[INFO] fetching crate stable-skiplist 0.1.1...
[INFO] checking stable-skiplist-0.1.1 against master#ab869e094a907cc5d19b4080f22eccaf347f1f95 for pr-129604
[INFO] extracting crate stable-skiplist 0.1.1 into /workspace/builds/worker-6-tc1/source
[INFO] validating manifest of crates.io crate stable-skiplist 0.1.1 on toolchain ab869e094a907cc5d19b4080f22eccaf347f1f95
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+ab869e094a907cc5d19b4080f22eccaf347f1f95" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate stable-skiplist 0.1.1
[INFO] finished tweaking crates.io crate stable-skiplist 0.1.1
[INFO] tweaked toml for crates.io crate stable-skiplist 0.1.1 written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+ab869e094a907cc5d19b4080f22eccaf347f1f95" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 11 packages to latest compatible versions
[INFO] [stderr]       Adding rand v0.3.23 (latest: v0.8.5)
[INFO] [stderr]       Adding rand v0.4.6 (latest: v0.8.5)
[INFO] [stderr]       Adding rand_core v0.3.1 (latest: v0.6.4)
[INFO] [stderr]       Adding rand_core v0.4.2 (latest: v0.6.4)
[INFO] [stderr]       Adding rdrand v0.4.0 (latest: v0.8.3)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+ab869e094a907cc5d19b4080f22eccaf347f1f95" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr] warning: no edition set: defaulting to the 2015 edition while the latest is 2021
[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@sha256:923055f121b5182466d55868a8b05e67af8ba4a3a3f6bad814e953ca3cd3ac2a" "/opt/rustwide/cargo-home/bin/cargo" "+ab869e094a907cc5d19b4080f22eccaf347f1f95" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] a9ae5ba475ceeb8abfcce31aeb5d3218c20400bf8abcd9198e34f5f264978e31
[INFO] running `Command { std: "docker" "start" "-a" "a9ae5ba475ceeb8abfcce31aeb5d3218c20400bf8abcd9198e34f5f264978e31", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a9ae5ba475ceeb8abfcce31aeb5d3218c20400bf8abcd9198e34f5f264978e31", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a9ae5ba475ceeb8abfcce31aeb5d3218c20400bf8abcd9198e34f5f264978e31", kill_on_drop: false }`
[INFO] [stdout] a9ae5ba475ceeb8abfcce31aeb5d3218c20400bf8abcd9198e34f5f264978e31
[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=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@sha256:923055f121b5182466d55868a8b05e67af8ba4a3a3f6bad814e953ca3cd3ac2a" "/opt/rustwide/cargo-home/bin/cargo" "+ab869e094a907cc5d19b4080f22eccaf347f1f95" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 73787566c7b84ad01dd607cd4d89b31826b141a28a7714f057b6f3a43ac66e34
[INFO] running `Command { std: "docker" "start" "-a" "73787566c7b84ad01dd607cd4d89b31826b141a28a7714f057b6f3a43ac66e34", kill_on_drop: false }`
[INFO] [stderr] warning: no edition set: defaulting to the 2015 edition while the latest is 2021
[INFO] [stderr]     Checking rand v0.4.6
[INFO] [stderr]     Checking rand v0.3.23
[INFO] [stderr]     Checking stable-skiplist v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unexpected `cfg` condition value: `bench`
[INFO] [stdout]     --> src/ordered_skiplist.rs:1878:17
[INFO] [stdout]      |
[INFO] [stdout] 1878 | #[cfg(all(test, feature="bench"))]
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: expected values for `feature` are: `unstable`
[INFO] [stdout]      = help: consider adding `bench` as a feature in `Cargo.toml`
[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: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1415:9
[INFO] [stdout]      |
[INFO] [stdout] 1415 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: `#[warn(deprecated)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1421:13
[INFO] [stdout]      |
[INFO] [stdout] 1421 |             try!(write!(f, "{:?}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1419:17
[INFO] [stdout]      |
[INFO] [stdout] 1419 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1430:9
[INFO] [stdout]      |
[INFO] [stdout] 1430 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1436:13
[INFO] [stdout]      |
[INFO] [stdout] 1436 |             try!(write!(f, "{}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1434:17
[INFO] [stdout]      |
[INFO] [stdout] 1434 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition value: `bench`
[INFO] [stdout]     --> src/skipmap.rs:1944:17
