[INFO] fetching crate oncemutex 0.1.1...
[INFO] checking oncemutex-0.1.1 against master#c2f2db79ca3024f68d22b45aa22b570775c2c4ad for pr-124157
[INFO] extracting crate oncemutex 0.1.1 into /workspace/builds/worker-6-tc1/source
[INFO] validating manifest of crates.io crate oncemutex 0.1.1 on toolchain c2f2db79ca3024f68d22b45aa22b570775c2c4ad
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c2f2db79ca3024f68d22b45aa22b570775c2c4ad" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate oncemutex 0.1.1
[INFO] finished tweaking crates.io crate oncemutex 0.1.1
[INFO] tweaked toml for crates.io crate oncemutex 0.1.1 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" "+c2f2db79ca3024f68d22b45aa22b570775c2c4ad" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+c2f2db79ca3024f68d22b45aa22b570775c2c4ad" "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@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+c2f2db79ca3024f68d22b45aa22b570775c2c4ad" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 27521ff0e4202f257315e7af10130b32a2050da36571586b24575a136ba40394
[INFO] running `Command { std: "docker" "start" "-a" "27521ff0e4202f257315e7af10130b32a2050da36571586b24575a136ba40394", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "27521ff0e4202f257315e7af10130b32a2050da36571586b24575a136ba40394", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "27521ff0e4202f257315e7af10130b32a2050da36571586b24575a136ba40394", kill_on_drop: false }`
[INFO] [stdout] 27521ff0e4202f257315e7af10130b32a2050da36571586b24575a136ba40394
[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@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+c2f2db79ca3024f68d22b45aa22b570775c2c4ad" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] a93973f904d060d85dfeaf55162d8e3f4117c468ff61d96e4de27f752069c9c4
[INFO] running `Command { std: "docker" "start" "-a" "a93973f904d060d85dfeaf55162d8e3f4117c468ff61d96e4de27f752069c9c4", kill_on_drop: false }`
[INFO] [stderr]     Checking oncemutex v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]   --> src/lib.rs:63:26
[INFO] [stdout]    |
[INFO] [stdout] 63 |         match self.state.compare_and_swap(UNUSED, LOCKED, SeqCst) {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:1:23
[INFO] [stdout]    |
[INFO] [stdout] 1  | #![deny(missing_docs, warnings)]
[INFO] [stdout]    |                       ^^^^^^^^
[INFO] [stdout]    = note: `#[deny(deprecated)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]    --> src/lib.rs:103:33
[INFO] [stdout]     |
[INFO] [stdout] 103 |         if LOCKED == self.state.compare_and_swap(UNUSED, FREE, SeqCst) {
[INFO] [stdout]     |                                 ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]   --> src/lib.rs:63:26
[INFO] [stdout]    |
[INFO] [stdout] 63 |         match self.state.compare_and_swap(UNUSED, LOCKED, SeqCst) {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:1:23
[INFO] [stdout]    |
[INFO] [stdout] 1  | #![deny(missing_docs, warnings)]
[INFO] [stdout]    |                       ^^^^^^^^
[INFO] [stdout]    = note: `#[deny(deprecated)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]    --> src/lib.rs:103:33
[INFO] [stdout]     |
[INFO] [stdout] 103 |         if LOCKED == self.state.compare_and_swap(UNUSED, FREE, SeqCst) {
[INFO] [stdout]     |                                 ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: unnecessary `unsafe` block
[INFO] [stdout]   --> src/lib.rs:86:9
[INFO] [stdout]    |
[INFO] [stdout] 86 |         unsafe { self.data.into_inner() }
[INFO] [stdout]    |         ^^^^^^ unnecessary `unsafe` block
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(unused_unsafe)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]   --> src/lib.rs:81:32
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _ = self.lock.lock(); }
[INFO] [stdout]    |                                ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(let_underscore_lock)]` on by default
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _unused = self.lock.lock(); }
[INFO] [stdout]    |                                ~~~~~~~
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { drop(self.lock.lock()); }
[INFO] [stdout]    |                            ~~~~~                +
