[INFO] cloning repository https://github.com/rlkelly/minimum-viable-blockchain [INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/rlkelly/minimum-viable-blockchain" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frlkelly%2Fminimum-viable-blockchain", kill_on_drop: false }` [INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frlkelly%2Fminimum-viable-blockchain'... [INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }` [INFO] [stdout] 1d9e5c28ee4995ba16d501c42d9d5d7577f19fe4 [INFO] testing rlkelly/minimum-viable-blockchain against master#a77da2d454e6caa227a85b16410b95f93495e7e0 for pr-91031 [INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frlkelly%2Fminimum-viable-blockchain" "/workspace/builds/worker-58/source", kill_on_drop: false }` [INFO] [stderr] Cloning into '/workspace/builds/worker-58/source'... [INFO] [stderr] done. [INFO] validating manifest of git repo https://github.com/rlkelly/minimum-viable-blockchain on toolchain a77da2d454e6caa227a85b16410b95f93495e7e0 [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }` [INFO] started tweaking git repo https://github.com/rlkelly/minimum-viable-blockchain [INFO] finished tweaking git repo https://github.com/rlkelly/minimum-viable-blockchain [INFO] tweaked toml for git repo https://github.com/rlkelly/minimum-viable-blockchain written to /workspace/builds/worker-58/source/Cargo.toml [INFO] crate git repo https://github.com/rlkelly/minimum-viable-blockchain already has a lockfile, it will not be regenerated [INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }` [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] Downloading crates ... [INFO] [stderr] Downloaded scoped-tls v0.1.2 [INFO] [stderr] Downloaded rmp-serde v0.13.7 [INFO] [stderr] Downloaded tokio-core v0.1.17 [INFO] [stderr] Downloaded cc v1.0.26 [INFO] [stderr] Downloaded rmp v0.8.7 [INFO] [stderr] Downloaded secp256k1 v0.12.2 [INFO] [stderr] Downloaded bitcoin-bech32 v0.8.1 [INFO] [stderr] Downloaded bitcoin v0.16.0 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }` [INFO] [stdout] d81d46579e2aaa151da70d680df60233b9f8cdb0072a9bccbc29c2c939b31b83 [INFO] running `Command { std: "docker" "start" "-a" "d81d46579e2aaa151da70d680df60233b9f8cdb0072a9bccbc29c2c939b31b83", kill_on_drop: false }` [INFO] running `Command { std: "docker" "inspect" "d81d46579e2aaa151da70d680df60233b9f8cdb0072a9bccbc29c2c939b31b83", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "d81d46579e2aaa151da70d680df60233b9f8cdb0072a9bccbc29c2c939b31b83", kill_on_drop: false }` [INFO] [stdout] d81d46579e2aaa151da70d680df60233b9f8cdb0072a9bccbc29c2c939b31b83 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "build" "--frozen" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] f68a10c0076ba6892ac49d79e5e905a03e2f268b206f35d81ae1a05d061b787c [INFO] running `Command { std: "docker" "start" "-a" "f68a10c0076ba6892ac49d79e5e905a03e2f268b206f35d81ae1a05d061b787c", kill_on_drop: false }` [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] Compiling autocfg v0.1.2 [INFO] [stderr] Compiling byteorder v1.3.1 [INFO] [stderr] Compiling futures v0.1.25 [INFO] [stderr] Compiling lazy_static v1.2.0 [INFO] [stderr] Compiling arrayvec v0.4.10 [INFO] [stderr] Compiling lazycell v1.2.1 [INFO] [stderr] Compiling nodrop v0.1.13 [INFO] [stderr] Compiling num-traits v0.2.6 [INFO] [stderr] Compiling proc-macro2 v0.4.26 [INFO] [stderr] Compiling serde v1.0.85 [INFO] [stderr] Compiling gcc v0.3.55 [INFO] [stderr] Compiling