[INFO] [stdout]      |
[INFO] [stdout] 1944 | #[cfg(all(test, feature="bench"))]
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: expected values for `feature` are: `unstable`
[INFO] [stdout]      = help: consider adding `bench` as a feature in `Cargo.toml`
[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: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1356:9
[INFO] [stdout]      |
[INFO] [stdout] 1356 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1362:13
[INFO] [stdout]      |
[INFO] [stdout] 1362 |             try!(write!(f, "({:?}, {:?})", k, v));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1360:17
[INFO] [stdout]      |
[INFO] [stdout] 1360 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1373:9
[INFO] [stdout]      |
[INFO] [stdout] 1373 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1379:13
[INFO] [stdout]      |
[INFO] [stdout] 1379 |             try!(write!(f, "({}, {})", k, v));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1377:17
[INFO] [stdout]      |
[INFO] [stdout] 1377 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition value: `bench`
[INFO] [stdout]     --> src/skiplist.rs:1671:17
[INFO] [stdout]      |
[INFO] [stdout] 1671 | #[cfg(all(test, feature="bench"))]
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: expected values for `feature` are: `unstable`
[INFO] [stdout]      = help: consider adding `bench` as a feature in `Cargo.toml`
[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: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1156:9
[INFO] [stdout]      |
[INFO] [stdout] 1156 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1162:13
[INFO] [stdout]      |
[INFO] [stdout] 1162 |             try!(write!(f, "{:?}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1160:17
[INFO] [stdout]      |
[INFO] [stdout] 1160 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1171:9
[INFO] [stdout]      |
[INFO] [stdout] 1171 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1177:13
[INFO] [stdout]      |
[INFO] [stdout] 1177 |             try!(write!(f, "{}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1175:17
[INFO] [stdout]      |
[INFO] [stdout] 1175 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition value: `bench`
[INFO] [stdout]     --> src/ordered_skiplist.rs:1878:17
[INFO] [stdout]      |
[INFO] [stdout] 1878 | #[cfg(all(test, feature="bench"))]
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: expected values for `feature` are: `unstable`
[INFO] [stdout]      = help: consider adding `bench` as a feature in `Cargo.toml`
[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: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1415:9
[INFO] [stdout]      |
[INFO] [stdout] 1415 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: `#[warn(deprecated)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1421:13
[INFO] [stdout]      |
[INFO] [stdout] 1421 |             try!(write!(f, "{:?}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1419:17
[INFO] [stdout]      |
[INFO] [stdout] 1419 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1430:9
[INFO] [stdout]      |
[INFO] [stdout] 1430 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1436:13
[INFO] [stdout]      |
[INFO] [stdout] 1436 |             try!(write!(f, "{}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/ordered_skiplist.rs:1434:17
[INFO] [stdout]      |
[INFO] [stdout] 1434 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition value: `bench`
[INFO] [stdout]     --> src/skipmap.rs:1944:17
[INFO] [stdout]      |
[INFO] [stdout] 1944 | #[cfg(all(test, feature="bench"))]
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: expected values for `feature` are: `unstable`
[INFO] [stdout]      = help: consider adding `bench` as a feature in `Cargo.toml`
[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: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1356:9
[INFO] [stdout]      |
[INFO] [stdout] 1356 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1362:13
[INFO] [stdout]      |
[INFO] [stdout] 1362 |             try!(write!(f, "({:?}, {:?})", k, v));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1360:17
[INFO] [stdout]      |
[INFO] [stdout] 1360 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1373:9
