[INFO] fetching crate const-concat 0.1.0...
[INFO] testing const-concat-0.1.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate const-concat 0.1.0 into /workspace/builds/worker-5/source
[INFO] validating manifest of crates.io crate const-concat 0.1.0 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate const-concat 0.1.0
[INFO] finished tweaking crates.io crate const-concat 0.1.0
[INFO] tweaked toml for crates.io crate const-concat 0.1.0 written to /workspace/builds/worker-5/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 519b10fae7b6f1a959ec6db14f17219ed0dc8a548f750dda6131b116737d4564
[INFO] running `Command { std: "docker" "start" "-a" "519b10fae7b6f1a959ec6db14f17219ed0dc8a548f750dda6131b116737d4564", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "519b10fae7b6f1a959ec6db14f17219ed0dc8a548f750dda6131b116737d4564", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "519b10fae7b6f1a959ec6db14f17219ed0dc8a548f750dda6131b116737d4564", kill_on_drop: false }`
[INFO] [stdout] 519b10fae7b6f1a959ec6db14f17219ed0dc8a548f750dda6131b116737d4564
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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=warn" "-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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] fcc9dab46a6bced3b18360825b14760c38ade40f96479f86844577e8c298c284
[INFO] running `Command { std: "docker" "start" "-a" "fcc9dab46a6bced3b18360825b14760c38ade40f96479f86844577e8c298c284", kill_on_drop: false }`
[INFO] [stderr]    Compiling const-concat v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0557]: feature has been removed
[INFO] [stdout]  --> src/lib.rs:1:12
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(const_fn, const_str_as_bytes, const_str_len, const_let, untagged_unions)]
[INFO] [stdout]   |            ^^^^^^^^ feature has been removed
[INFO] [stdout]   |
[INFO] [stdout]   = note: split into finer-grained feature gates
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unknown lint: `unions_with_drop_fields`
[INFO] [stdout]  --> src/lib.rs:3:9
[INFO] [stdout]   |
[INFO] [stdout] 3 | #[allow(unions_with_drop_fields)]
[INFO] [stdout]   |         ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unknown_lints)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(const_fn, const_str_as_bytes, const_str_len, const_let, untagged_unions)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `const_let` has been stable since 1.33.0 and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0740]: unions may not contain fields that need dropping
[INFO] [stdout]  --> src/lib.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |         from: From,
[INFO] [stdout]   |         ^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout] note: `std::mem::ManuallyDrop` can be used to wrap the type
[INFO] [stdout]  --> src/lib.rs:6:9
[INFO] [stdout]   |
[INFO] [stdout] 6 |         from: From,
[INFO] [stdout]   |         ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0554, E0557, E0740.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `const-concat` due to 4 previous errors; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "fcc9dab46a6bced3b18360825b14760c38ade40f96479f86844577e8c298c284", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fcc9dab46a6bced3b18360825b14760c38ade40f96479f86844577e8c298c284", kill_on_drop: false }`
[INFO] [stdout] fcc9dab46a6bced3b18360825b14760c38ade40f96479f86844577e8c298c284