cc v1.0.26 [INFO] [stderr] Compiling ryu v0.2.7 [INFO] [stderr] Compiling bech32 v0.5.0 [INFO] [stderr] Compiling rustc-serialize v0.3.24 [INFO] [stderr] Compiling crossbeam-utils v0.6.3 [INFO] [stderr] Compiling log v0.4.6 [INFO] [stderr] Compiling rand_core v0.3.1 [INFO] [stderr] Compiling unreachable v1.0.0 [INFO] [stderr] Compiling rand_pcg v0.1.1 [INFO] [stderr] Compiling iovec v0.1.2 [INFO] [stderr] Compiling num_cpus v1.9.0 [INFO] [stderr] Compiling net2 v0.2.33 [INFO] [stderr] Compiling rand v0.4.5 [INFO] [stderr] Compiling time v0.1.42 [INFO] [stderr] Compiling smallvec v0.6.8 [INFO] [stderr] Compiling rand_os v0.1.1 [INFO] [stderr] Compiling rand_hc v0.1.0 [INFO] [stderr] Compiling rand_xorshift v0.1.1 [INFO] [stderr] Compiling rand_isaac v0.1.1 [INFO] [stderr] Compiling bitcoin-bech32 v0.8.1 [INFO] [stderr] Compiling rand_chacha v0.1.1 [INFO] [stderr] Compiling rand v0.6.4 [INFO] [stderr] Compiling mio v0.6.16 [INFO] [stderr] Compiling rand v0.3.22 [INFO] [stderr] Compiling bytes v0.4.11 [INFO] [stderr] Compiling crossbeam-epoch v0.7.0 [INFO] [stderr] Compiling quote v0.6.11 [INFO] [stderr] Compiling syn v0.15.26 [INFO] [stderr] Compiling mio-uds v0.6.7 [INFO] [stderr] Compiling crossbeam-deque v0.6.3 [INFO] [stderr] Compiling num-traits v0.1.43 [INFO] [stderr] Compiling num-integer v0.1.39 [INFO] [stderr] Compiling rust-crypto v0.2.36 [INFO] [stderr] Compiling tokio-executor v0.1.6 [INFO] [stderr] Compiling tokio-sync v0.1.0 [INFO] [stderr] Compiling rmp v0.8.7 [INFO] [stderr] Compiling tokio-io v0.1.11 [INFO] [stderr] Compiling secp256k1 v0.12.2 [INFO] [stderr] Compiling tokio-timer v0.2.9 [INFO] [stderr] Compiling tokio-current-thread v0.1.4 [INFO] [stderr] Compiling chrono v0.4.6 [INFO] [stderr] Compiling tokio-codec v0.1.1 [INFO] [stderr] Compiling parking_lot_core v0.4.0 [INFO] [stderr] Compiling parking_lot v0.7.1 [INFO] [stderr] Compiling crossbeam-channel v0.3.6 [INFO] [stderr] Compiling tokio-reactor v0.1.8 [INFO] [stderr] Compiling tokio-udp v0.1.3 [INFO] [stderr] Compiling tokio-uds v0.2.5 [INFO] [stderr] Compiling tokio-tcp v0.1.3 [INFO] [stderr] Compiling crossbeam v0.6.0 [INFO] [stderr] Compiling tokio-threadpool v0.1.11 [INFO] [stderr] Compiling serde_derive v1.0.85 [INFO] [stderr] Compiling tokio-fs v0.1.5 [INFO] [stderr] Compiling tokio v0.1.15 [INFO] [stderr] Compiling tokio-core v0.1.17 [INFO] [stderr] Compiling bitcoin v0.16.0 [INFO] [stderr] Compiling rmp-serde v0.13.7 [INFO] [stderr] Compiling serde_json v1.0.37 [INFO] [stderr] Compiling blockchain v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/consensus/node.rs:40:19 [INFO] [stdout] | [INFO] [stdout] 40 | (self as &fmt::Display).fmt(f) [INFO] [stdout] | ^^^^^^^^^^^^ help: use `dyn`: `dyn fmt::Display` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(bare_trait_objects)]` on by default [INFO] [stdout] = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021! [INFO] [stdout] = note: for more information, see [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused borrow that must be used [INFO] [stdout] --> src/chain/block.rs:61:9 [INFO] [stdout] | [INFO] [stdout] 61 | &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] help: use `let _ = ...