[INFO] [stdout]      |
[INFO] [stdout] 1373 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1379:13
[INFO] [stdout]      |
[INFO] [stdout] 1379 |             try!(write!(f, "({}, {})", k, v));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skipmap.rs:1377:17
[INFO] [stdout]      |
[INFO] [stdout] 1377 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unexpected `cfg` condition value: `bench`
[INFO] [stdout]     --> src/skiplist.rs:1671:17
[INFO] [stdout]      |
[INFO] [stdout] 1671 | #[cfg(all(test, feature="bench"))]
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: expected values for `feature` are: `unstable`
[INFO] [stdout]      = help: consider adding `bench` as a feature in `Cargo.toml`
[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: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1156:9
[INFO] [stdout]      |
[INFO] [stdout] 1156 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1162:13
[INFO] [stdout]      |
[INFO] [stdout] 1162 |             try!(write!(f, "{:?}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1160:17
[INFO] [stdout]      |
[INFO] [stdout] 1160 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1171:9
[INFO] [stdout]      |
[INFO] [stdout] 1171 |         try!(write!(f, "["));
[INFO] [stdout]      |         ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1177:13
[INFO] [stdout]      |
[INFO] [stdout] 1177 |             try!(write!(f, "{}", entry));
[INFO] [stdout]      |             ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]     --> src/skiplist.rs:1175:17
[INFO] [stdout]      |
[INFO] [stdout] 1175 |                 try!(write!(f, ", "));
[INFO] [stdout]      |                 ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/ordered_skiplist.rs:44:18
[INFO] [stdout]    |
[INFO] [stdout] 44 |     compare: Box<Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                  ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] help: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 44 |     compare: Box<dyn Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                  +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/ordered_skiplist.rs:44:18
[INFO] [stdout]    |
[INFO] [stdout] 44 |     compare: Box<Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                  ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[INFO] [stdout] help: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 44 |     compare: Box<dyn Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                  +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/ordered_skiplist.rs:81:24
[INFO] [stdout]    |
[INFO] [stdout] 81 |             })) as Box<Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                        ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 81 |             })) as Box<dyn Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                        +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/ordered_skiplist.rs:115:24
[INFO] [stdout]     |
[INFO] [stdout] 115 |             })) as Box<Fn(&T, &T) -> Ordering>,
[INFO] [stdout]     |                        ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is an object-safe trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 115 |             })) as Box<dyn Fn(&T, &T) -> Ordering>,
[INFO] [stdout]     |                        +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]   --> src/ordered_skiplist.rs:81:24
[INFO] [stdout]    |
[INFO] [stdout] 81 |             })) as Box<Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                        ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]    = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is an object-safe trait, use `dyn`
[INFO] [stdout]    |
[INFO] [stdout] 81 |             })) as Box<dyn Fn(&T, &T) -> Ordering>,
[INFO] [stdout]    |                        +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/ordered_skiplist.rs:115:24
[INFO] [stdout]     |
[INFO] [stdout] 115 |             })) as Box<Fn(&T, &T) -> Ordering>,
[INFO] [stdout]     |                        ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = warning: this is accepted in the current edition (Rust 2015) but is a hard error in Rust 2021!
