[INFO] cloning repository https://github.com/BurningBlueFox/rust-treehouse-club
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/BurningBlueFox/rust-treehouse-club" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FBurningBlueFox%2Frust-treehouse-club", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FBurningBlueFox%2Frust-treehouse-club'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4d8d619ef4dc478e0f2bbb0f105c886f2704d421
[INFO] checking BurningBlueFox/rust-treehouse-club against master#385fa9d845dd326c6bbfd58c22244215e431948a for absurd-question-mark-desugar
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FBurningBlueFox%2Frust-treehouse-club" "/workspace/builds/worker-6-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/BurningBlueFox/rust-treehouse-club on toolchain 385fa9d845dd326c6bbfd58c22244215e431948a
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/BurningBlueFox/rust-treehouse-club
[INFO] finished tweaking git repo https://github.com/BurningBlueFox/rust-treehouse-club
[INFO] tweaked toml for git repo https://github.com/BurningBlueFox/rust-treehouse-club written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/BurningBlueFox/rust-treehouse-club 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" "+385fa9d845dd326c6bbfd58c22244215e431948a" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] f61d8a0bf100acba8af2887e64f8b4a14d8a7878672f566a100a5b6264983499
[INFO] running `Command { std: "docker" "start" "-a" "f61d8a0bf100acba8af2887e64f8b4a14d8a7878672f566a100a5b6264983499", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f61d8a0bf100acba8af2887e64f8b4a14d8a7878672f566a100a5b6264983499", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f61d8a0bf100acba8af2887e64f8b4a14d8a7878672f566a100a5b6264983499", kill_on_drop: false }`
[INFO] [stdout] f61d8a0bf100acba8af2887e64f8b4a14d8a7878672f566a100a5b6264983499
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b94a14a56847f443920cff837ffd1e8ace543fb8ceb8054fc86870d1ea53a3af
[INFO] running `Command { std: "docker" "start" "-a" "b94a14a56847f443920cff837ffd1e8ace543fb8ceb8054fc86870d1ea53a3af", kill_on_drop: false }`
[INFO] [stderr]     Checking treehouse v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/visitor.rs:29:17
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 &self.do_something_more_involved();
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 let _ = &self.do_something_more_involved();
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/visitor.rs:29:17
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 &self.do_something_more_involved();
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 let _ = &self.do_something_more_involved();
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.21s
[INFO] running `Command { std: "docker" "inspect" "b94a14a56847f443920cff837ffd1e8ace543fb8ceb8054fc86870d1ea53a3af", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b94a14a56847f443920cff837ffd1e8ace543fb8ceb8054fc86870d1ea53a3af", kill_on_drop: false }`
[INFO] [stdout] b94a14a56847f443920cff837ffd1e8ace543fb8ceb8054fc86870d1ea53a3af
[INFO] checking BurningBlueFox/rust-treehouse-club against try#645bb72776a6a56a1a8f52631a44bd082b2ba509 for absurd-question-mark-desugar
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FBurningBlueFox%2Frust-treehouse-club" "/workspace/builds/worker-6-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/BurningBlueFox/rust-treehouse-club on toolchain 645bb72776a6a56a1a8f52631a44bd082b2ba509
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/BurningBlueFox/rust-treehouse-club
[INFO] finished tweaking git repo https://github.com/BurningBlueFox/rust-treehouse-club
[INFO] tweaked toml for git repo https://github.com/BurningBlueFox/rust-treehouse-club written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/BurningBlueFox/rust-treehouse-club 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" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 01af11108dea68a9b5bbae1a0b24972a36fa4ed52ae2326c69636ae9e28fd40a
[INFO] running `Command { std: "docker" "start" "-a" "01af11108dea68a9b5bbae1a0b24972a36fa4ed52ae2326c69636ae9e28fd40a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "01af11108dea68a9b5bbae1a0b24972a36fa4ed52ae2326c69636ae9e28fd40a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "01af11108dea68a9b5bbae1a0b24972a36fa4ed52ae2326c69636ae9e28fd40a", kill_on_drop: false }`
[INFO] [stdout] 01af11108dea68a9b5bbae1a0b24972a36fa4ed52ae2326c69636ae9e28fd40a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+645bb72776a6a56a1a8f52631a44bd082b2ba509" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 876cf02d728d311719e1a1199fa88f2f80dd127d58b4fe840617b571b85b61cd
[INFO] running `Command { std: "docker" "start" "-a" "876cf02d728d311719e1a1199fa88f2f80dd127d58b4fe840617b571b85b61cd", kill_on_drop: false }`
[INFO] [stderr]     Checking treehouse v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/visitor.rs:29:17
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 &self.do_something_more_involved();
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 let _ = &self.do_something_more_involved();
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused borrow that must be used
[INFO] [stdout]   --> src/visitor.rs:29:17
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 &self.do_something_more_involved();
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 29 |                 let _ = &self.do_something_more_involved();
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.21s
[INFO] running `Command { std: "docker" "inspect" "876cf02d728d311719e1a1199fa88f2f80dd127d58b4fe840617b571b85b61cd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "876cf02d728d311719e1a1199fa88f2f80dd127d58b4fe840617b571b85b61cd", kill_on_drop: false }`
[INFO] [stdout] 876cf02d728d311719e1a1199fa88f2f80dd127d58b4fe840617b571b85b61cd