[INFO] fetching crate syswall 0.3.1...
[INFO] checking syswall-0.3.1 against master#385fa9d845dd326c6bbfd58c22244215e431948a for absurd-question-mark-desugar
[INFO] extracting crate syswall 0.3.1 into /workspace/builds/worker-6-tc1/source
[INFO] validating manifest of crates.io crate syswall 0.3.1 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 crates.io crate syswall 0.3.1
[INFO] finished tweaking crates.io crate syswall 0.3.1
[INFO] tweaked toml for crates.io crate syswall 0.3.1 written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 19 packages
[INFO] [stderr]       Adding bitflags v1.3.2 (latest: v2.5.0)
[INFO] [stderr]       Adding cfg-if v0.1.10 (latest: v1.0.0)
[INFO] [stderr]       Adding nix v0.13.1 (latest: v0.28.0)
[INFO] [stderr]       Adding signal-hook v0.1.17 (latest: v0.3.17)
[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] bfc8c051beb2fa17fce9bbb1b7bda91bda684d88ab7ab85462a33c636f514ad8
[INFO] running `Command { std: "docker" "start" "-a" "bfc8c051beb2fa17fce9bbb1b7bda91bda684d88ab7ab85462a33c636f514ad8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "bfc8c051beb2fa17fce9bbb1b7bda91bda684d88ab7ab85462a33c636f514ad8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bfc8c051beb2fa17fce9bbb1b7bda91bda684d88ab7ab85462a33c636f514ad8", kill_on_drop: false }`
[INFO] [stdout] bfc8c051beb2fa17fce9bbb1b7bda91bda684d88ab7ab85462a33c636f514ad8
[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] df63be1db0e7a7bfe69ca1280f957ea31d73852c3b511052c26882c1e5de483f
[INFO] running `Command { std: "docker" "start" "-a" "df63be1db0e7a7bfe69ca1280f957ea31d73852c3b511052c26882c1e5de483f", kill_on_drop: false }`
[INFO] [stderr]    Compiling nix v0.13.1
[INFO] [stderr]     Checking void v1.0.2
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking signal-hook-registry v1.4.1
[INFO] [stderr]     Checking serde v1.0.197
[INFO] [stderr]     Checking signal-hook v0.1.17
[INFO] [stderr]     Checking serde_json v1.0.115
[INFO] [stderr]     Checking syswall v0.3.1 (/opt/rustwide/workdir)
[INFO] [stdout] warning: the item `signal_hook` is imported redundantly
[INFO] [stdout]  --> src/child_process.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 7 | use signal_hook;
[INFO] [stdout]   |     ^^^^^^^^^^^ the item `signal_hook` 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 `libc` is imported redundantly
[INFO] [stdout]  --> src/syscalls.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use libc;
[INFO] [stdout]   |     ^^^^ the item `libc` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `serde_json` is imported redundantly
[INFO] [stdout]  --> src/tracer_conf.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use serde_json;
[INFO] [stdout]   |     ^^^^^^^^^^ the item `serde_json` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `signal_hook` is imported redundantly
[INFO] [stdout]  --> src/child_process.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 7 | use signal_hook;
[INFO] [stdout]   |     ^^^^^^^^^^^ the item `signal_hook` 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 `libc` is imported redundantly
[INFO] [stdout]  --> src/syscalls.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use libc;
[INFO] [stdout]   |     ^^^^ the item `libc` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `serde_json` is imported redundantly
[INFO] [stdout]  --> src/tracer_conf.rs:2:5
[INFO] [stdout]   |
[INFO] [stdout] 2 | use serde_json;
[INFO] [stdout]   |     ^^^^^^^^^^ the item `serde_json` is already defined by prelude
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/child_process.rs:300:17
[INFO] [stdout]     |
[INFO] [stdout] 300 |             let mut child = processes.0.get_mut(&pid).ok_or_else(|| format!(
[INFO] [stdout]     |                 ----^^^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/child_process.rs:418:32
[INFO] [stdout]     |
[INFO] [stdout] 418 |             } else if let Some(mut child) = processes.0.get_mut(&pid) {
[INFO] [stdout]     |                                ----^^^^^
[INFO] [stdout]     |                                |
[INFO] [stdout]     |                                help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/child_process.rs:300:17
[INFO] [stdout]     |
[INFO] [stdout] 300 |             let mut child = processes.0.get_mut(&pid).ok_or_else(|| format!(
[INFO] [stdout]     |                 ----^^^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/child_process.rs:418:32
[INFO] [stdout]     |
[INFO] [stdout] 418 |             } else if let Some(mut child) = processes.0.get_mut(&pid) {
[INFO] [stdout]     |                                ----^^^^^
[INFO] [stdout]     |                                |
[INFO] [stdout]     |                                help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 5.24s
[INFO] running `Command { std: "docker" "inspect" "df63be1db0e7a7bfe69ca1280f957ea31d73852c3b511052c26882c1e5de483f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "df63be1db0e7a7bfe69ca1280f957ea31d73852c3b511052c26882c1e5de483f", kill_on_drop: false }`
[INFO] [stdout] df63be1db0e7a7bfe69ca1280f957ea31d73852c3b511052c26882c1e5de483f