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/nightly/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is an object-safe trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 115 |             })) as Box<dyn Fn(&T, &T) -> Ordering>,
[INFO] [stdout]     |                        +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:236:17
[INFO] [stdout]     |
[INFO] [stdout] 236 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 236 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:241:9
[INFO] [stdout]     |
[INFO] [stdout] 241 |         mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 241 |         let _ = mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:847:21
[INFO] [stdout]     |
[INFO] [stdout] 847 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 847 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:922:21
[INFO] [stdout]     |
[INFO] [stdout] 922 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 922 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]     --> src/ordered_skiplist.rs:1347:17
[INFO] [stdout]      |
[INFO] [stdout] 1347 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]      |
[INFO] [stdout] 1347 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skipmap.rs:308:17
[INFO] [stdout]     |
[INFO] [stdout] 308 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 308 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skipmap.rs:313:9
[INFO] [stdout]     |
[INFO] [stdout] 313 |         mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 313 |         let _ = mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]     --> src/skipmap.rs:1255:17
[INFO] [stdout]      |
[INFO] [stdout] 1255 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]      |
[INFO] [stdout] 1255 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/skiplist.rs:94:17
[INFO] [stdout]    |
[INFO] [stdout] 94 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 94 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/skiplist.rs:99:9
[INFO] [stdout]    |
[INFO] [stdout] 99 |         mem::replace(&mut self.head, new_head);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 99 |         let _ = mem::replace(&mut self.head, new_head);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skiplist.rs:567:21
[INFO] [stdout]     |
[INFO] [stdout] 567 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 567 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skiplist.rs:863:21
[INFO] [stdout]     |
[INFO] [stdout] 863 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 863 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]     --> src/skiplist.rs:1088:17
[INFO] [stdout]      |
[INFO] [stdout] 1088 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]      |
[INFO] [stdout] 1088 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 37 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:236:17
[INFO] [stdout]     |
[INFO] [stdout] 236 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 236 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:241:9
[INFO] [stdout]     |
[INFO] [stdout] 241 |         mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 241 |         let _ = mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:847:21
[INFO] [stdout]     |
[INFO] [stdout] 847 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 847 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/ordered_skiplist.rs:922:21
[INFO] [stdout]     |
[INFO] [stdout] 922 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 922 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]     --> src/ordered_skiplist.rs:1347:17
[INFO] [stdout]      |
[INFO] [stdout] 1347 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]      |
[INFO] [stdout] 1347 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skipmap.rs:308:17
[INFO] [stdout]     |
[INFO] [stdout] 308 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 308 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]     |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skipmap.rs:313:9
[INFO] [stdout]     |
[INFO] [stdout] 313 |         mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 313 |         let _ = mem::replace(&mut self.head, new_head);
[INFO] [stdout]     |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]     --> src/skipmap.rs:1255:17
[INFO] [stdout]      |
[INFO] [stdout] 1255 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]      |
[INFO] [stdout] 1255 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/skiplist.rs:94:17
[INFO] [stdout]    |
[INFO] [stdout] 94 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 94 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]    |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/skiplist.rs:99:9
[INFO] [stdout]    |
[INFO] [stdout] 99 |         mem::replace(&mut self.head, new_head);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 99 |         let _ = mem::replace(&mut self.head, new_head);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skiplist.rs:567:21
[INFO] [stdout]     |
[INFO] [stdout] 567 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 567 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/skiplist.rs:863:21
[INFO] [stdout]     |
[INFO] [stdout] 863 |                     mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 863 |                     let _ = mem::replace(&mut (*prev).next, mem::replace(&mut (*node).next, None));
[INFO] [stdout]     |                     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]     --> src/skiplist.rs:1088:17
[INFO] [stdout]      |
[INFO] [stdout] 1088 |                 mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]      |
[INFO] [stdout]      = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]      |
[INFO] [stdout] 1088 |                 let _ = mem::replace(&mut (*node).next, mem::replace(&mut next.next, None));
[INFO] [stdout]      |                 +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 37 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.50s
[INFO] running `Command { std: "docker" "inspect" "73787566c7b84ad01dd607cd4d89b31826b141a28a7714f057b6f3a43ac66e34", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "73787566c7b84ad01dd607cd4d89b31826b141a28a7714f057b6f3a43ac66e34", kill_on_drop: false }`
[INFO] [stdout] 73787566c7b84ad01dd607cd4d89b31826b141a28a7714f057b6f3a43ac66e34