c69bf52a5cf79d5eb754808359e18ad0e3d13f18b575efc9e3a523aa0f
[INFO] running `Command { std: "docker" "start" "-a" "553b70c69bf52a5cf79d5eb754808359e18ad0e3d13f18b575efc9e3a523aa0f", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.66
[INFO] [stderr]    Compiling bitflags v1.2.1
[INFO] [stderr]     Checking unicode-width v0.1.7
[INFO] [stderr]     Checking vec_map v0.8.1
[INFO] [stderr]     Checking ansi_term v0.11.0
[INFO] [stderr]     Checking strsim v0.8.0
[INFO] [stderr]     Checking bit-vec v0.4.4
[INFO] [stderr]     Checking textwrap v0.11.0
[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 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 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 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] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 15.58s
[INFO] running `Command { std: "docker" "inspect" "553b70c69bf52a5cf79d5eb754808359e18ad0e3d13f18b575efc9e3a523aa0f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "553b70c69bf52a5cf79d5eb754808359e18ad0e3d13f18b575efc9e3a523aa0f", kill_on_drop: false }`
[INFO] [stdout] 553b70c69bf52a5cf79d5eb754808359e18ad0e3d13f18b575efc9e3a523aa0f