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 4 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: unnecessary `unsafe` block
[INFO] [stdout]   --> src/lib.rs:86:9
[INFO] [stdout]    |
[INFO] [stdout] 86 |         unsafe { self.data.into_inner() }
[INFO] [stdout]    |         ^^^^^^ unnecessary `unsafe` block
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(unused_unsafe)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `oncemutex` (lib) due to 5 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]   --> src/lib.rs:81:32
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _ = self.lock.lock(); }
[INFO] [stdout]    |                                ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(let_underscore_lock)]` on by default
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _unused = self.lock.lock(); }
[INFO] [stdout]    |                                ~~~~~~~
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { drop(self.lock.lock()); }
[INFO] [stdout]    |                            ~~~~~                +
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: unused unary operation that must be used
[INFO] [stdout]    --> src/lib.rs:199:9
[INFO] [stdout]     |
[INFO] [stdout] 199 |         *mutex;
[INFO] [stdout]     |         ^^^^^^ the unary operation produces a value
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[deny(unused_must_use)]` implied by `#[deny(warnings)]`
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 199 |         let _ = *mutex;
[INFO] [stdout]     |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 5 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `oncemutex` (lib test) due to 6 previous errors
[INFO] running `Command { std: "docker" "inspect" "a93973f904d060d85dfeaf55162d8e3f4117c468ff61d96e4de27f752069c9c4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a93973f904d060d85dfeaf55162d8e3f4117c468ff61d96e4de27f752069c9c4", kill_on_drop: false }`
[INFO] [stdout] a93973f904d060d85dfeaf55162d8e3f4117c468ff61d96e4de27f752069c9c4
[INFO] checking oncemutex-0.1.1 against try#9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88 for pr-124157
[INFO] extracting crate oncemutex 0.1.1 into /workspace/builds/worker-6-tc2/source
[INFO] validating manifest of crates.io crate oncemutex 0.1.1 on toolchain 9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate oncemutex 0.1.1
[INFO] finished tweaking crates.io crate oncemutex 0.1.1
[INFO] tweaked toml for crates.io crate oncemutex 0.1.1 written to /workspace/builds/worker-6-tc2/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88" "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@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 70bfeeac4f348d65ce490e7d93ce26c5b4235735f66b14d0e3b62ce8d3a4909b
[INFO] running `Command { std: "docker" "start" "-a" "70bfeeac4f348d65ce490e7d93ce26c5b4235735f66b14d0e3b62ce8d3a4909b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "70bfeeac4f348d65ce490e7d93ce26c5b4235735f66b14d0e3b62ce8d3a4909b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "70bfeeac4f348d65ce490e7d93ce26c5b4235735f66b14d0e3b62ce8d3a4909b", kill_on_drop: false }`
[INFO] [stdout] 70bfeeac4f348d65ce490e7d93ce26c5b4235735f66b14d0e3b62ce8d3a4909b
[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@sha256:99613afd962a8cfa530ec1899472a458bd015a1ab0af876cf7eb06f6006d81ea" "/opt/rustwide/cargo-home/bin/cargo" "+9c7b5f5b6b8ec32bbbcf9f07fc0e5208da6c5f88" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9be59ca06b8b3ce4051b3a0de78e4de3fdc330c4741efda1291ce241c3e6647d
[INFO] running `Command { std: "docker" "start" "-a" "9be59ca06b8b3ce4051b3a0de78e4de3fdc330c4741efda1291ce241c3e6647d", kill_on_drop: false }`
[INFO] [stderr]     Checking oncemutex v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]   --> src/lib.rs:63:26
[INFO] [stdout]    |
[INFO] [stdout] 63 |         match self.state.compare_and_swap(UNUSED, LOCKED, SeqCst) {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:1:23
[INFO] [stdout]    |
[INFO] [stdout] 1  | #![deny(missing_docs, warnings)]
[INFO] [stdout]    |                       ^^^^^^^^
[INFO] [stdout]    = note: `#[deny(deprecated)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]    --> src/lib.rs:103:33
[INFO] [stdout]     |
