[INFO] fetching crate mwmatching 0.1.1...
[INFO] checking mwmatching-0.1.1 against master#c724b67e1b474262917a5154d74e7072267593fe for pr-74315
[INFO] extracting crate mwmatching 0.1.1 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate mwmatching 0.1.1 on toolchain c724b67e1b474262917a5154d74e7072267593fe
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mwmatching 0.1.1
[INFO] finished tweaking crates.io crate mwmatching 0.1.1
[INFO] tweaked toml for crates.io crate mwmatching 0.1.1 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "metadata" "--no-deps" "--format-version=1", 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] 8ba9339415380a610b71ac806cd1a1aa6429c53303f7afc5e7894e6037179db7
[INFO] running `Command { std: "docker" "start" "-a" "8ba9339415380a610b71ac806cd1a1aa6429c53303f7afc5e7894e6037179db7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8ba9339415380a610b71ac806cd1a1aa6429c53303f7afc5e7894e6037179db7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8ba9339415380a610b71ac806cd1a1aa6429c53303f7afc5e7894e6037179db7", kill_on_drop: false }`
[INFO] [stdout] 8ba9339415380a610b71ac806cd1a1aa6429c53303f7afc5e7894e6037179db7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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" "MAP_USER_ID=0" "-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@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "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] 04b565dfd2b5f64339c83a2392dc7998580d91f0af94f0a24b61dfa0d0456efb
[INFO] running `Command { std: "docker" "start" "-a" "04b565dfd2b5f64339c83a2392dc7998580d91f0af94f0a24b61dfa0d0456efb", kill_on_drop: false }`
[INFO] [stderr]     Checking mwmatching v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unnecessary parentheses around block return value
[INFO] [stdout]     --> src/lib.rs:1083:60
[INFO] [stdout]      |
[INFO] [stdout] 1083 |     let actual_index = if index>= 0 {index as usize} else {(v.len()-(-index) as usize)};
[INFO] [stdout]      |                                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove these parentheses
[INFO] [stdout]      |
[INFO] [stdout]      = note: `#[warn(unused_parens)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around block return value
[INFO] [stdout]     --> src/lib.rs:1083:60
[INFO] [stdout]      |
[INFO] [stdout] 1083 |     let actual_index = if index>= 0 {index as usize} else {(v.len()-(-index) as usize)};
[INFO] [stdout]      |                                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove these parentheses
[INFO] [stdout]      |
[INFO] [stdout]      = note: `#[warn(unused_parens)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/lib.rs:744:25
[INFO] [stdout]     |
[INFO] [stdout] 744 |                     let mut k = p / 2;
[INFO] [stdout]     |                         ----^
[INFO] [stdout]     |                         |
[INFO] [stdout]     |                         help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/lib.rs:852:29
[INFO] [stdout]     |
[INFO] [stdout] 852 |                         let mut k = p / 2;
[INFO] [stdout]     |                             ----^
[INFO] [stdout]     |                             |
[INFO] [stdout]     |                             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/lib.rs:744:25
[INFO] [stdout]     |
[INFO] [stdout] 744 |                     let mut k = p / 2;
[INFO] [stdout]     |                         ----^
[INFO] [stdout]     |                         |
[INFO] [stdout]     |                         help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `mwmatching`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error[E0463]: can't find crate for `rand`
[INFO] [stdout]  --> examples/largedata/main.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | extern crate rand;
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^ can't find crate
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0463`.
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/lib.rs:852:29
[INFO] [stdout]     |
[INFO] [stdout] 852 |                         let mut k = p / 2;
[INFO] [stdout]     |                             ----^
[INFO] [stdout]     |                             |
[INFO] [stdout]     |                             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "04b565dfd2b5f64339c83a2392dc7998580d91f0af94f0a24b61dfa0d0456efb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "04b565dfd2b5f64339c83a2392dc7998580d91f0af94f0a24b61dfa0d0456efb", kill_on_drop: false }`
[INFO] [stdout] 04b565dfd2b5f64339c83a2392dc7998580d91f0af94f0a24b61dfa0d0456efb