[INFO] fetching crate serde-html 0.0.1...
[INFO] testing serde-html-0.0.1 against beta-2025-10-28 for beta-1.92-2
[INFO] extracting crate serde-html 0.0.1 into /workspace/builds/worker-4-tc2/source
[INFO] started tweaking crates.io crate serde-html 0.0.1
[INFO] finished tweaking crates.io crate serde-html 0.0.1
[INFO] tweaked toml for crates.io crate serde-html 0.0.1 written to /workspace/builds/worker-4-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate serde-html 0.0.1 on toolchain beta-2025-10-28
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2025-10-28" "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" "+beta-2025-10-28" "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" "+beta-2025-10-28" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2025-10-28" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 07f36b7be289a7798a0b971e27de0fe05890a0e7386bff07f2bf56c533625d37
[INFO] running `Command { std: "docker" "start" "-a" "07f36b7be289a7798a0b971e27de0fe05890a0e7386bff07f2bf56c533625d37", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "07f36b7be289a7798a0b971e27de0fe05890a0e7386bff07f2bf56c533625d37", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "07f36b7be289a7798a0b971e27de0fe05890a0e7386bff07f2bf56c533625d37", kill_on_drop: false }`
[INFO] [stdout] 07f36b7be289a7798a0b971e27de0fe05890a0e7386bff07f2bf56c533625d37
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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=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" "+beta-2025-10-28" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 284efd4ea4c729b371eb73ddd4d764587d86fdd366e4d4c54d1717319d32cb1c
[INFO] running `Command { std: "docker" "start" "-a" "284efd4ea4c729b371eb73ddd4d764587d86fdd366e4d4c54d1717319d32cb1c", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde-html v0.0.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(return_position_impl_trait_in_trait)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `return_position_impl_trait_in_trait` has been stable since `1.75.0` and no longer requires an attribute to enable
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `core::ops::AddAssign`
[INFO] [stdout]  --> src/traits/mod.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use core::ops::AddAssign;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `return_position_impl_trait_in_trait` has been stable since 1.75.0 and no longer requires an attribute to enable
[INFO] [stdout]  --> src/lib.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(return_position_impl_trait_in_trait)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(stable_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated method `indexmap::IndexSet::<T, S>::remove`: `remove` disrupts the set order -- use `swap_remove` or `shift_remove` for explicit behavior.
[INFO] [stdout]   --> src/traits/edit.rs:48:22
[INFO] [stdout]    |
[INFO] [stdout] 48 |         self.classes.remove(class)
[INFO] [stdout]    |                      ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(deprecated)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `serde-html` (lib) due to 1 previous error; 3 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "284efd4ea4c729b371eb73ddd4d764587d86fdd366e4d4c54d1717319d32cb1c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "284efd4ea4c729b371eb73ddd4d764587d86fdd366e4d4c54d1717319d32cb1c", kill_on_drop: false }`
[INFO] [stdout] 284efd4ea4c729b371eb73ddd4d764587d86fdd366e4d4c54d1717319d32cb1c