[INFO] updating cached repository EthanTheMaster/sudoku_solver
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/EthanTheMaster/sudoku_solver
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/EthanTheMaster/sudoku_solver" "work/ex/pr-63247/sources/master#452087b4bf18cece2d52d7cd8c9147195e5404bf/gh/EthanTheMaster/sudoku_solver"`
[INFO] [stderr] Cloning into 'work/ex/pr-63247/sources/master#452087b4bf18cece2d52d7cd8c9147195e5404bf/gh/EthanTheMaster/sudoku_solver'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/EthanTheMaster/sudoku_solver" "work/ex/pr-63247/sources/try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab/gh/EthanTheMaster/sudoku_solver"`
[INFO] [stderr] Cloning into 'work/ex/pr-63247/sources/try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab/gh/EthanTheMaster/sudoku_solver'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] f0d269d3d954a9b6c82d6d0856dd0175544949f6
[INFO] sha for GitHub repo EthanTheMaster/sudoku_solver: f0d269d3d954a9b6c82d6d0856dd0175544949f6
[INFO] validating manifest of EthanTheMaster/sudoku_solver on toolchain master#452087b4bf18cece2d52d7cd8c9147195e5404bf
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+452087b4bf18cece2d52d7cd8c9147195e5404bf-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of EthanTheMaster/sudoku_solver on toolchain try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+757dacae0a9f1b46b3ab58a1f1232332e8fc7dab-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing EthanTheMaster/sudoku_solver
[INFO] finished frobbing EthanTheMaster/sudoku_solver
[INFO] frobbed toml for EthanTheMaster/sudoku_solver written to work/ex/pr-63247/sources/master#452087b4bf18cece2d52d7cd8c9147195e5404bf/gh/EthanTheMaster/sudoku_solver/Cargo.toml
[INFO] started frobbing EthanTheMaster/sudoku_solver
[INFO] finished frobbing EthanTheMaster/sudoku_solver
[INFO] frobbed toml for EthanTheMaster/sudoku_solver written to work/ex/pr-63247/sources/try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab/gh/EthanTheMaster/sudoku_solver/Cargo.toml
[INFO] crate EthanTheMaster/sudoku_solver already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+452087b4bf18cece2d52d7cd8c9147195e5404bf-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+757dacae0a9f1b46b3ab58a1f1232332e8fc7dab-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] checking EthanTheMaster/sudoku_solver against try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab for pr-63247
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/pr-63247/worker-2/try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/pr-63247/sources/try#757dacae0a9f1b46b3ab58a1f1232332e8fc7dab/gh/EthanTheMaster/sudoku_solver:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+757dacae0a9f1b46b3ab58a1f1232332e8fc7dab-alt" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stdout] 4b73df986dd80e31d8a6dc0abe23c84cc887d967f8f62acc6390c908380030a6
[INFO] running `"docker" "start" "-a" "4b73df986dd80e31d8a6dc0abe23c84cc887d967f8f62acc6390c908380030a6"`
[INFO] [stderr]     Checking sudoku_solver v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused variable: `operation`
[INFO] [stderr]   --> src/sudoku_solver_dancinglinks/mod.rs:96:32
[INFO] [stderr]    |
[INFO] [stderr] 96 |         if let NodeType::Field(operation, column_header_id) = node_type {
[INFO] [stderr]    |                                ^^^^^^^^^ help: consider prefixing with an underscore: `_operation`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:100:48
[INFO] [stderr]     |
[INFO] [stderr] 100 |                 NodeType::ColumnHeader(ref mut constraint, ref mut size) => {
[INFO] [stderr]     |                                                ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `operation`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:119:29
[INFO] [stderr]     |
[INFO] [stderr] 119 |             NodeType::Field(operation, column_header_id) => {
[INFO] [stderr]     |                             ^^^^^^^^^ help: consider prefixing with an underscore: `_operation`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:127:36
[INFO] [stderr]     |
[INFO] [stderr] 127 |             NodeType::ColumnHeader(constraint, size) => {
[INFO] [stderr]     |                                    ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:226:44
[INFO] [stderr]     |
