[INFO] cloning repository https://github.com/adragott/Serial_Rust_Learning
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/adragott/Serial_Rust_Learning" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fadragott%2FSerial_Rust_Learning", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fadragott%2FSerial_Rust_Learning'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 793ed8bd526ac92504690f517e2e45b85f92cbc9
[INFO] checking adragott/Serial_Rust_Learning against master#3aedcf06b73fc36feeebca3d579e1d2a6c40acc5 for pr-65819
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fadragott%2FSerial_Rust_Learning" "/workspace/builds/worker-3/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/adragott/Serial_Rust_Learning on toolchain 3aedcf06b73fc36feeebca3d579e1d2a6c40acc5
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+3aedcf06b73fc36feeebca3d579e1d2a6c40acc5" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] removed /workspace/builds/worker-3/source/.cargo/config
[INFO] started tweaking git repo https://github.com/adragott/Serial_Rust_Learning
[INFO] finished tweaking git repo https://github.com/adragott/Serial_Rust_Learning
[INFO] tweaked toml for git repo https://github.com/adragott/Serial_Rust_Learning written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/adragott/Serial_Rust_Learning already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+3aedcf06b73fc36feeebca3d579e1d2a6c40acc5" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "rustops/crates-build-env@sha256:c46a2d1a26fb48b37929c74ca49dd9409f2375a0a3bdb8fe07617f3ffccaa889" "/opt/rustwide/cargo-home/bin/cargo" "+3aedcf06b73fc36feeebca3d579e1d2a6c40acc5" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] fbacf3cd2da27fe8934b856468db4c3c75580268be6aa0b4e6966cb5db906412
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "fbacf3cd2da27fe8934b856468db4c3c75580268be6aa0b4e6966cb5db906412", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fbacf3cd2da27fe8934b856468db4c3c75580268be6aa0b4e6966cb5db906412", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fbacf3cd2da27fe8934b856468db4c3c75580268be6aa0b4e6966cb5db906412", kill_on_drop: false }`
[INFO] [stdout] fbacf3cd2da27fe8934b856468db4c3c75580268be6aa0b4e6966cb5db906412
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "rustops/crates-build-env@sha256:c46a2d1a26fb48b37929c74ca49dd9409f2375a0a3bdb8fe07617f3ffccaa889" "/opt/rustwide/cargo-home/bin/cargo" "+3aedcf06b73fc36feeebca3d579e1d2a6c40acc5" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] bc72b6cba5d186af8d6469ebfcb554088ba17aa742f34f726241dd975d9aea61
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "bc72b6cba5d186af8d6469ebfcb554088ba17aa742f34f726241dd975d9aea61", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.66
[INFO] [stderr]     Checking ioctl-rs v0.1.6
[INFO] [stderr]     Checking termios v0.2.2
[INFO] [stderr]     Checking serial-core v0.4.0
[INFO] [stderr]     Checking serial-unix v0.4.0
[INFO] [stderr]     Checking serial v0.4.0
[INFO] [stderr]     Checking serial_rust v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `std::str`
[INFO] [stdout]  --> src/main.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use std::str;
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::str`
[INFO] [stdout]  --> src/main.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use std::str;
[INFO] [stdout]   |     ^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unreachable expression
[INFO] [stdout]   --> src/main.rs:45:5
[INFO] [stdout]    |
[INFO] [stdout] 28 | /     loop
[INFO] [stdout] 29 | |     {
[INFO] [stdout] 30 | |         let mut buf = [0_u8; 256];
[INFO] [stdout] 31 | |         let count = match port.read(&mut buf)
[INFO] [stdout] ...  |
[INFO] [stdout] 43 | |         io::stdout().flush().unwrap();
[INFO] [stdout] 44 | |    }
[INFO] [stdout]    | |____- any code following this expression is unreachable
[INFO] [stdout] 45 |       Ok(())
[INFO] [stdout]    |       ^^^^^^ unreachable expression
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unreachable_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unreachable expression
[INFO] [stdout]   --> src/main.rs:45:5
[INFO] [stdout]    |
[INFO] [stdout] 28 | /     loop
[INFO] [stdout] 29 | |     {
[INFO] [stdout] 30 | |         let mut buf = [0_u8; 256];
[INFO] [stdout] 31 | |         let count = match port.read(&mut buf)
[INFO] [stdout] ...  |
[INFO] [stdout] 43 | |         io::stdout().flush().unwrap();
[INFO] [stdout] 44 | |    }
[INFO] [stdout]    | |____- any code following this expression is unreachable
[INFO] [stdout] 45 |       Ok(())
[INFO] [stdout]    |       ^^^^^^ unreachable expression
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unreachable_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 4.28s
[INFO] running `Command { std: "docker" "inspect" "bc72b6cba5d186af8d6469ebfcb554088ba17aa742f34f726241dd975d9aea61", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bc72b6cba5d186af8d6469ebfcb554088ba17aa742f34f726241dd975d9aea61", kill_on_drop: false }`
[INFO] [stdout] bc72b6cba5d186af8d6469ebfcb554088ba17aa742f34f726241dd975d9aea61