[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/clippy-test-run/sources/stable/gh/EthanTheMaster/sudoku_solver"`
[INFO] [stderr] Cloning into 'work/ex/clippy-test-run/sources/stable/gh/EthanTheMaster/sudoku_solver'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/EthanTheMaster/sudoku_solver" "work/ex/clippy-test-run/sources/stable+rustflags=-Dclippy%3A%3Ainto_iter_on_array/gh/EthanTheMaster/sudoku_solver"`
[INFO] [stderr] Cloning into 'work/ex/clippy-test-run/sources/stable+rustflags=-Dclippy%3A%3Ainto_iter_on_array/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 stable
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+stable" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of EthanTheMaster/sudoku_solver on toolchain stable+rustflags=-Dclippy::into_iter_on_array
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+stable" "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/clippy-test-run/sources/stable/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/clippy-test-run/sources/stable+rustflags=-Dclippy%3A%3Ainto_iter_on_array/gh/EthanTheMaster/sudoku_solver/Cargo.toml
[INFO] crate EthanTheMaster/sudoku_solver has a lockfile. skipping
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+stable" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+stable" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] linting EthanTheMaster/sudoku_solver against stable+rustflags=-Dclippy::into_iter_on_array for clippy-test-run
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/clippy-test-run/worker-4/stable+rustflags=-Dclippy%3A%3Ainto_iter_on_array:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/clippy-test-run/sources/stable+rustflags=-Dclippy%3A%3Ainto_iter_on_array/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 -Dclippy::into_iter_on_array" "-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" "+stable" "clippy" "--frozen" "--all" "--all-targets"`
[INFO] [stdout] d1727cb11cfe5958e1eb165107cefa7541b9818d936c4f6f2d26bd271440452f
[INFO] running `"docker" "start" "-a" "d1727cb11cfe5958e1eb165107cefa7541b9818d936c4f6f2d26bd271440452f"`
[INFO] [stderr]     Checking sudoku_solver v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:107:9
[INFO] [stderr]     |
[INFO] [stderr] 107 |         return node_id;
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^ help: remove `return` as shown: `node_id`
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(clippy::needless_return)] on by default
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:120:17
[INFO] [stderr]     |
[INFO] [stderr] 120 |                 return self.get_node(column_header_id);
[INFO] [stderr]     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `self.get_node(column_header_id)`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:128:17
[INFO] [stderr]     |
[INFO] [stderr] 128 |                 return size;
[INFO] [stderr]     |                 ^^^^^^^^^^^^ help: remove `return` as shown: `size`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:343:9
[INFO] [stderr]     |
[INFO] [stderr] 343 |         return false;
[INFO] [stderr]     |         ^^^^^^^^^^^^^ help: remove `return` as shown: `false`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:365:9
[INFO] [stderr]     |
[INFO] [stderr] 365 |         return Some(next_node_id);
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `Some(next_node_id)`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:387:9
[INFO] [stderr]     |
[INFO] [stderr] 387 |         return Some(next_node_id);
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `Some(next_node_id)`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:509:5
[INFO] [stderr]     |
[INFO] [stderr] 509 |     return result;
[INFO] [stderr]     |     ^^^^^^^^^^^^^^ help: remove `return` as shown: `result`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:36:17
[INFO] [stderr]    |
[INFO] [stderr] 36 |                 return *val == 0;
[INFO] [stderr]    |                 ^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `*val == 0`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:38:17
[INFO] [stderr]    |
[INFO] [stderr] 38 |                 return  idx;
[INFO] [stderr]    |                 ^^^^^^^^^^^^ help: remove `return` as shown: `idx`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:45:43
[INFO] [stderr]    |
[INFO] [stderr] 45 |             let mut target_cell_val: u8 = *&board_copy[*current_blank_pos as usize];
[INFO] [stderr]    |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[*current_blank_pos as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(clippy::deref_addrof)] on by default
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: this if statement can be collapsed
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:70:17
[INFO] [stderr]    |
[INFO] [stderr] 70 | /                 if current_row_cell != *current_blank_pos {
[INFO] [stderr] 71 | |                     if *&board_copy[current_row_cell as usize] == target_cell_val {
[INFO] [stderr] 72 | |                         passed_row_col_check = false;
[INFO] [stderr] 73 | |                         break;
[INFO] [stderr] 74 | |                     }
[INFO] [stderr] 75 | |                 }
[INFO] [stderr]    | |_________________^
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(clippy::collapsible_if)] on by default
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
[INFO] [stderr] help: try
[INFO] [stderr]    |
[INFO] [stderr] 70 |                 if current_row_cell != *current_blank_pos && *&board_copy[current_row_cell as usize] == target_cell_val {
[INFO] [stderr] 71 |     passed_row_col_check = false;
[INFO] [stderr] 72 |     break;
[INFO] [stderr] 73 | }
[INFO] [stderr]    |
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:71:24
[INFO] [stderr]    |
[INFO] [stderr] 71 |                     if *&board_copy[current_row_cell as usize] == target_cell_val {
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[current_row_cell as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: this if statement can be collapsed