[INFO] [stderr] 226 |                     NodeType::ColumnHeader(constraint, ref mut size) => {
[INFO] [stderr]     |                                            ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:269:44
[INFO] [stderr]     |
[INFO] [stderr] 269 |                     NodeType::ColumnHeader(constraint, ref mut size) => {
[INFO] [stderr]     |                                            ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `idx`
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:35:24
[INFO] [stderr]    |
[INFO] [stderr] 35 |             .filter(|&(idx, val)| {
[INFO] [stderr]    |                        ^^^ help: consider prefixing with an underscore: `_idx`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `val`
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:37:27
[INFO] [stderr]    |
[INFO] [stderr] 37 |             }).map(|(idx, val)| {
[INFO] [stderr]    |                           ^^^ help: consider prefixing with an underscore: `_val`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `operation`
[INFO] [stderr]   --> src/sudoku_solver_dancinglinks/mod.rs:96:32
[INFO] [stderr]    |
[INFO] [stderr] 96 |         if let NodeType::Field(operation, column_header_id) = node_type {
[INFO] [stderr]    |                                ^^^^^^^^^ help: consider prefixing with an underscore: `_operation`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:100:48
[INFO] [stderr]     |
[INFO] [stderr] 100 |                 NodeType::ColumnHeader(ref mut constraint, ref mut size) => {
[INFO] [stderr]     |                                                ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `operation`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:119:29
[INFO] [stderr]     |
[INFO] [stderr] 119 |             NodeType::Field(operation, column_header_id) => {
[INFO] [stderr]     |                             ^^^^^^^^^ help: consider prefixing with an underscore: `_operation`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:127:36
[INFO] [stderr]     |
[INFO] [stderr] 127 |             NodeType::ColumnHeader(constraint, size) => {
[INFO] [stderr]     |                                    ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:226:44
[INFO] [stderr]     |
[INFO] [stderr] 226 |                     NodeType::ColumnHeader(constraint, ref mut size) => {
[INFO] [stderr]     |                                            ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `constraint`
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:269:44
[INFO] [stderr]     |
[INFO] [stderr] 269 |                     NodeType::ColumnHeader(constraint, ref mut size) => {
[INFO] [stderr]     |                                            ^^^^^^^^^^ help: consider prefixing with an underscore: `_constraint`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `idx`
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:35:24
[INFO] [stderr]    |
[INFO] [stderr] 35 |             .filter(|&(idx, val)| {
[INFO] [stderr]    |                        ^^^ help: consider prefixing with an underscore: `_idx`
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `val`
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:37:27
[INFO] [stderr]    |
[INFO] [stderr] 37 |             }).map(|(idx, val)| {
[INFO] [stderr]    |                           ^^^ help: consider prefixing with an underscore: `_val`
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:34:13
[INFO] [stderr]    |
[INFO] [stderr] 34 |         let mut blank_positions: Vec<usize> = self.board.iter().enumerate()
[INFO] [stderr]    |             ----^^^^^^^^^^^^^^^
[INFO] [stderr]    |             |
[INFO] [stderr]    |             help: remove this `mut`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:34:13
[INFO] [stderr]    |
[INFO] [stderr] 34 |         let mut blank_positions: Vec<usize> = self.board.iter().enumerate()
[INFO] [stderr]    |             ----^^^^^^^^^^^^^^^
[INFO] [stderr]    |             |
[INFO] [stderr]    |             help: remove this `mut`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.89s
[INFO] running `"docker" "inspect" "4b73df986dd80e31d8a6dc0abe23c84cc887d967f8f62acc6390c908380030a6"`
[INFO] running `"docker" "rm" "-f" "4b73df986dd80e31d8a6dc0abe23c84cc887d967f8f62acc6390c908380030a6"`
[INFO] [stdout] 4b73df986dd80e31d8a6dc0abe23c84cc887d967f8f62acc6390c908380030a6