[INFO] fetching crate syncell 0.1.0...
[INFO] testing syncell-0.1.0 against beta-2026-04-21 for beta-1.96-2
[INFO] extracting crate syncell 0.1.0 into /workspace/builds/worker-2-tc2/source
[INFO] started tweaking crates.io crate syncell 0.1.0
[INFO] finished tweaking crates.io crate syncell 0.1.0
[INFO] tweaked toml for crates.io crate syncell 0.1.0 written to /workspace/builds/worker-2-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate syncell 0.1.0 on toolchain beta-2026-04-21
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2026-04-21" "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-2026-04-21" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 43 packages to latest compatible versions
[INFO] [stderr]       Adding loom v0.5.6 (available: v0.7.2)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2026-04-21" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-04-21" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 3278cee51392d1b51d9647bf3e4d743225691d73fb31ab9df0c32f4195e05970
[INFO] running `Command { std: "docker" "start" "-a" "3278cee51392d1b51d9647bf3e4d743225691d73fb31ab9df0c32f4195e05970", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "3278cee51392d1b51d9647bf3e4d743225691d73fb31ab9df0c32f4195e05970", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3278cee51392d1b51d9647bf3e4d743225691d73fb31ab9df0c32f4195e05970", kill_on_drop: false }`
[INFO] [stdout] 3278cee51392d1b51d9647bf3e4d743225691d73fb31ab9df0c32f4195e05970
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-04-21" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 39581a8c6369c9e6a2806ec6b03f55cb3edf15be4f3cd63a603a15d3605e02ef
[INFO] running `Command { std: "docker" "start" "-a" "39581a8c6369c9e6a2806ec6b03f55cb3edf15be4f3cd63a603a15d3605e02ef", kill_on_drop: false }`
[INFO] [stderr]    Compiling syncell v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unexpected `cfg` condition name: `loom`
[INFO] [stdout]  --> src/lib.rs:7:7
[INFO] [stdout]   |
[INFO] [stdout] 7 | #[cfg(loom)]
[INFO] [stdout]   |       ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stdout]   |
[INFO] [stdout]   = help: expected names are: `docsrs`, `feature`, and `test` and 31 more
[INFO] [stdout]   = help: consider using a Cargo feature instead
[INFO] [stdout]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stdout]            [lints.rust]
[INFO] [stdout]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stdout]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stdout]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stdout]   = note: `#[warn(unexpected_cfgs)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition name: `loom`
[INFO] [stdout]  --> src/lib.rs:9:11
[INFO] [stdout]   |
[INFO] [stdout] 9 | #[cfg(not(loom))]
[INFO] [stdout]   |           ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider using a Cargo feature instead
[INFO] [stdout]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stdout]            [lints.rust]
[INFO] [stdout]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stdout]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stdout]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> src/lib.rs:98:19
[INFO] [stdout]    |
[INFO] [stdout] 98 |     pub fn borrow(&self) -> SynRef<T> {
[INFO] [stdout]    |                   ^^^^^     ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]    |                   |
[INFO] [stdout]    |                   the lifetime is elided here
[INFO] [stdout]    |
[INFO] [stdout]    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout]    = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]    |
[INFO] [stdout] 98 |     pub fn borrow(&self) -> SynRef<'_, T> {
[INFO] [stdout]    |                                    +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/lib.rs:113:23
[INFO] [stdout]     |
[INFO] [stdout] 113 |     pub fn borrow_mut(&self) -> SynRefMut<T> {
[INFO] [stdout]     |                       ^^^^^     ^^^^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 113 |     pub fn borrow_mut(&self) -> SynRefMut<'_, T> {
[INFO] [stdout]     |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.12s
[INFO] running `Command { std: "docker" "inspect" "39581a8c6369c9e6a2806ec6b03f55cb3edf15be4f3cd63a603a15d3605e02ef", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "39581a8c6369c9e6a2806ec6b03f55cb3edf15be4f3cd63a603a15d3605e02ef", kill_on_drop: false }`
[INFO] [stdout] 39581a8c6369c9e6a2806ec6b03f55cb3edf15be4f3cd63a603a15d3605e02ef
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-04-21" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] dad658bbb02895277d03641a37fd952a4130ca563889f3cda250f5fe4de1846a
[INFO] running `Command { std: "docker" "start" "-a" "dad658bbb02895277d03641a37fd952a4130ca563889f3cda250f5fe4de1846a", kill_on_drop: false }`
[INFO] [stdout] warning: unexpected `cfg` condition name: `loom`
