[INFO] fetching crate disk-queue 0.1.1...
[INFO] testing disk-queue-0.1.1 against master#c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38 for pr-146098-7
[INFO] extracting crate disk-queue 0.1.1 into /workspace/builds/worker-2-tc1/source
[INFO] started tweaking crates.io crate disk-queue 0.1.1
[INFO] finished tweaking crates.io crate disk-queue 0.1.1
[INFO] tweaked toml for crates.io crate disk-queue 0.1.1 written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate disk-queue 0.1.1 on toolchain c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate crates.io crate disk-queue 0.1.1 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" "+c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded plotters v0.3.3
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] fa0632916481f95711dea94935ecb2f7b0716bba1ecb92c5499e74c99709254c
[INFO] running `Command { std: "docker" "start" "-a" "fa0632916481f95711dea94935ecb2f7b0716bba1ecb92c5499e74c99709254c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fa0632916481f95711dea94935ecb2f7b0716bba1ecb92c5499e74c99709254c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fa0632916481f95711dea94935ecb2f7b0716bba1ecb92c5499e74c99709254c", kill_on_drop: false }`
[INFO] [stdout] fa0632916481f95711dea94935ecb2f7b0716bba1ecb92c5499e74c99709254c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+c90bcb9571b7aab0d8beaa2ce8a998ffaf079d38" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 2ca6fd538eea9a58d2e272a3e59ebf7130910cb31ee2a2a921bffd87e0d913ab
[INFO] running `Command { std: "docker" "start" "-a" "2ca6fd538eea9a58d2e272a3e59ebf7130910cb31ee2a2a921bffd87e0d913ab", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.132
[INFO] [stderr]    Compiling memmap v0.7.0
[INFO] [stderr]    Compiling disk-queue v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]    --> src/page.rs:192:17
[INFO] [stdout]     |
[INFO] [stdout] 192 |             let _ = rwlatch.read().unwrap();
[INFO] [stdout]     |                 ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[deny(let_underscore_lock)]` (part of `#[deny(let_underscore)]`) on by default
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 192 |             let _unused = rwlatch.read().unwrap();
[INFO] [stdout]     |                  ++++++
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 192 -             let _ = rwlatch.read().unwrap();
[INFO] [stdout] 192 +             drop(rwlatch.read().unwrap());
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]    --> src/page.rs:233:17
[INFO] [stdout]     |
[INFO] [stdout] 233 |             let _ = self.rwlatch.read().unwrap();
[INFO] [stdout]     |                 ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]     |
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 233 |             let _unused = self.rwlatch.read().unwrap();
[INFO] [stdout]     |                  ++++++
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 233 -             let _ = self.rwlatch.read().unwrap();
[INFO] [stdout] 233 +             drop(self.rwlatch.read().unwrap());
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]    --> src/page.rs:242:17
[INFO] [stdout]     |
[INFO] [stdout] 242 |             let _ = self.rwlatch.write().unwrap();
[INFO] [stdout]     |                 ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]     |
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 242 |             let _unused = self.rwlatch.write().unwrap();
[INFO] [stdout]     |                  ++++++
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 242 -             let _ = self.rwlatch.write().unwrap();
[INFO] [stdout] 242 +             drop(self.rwlatch.write().unwrap());
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]    --> src/page.rs:256:21
[INFO] [stdout]     |
[INFO] [stdout] 256 |                 let _ = self.rwlatch.read().unwrap();
[INFO] [stdout]     |                     ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]     |
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 256 |                 let _unused = self.rwlatch.read().unwrap();
[INFO] [stdout]     |                      ++++++
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 256 -                 let _ = self.rwlatch.read().unwrap();
[INFO] [stdout] 256 +                 drop(self.rwlatch.read().unwrap());
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]    --> src/page.rs:274:21
[INFO] [stdout]     |
[INFO] [stdout] 274 |                 let _ = self.rwlatch.read().unwrap();
[INFO] [stdout]     |                     ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]     |
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 274 |                 let _unused = self.rwlatch.read().unwrap();
[INFO] [stdout]     |                      ++++++
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 274 -                 let _ = self.rwlatch.read().unwrap();
[INFO] [stdout] 274 +                 drop(self.rwlatch.read().unwrap());
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]    --> src/page.rs:307:17
[INFO] [stdout]     |
[INFO] [stdout] 307 |             let _ = self.rwlatch.write().unwrap();
[INFO] [stdout]     |                 ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]     |
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 307 |             let _unused = self.rwlatch.write().unwrap();
[INFO] [stdout]     |                  ++++++
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]     |
[INFO] [stdout] 307 -             let _ = self.rwlatch.write().unwrap();
[INFO] [stdout] 307 +             drop(self.rwlatch.write().unwrap());
[INFO] [stdout]     |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `disk-queue` (lib) due to 6 previous errors
[INFO] running `Command { std: "docker" "inspect" "2ca6fd538eea9a58d2e272a3e59ebf7130910cb31ee2a2a921bffd87e0d913ab", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2ca6fd538eea9a58d2e272a3e59ebf7130910cb31ee2a2a921bffd87e0d913ab", kill_on_drop: false }`
[INFO] [stdout] 2ca6fd538eea9a58d2e272a3e59ebf7130910cb31ee2a2a921bffd87e0d913ab