[INFO] updating cached repository suelz/chapter_4
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/suelz/chapter_4
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/suelz/chapter_4" "work/ex/pr-61753/sources/master#8e948df707ea8a3c88c65bf2ffdcb2f1cf5491be/gh/suelz/chapter_4"`
[INFO] [stderr] Cloning into 'work/ex/pr-61753/sources/master#8e948df707ea8a3c88c65bf2ffdcb2f1cf5491be/gh/suelz/chapter_4'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/suelz/chapter_4" "work/ex/pr-61753/sources/try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af/gh/suelz/chapter_4"`
[INFO] [stderr] Cloning into 'work/ex/pr-61753/sources/try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af/gh/suelz/chapter_4'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 5266a4ada4918881254cc79de937fbc229bb69a4
[INFO] sha for GitHub repo suelz/chapter_4: 5266a4ada4918881254cc79de937fbc229bb69a4
[INFO] validating manifest of suelz/chapter_4 on toolchain master#8e948df707ea8a3c88c65bf2ffdcb2f1cf5491be
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+8e948df707ea8a3c88c65bf2ffdcb2f1cf5491be-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of suelz/chapter_4 on toolchain try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+af22dfc7f56a5057c6b6120a65c74e7b6c1530af-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing suelz/chapter_4
[INFO] finished frobbing suelz/chapter_4
[INFO] frobbed toml for suelz/chapter_4 written to work/ex/pr-61753/sources/master#8e948df707ea8a3c88c65bf2ffdcb2f1cf5491be/gh/suelz/chapter_4/Cargo.toml
[INFO] started frobbing suelz/chapter_4
[INFO] finished frobbing suelz/chapter_4
[INFO] frobbed toml for suelz/chapter_4 written to work/ex/pr-61753/sources/try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af/gh/suelz/chapter_4/Cargo.toml
[INFO] crate suelz/chapter_4 already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+8e948df707ea8a3c88c65bf2ffdcb2f1cf5491be-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+af22dfc7f56a5057c6b6120a65c74e7b6c1530af-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] checking suelz/chapter_4 against try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af for pr-61753
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/pr-61753/worker-3/try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/pr-61753/sources/try#af22dfc7f56a5057c6b6120a65c74e7b6c1530af/gh/suelz/chapter_4:/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" "-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" "+af22dfc7f56a5057c6b6120a65c74e7b6c1530af-alt" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stdout] a4f8a99373a59250e2f12a7ff8240ce951ec6baead9a227915fcbd4af7c77fcf
[INFO] running `"docker" "start" "-a" "a4f8a99373a59250e2f12a7ff8240ce951ec6baead9a227915fcbd4af7c77fcf"`
[INFO] [stderr]     Checking ch4 v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused variable: `word`
[INFO] [stderr]   --> src/main.rs:28:9
[INFO] [stderr]    |
[INFO] [stderr] 28 |     let word = first_word(&x);
[INFO] [stderr]    |         ^^^^ help: consider prefixing with an underscore: `_word`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(unused_variables)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/main.rs:26:9
[INFO] [stderr]    |
[INFO] [stderr] 26 |     let mut x = String::from("Conor Kennedy");
[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: unused variable: `word`
[INFO] [stderr]   --> src/main.rs:28:9
[INFO] [stderr]    |
[INFO] [stderr] 28 |     let word = first_word(&x);
[INFO] [stderr]    |         ^^^^ help: consider prefixing with an underscore: `_word`
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(unused_variables)] on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/main.rs:26:9
[INFO] [stderr]    |
[INFO] [stderr] 26 |     let mut x = String::from("Conor Kennedy");
[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]     Finished dev [unoptimized + debuginfo] target(s) in 0.45s
[INFO] running `"docker" "inspect" "a4f8a99373a59250e2f12a7ff8240ce951ec6baead9a227915fcbd4af7c77fcf"`
[INFO] running `"docker" "rm" "-f" "a4f8a99373a59250e2f12a7ff8240ce951ec6baead9a227915fcbd4af7c77fcf"`
[INFO] [stdout] a4f8a99373a59250e2f12a7ff8240ce951ec6baead9a227915fcbd4af7c77fcf