[INFO] fetching crate async-option 0.1.1...
[INFO] checking async-option-0.1.1 against try#72f88fc4e9458f89516a0b8b0868f3718aec5b47 for pr-74989
[INFO] extracting crate async-option 0.1.1 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate async-option 0.1.1 on toolchain 72f88fc4e9458f89516a0b8b0868f3718aec5b47
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+72f88fc4e9458f89516a0b8b0868f3718aec5b47" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate async-option 0.1.1
[INFO] finished tweaking crates.io crate async-option 0.1.1
[INFO] tweaked toml for crates.io crate async-option 0.1.1 written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+72f88fc4e9458f89516a0b8b0868f3718aec5b47" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+72f88fc4e9458f89516a0b8b0868f3718aec5b47" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+72f88fc4e9458f89516a0b8b0868f3718aec5b47" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 35631bd56e8fc59ed7280cbde376746a4320ea12d52b28937df0449ce739ba87
[INFO] running `Command { std: "docker" "start" "-a" "35631bd56e8fc59ed7280cbde376746a4320ea12d52b28937df0449ce739ba87", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "35631bd56e8fc59ed7280cbde376746a4320ea12d52b28937df0449ce739ba87", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "35631bd56e8fc59ed7280cbde376746a4320ea12d52b28937df0449ce739ba87", kill_on_drop: false }`
[INFO] [stdout] 35631bd56e8fc59ed7280cbde376746a4320ea12d52b28937df0449ce739ba87
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+72f88fc4e9458f89516a0b8b0868f3718aec5b47" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 6780ec1270429844d0b02a06ee042ba2cc5a9505f8c648e4ada314d373334777
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "6780ec1270429844d0b02a06ee042ba2cc5a9505f8c648e4ada314d373334777", kill_on_drop: false }`
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]    Compiling libc v0.2.77
[INFO] [stderr]    Compiling maybe-uninit v2.0.0
[INFO] [stderr]     Checking futures v0.1.29
[INFO] [stderr]     Checking lazy_static v1.4.0
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling log v0.4.11
[INFO] [stderr]    Compiling byteorder v1.3.4
[INFO] [stderr]     Checking scopeguard v1.1.0
[INFO] [stderr]     Checking slab v0.4.2
[INFO] [stderr]     Checking fnv v1.0.7
[INFO] [stderr]     Checking lock_api v0.3.4
[INFO] [stderr]    Compiling semver v0.9.0
[INFO] [stderr]    Compiling rustc_version v0.2.3
[INFO] [stderr]     Checking smallvec v0.6.13
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling memoffset v0.5.5
[INFO] [stderr]    Compiling crossbeam-epoch v0.8.2
[INFO] [stderr]    Compiling parking_lot_core v0.6.2
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking num_cpus v1.13.0
[INFO] [stderr]     Checking net2 v0.2.35
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking mio v0.6.22
[INFO] [stderr]     Checking crossbeam-queue v0.2.3
[INFO] [stderr]     Checking crossbeam-deque v0.7.3
[INFO] [stderr]     Checking tokio-executor v0.1.10
[INFO] [stderr]     Checking tokio-sync v0.1.8
[INFO] [stderr]     Checking tokio-mock-task v0.1.1
[INFO] [stderr]     Checking tokio-io v0.1.13
[INFO] [stderr]     Checking tokio-current-thread v0.1.7
[INFO] [stderr]     Checking tokio-timer v0.2.13
[INFO] [stderr]     Checking mio-uds v0.6.8
[INFO] [stderr]     Checking tokio-threadpool v0.1.18
[INFO] [stderr]     Checking tokio-codec v0.1.2
[INFO] [stderr]     Checking tokio-reactor v0.1.12
[INFO] [stderr]     Checking async-option v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/lib.rs:96:17
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking tokio-tcp v0.1.4
[INFO] [stderr]     Checking tokio-uds v0.2.7
[INFO] [stderr]     Checking tokio-udp v0.1.6
[INFO] [stderr]     Checking tokio-fs v0.1.7
[INFO] [stderr]     Checking tokio v0.1.22
[INFO] [stdout] error: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/lib.rs:96:17
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:26:24
[INFO] [stdout]    |
[INFO] [stdout] 26 | #![cfg_attr(test, deny(warnings))]
[INFO] [stdout]    |                        ^^^^^^^^
[INFO] [stdout]    = note: `#[deny(unused_must_use)]` implied by `#[deny(warnings)]`
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `async-option`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "6780ec1270429844d0b02a06ee042ba2cc5a9505f8c648e4ada314d373334777", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6780ec1270429844d0b02a06ee042ba2cc5a9505f8c648e4ada314d373334777", kill_on_drop: false }`
[INFO] [stdout] 6780ec1270429844d0b02a06ee042ba2cc5a9505f8c648e4ada314d373334777
