[INFO] cloning repository https://github.com/artran/rudoku
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/artran/rudoku" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fartran%2Frudoku", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fartran%2Frudoku'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 5c112775cdf80d3859ea4ce81dc1eb4c735473a5
[INFO] checking artran/rudoku against master#33fdb797f59421c7bbecaa4588ed5d7a31a9494a for pr-87190-3
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fartran%2Frudoku" "/workspace/builds/worker-4/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/artran/rudoku on toolchain 33fdb797f59421c7bbecaa4588ed5d7a31a9494a
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/artran/rudoku
[INFO] finished tweaking git repo https://github.com/artran/rudoku
[INFO] tweaked toml for git repo https://github.com/artran/rudoku written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/artran/rudoku already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] dc220c17cd4a21ffa6836d1f7c363def76b892072e35dac10f4e8f0797fa7705
[INFO] running `Command { std: "docker" "start" "-a" "dc220c17cd4a21ffa6836d1f7c363def76b892072e35dac10f4e8f0797fa7705", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "dc220c17cd4a21ffa6836d1f7c363def76b892072e35dac10f4e8f0797fa7705", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "dc220c17cd4a21ffa6836d1f7c363def76b892072e35dac10f4e8f0797fa7705", kill_on_drop: false }`
[INFO] [stdout] dc220c17cd4a21ffa6836d1f7c363def76b892072e35dac10f4e8f0797fa7705
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "+33fdb797f59421c7bbecaa4588ed5d7a31a9494a" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9951d06305e8234ec6061a2d01797197b590f2da62039d182ea7940726061278
[INFO] running `Command { std: "docker" "start" "-a" "9951d06305e8234ec6061a2d01797197b590f2da62039d182ea7940726061278", kill_on_drop: false }`
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling num-integer v0.1.44
[INFO] [stderr]    Compiling num-iter v0.1.42
[INFO] [stderr]     Checking rand v0.4.6
[INFO] [stderr]     Checking sudoku v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/board.rs:68:9
[INFO] [stdout]    |
[INFO] [stdout] 68 |         &mut self.cols[col_idx - 1].remove(&value);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 68 |         let _ = &mut self.cols[col_idx - 1].remove(&value);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/board.rs:69:9
[INFO] [stdout]    |
[INFO] [stdout] 69 |         &mut self.rows[row_idx - 1].remove(&value);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 69 |         let _ = &mut self.rows[row_idx - 1].remove(&value);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/board.rs:70:9
[INFO] [stdout]    |
[INFO] [stdout] 70 |         &mut self.squares[(col_idx - 1) / 3 + 3 * ((row_idx - 1) / 3)].remove(&value);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 70 |         let _ = &mut self.squares[(col_idx - 1) / 3 + 3 * ((row_idx - 1) / 3)].remove(&value);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking num-complex v0.1.43
[INFO] [stderr]     Checking num-bigint v0.1.44
[INFO] [stderr]     Checking num-rational v0.1.42
[INFO] [stderr]     Checking num v0.1.42
[INFO] [stderr]     Checking spectral v0.6.0
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/board.rs:68:9
[INFO] [stdout]    |
[INFO] [stdout] 68 |         &mut self.cols[col_idx - 1].remove(&value);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 68 |         let _ = &mut self.cols[col_idx - 1].remove(&value);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/board.rs:69:9
[INFO] [stdout]    |
[INFO] [stdout] 69 |         &mut self.rows[row_idx - 1].remove(&value);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 69 |         let _ = &mut self.rows[row_idx - 1].remove(&value);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/board.rs:70:9
[INFO] [stdout]    |
[INFO] [stdout] 70 |         &mut self.squares[(col_idx - 1) / 3 + 3 * ((row_idx - 1) / 3)].remove(&value);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 70 |         let _ = &mut self.squares[(col_idx - 1) / 3 + 3 * ((row_idx - 1) / 3)].remove(&value);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 2.48s
[INFO] running `Command { std: "docker" "inspect" "9951d06305e8234ec6061a2d01797197b590f2da62039d182ea7940726061278", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9951d06305e8234ec6061a2d01797197b590f2da62039d182ea7940726061278", kill_on_drop: false }`
[INFO] [stdout] 9951d06305e8234ec6061a2d01797197b590f2da62039d182ea7940726061278