[INFO] cloning repository https://github.com/lucaspoffo/markov_chain
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/lucaspoffo/markov_chain" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flucaspoffo%2Fmarkov_chain", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flucaspoffo%2Fmarkov_chain'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d67657284eacd67f24653a0209b22304c163396b
[INFO] checking lucaspoffo/markov_chain against master#c756124775121dea0e640652c5ee3c89e3dd0eb4 for pr-154971-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Flucaspoffo%2Fmarkov_chain" "/workspace/builds/worker-2-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/lucaspoffo/markov_chain
[INFO] finished tweaking git repo https://github.com/lucaspoffo/markov_chain
[INFO] tweaked toml for git repo https://github.com/lucaspoffo/markov_chain written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/lucaspoffo/markov_chain on toolchain c756124775121dea0e640652c5ee3c89e3dd0eb4
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c756124775121dea0e640652c5ee3c89e3dd0eb4" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/lucaspoffo/markov_chain already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c756124775121dea0e640652c5ee3c89e3dd0eb4" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded rand_chacha v0.2.1
[INFO] [stderr]   Downloaded getrandom v0.1.14
[INFO] [stderr]   Downloaded rand v0.7.2
[INFO] [stderr]   Downloaded c2-chacha v0.2.3
[INFO] [stderr]   Downloaded ppv-lite86 v0.2.6
[INFO] [stderr]   Downloaded libc v0.2.66
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+c756124775121dea0e640652c5ee3c89e3dd0eb4" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] af60e040b54a114945ad51b42b0d47839ec2239d17cfaf8e580f9b2354a0d44a
[INFO] running `Command { std: "docker" "start" "-a" "af60e040b54a114945ad51b42b0d47839ec2239d17cfaf8e580f9b2354a0d44a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "af60e040b54a114945ad51b42b0d47839ec2239d17cfaf8e580f9b2354a0d44a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "af60e040b54a114945ad51b42b0d47839ec2239d17cfaf8e580f9b2354a0d44a", kill_on_drop: false }`
[INFO] [stdout] af60e040b54a114945ad51b42b0d47839ec2239d17cfaf8e580f9b2354a0d44a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+c756124775121dea0e640652c5ee3c89e3dd0eb4" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d6799a76a57e4abe28c4407908414d7d5ef41b6256c315540f6de33f345d802a
[INFO] running `Command { std: "docker" "start" "-a" "d6799a76a57e4abe28c4407908414d7d5ef41b6256c315540f6de33f345d802a", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.66
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking ppv-lite86 v0.2.6
[INFO] [stderr]     Checking c2-chacha v0.2.3
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.1
[INFO] [stderr]     Checking rand v0.7.2
[INFO] [stderr]     Checking markov_chain v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: call to `.clone()` on a reference in this situation does nothing
[INFO] [stdout]   --> src/lib.rs:71:39
[INFO] [stdout]    |
[INFO] [stdout] 71 |     result.append(&mut next_word_chain.clone().to_vec());
[INFO] [stdout]    |                                       ^^^^^^^^ help: remove this redundant call
[INFO] [stdout]    |
[INFO] [stdout]    = note: the type `[String]` does not implement `Clone`, so calling `clone` on `&[String]` copies the reference, which does not do anything and can be removed
[INFO] [stdout]    = note: `#[warn(noop_method_call)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/lib.rs:133:7
[INFO] [stdout]     |
[INFO] [stdout] 133 |       write!(f, "\t{:?}:\n", key);
[INFO] [stdout]     |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 133 |       let _ = write!(f, "\t{:?}:\n", key);
[INFO] [stdout]     |       +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: call to `.clone()` on a reference in this situation does nothing
[INFO] [stdout]   --> src/lib.rs:71:39
[INFO] [stdout]    |
[INFO] [stdout] 71 |     result.append(&mut next_word_chain.clone().to_vec());
[INFO] [stdout]    |                                       ^^^^^^^^ help: remove this redundant call
[INFO] [stdout]    |
[INFO] [stdout]    = note: the type `[String]` does not implement `Clone`, so calling `clone` on `&[String]` copies the reference, which does not do anything and can be removed
[INFO] [stdout]    = note: `#[warn(noop_method_call)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/lib.rs:133:7
[INFO] [stdout]     |
[INFO] [stdout] 133 |       write!(f, "\t{:?}:\n", key);
[INFO] [stdout]     |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 133 |       let _ = write!(f, "\t{:?}:\n", key);
[INFO] [stdout]     |       +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.74s
[INFO] running `Command { std: "docker" "inspect" "d6799a76a57e4abe28c4407908414d7d5ef41b6256c315540f6de33f345d802a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d6799a76a57e4abe28c4407908414d7d5ef41b6256c315540f6de33f345d802a", kill_on_drop: false }`
[INFO] [stdout] d6799a76a57e4abe28c4407908414d7d5ef41b6256c315540f6de33f345d802a