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:78:17
[INFO] [stderr]    |
[INFO] [stderr] 78 | /                 if current_col_cell != *current_blank_pos {
[INFO] [stderr] 79 | |                     if *&board_copy[current_col_cell as usize] == target_cell_val {
[INFO] [stderr] 80 | |                         passed_row_col_check = false;
[INFO] [stderr] 81 | |                         break;
[INFO] [stderr] 82 | |                     }
[INFO] [stderr] 83 | |                 }
[INFO] [stderr]    | |_________________^
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
[INFO] [stderr] help: try
[INFO] [stderr]    |
[INFO] [stderr] 78 |                 if current_col_cell != *current_blank_pos && *&board_copy[current_col_cell as usize] == target_cell_val {
[INFO] [stderr] 79 |     passed_row_col_check = false;
[INFO] [stderr] 80 |     break;
[INFO] [stderr] 81 | }
[INFO] [stderr]    |
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:79:24
[INFO] [stderr]    |
[INFO] [stderr] 79 |                     if *&board_copy[current_col_cell as usize] == target_cell_val {
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[current_col_cell as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: this if statement can be collapsed
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:93:25
[INFO] [stderr]    |
[INFO] [stderr] 93 | /                         if current_block_cell != *current_blank_pos {
[INFO] [stderr] 94 | |                             if *&board_copy[current_block_cell as usize] == target_cell_val {
[INFO] [stderr] 95 | |                                 passed_block_check = false;
[INFO] [stderr] 96 | |                                 break;
[INFO] [stderr] 97 | |                             }
[INFO] [stderr] 98 | |                         }
[INFO] [stderr]    | |_________________________^
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
[INFO] [stderr] help: try
[INFO] [stderr]    |
[INFO] [stderr] 93 |                         if current_block_cell != *current_blank_pos && *&board_copy[current_block_cell as usize] == target_cell_val {
[INFO] [stderr] 94 |     passed_block_check = false;
[INFO] [stderr] 95 |     break;
[INFO] [stderr] 96 | }
[INFO] [stderr]    |
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:94:32
[INFO] [stderr]    |
[INFO] [stderr] 94 |                             if *&board_copy[current_block_cell as usize] == target_cell_val {
[INFO] [stderr]    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[current_block_cell as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:107:9
[INFO] [stderr]     |
[INFO] [stderr] 107 |         return node_id;
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^ help: remove `return` as shown: `node_id`
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(clippy::needless_return)] on by default
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:120:17
[INFO] [stderr]     |
[INFO] [stderr] 120 |                 return self.get_node(column_header_id);
[INFO] [stderr]     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `self.get_node(column_header_id)`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:128:17
[INFO] [stderr]     |
[INFO] [stderr] 128 |                 return size;
[INFO] [stderr]     |                 ^^^^^^^^^^^^ help: remove `return` as shown: `size`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:343:9
[INFO] [stderr]     |
[INFO] [stderr] 343 |         return false;
[INFO] [stderr]     |         ^^^^^^^^^^^^^ help: remove `return` as shown: `false`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:365:9
[INFO] [stderr]     |
[INFO] [stderr] 365 |         return Some(next_node_id);
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `Some(next_node_id)`
[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 using `_operation` instead
[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 using `_constraint` instead
[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 using `_operation` instead
[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 using `_constraint` instead
[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 using `_constraint` instead
[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 using `_constraint` instead
[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 using `_idx` instead
[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 using `_val` instead
[INFO] [stderr] 
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:387:9
[INFO] [stderr]     |
[INFO] [stderr] 387 |         return Some(next_node_id);
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `Some(next_node_id)`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:509:5
[INFO] [stderr]     |
[INFO] [stderr] 509 |     return result;
[INFO] [stderr]     |     ^^^^^^^^^^^^^^ help: remove `return` as shown: `result`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:36:17
[INFO] [stderr]    |
[INFO] [stderr] 36 |                 return *val == 0;
[INFO] [stderr]    |                 ^^^^^^^^^^^^^^^^^ help: remove `return` as shown: `*val == 0`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: unneeded return statement
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:38:17
[INFO] [stderr]    |
[INFO] [stderr] 38 |                 return  idx;
[INFO] [stderr]    |                 ^^^^^^^^^^^^ help: remove `return` as shown: `idx`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_return
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:45:43
[INFO] [stderr]    |
[INFO] [stderr] 45 |             let mut target_cell_val: u8 = *&board_copy[*current_blank_pos as usize];
[INFO] [stderr]    |                                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[*current_blank_pos as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(clippy::deref_addrof)] on by default
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: this if statement can be collapsed
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:70:17
[INFO] [stderr]    |
[INFO] [stderr] 70 | /                 if current_row_cell != *current_blank_pos {