[INFO] [stdout]  --> src/lib.rs:7:7
[INFO] [stdout]   |
[INFO] [stdout] 7 | #[cfg(loom)]
[INFO] [stdout]   |       ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stdout]   |
[INFO] [stdout]   = help: expected names are: `docsrs`, `feature`, and `test` and 31 more
[INFO] [stdout]   = help: consider using a Cargo feature instead
[INFO] [stdout]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stdout]            [lints.rust]
[INFO] [stdout]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stdout]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stdout]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stdout]   = note: `#[warn(unexpected_cfgs)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition name: `loom`
[INFO] [stdout]  --> src/lib.rs:9:11
[INFO] [stdout]   |
[INFO] [stdout] 9 | #[cfg(not(loom))]
[INFO] [stdout]   |           ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider using a Cargo feature instead
[INFO] [stdout]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stdout]            [lints.rust]
[INFO] [stdout]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stdout]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stdout]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling syncell v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> src/lib.rs:98:19
[INFO] [stdout]    |
[INFO] [stdout] 98 |     pub fn borrow(&self) -> SynRef<T> {
[INFO] [stdout]    |                   ^^^^^     ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]    |                   |
[INFO] [stdout]    |                   the lifetime is elided here
[INFO] [stdout]    |
[INFO] [stdout]    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout]    = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]    |
[INFO] [stdout] 98 |     pub fn borrow(&self) -> SynRef<'_, T> {
[INFO] [stdout]    |                                    +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/lib.rs:113:23
[INFO] [stdout]     |
[INFO] [stdout] 113 |     pub fn borrow_mut(&self) -> SynRefMut<T> {
[INFO] [stdout]     |                       ^^^^^     ^^^^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 113 |     pub fn borrow_mut(&self) -> SynRefMut<'_, T> {
[INFO] [stdout]     |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition name: `loom`
[INFO] [stdout]  --> src/lib.rs:7:7
[INFO] [stdout]   |
[INFO] [stdout] 7 | #[cfg(loom)]
[INFO] [stdout]   |       ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stdout]   |
[INFO] [stdout]   = help: expected names are: `docsrs`, `feature`, and `test` and 31 more
[INFO] [stdout]   = help: consider using a Cargo feature instead
[INFO] [stdout]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stdout]            [lints.rust]
[INFO] [stdout]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stdout]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stdout]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stdout]   = note: `#[warn(unexpected_cfgs)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition name: `loom`
[INFO] [stdout]  --> src/lib.rs:9:11
[INFO] [stdout]   |
[INFO] [stdout] 9 | #[cfg(not(loom))]
[INFO] [stdout]   |           ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider using a Cargo feature instead
[INFO] [stdout]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stdout]            [lints.rust]
[INFO] [stdout]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stdout]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stdout]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]   --> src/lib.rs:98:19
[INFO] [stdout]    |
[INFO] [stdout] 98 |     pub fn borrow(&self) -> SynRef<T> {
[INFO] [stdout]    |                   ^^^^^     ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]    |                   |
[INFO] [stdout]    |                   the lifetime is elided here
[INFO] [stdout]    |
[INFO] [stdout]    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout]    = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]    |
[INFO] [stdout] 98 |     pub fn borrow(&self) -> SynRef<'_, T> {
[INFO] [stdout]    |                                    +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stdout]    --> src/lib.rs:113:23
[INFO] [stdout]     |
[INFO] [stdout] 113 |     pub fn borrow_mut(&self) -> SynRefMut<T> {
[INFO] [stdout]     |                       ^^^^^     ^^^^^^^^^^^^ the same lifetime is hidden here
[INFO] [stdout]     |                       |
[INFO] [stdout]     |                       the lifetime is elided here
[INFO] [stdout]     |
[INFO] [stdout]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stdout] help: use `'_` for type paths
[INFO] [stdout]     |
[INFO] [stdout] 113 |     pub fn borrow_mut(&self) -> SynRefMut<'_, T> {
[INFO] [stdout]     |                                           +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.43s
