[INFO] cloning repository https://github.com/SpencerN319/rust_book
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/SpencerN319/rust_book" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FSpencerN319%2Frust_book", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FSpencerN319%2Frust_book'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] be2430bf15ffea5439b933e5cffc8695a78c941c
[INFO] testing SpencerN319/rust_book against try#722e1797249a965b6335aebd65d777f917e498f1 for pr-91031
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FSpencerN319%2Frust_book" "/workspace/builds/worker-103/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-103/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/SpencerN319/rust_book on toolchain 722e1797249a965b6335aebd65d777f917e498f1
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/SpencerN319/rust_book
[INFO] finished tweaking git repo https://github.com/SpencerN319/rust_book
[INFO] tweaked toml for git repo https://github.com/SpencerN319/rust_book written to /workspace/builds/worker-103/source/Cargo.toml
[INFO] crate git repo https://github.com/SpencerN319/rust_book already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-103/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-103/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 4b0d0baaa8133a85a64821d73132b381999da280e01ec32cd34685087dfbe460
[INFO] running `Command { std: "docker" "start" "-a" "4b0d0baaa8133a85a64821d73132b381999da280e01ec32cd34685087dfbe460", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "4b0d0baaa8133a85a64821d73132b381999da280e01ec32cd34685087dfbe460", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4b0d0baaa8133a85a64821d73132b381999da280e01ec32cd34685087dfbe460", kill_on_drop: false }`
[INFO] [stdout] 4b0d0baaa8133a85a64821d73132b381999da280e01ec32cd34685087dfbe460
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-103/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-103/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5d2cd359e1c884cc2f7eadfc3a60fa483d66f59b98a6017c04800452f98c5ff3
[INFO] running `Command { std: "docker" "start" "-a" "5d2cd359e1c884cc2f7eadfc3a60fa483d66f59b98a6017c04800452f98c5ff3", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.97
[INFO] [stderr]    Compiling getrandom v0.2.3
[INFO] [stderr]    Compiling rand_core v0.6.3
[INFO] [stderr]    Compiling rand_chacha v0.3.1
[INFO] [stderr]    Compiling rand v0.8.4
[INFO] [stderr]    Compiling rust_book v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0277]: the trait bound `String: From<()>` is not satisfied
[INFO] [stdout]    --> src/functions.rs:14:5
[INFO] [stdout]     |
[INFO] [stdout] 14  |     String::from(s1.push_str(s2))
[INFO] [stdout]     |     ^^^^^^^^^^^^ the trait `From<()>` is not implemented for `String`
[INFO] [stdout]     |
[INFO] [stdout]     = help: the following implementations were found:
[INFO] [stdout]               <String as From<&String>>
[INFO] [stdout]               <String as From<&mut str>>
[INFO] [stdout]               <String as From<&str>>
[INFO] [stdout]               <String as From<Box<str>>>
[INFO] [stdout]             and 2 others
[INFO] [stdout] note: required by `from`
[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 E0277`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `rust_book` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "5d2cd359e1c884cc2f7eadfc3a60fa483d66f59b98a6017c04800452f98c5ff3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5d2cd359e1c884cc2f7eadfc3a60fa483d66f59b98a6017c04800452f98c5ff3", kill_on_drop: false }`
[INFO] [stdout] 5d2cd359e1c884cc2f7eadfc3a60fa483d66f59b98a6017c04800452f98c5ff3