[INFO] fetching crate x86_serial_logger 1.1.0...
[INFO] testing x86_serial_logger-1.1.0 against 1.91.0 for beta-1.92-2
[INFO] extracting crate x86_serial_logger 1.1.0 into /workspace/builds/worker-7-tc1/source
[INFO] removed /workspace/builds/worker-7-tc1/source/rust-toolchain
[INFO] started tweaking crates.io crate x86_serial_logger 1.1.0
[INFO] finished tweaking crates.io crate x86_serial_logger 1.1.0
[INFO] tweaked toml for crates.io crate x86_serial_logger 1.1.0 written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate x86_serial_logger 1.1.0 on toolchain 1.91.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.91.0" "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" "+1.91.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 11 packages to latest compatible versions
[INFO] [stderr]       Adding spin v0.9.8 (available: v0.10.0)
[INFO] [stderr]       Adding uart_16550 v0.2.19 (available: v0.4.0)
[INFO] [stderr]       Adding x86_64 v0.14.13 (available: v0.15.2)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.91.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded uart_16550 v0.2.19
[INFO] [stderr]   Downloaded volatile v0.4.6
[INFO] [stderr]   Downloaded x86_64 v0.14.13
[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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+1.91.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c26cdbb0ea0c040db3fba3bbf8ebcf6a7690cec1fa74cd105c2e1faf98954a4c
[INFO] running `Command { std: "docker" "start" "-a" "c26cdbb0ea0c040db3fba3bbf8ebcf6a7690cec1fa74cd105c2e1faf98954a4c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c26cdbb0ea0c040db3fba3bbf8ebcf6a7690cec1fa74cd105c2e1faf98954a4c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c26cdbb0ea0c040db3fba3bbf8ebcf6a7690cec1fa74cd105c2e1faf98954a4c", kill_on_drop: false }`
[INFO] [stdout] c26cdbb0ea0c040db3fba3bbf8ebcf6a7690cec1fa74cd105c2e1faf98954a4c
[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=warn" "-e" "RUSTDOCFLAGS=--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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+1.91.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] fcd937b7e792e7afd2c92c95b25d879ad43cbde2c87738f345d5d42f87c6db4f
[INFO] running `Command { std: "docker" "start" "-a" "fcd937b7e792e7afd2c92c95b25d879ad43cbde2c87738f345d5d42f87c6db4f", kill_on_drop: false }`
[INFO] [stderr]    Compiling volatile v0.4.6
[INFO] [stderr]    Compiling bit_field v0.10.3
[INFO] [stderr]    Compiling spin v0.9.8
[INFO] [stderr]    Compiling x86_64 v0.14.13
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/x86_64-0.14.13/src/lib.rs:5:35
[INFO] [stdout]   |
[INFO] [stdout] 5 | #![cfg_attr(feature = "const_fn", feature(const_mut_refs))] // GDT add_entry()
[INFO] [stdout]   |                                   ^^^^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `const_mut_refs` has been stable since `1.83.0` and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/x86_64-0.14.13/src/lib.rs:6:44
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![cfg_attr(feature = "abi_x86_interrupt", feature(abi_x86_interrupt))]
[INFO] [stdout]   |                                            ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/x86_64-0.14.13/src/lib.rs:7:37
[INFO] [stdout]   |
[INFO] [stdout] 7 | #![cfg_attr(feature = "step_trait", feature(step_trait))]
[INFO] [stdout]   |                                     ^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `x86_64` (lib) due to 3 previous errors
[INFO] running `Command { std: "docker" "inspect" "fcd937b7e792e7afd2c92c95b25d879ad43cbde2c87738f345d5d42f87c6db4f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fcd937b7e792e7afd2c92c95b25d879ad43cbde2c87738f345d5d42f87c6db4f", kill_on_drop: false }`
[INFO] [stdout] fcd937b7e792e7afd2c92c95b25d879ad43cbde2c87738f345d5d42f87c6db4f