[INFO] cloning repository https://github.com/jli/rustlearn
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/jli/rustlearn" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjli%2Frustlearn", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjli%2Frustlearn'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] b28594df8df1619fea55d74a80fecf4e41b24d77
[INFO] checking jli/rustlearn against master#385fa9d845dd326c6bbfd58c22244215e431948a for absurd-question-mark-desugar
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjli%2Frustlearn" "/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/jli/rustlearn 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/jli/rustlearn
[INFO] finished tweaking git repo https://github.com/jli/rustlearn
[INFO] tweaked toml for git repo https://github.com/jli/rustlearn written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/jli/rustlearn 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] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded aho-corasick v0.7.14
[INFO] [stderr]   Downloaded regex-syntax v0.6.20
[INFO] [stderr]   Downloaded regex v1.4.1
[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] ceba96109f56014c35907e4687164ca561772f238730ec250ed5c99fcddab291
[INFO] running `Command { std: "docker" "start" "-a" "ceba96109f56014c35907e4687164ca561772f238730ec250ed5c99fcddab291", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ceba96109f56014c35907e4687164ca561772f238730ec250ed5c99fcddab291", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ceba96109f56014c35907e4687164ca561772f238730ec250ed5c99fcddab291", kill_on_drop: false }`
[INFO] [stdout] ceba96109f56014c35907e4687164ca561772f238730ec250ed5c99fcddab291
[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] 735f5364f10d8a10bc143fe267639977494ccf855ca5647a401a2c99c4fc1d48
[INFO] running `Command { std: "docker" "start" "-a" "735f5364f10d8a10bc143fe267639977494ccf855ca5647a401a2c99c4fc1d48", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.80
[INFO] [stderr]    Compiling syn v1.0.48
[INFO] [stderr]    Compiling log v0.4.11
[INFO] [stderr]     Checking regex-syntax v0.6.20
[INFO] [stderr]    Compiling unicode-segmentation v1.7.0
[INFO] [stderr]    Compiling anyhow v1.0.34
[INFO] [stderr]    Compiling quote v1.0.7
[INFO] [stderr]     Checking either v1.6.1
[INFO] [stderr]     Checking aho-corasick v0.7.14
[INFO] [stderr]     Checking itertools v0.9.0
[INFO] [stderr]    Compiling heck v0.3.1
[INFO] [stderr]    Compiling proc-macro-error-attr v1.0.4
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking clap v2.33.3
[INFO] [stderr]     Checking regex v1.4.1
[INFO] [stderr]    Compiling proc-macro-error v1.0.4
[INFO] [stderr]     Checking env_logger v0.7.1
[INFO] [stderr]     Checking pretty_env_logger v0.4.0
[INFO] [stderr]    Compiling structopt-derive v0.4.13
[INFO] [stderr]     Checking structopt v0.3.20
[INFO] [stderr]     Checking rustlearn v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: fields `i` and `s` are never read
[INFO] [stdout]  --> src/bin/structs.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct U {
[INFO] [stdout]   |        - fields in this struct
[INFO] [stdout] 3 |     i: i32,
[INFO] [stdout]   |     ^
[INFO] [stdout] 4 |     s: String,
[INFO] [stdout]   |     ^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `U` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `pretty_env_logger` is imported redundantly
[INFO] [stdout]  --> src/bin/why_ansible_slow.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use pretty_env_logger;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^ the item `pretty_env_logger` is already defined by prelude
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `log` is imported redundantly
[INFO] [stdout]   --> src/bin/why_ansible_slow.rs:11:5
[INFO] [stdout]    |
[INFO] [stdout] 11 | use log;
[INFO] [stdout]    |     ^^^ the item `log` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `pretty_env_logger` is imported redundantly
[INFO] [stdout]  --> src/bin/why_ansible_slow.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use pretty_env_logger;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^ the item `pretty_env_logger` is already defined by prelude
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `log` is imported redundantly
[INFO] [stdout]   --> src/bin/why_ansible_slow.rs:11:5
[INFO] [stdout]    |
[INFO] [stdout] 11 | use log;
[INFO] [stdout]    |     ^^^ the item `log` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `i` and `s` are never read
[INFO] [stdout]  --> src/bin/structs.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct U {
[INFO] [stdout]   |        - fields in this struct
[INFO] [stdout] 3 |     i: i32,
[INFO] [stdout]   |     ^
[INFO] [stdout] 4 |     s: String,
[INFO] [stdout]   |     ^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `U` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[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` profile [unoptimized + debuginfo] target(s) in 7.06s
[INFO] running `Command { std: "docker" "inspect" "735f5364f10d8a10bc143fe267639977494ccf855ca5647a401a2c99c4fc1d48", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "735f5364f10d8a10bc143fe267639977494ccf855ca5647a401a2c99c4fc1d48", kill_on_drop: false }`
[INFO] [stdout] 735f5364f10d8a10bc143fe267639977494ccf855ca5647a401a2c99c4fc1d48