[INFO] running `Command { std: "docker" "inspect" "dad658bbb02895277d03641a37fd952a4130ca563889f3cda250f5fe4de1846a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "dad658bbb02895277d03641a37fd952a4130ca563889f3cda250f5fe4de1846a", kill_on_drop: false }`
[INFO] [stdout] dad658bbb02895277d03641a37fd952a4130ca563889f3cda250f5fe4de1846a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-04-21" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 643fe59825b4efca81385466f1baf84ac998fbfc5ab605bfc3ba4ec15a9d89b2
[INFO] running `Command { std: "docker" "start" "-a" "643fe59825b4efca81385466f1baf84ac998fbfc5ab605bfc3ba4ec15a9d89b2", kill_on_drop: false }`
[INFO] [stderr] warning: unexpected `cfg` condition name: `loom`
[INFO] [stderr]  --> src/lib.rs:7:7
[INFO] [stderr]   |
[INFO] [stderr] 7 | #[cfg(loom)]
[INFO] [stderr]   |       ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stderr]   |
[INFO] [stderr]   = help: expected names are: `docsrs`, `feature`, and `test` and 31 more
[INFO] [stderr]   = help: consider using a Cargo feature instead
[INFO] [stderr]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stderr]            [lints.rust]
[INFO] [stderr]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stderr]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stderr]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stderr]   = note: `#[warn(unexpected_cfgs)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unexpected `cfg` condition name: `loom`
[INFO] [stderr]  --> src/lib.rs:9:11
[INFO] [stderr]   |
[INFO] [stderr] 9 | #[cfg(not(loom))]
[INFO] [stderr]   |           ^^^^ help: found config with similar value: `feature = "loom"`
[INFO] [stderr]   |
[INFO] [stderr]   = help: consider using a Cargo feature instead
[INFO] [stderr]   = help: or consider adding in `Cargo.toml` the `check-cfg` lint config for the lint:
[INFO] [stderr]            [lints.rust]
[INFO] [stderr]            unexpected_cfgs = { level = "warn", check-cfg = ['cfg(loom)'] }
[INFO] [stderr]   = help: or consider adding `println!("cargo::rustc-check-cfg=cfg(loom)");` to the top of the `build.rs`
[INFO] [stderr]   = note: see <https://doc.rust-lang.org/nightly/rustc/check-cfg/cargo-specifics.html> for more information about checking conditional configuration
[INFO] [stderr] 
[INFO] [stderr] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stderr]   --> src/lib.rs:98:19
[INFO] [stderr]    |
[INFO] [stderr] 98 |     pub fn borrow(&self) -> SynRef<T> {
[INFO] [stderr]    |                   ^^^^^     ^^^^^^^^^ the same lifetime is hidden here
[INFO] [stderr]    |                   |
[INFO] [stderr]    |                   the lifetime is elided here
[INFO] [stderr]    |
[INFO] [stderr]    = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stderr]    = note: `#[warn(mismatched_lifetime_syntaxes)]` on by default
[INFO] [stderr] help: use `'_` for type paths
[INFO] [stderr]    |
[INFO] [stderr] 98 |     pub fn borrow(&self) -> SynRef<'_, T> {
[INFO] [stderr]    |                                    +++
[INFO] [stderr] 
[INFO] [stderr] warning: hiding a lifetime that's elided elsewhere is confusing
[INFO] [stderr]    --> src/lib.rs:113:23
[INFO] [stderr]     |
[INFO] [stderr] 113 |     pub fn borrow_mut(&self) -> SynRefMut<T> {
[INFO] [stderr]     |                       ^^^^^     ^^^^^^^^^^^^ the same lifetime is hidden here
[INFO] [stderr]     |                       |
[INFO] [stderr]     |                       the lifetime is elided here
[INFO] [stderr]     |
[INFO] [stderr]     = help: the same lifetime is referred to in inconsistent ways, making the signature confusing
[INFO] [stderr] help: use `'_` for type paths
[INFO] [stderr]     |
[INFO] [stderr] 113 |     pub fn borrow_mut(&self) -> SynRefMut<'_, T> {
[INFO] [stderr]     |                                           +++
[INFO] [stderr] 
[INFO] [stderr] warning: `syncell` (lib) generated 4 warnings (run `cargo fix --lib -p syncell` to apply 2 suggestions)
[INFO] [stderr] warning: `syncell` (lib test) generated 4 warnings (4 duplicates)
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.05s
[INFO] [stderr]      Running unittests src/lib.rs (/opt/rustwide/target/debug/deps/syncell-5e724c03239cbd60)
[INFO] [stdout] 
[INFO] [stdout] running 5 tests
[INFO] [stdout] test valid ... ok
[INFO] [stdout] test fight ... ok
[INFO] [stdout] test bad_read_write - should panic ... ok
[INFO] [stdout] test bad_write_write - should panic ... ok
[INFO] [stdout] test bad_write_read - should panic ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.02s
[INFO] [stdout] 
[INFO] [stderr]    Doc-tests syncell
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "643fe59825b4efca81385466f1baf84ac998fbfc5ab605bfc3ba4ec15a9d89b2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "643fe59825b4efca81385466f1baf84ac998fbfc5ab605bfc3ba4ec15a9d89b2", kill_on_drop: false }`
[INFO] [stdout] 643fe59825b4efca81385466f1baf84ac998fbfc5ab605bfc3ba4ec15a9d89b2
