[INFO] updating cached repository https://github.com/slavovojacek/8QP_rust
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/mnt/big/crater/work/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] d954f74f594f63fe348d514e1cdd08ecc3d3580f
[INFO] checking slavovojacek/8QP_rust against master#c9edc02e8320a9e5799d185910ece7d491f524e6 for pr-64398
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fslavovojacek%2F8QP_rust" "work/builds/worker-1/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/slavovojacek/8QP_rust on toolchain c9edc02e8320a9e5799d185910ece7d491f524e6-alt
[INFO] running `"/mnt/big/crater/work/cargo-home/bin/cargo" "+c9edc02e8320a9e5799d185910ece7d491f524e6-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/slavovojacek/8QP_rust
[INFO] finished tweaking git repo https://github.com/slavovojacek/8QP_rust
[INFO] tweaked toml for git repo https://github.com/slavovojacek/8QP_rust written to work/builds/worker-1/source/Cargo.toml
[INFO] crate git repo https://github.com/slavovojacek/8QP_rust already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/cargo-home/bin/cargo" "+c9edc02e8320a9e5799d185910ece7d491f524e6-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/mnt/big/crater/work/builds/worker-1/source:/opt/rustwide/workdir:ro,Z" "-v" "/mnt/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+c9edc02e8320a9e5799d185910ece7d491f524e6-alt" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stdout] 51c207ff8f62d408a40ba75a9628edac00db29d4fe2bfae0cc1a841f15c74267
[INFO] running `"docker" "start" "-a" "51c207ff8f62d408a40ba75a9628edac00db29d4fe2bfae0cc1a841f15c74267"`
[INFO] [stderr]     Checking eight_queen_problem v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] warning: value assigned to `empty_squares` is never read
[INFO] [stderr]   --> src/main.rs:20:13
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let mut empty_squares: Vec<Position> = Vec::new();
[INFO] [stderr]    |             ^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr]    = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `r`
[INFO] [stderr]    --> src/main.rs:113:33
[INFO] [stderr]     |
[INFO] [stderr] 113 | fn fill_col(board: &mut Board, (r, c): Position) -> Result<(), Position> {
[INFO] [stderr]     |                                 ^ help: consider prefixing with an underscore: `_r`
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `empty_squares` is never read
[INFO] [stderr]   --> src/main.rs:20:13
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let mut empty_squares: Vec<Position> = Vec::new();
[INFO] [stderr]    |             ^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr]    = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `r`
[INFO] [stderr]    --> src/main.rs:113:33
[INFO] [stderr]     |
[INFO] [stderr] 113 | fn fill_col(board: &mut Board, (r, c): Position) -> Result<(), Position> {
[INFO] [stderr]     |                                 ^ help: consider prefixing with an underscore: `_r`
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.82s
[INFO] running `"docker" "inspect" "51c207ff8f62d408a40ba75a9628edac00db29d4fe2bfae0cc1a841f15c74267"`
[INFO] running `"docker" "rm" "-f" "51c207ff8f62d408a40ba75a9628edac00db29d4fe2bfae0cc1a841f15c74267"`
[INFO] [stdout] 51c207ff8f62d408a40ba75a9628edac00db29d4fe2bfae0cc1a841f15c74267