[INFO] fetching crate maybe-serde 0.2.1...
[INFO] checking maybe-serde-0.2.1 against master#38352b01ae4af9300be03b805d6db68c45e51068 for pr-129864
[INFO] extracting crate maybe-serde 0.2.1 into /workspace/builds/worker-7-tc1/source
[INFO] validating manifest of crates.io crate maybe-serde 0.2.1 on toolchain 38352b01ae4af9300be03b805d6db68c45e51068
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+38352b01ae4af9300be03b805d6db68c45e51068" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate maybe-serde 0.2.1
[INFO] finished tweaking crates.io crate maybe-serde 0.2.1
[INFO] tweaked toml for crates.io crate maybe-serde 0.2.1 written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+38352b01ae4af9300be03b805d6db68c45e51068" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 10 packages to latest compatible versions
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+38352b01ae4af9300be03b805d6db68c45e51068" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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:ceb6ea022f8a89cebbe621bb4987e73a935bd40dfbb726f832cfff4742a5b95a" "/opt/rustwide/cargo-home/bin/cargo" "+38352b01ae4af9300be03b805d6db68c45e51068" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] fe16021803dc61869ea746dd3ec5c51bc67b86443fa10bb78e236f0f7a89c954
[INFO] running `Command { std: "docker" "start" "-a" "fe16021803dc61869ea746dd3ec5c51bc67b86443fa10bb78e236f0f7a89c954", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fe16021803dc61869ea746dd3ec5c51bc67b86443fa10bb78e236f0f7a89c954", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fe16021803dc61869ea746dd3ec5c51bc67b86443fa10bb78e236f0f7a89c954", kill_on_drop: false }`
[INFO] [stdout] fe16021803dc61869ea746dd3ec5c51bc67b86443fa10bb78e236f0f7a89c954
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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:ceb6ea022f8a89cebbe621bb4987e73a935bd40dfbb726f832cfff4742a5b95a" "/opt/rustwide/cargo-home/bin/cargo" "+38352b01ae4af9300be03b805d6db68c45e51068" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ad7d31db643a400372e2e2e8f45112a54d481ad1ee28bc264a9a49b42714b781
[INFO] running `Command { std: "docker" "start" "-a" "ad7d31db643a400372e2e2e8f45112a54d481ad1ee28bc264a9a49b42714b781", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.86
[INFO] [stderr]    Compiling serde v1.0.210
[INFO] [stderr]    Compiling serde_json v1.0.128
[INFO] [stderr]     Checking memchr v2.7.4
[INFO] [stderr]     Checking ryu v1.0.18
[INFO] [stderr]     Checking itoa v1.0.11
[INFO] [stderr]    Compiling quote v1.0.37
[INFO] [stderr]    Compiling syn v2.0.77
[INFO] [stderr]     Checking maybe-serde v0.2.1 (/opt/rustwide/workdir)
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(specialization)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]   = help: consider using `min_specialization` instead, which is more stable and complete
[INFO] [stdout]   = note: `#[warn(incomplete_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling serde_derive v1.0.210
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(specialization)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]   = help: consider using `min_specialization` instead, which is more stable and complete
[INFO] [stdout]   = note: `#[warn(incomplete_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]    --> src/lib.rs:179:22
[INFO] [stdout]     |
[INFO] [stdout] 179 |     struct NoneSerde(i32);
[INFO] [stdout]     |            --------- ^^^
[INFO] [stdout]     |            |
[INFO] [stdout]     |            field in this struct
[INFO] [stdout]     |
[INFO] [stdout]     = help: consider removing this field
[INFO] [stdout]     = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]    --> src/lib.rs:186:26
[INFO] [stdout]     |
[INFO] [stdout] 186 |         struct NoneSerde(i32);
[INFO] [stdout]     |                --------- ^^^
[INFO] [stdout]     |                |
[INFO] [stdout]     |                field in this struct
[INFO] [stdout]     |
[INFO] [stdout]     = help: consider removing this field
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 11.37s
[INFO] running `Command { std: "docker" "inspect" "ad7d31db643a400372e2e2e8f45112a54d481ad1ee28bc264a9a49b42714b781", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ad7d31db643a400372e2e2e8f45112a54d481ad1ee28bc264a9a49b42714b781", kill_on_drop: false }`
[INFO] [stdout] ad7d31db643a400372e2e2e8f45112a54d481ad1ee28bc264a9a49b42714b781