[INFO] fetching crate slabmalloc 0.11.0...
[INFO] testing slabmalloc-0.11.0 against 1.91.0 for beta-1.92-2
[INFO] extracting crate slabmalloc 0.11.0 into /workspace/builds/worker-6-tc1/source
[INFO] started tweaking crates.io crate slabmalloc 0.11.0
[INFO] finished tweaking crates.io crate slabmalloc 0.11.0
[INFO] tweaked toml for crates.io crate slabmalloc 0.11.0 written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate slabmalloc 0.11.0 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] crate crates.io crate slabmalloc 0.11.0 already has a lockfile, it will not be regenerated
[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 spin v0.9.0
[INFO] [stderr]   Downloaded rand_hc v0.3.0
[INFO] [stderr]   Downloaded rand_chacha v0.3.0
[INFO] [stderr]   Downloaded log v0.4.14
[INFO] [stderr]   Downloaded rand v0.8.3
[INFO] [stderr]   Downloaded memchr v2.4.0
[INFO] [stderr]   Downloaded lock_api v0.4.4
[INFO] [stderr]   Downloaded rand_core v0.6.2
[INFO] [stderr]   Downloaded regex v1.5.4
[INFO] [stderr]   Downloaded libc v0.2.95
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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] 76fe0dd2602ef322ae09b6da097f29bc534f58a6fbca76765bdffc51c2b39cb2
[INFO] running `Command { std: "docker" "start" "-a" "76fe0dd2602ef322ae09b6da097f29bc534f58a6fbca76765bdffc51c2b39cb2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "76fe0dd2602ef322ae09b6da097f29bc534f58a6fbca76765bdffc51c2b39cb2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "76fe0dd2602ef322ae09b6da097f29bc534f58a6fbca76765bdffc51c2b39cb2", kill_on_drop: false }`
[INFO] [stdout] 76fe0dd2602ef322ae09b6da097f29bc534f58a6fbca76765bdffc51c2b39cb2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-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] a40dc83d1c85ae811bdacde14687c42afb7ed767105af889d8296f1f9b81a2e3
[INFO] running `Command { std: "docker" "start" "-a" "a40dc83d1c85ae811bdacde14687c42afb7ed767105af889d8296f1f9b81a2e3", kill_on_drop: false }`
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling slabmalloc v0.11.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:21:35
[INFO] [stdout]    |
[INFO] [stdout] 21 | #![cfg_attr(feature = "unstable", feature(const_mut_refs))]
[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] warning: the feature `const_mut_refs` has been stable since 1.83.0 and no longer requires an attribute to enable
[INFO] [stdout]   --> src/lib.rs:21:43
[INFO] [stdout]    |
[INFO] [stdout] 21 | #![cfg_attr(feature = "unstable", feature(const_mut_refs))]
[INFO] [stdout]    |                                           ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(stable_features)]` 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 `slabmalloc` (lib) due to 1 previous error; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "a40dc83d1c85ae811bdacde14687c42afb7ed767105af889d8296f1f9b81a2e3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a40dc83d1c85ae811bdacde14687c42afb7ed767105af889d8296f1f9b81a2e3", kill_on_drop: false }`
[INFO] [stdout] a40dc83d1c85ae811bdacde14687c42afb7ed767105af889d8296f1f9b81a2e3