[INFO] [stderr] 71 | |                     if *&board_copy[current_row_cell as usize] == target_cell_val {
[INFO] [stderr] 72 | |                         passed_row_col_check = false;
[INFO] [stderr] 73 | |                         break;
[INFO] [stderr] 74 | |                     }
[INFO] [stderr] 75 | |                 }
[INFO] [stderr]    | |_________________^
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(clippy::collapsible_if)] on by default
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
[INFO] [stderr] help: try
[INFO] [stderr]    |
[INFO] [stderr] 70 |                 if current_row_cell != *current_blank_pos && *&board_copy[current_row_cell as usize] == target_cell_val {
[INFO] [stderr] 71 |     passed_row_col_check = false;
[INFO] [stderr] 72 |     break;
[INFO] [stderr] 73 | }
[INFO] [stderr]    |
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:71:24
[INFO] [stderr]    |
[INFO] [stderr] 71 |                     if *&board_copy[current_row_cell as usize] == target_cell_val {
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[current_row_cell as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: this if statement can be collapsed
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:78:17
[INFO] [stderr]    |
[INFO] [stderr] 78 | /                 if current_col_cell != *current_blank_pos {
[INFO] [stderr] 79 | |                     if *&board_copy[current_col_cell as usize] == target_cell_val {
[INFO] [stderr] 80 | |                         passed_row_col_check = false;
[INFO] [stderr] 81 | |                         break;
[INFO] [stderr] 82 | |                     }
[INFO] [stderr] 83 | |                 }
[INFO] [stderr]    | |_________________^
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
[INFO] [stderr] help: try
[INFO] [stderr]    |
[INFO] [stderr] 78 |                 if current_col_cell != *current_blank_pos && *&board_copy[current_col_cell as usize] == target_cell_val {
[INFO] [stderr] 79 |     passed_row_col_check = false;
[INFO] [stderr] 80 |     break;
[INFO] [stderr] 81 | }
[INFO] [stderr]    |
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:79:24
[INFO] [stderr]    |
[INFO] [stderr] 79 |                     if *&board_copy[current_col_cell as usize] == target_cell_val {
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[current_col_cell as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[INFO] [stderr] 
[INFO] [stderr] warning: this if statement can be collapsed
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:93:25
[INFO] [stderr]    |
[INFO] [stderr] 93 | /                         if current_block_cell != *current_blank_pos {
[INFO] [stderr] 94 | |                             if *&board_copy[current_block_cell as usize] == target_cell_val {
[INFO] [stderr] 95 | |                                 passed_block_check = false;
[INFO] [stderr] 96 | |                                 break;
[INFO] [stderr] 97 | |                             }
[INFO] [stderr] 98 | |                         }
[INFO] [stderr]    | |_________________________^
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
[INFO] [stderr] help: try
[INFO] [stderr]    |
[INFO] [stderr] 93 |                         if current_block_cell != *current_blank_pos && *&board_copy[current_block_cell as usize] == target_cell_val {
[INFO] [stderr] 94 |     passed_block_check = false;
[INFO] [stderr] 95 |     break;
[INFO] [stderr] 96 | }
[INFO] [stderr]    |
[INFO] [stderr] 
[INFO] [stderr] warning: immediately dereferencing a reference
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:94:32
[INFO] [stderr]    |
[INFO] [stderr] 94 |                             if *&board_copy[current_block_cell as usize] == target_cell_val {
[INFO] [stderr]    |                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[current_block_cell as usize]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#deref_addrof
[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: using `clone` on a `Copy` type
[INFO] [stderr]   --> src/sudoku_solver_dancinglinks/mod.rs:83:24
[INFO] [stderr]    |
[INFO] [stderr] 83 |             node_type: node_type.clone(),
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `node_type`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(clippy::clone_on_copy)] on by default
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a Vec. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:111:9
[INFO] [stderr]     |
[INFO] [stderr] 111 |         self.network.get(node_id).unwrap()
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `self.network[node_id]`
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(clippy::get_unwrap)] on by default
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:320:21
[INFO] [stderr]     |
[INFO] [stderr] 320 |                     operation.clone()
[INFO] [stderr]     |                     ^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:454:84
[INFO] [stderr]     |
[INFO] [stderr] 454 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(row_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `row_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:456:40
[INFO] [stderr]     |
[INFO] [stderr] 456 |                     constraints.insert(row_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `row_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:458:44
[INFO] [stderr]     |
[INFO] [stderr] 458 |                 let row_column_header_id = constraints.get(&row_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&row_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:458:44
[INFO] [stderr]     |
[INFO] [stderr] 458 |                 let row_column_header_id = constraints.get(&row_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&row_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:463:84
[INFO] [stderr]     |
[INFO] [stderr] 463 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(col_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `col_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:465:40
[INFO] [stderr]     |
