[INFO] fetching crate async-option 0.1.1...
[INFO] testing async-option-0.1.1 against try#b83b707f97d809763b7861afa7638871f3339a33 for pr-145838-1
[INFO] extracting crate async-option 0.1.1 into /workspace/builds/worker-5-tc2/source
[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-5-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate async-option 0.1.1 on toolchain b83b707f97d809763b7861afa7638871f3339a33
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+b83b707f97d809763b7861afa7638871f3339a33" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+b83b707f97d809763b7861afa7638871f3339a33" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 57 packages to latest compatible versions
[INFO] [stderr]       Adding futures v0.1.31 (available: v0.3.31)
[INFO] [stderr]       Adding tokio v0.1.22 (available: v1.47.1)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+b83b707f97d809763b7861afa7638871f3339a33" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+b83b707f97d809763b7861afa7638871f3339a33" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 81e58f5a2239181790919d71cf7791a66cacbf53abaa6317cf4d055bc5a8f20c
[INFO] running `Command { std: "docker" "start" "-a" "81e58f5a2239181790919d71cf7791a66cacbf53abaa6317cf4d055bc5a8f20c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "81e58f5a2239181790919d71cf7791a66cacbf53abaa6317cf4d055bc5a8f20c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "81e58f5a2239181790919d71cf7791a66cacbf53abaa6317cf4d055bc5a8f20c", kill_on_drop: false }`
[INFO] [stdout] 81e58f5a2239181790919d71cf7791a66cacbf53abaa6317cf4d055bc5a8f20c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+b83b707f97d809763b7861afa7638871f3339a33" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b739cedfad1da043340c2137990896cc7812f7d1823bb71b2a982f530a018805
[INFO] running `Command { std: "docker" "start" "-a" "b739cedfad1da043340c2137990896cc7812f7d1823bb71b2a982f530a018805", kill_on_drop: false }`
[INFO] [stderr]    Compiling fnv v1.0.7
[INFO] [stderr]    Compiling futures v0.1.31
[INFO] [stderr]    Compiling tokio-sync v0.1.8
[INFO] [stderr]    Compiling 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: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 let _ = mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.21s
[INFO] running `Command { std: "docker" "inspect" "b739cedfad1da043340c2137990896cc7812f7d1823bb71b2a982f530a018805", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b739cedfad1da043340c2137990896cc7812f7d1823bb71b2a982f530a018805", kill_on_drop: false }`
[INFO] [stdout] b739cedfad1da043340c2137990896cc7812f7d1823bb71b2a982f530a018805
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-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@sha256:7ad1b28ee6f5f7f699f6cf7015098d6ccdd96d6f2d78dd06228f5b4c9faf309c" "/opt/rustwide/cargo-home/bin/cargo" "+b83b707f97d809763b7861afa7638871f3339a33" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d98b6469753ac68e73be1ceb8c4d4893125cb97b6f2fc641f8d28bfee0adadc9
[INFO] running `Command { std: "docker" "start" "-a" "d98b6469753ac68e73be1ceb8c4d4893125cb97b6f2fc641f8d28bfee0adadc9", kill_on_drop: false }`
[INFO] [stderr]    Compiling cfg-if v0.1.10
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling maybe-uninit v2.0.0
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling scopeguard v1.2.0
[INFO] [stderr]    Compiling log v0.4.27
[INFO] [stderr]    Compiling memoffset v0.5.6
[INFO] [stderr]    Compiling libc v0.2.175
[INFO] [stderr]    Compiling crossbeam-epoch v0.8.2
[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: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 let _ = mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling tokio-mock-task v0.1.1
[INFO] [stderr]    Compiling lock_api v0.3.4
[INFO] [stderr]    Compiling semver v0.9.0
[INFO] [stderr]    Compiling smallvec v0.6.14
[INFO] [stderr]    Compiling rustc_version v0.2.3
[INFO] [stderr]    Compiling parking_lot_core v0.6.3
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]    Compiling iovec v0.1.4
[INFO] [stderr]    Compiling num_cpus v1.17.0
[INFO] [stderr]    Compiling net2 v0.2.39
[INFO] [stderr]    Compiling bytes v0.4.12
[INFO] [stderr]    Compiling tokio-executor v0.1.10
[INFO] [stderr]    Compiling crossbeam-queue v0.2.3
[INFO] [stderr]    Compiling tokio-io v0.1.13
[INFO] [stderr]    Compiling mio v0.6.23
[INFO] [stderr]    Compiling tokio-current-thread v0.1.7
[INFO] [stderr]    Compiling tokio-timer v0.2.13
[INFO] [stderr]    Compiling crossbeam-deque v0.7.4
[INFO] [stderr]    Compiling tokio-threadpool v0.1.18
[INFO] [stderr]    Compiling tokio-codec v0.1.2
[INFO] [stderr]    Compiling tokio-reactor v0.1.12
[INFO] [stderr]    Compiling mio-uds v0.6.8
[INFO] [stderr]    Compiling tokio-fs v0.1.7
[INFO] [stderr]    Compiling tokio-tcp v0.1.4
[INFO] [stderr]    Compiling tokio-udp v0.1.6
[INFO] [stderr]    Compiling tokio-uds v0.2.7
[INFO] [stderr]    Compiling tokio v0.1.22
[INFO] [stderr]    Compiling async-option v0.1.1 (/opt/rustwide/workdir)
[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: if you don't need the old value, you can just assign the new value directly
[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] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 let _ = mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `async-option` (lib test) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "d98b6469753ac68e73be1ceb8c4d4893125cb97b6f2fc641f8d28bfee0adadc9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d98b6469753ac68e73be1ceb8c4d4893125cb97b6f2fc641f8d28bfee0adadc9", kill_on_drop: false }`
[INFO] [stdout] d98b6469753ac68e73be1ceb8c4d4893125cb97b6f2fc641f8d28bfee0adadc9