[INFO] fetching crate libmcs 0.1.0... [INFO] testing libmcs-0.1.0 against master#562dee4820c458d823175268e41601d4c060588a for pr-154210-1 [INFO] extracting crate libmcs 0.1.0 into /workspace/builds/worker-3-tc1/source [INFO] started tweaking crates.io crate libmcs 0.1.0 [INFO] finished tweaking crates.io crate libmcs 0.1.0 [INFO] tweaked toml for crates.io crate libmcs 0.1.0 written to /workspace/builds/worker-3-tc1/source/Cargo.toml [INFO] validating manifest of crates.io crate libmcs 0.1.0 on toolchain 562dee4820c458d823175268e41601d4c060588a [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+562dee4820c458d823175268e41601d4c060588a" "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" "+562dee4820c458d823175268e41601d4c060588a" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+562dee4820c458d823175268e41601d4c060588a" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] [stderr] warning: `package.edition` is unspecified, defaulting to `2015` while the latest is `2024` [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+562dee4820c458d823175268e41601d4c060588a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] f7b3e4a2bd2d41e369f09b32b5a952ab037cedca9bd6d9f0a87df04e99a64154 [INFO] running `Command { std: "docker" "start" "-a" "f7b3e4a2bd2d41e369f09b32b5a952ab037cedca9bd6d9f0a87df04e99a64154", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "f7b3e4a2bd2d41e369f09b32b5a952ab037cedca9bd6d9f0a87df04e99a64154", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "f7b3e4a2bd2d41e369f09b32b5a952ab037cedca9bd6d9f0a87df04e99a64154", kill_on_drop: false }` [INFO] [stdout] f7b3e4a2bd2d41e369f09b32b5a952ab037cedca9bd6d9f0a87df04e99a64154 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+562dee4820c458d823175268e41601d4c060588a" "build" "--frozen" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] 856bebf1776d8af3ca79d73108b1658b22c28355e9bf7b9eda4cba7103f94b82 [INFO] running `Command { std: "docker" "start" "-a" "856bebf1776d8af3ca79d73108b1658b22c28355e9bf7b9eda4cba7103f94b82", kill_on_drop: false }` [INFO] [stderr] warning: `package.edition` is unspecified, defaulting to `2015` while the latest is `2024` [INFO] [stderr] Compiling libmcs v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] error[E0557]: feature has been removed [INFO] [stdout] --> src/lib.rs:15:12 [INFO] [stdout] | [INFO] [stdout] 15 | #![feature(optin_builtin_traits)] [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^ feature has been removed [INFO] [stdout] | [INFO] [stdout] = note: removed in 1.50.0; see for more information [INFO] [stdout] = note: renamed to `auto_traits` [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] error[E0557]: feature has been removed [INFO] [stdout] --> src/lib.rs:16:12 [INFO] [stdout] | [INFO] [stdout] 16 | #![feature(const_fn)] [INFO] [stdout] | ^^^^^^^^ feature has been removed [INFO] [stdout] | [INFO] [stdout] = note: removed in 1.54.0; see for more information [INFO] [stdout] = note: split into finer-grained feature gates [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] error[E0658]: negative trait bounds are not fully implemented; use marker types for now [INFO] [stdout] --> src/mcs.rs:131:21 [INFO] [stdout] | [INFO] [stdout] 131 | impl<'a, T: ?Sized> !marker::Send for MutexGuard<'a, T> { } [INFO] [stdout] | ^^^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: see issue #68318 for more information [INFO] [stdout] = help: add `#![feature(negative_impls)]` to the crate attributes to enable [INFO] [stdout] = note: this compiler was built on 2026-03-21; consider upgrading it if it is out of date [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: use of deprecated method `std::sync::atomic::Atomic::<*mut T>::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead [INFO] [stdout] --> src/mcs.rs:173:43 [INFO] [stdout] | [INFO] [stdout] 173 | let prev_tail = self.tail.compare_and_swap(prev, node, Acquire); [INFO] [stdout] | ^^^^^^^^^^^^^^^^ [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(deprecated)]` on by default [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: use of deprecated method `std::sync::atomic::Atomic::<*mut T>::compare_and_swap`: Use `compare_exchange` or `compare_exchange_weak` instead [INFO] [stdout] --> src/mcs.rs:281:36 [INFO] [stdout] | [INFO] [stdout] 281 | if self.__mtx.tail.compare_and_swap(raw_node_ptr, ptr::null_mut(), Release) == raw_node_ptr { [INFO] [stdout] | ^^^^^^^^^^^^^^^^ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] Some errors have detailed explanations: E0557, E0658. [INFO] [stdout] [INFO] [stdout] For more information about an error, try `rustc --explain E0557`. [INFO] [stdout] [INFO] [stderr] error: could not compile `libmcs` (lib) due to 3 previous errors; 2 warnings emitted [INFO] running `Command { std: "docker" "inspect" "856bebf1776d8af3ca79d73108b1658b22c28355e9bf7b9eda4cba7103f94b82", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "856bebf1776d8af3ca79d73108b1658b22c28355e9bf7b9eda4cba7103f94b82", kill_on_drop: false }` [INFO] [stdout] 856bebf1776d8af3ca79d73108b1658b22c28355e9bf7b9eda4cba7103f94b82