[INFO] [stderr] 465 |                     constraints.insert(col_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `col_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:467:44
[INFO] [stderr]     |
[INFO] [stderr] 467 |                 let col_column_header_id = constraints.get(&col_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&col_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:467:44
[INFO] [stderr]     |
[INFO] [stderr] 467 |                 let col_column_header_id = constraints.get(&col_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&col_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:472:84
[INFO] [stderr]     |
[INFO] [stderr] 472 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(block_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `block_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:474:40
[INFO] [stderr]     |
[INFO] [stderr] 474 |                     constraints.insert(block_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `block_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:476:46
[INFO] [stderr]     |
[INFO] [stderr] 476 |                 let block_column_header_id = constraints.get(&block_constraint).unwrap().clone();
[INFO] [stderr]     |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&block_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:476:46
[INFO] [stderr]     |
[INFO] [stderr] 476 |                 let block_column_header_id = constraints.get(&block_constraint).unwrap().clone();
[INFO] [stderr]     |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&block_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:481:84
[INFO] [stderr]     |
[INFO] [stderr] 481 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(position_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `position_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:483:40
[INFO] [stderr]     |
[INFO] [stderr] 483 |                     constraints.insert(position_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `position_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:485:44
[INFO] [stderr]     |
[INFO] [stderr] 485 |                 let pos_column_header_id = constraints.get(&position_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&position_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:485:44
[INFO] [stderr]     |
[INFO] [stderr] 485 |                 let pos_column_header_id = constraints.get(&position_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&position_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:488:66
[INFO] [stderr]     |
[INFO] [stderr] 488 |                 let field1 = network.create_node(NodeType::Field(current_operation.clone(), row_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:489:66
[INFO] [stderr]     |
[INFO] [stderr] 489 |                 let field2 = network.create_node(NodeType::Field(current_operation.clone(), col_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:490:66
[INFO] [stderr]     |
[INFO] [stderr] 490 |                 let field3 = network.create_node(NodeType::Field(current_operation.clone(), block_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:491:66
[INFO] [stderr]     |
[INFO] [stderr] 491 |                 let field4 = network.create_node(NodeType::Field(current_operation.clone(), pos_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:506:10
[INFO] [stderr]     |
[INFO] [stderr] 506 |         *result.get_mut((operation.y_pos * 9 + operation.x_pos) as usize).unwrap() = operation.value;
[INFO] [stderr]     |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `result[(operation.y_pos * 9 + operation.x_pos) as usize]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:49:14
[INFO] [stderr]    |
[INFO] [stderr] 49 |             *board_copy.get_mut(*current_blank_pos).unwrap() = target_cell_val;
[INFO] [stderr]    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[*current_blank_pos]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[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 using `_operation` instead
[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 using `_constraint` instead
[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 using `_operation` instead
[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 using `_constraint` instead
[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 using `_constraint` instead
[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 using `_constraint` instead
[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 using `_idx` instead
[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 using `_val` instead
[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: using `clone` on a `Copy` type
[INFO] [stderr]   --> src/sudoku_solver_dancinglinks/mod.rs:83:24
[INFO] [stderr]    |
[INFO] [stderr] 83 |             node_type: node_type.clone(),
[INFO] [stderr]    |                        ^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `node_type`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(clippy::clone_on_copy)] on by default
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a Vec. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:111:9
[INFO] [stderr]     |
[INFO] [stderr] 111 |         self.network.get(node_id).unwrap()
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `self.network[node_id]`
[INFO] [stderr]     |
[INFO] [stderr]     = note: #[warn(clippy::get_unwrap)] on by default
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:320:21
[INFO] [stderr]     |
[INFO] [stderr] 320 |                     operation.clone()
[INFO] [stderr]     |                     ^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:454:84
[INFO] [stderr]     |
[INFO] [stderr] 454 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(row_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `row_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:456:40
[INFO] [stderr]     |
[INFO] [stderr] 456 |                     constraints.insert(row_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `row_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:458:44
[INFO] [stderr]     |
