[INFO] fetching crate fast-btree 0.1.0...
[INFO] testing fast-btree-0.1.0 against 1.90.0 for beta-1.91-3
[INFO] extracting crate fast-btree 0.1.0 into /workspace/builds/worker-7-tc1/source
[INFO] removed /workspace/builds/worker-7-tc1/source/rust-toolchain.toml
[INFO] started tweaking crates.io crate fast-btree 0.1.0
[INFO] finished tweaking crates.io crate fast-btree 0.1.0
[INFO] tweaked toml for crates.io crate fast-btree 0.1.0 written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate fast-btree 0.1.0 on toolchain 1.90.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "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" "+1.90.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 53 packages to latest compatible versions
[INFO] [stderr]       Adding env_logger v0.10.2 (available: v0.11.8)
[INFO] [stderr]       Adding rand v0.8.5 (available: v0.9.2)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded rusty-hook v0.11.2
[INFO] [stderr]   Downloaded nias v0.5.0
[INFO] [stderr]   Downloaded bitmask-enum v2.2.5
[INFO] [stderr]   Downloaded ci_info v0.10.2
[INFO] [stderr]   Downloaded fsio v0.1.3
[INFO] [stderr]   Downloaded envmnt v0.8.4
[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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 4195676aebaf48f302c76c9138d1aef081f0cfa7f16e233f526f2f1da2b1d19e
[INFO] running `Command { std: "docker" "start" "-a" "4195676aebaf48f302c76c9138d1aef081f0cfa7f16e233f526f2f1da2b1d19e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "4195676aebaf48f302c76c9138d1aef081f0cfa7f16e233f526f2f1da2b1d19e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4195676aebaf48f302c76c9138d1aef081f0cfa7f16e233f526f2f1da2b1d19e", kill_on_drop: false }`
[INFO] [stdout] 4195676aebaf48f302c76c9138d1aef081f0cfa7f16e233f526f2f1da2b1d19e
[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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d10591e5b85f3619d34a6359ad9b8642e8d7c9a4e0977da97463dac652f2f981
[INFO] running `Command { std: "docker" "start" "-a" "d10591e5b85f3619d34a6359ad9b8642e8d7c9a4e0977da97463dac652f2f981", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.101
[INFO] [stderr]    Compiling log v0.4.28
[INFO] [stderr]    Compiling humantime v2.3.0
[INFO] [stderr]    Compiling regex-automata v0.4.11
[INFO] [stderr]    Compiling is-terminal v0.4.16
[INFO] [stderr]    Compiling quote v1.0.41
[INFO] [stderr]    Compiling syn v2.0.106
[INFO] [stderr]    Compiling regex v1.11.3
[INFO] [stderr]    Compiling env_logger v0.10.2
[INFO] [stderr]    Compiling bitmask-enum v2.2.5
[INFO] [stderr]    Compiling fast-btree v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(generic_const_exprs)]
[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 `fast-btree` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "d10591e5b85f3619d34a6359ad9b8642e8d7c9a4e0977da97463dac652f2f981", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d10591e5b85f3619d34a6359ad9b8642e8d7c9a4e0977da97463dac652f2f981", kill_on_drop: false }`
[INFO] [stdout] d10591e5b85f3619d34a6359ad9b8642e8d7c9a4e0977da97463dac652f2f981