[INFO] fetching crate stable-skiplist 0.1.1...
[INFO] checking stable-skiplist-0.1.1 against master#dfd7b8d03fb93d0e03147d28b3be6d93260fa94d for pr-87050
[INFO] extracting crate stable-skiplist 0.1.1 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate stable-skiplist 0.1.1 on toolchain dfd7b8d03fb93d0e03147d28b3be6d93260fa94d
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "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-9/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e220497fe239191dfff7654f0e32e684993166b43236f09fc149a009aa133ff3
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "e220497fe239191dfff7654f0e32e684993166b43236f09fc149a009aa133ff3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e220497fe239191dfff7654f0e32e684993166b43236f09fc149a009aa133ff3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e220497fe239191dfff7654f0e32e684993166b43236f09fc149a009aa133ff3", kill_on_drop: false }`
[INFO] [stdout] e220497fe239191dfff7654f0e32e684993166b43236f09fc149a009aa133ff3
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7711da06a4ef14b3e279255ac23ae49d920f1783c0932295a4ce8ed4ec42b065
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "7711da06a4ef14b3e279255ac23ae49d920f1783c0932295a4ce8ed4ec42b065", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.98
[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: 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]    |                  ^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(&T, &T) -> Ordering`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[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 issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[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]    |                        ^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(&T, &T) -> Ordering`
[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 issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[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]     |                        ^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(&T, &T) -> Ordering`
[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 issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[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: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: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: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:1434:17
[INFO] [stdout]      |
[INFO] [stdout] 1434 |                 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/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: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: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: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:1377:17
[INFO] [stdout]      |
[INFO] [stdout] 1377 |                 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/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: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: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: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:1175:17
[INFO] [stdout]      |
[INFO] [stdout] 1175 |                 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: 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]    |                  ^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(&T, &T) -> Ordering`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(bare_trait_objects)]` on by default
[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 issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[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]    |                        ^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(&T, &T) -> Ordering`
[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 issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[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]     |                        ^^^^^^^^^^^^^^^^^^^^^^ help: use `dyn`: `dyn Fn(&T, &T) -> Ordering`
[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 issue #80165 <https://github.com/rust-lang/rust/issues/80165>
[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: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: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: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:1434:17
[INFO] [stdout]      |
[INFO] [stdout] 1434 |                 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/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: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: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: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:1377:17
[INFO] [stdout]      |
[INFO] [stdout] 1377 |                 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/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: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: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: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:1175:17
[INFO] [stdout]      |
[INFO] [stdout] 1175 |                 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: 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: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[INFO] [stdout] 
[INFO] [stdout] warning: 34 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: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: if you don't need the old value, you can just assign the new value directly
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[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] 
[INFO] [stdout] 
[INFO] [stdout] warning: 34 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 4.52s
[INFO] running `Command { std: "docker" "inspect" "7711da06a4ef14b3e279255ac23ae49d920f1783c0932295a4ce8ed4ec42b065", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7711da06a4ef14b3e279255ac23ae49d920f1783c0932295a4ce8ed4ec42b065", kill_on_drop: false }`
[INFO] [stdout] 7711da06a4ef14b3e279255ac23ae49d920f1783c0932295a4ce8ed4ec42b065