[INFO] [stderr] 458 |                 let row_column_header_id = constraints.get(&row_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&row_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:458:44
[INFO] [stderr]     |
[INFO] [stderr] 458 |                 let row_column_header_id = constraints.get(&row_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&row_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:463:84
[INFO] [stderr]     |
[INFO] [stderr] 463 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(col_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `col_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:465:40
[INFO] [stderr]     |
[INFO] [stderr] 465 |                     constraints.insert(col_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `col_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:467:44
[INFO] [stderr]     |
[INFO] [stderr] 467 |                 let col_column_header_id = constraints.get(&col_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&col_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:467:44
[INFO] [stderr]     |
[INFO] [stderr] 467 |                 let col_column_header_id = constraints.get(&col_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&col_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:472:84
[INFO] [stderr]     |
[INFO] [stderr] 472 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(block_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `block_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:474:40
[INFO] [stderr]     |
[INFO] [stderr] 474 |                     constraints.insert(block_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `block_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:476:46
[INFO] [stderr]     |
[INFO] [stderr] 476 |                 let block_column_header_id = constraints.get(&block_constraint).unwrap().clone();
[INFO] [stderr]     |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&block_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:476:46
[INFO] [stderr]     |
[INFO] [stderr] 476 |                 let block_column_header_id = constraints.get(&block_constraint).unwrap().clone();
[INFO] [stderr]     |                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&block_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:481:84
[INFO] [stderr]     |
[INFO] [stderr] 481 |                     let new_header_id = network.create_node(NodeType::ColumnHeader(position_constraint.clone(), 0));
[INFO] [stderr]     |                                                                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `position_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:483:40
[INFO] [stderr]     |
[INFO] [stderr] 483 |                     constraints.insert(position_constraint.clone(), new_header_id);
[INFO] [stderr]     |                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `position_constraint`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:485:44
[INFO] [stderr]     |
[INFO] [stderr] 485 |                 let pos_column_header_id = constraints.get(&position_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing it: `*constraints.get(&position_constraint).unwrap()`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get().unwrap()` on a HashMap. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:485:44
[INFO] [stderr]     |
[INFO] [stderr] 485 |                 let pos_column_header_id = constraints.get(&position_constraint).unwrap().clone();
[INFO] [stderr]     |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `&constraints[&position_constraint]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:488:66
[INFO] [stderr]     |
[INFO] [stderr] 488 |                 let field1 = network.create_node(NodeType::Field(current_operation.clone(), row_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:489:66
[INFO] [stderr]     |
[INFO] [stderr] 489 |                 let field2 = network.create_node(NodeType::Field(current_operation.clone(), col_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:490:66
[INFO] [stderr]     |
[INFO] [stderr] 490 |                 let field3 = network.create_node(NodeType::Field(current_operation.clone(), block_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: using `clone` on a `Copy` type
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:491:66
[INFO] [stderr]     |
[INFO] [stderr] 491 |                 let field4 = network.create_node(NodeType::Field(current_operation.clone(), pos_column_header_id));
[INFO] [stderr]     |                                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^ help: try removing the `clone` call: `current_operation`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#clone_on_copy
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
[INFO] [stderr]    --> src/sudoku_solver_dancinglinks/mod.rs:506:10
[INFO] [stderr]     |
[INFO] [stderr] 506 |         *result.get_mut((operation.y_pos * 9 + operation.x_pos) as usize).unwrap() = operation.value;
[INFO] [stderr]     |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `result[(operation.y_pos * 9 + operation.x_pos) as usize]`
[INFO] [stderr]     |
[INFO] [stderr]     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr] warning: called `.get_mut().unwrap()` on a Vec. Using `[]` is more clear and more concise
[INFO] [stderr]   --> src/sudoku_solver_backtrack/mod.rs:49:14
[INFO] [stderr]    |
[INFO] [stderr] 49 |             *board_copy.get_mut(*current_blank_pos).unwrap() = target_cell_val;
[INFO] [stderr]    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try this: `board_copy[*current_blank_pos]`
[INFO] [stderr]    |
[INFO] [stderr]    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#get_unwrap
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.97s
[INFO] running `"docker" "inspect" "d1727cb11cfe5958e1eb165107cefa7541b9818d936c4f6f2d26bd271440452f"`
[INFO] running `"docker" "rm" "-f" "d1727cb11cfe5958e1eb165107cefa7541b9818d936c4f6f2d26bd271440452f"`
[INFO] [stdout] d1727cb11cfe5958e1eb165107cefa7541b9818d936c4f6f2d26bd271440452f