[INFO] fetching crate maybe-serde 0.2.1...
[INFO] checking maybe-serde-0.2.1 against try#38c2997544af84fe301d600d6896397738163002 for pr-154205-1
[INFO] extracting crate maybe-serde 0.2.1 into /workspace/builds/worker-0-tc2/source
[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-0-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate maybe-serde 0.2.1 on toolchain 38c2997544af84fe301d600d6896397738163002
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+38c2997544af84fe301d600d6896397738163002" "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" "+38c2997544af84fe301d600d6896397738163002" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]      Locking 11 packages to latest compatible versions
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+38c2997544af84fe301d600d6896397738163002" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+38c2997544af84fe301d600d6896397738163002" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 114d4e0bd5e31e54b6b440a7643517cfbbe11401ee4f49222c06e748114a5fbd
[INFO] running `Command { std: "docker" "start" "-a" "114d4e0bd5e31e54b6b440a7643517cfbbe11401ee4f49222c06e748114a5fbd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "114d4e0bd5e31e54b6b440a7643517cfbbe11401ee4f49222c06e748114a5fbd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "114d4e0bd5e31e54b6b440a7643517cfbbe11401ee4f49222c06e748114a5fbd", kill_on_drop: false }`
[INFO] [stdout] 114d4e0bd5e31e54b6b440a7643517cfbbe11401ee4f49222c06e748114a5fbd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+38c2997544af84fe301d600d6896397738163002" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] bd406a38729fe86aae920d272c130cd8aec3849017352f877085220a531f9c66
[INFO] running `Command { std: "docker" "start" "-a" "bd406a38729fe86aae920d272c130cd8aec3849017352f877085220a531f9c66", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.106
[INFO] [stderr]    Compiling quote v1.0.45
[INFO] [stderr]    Compiling serde v1.0.228
[INFO] [stderr]     Checking itoa v1.0.18
[INFO] [stderr]     Checking serde_json v1.0.149
[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] [stderr]    Compiling syn v2.0.117
[INFO] [stderr]    Compiling serde_derive v1.0.228
[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)]` (part of `#[warn(unused)]`) 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] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 3.39s
[INFO] running `Command { std: "docker" "inspect" "bd406a38729fe86aae920d272c130cd8aec3849017352f877085220a531f9c66", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bd406a38729fe86aae920d272c130cd8aec3849017352f877085220a531f9c66", kill_on_drop: false }`
[INFO] [stdout] bd406a38729fe86aae920d272c130cd8aec3849017352f877085220a531f9c66