[INFO] [stdout] 103 |         if LOCKED == self.state.compare_and_swap(UNUSED, FREE, SeqCst) {
[INFO] [stdout]     |                                 ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]   --> src/lib.rs:63:26
[INFO] [stdout]    |
[INFO] [stdout] 63 |         match self.state.compare_and_swap(UNUSED, LOCKED, SeqCst) {
[INFO] [stdout]    |                          ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:1:23
[INFO] [stdout]    |
[INFO] [stdout] 1  | #![deny(missing_docs, warnings)]
[INFO] [stdout]    |                       ^^^^^^^^
[INFO] [stdout]    = note: `#[deny(deprecated)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: use of deprecated method `std::sync::atomic::AtomicUsize::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead
[INFO] [stdout]    --> src/lib.rs:103:33
[INFO] [stdout]     |
[INFO] [stdout] 103 |         if LOCKED == self.state.compare_and_swap(UNUSED, FREE, SeqCst) {
[INFO] [stdout]     |                                 ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: unnecessary `unsafe` block
[INFO] [stdout]   --> src/lib.rs:86:9
[INFO] [stdout]    |
[INFO] [stdout] 86 |         unsafe { self.data.into_inner() }
[INFO] [stdout]    |         ^^^^^^ unnecessary `unsafe` block
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(unused_unsafe)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]   --> src/lib.rs:81:32
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _ = self.lock.lock(); }
[INFO] [stdout]    |                                ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(let_underscore_lock)]` on by default
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _unused = self.lock.lock(); }
[INFO] [stdout]    |                                ~~~~~~~
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { drop(self.lock.lock()); }
[INFO] [stdout]    |                            ~~~~~                +
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 4 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: unnecessary `unsafe` block
[INFO] [stdout]   --> src/lib.rs:86:9
[INFO] [stdout]    |
[INFO] [stdout] 86 |         unsafe { self.data.into_inner() }
[INFO] [stdout]    |         ^^^^^^ unnecessary `unsafe` block
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(unused_unsafe)]` implied by `#[deny(warnings)]`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `oncemutex` (lib) due to 5 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] error: non-binding let on a synchronization lock
[INFO] [stdout]   --> src/lib.rs:81:32
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _ = self.lock.lock(); }
[INFO] [stdout]    |                                ^ this lock is not assigned to a binding and is immediately dropped
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[deny(let_underscore_lock)]` on by default
[INFO] [stdout] help: consider binding to an unused variable to avoid immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { let _unused = self.lock.lock(); }
[INFO] [stdout]    |                                ~~~~~~~
[INFO] [stdout] help: consider immediately dropping the value
[INFO] [stdout]    |
[INFO] [stdout] 81 |         if self.locked() { drop(self.lock.lock()); }
[INFO] [stdout]    |                            ~~~~~                +
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: unused unary operation that must be used
[INFO] [stdout]    --> src/lib.rs:199:9
[INFO] [stdout]     |
[INFO] [stdout] 199 |         *mutex;
[INFO] [stdout]     |         ^^^^^^ the unary operation produces a value
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[deny(unused_must_use)]` implied by `#[deny(warnings)]`
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 199 |         let _ = *mutex;
[INFO] [stdout]     |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 5 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `oncemutex` (lib test) due to 6 previous errors
[INFO] running `Command { std: "docker" "inspect" "9be59ca06b8b3ce4051b3a0de78e4de3fdc330c4741efda1291ce241c3e6647d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9be59ca06b8b3ce4051b3a0de78e4de3fdc330c4741efda1291ce241c3e6647d", kill_on_drop: false }`
[INFO] [stdout] 9be59ca06b8b3ce4051b3a0de78e4de3fdc330c4741efda1291ce241c3e6647d