` to ignore the resulting value [INFO] [stdout] | [INFO] [stdout] 61 | let _ = &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | +++++++ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/consensus/node.rs:40:19 [INFO] [stdout] | [INFO] [stdout] 40 | (self as &fmt::Display).fmt(f) [INFO] [stdout] | ^^^^^^^^^^^^ help: use `dyn`: `dyn fmt::Display` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(bare_trait_objects)]` on by default [INFO] [stdout] = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021! [INFO] [stdout] = note: for more information, see [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused borrow that must be used [INFO] [stdout] --> src/chain/block.rs:61:9 [INFO] [stdout] | [INFO] [stdout] 61 | &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] help: use `let _ = ...` to ignore the resulting value [INFO] [stdout] | [INFO] [stdout] 61 | let _ = &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | +++++++ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Finished dev [unoptimized + debuginfo] target(s) in 22.37s [INFO] running `Command { std: "docker" "inspect" "f68a10c0076ba6892ac49d79e5e905a03e2f268b206f35d81ae1a05d061b787c", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "f68a10c0076ba6892ac49d79e5e905a03e2f268b206f35d81ae1a05d061b787c", kill_on_drop: false }` [INFO] [stdout] f68a10c0076ba6892ac49d79e5e905a03e2f268b206f35d81ae1a05d061b787c [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }` [INFO] [stdout] a93f6a3efb86f586d860cea70ec1c036b0c3586e2c37000e4879a7c2ffbeedc1 [INFO] running `Command { std: "docker" "start" "-a" "a93f6a3efb86f586d860cea70ec1c036b0c3586e2c37000e4879a7c2ffbeedc1", kill_on_drop: false }` [INFO] [stderr] Compiling blockchain v0.1.0 (/opt/rustwide/workdir) [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/consensus/node.rs:40:19 [INFO] [stdout] | [INFO] [stdout] 40 | (self as &fmt::Display).fmt(f) [INFO] [stdout] | ^^^^^^^^^^^^ help: use `dyn`: `dyn fmt::Display` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(bare_trait_objects)]` on by default [INFO] [stdout] = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021! [INFO] [stdout] = note: for more information, see [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused borrow that must be used [INFO] [stdout] --> src/chain/block.rs:61:9 [INFO] [stdout] | [INFO] [stdout] 61 | &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] help: use `let _ = ...` to ignore the resulting value [INFO] [stdout] | [INFO] [stdout] 61 | let _ = &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | +++++++ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/consensus/node.rs:40:19 [INFO] [stdout] | [INFO] [stdout] 40 | (self as &fmt::Display).fmt(f) [INFO] [stdout] | ^^^^^^^^^^^^ help: use `dyn`: `dyn fmt::Display` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(bare_trait_objects)]` on by default [INFO] [stdout] = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021! [INFO] [stdout] = note: for more information, see [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stdout] --> src/consensus/node.rs:40:19 [INFO] [stdout] | [INFO] [stdout] 40 | (self as &fmt::Display).fmt(f) [INFO] [stdout] | ^^^^^^^^^^^^ help: use `dyn`: `dyn fmt::Display` [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(bare_trait_objects)]` on by default [INFO] [stdout] = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021! [INFO] [stdout] = note: for more information, see [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused borrow that must be used [INFO] [stdout] --> src/chain/block.rs:61:9 [INFO] [stdout] | [INFO] [stdout] 61 | &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] help: use `let _ = ...` to ignore the resulting value [INFO] [stdout] | [INFO] [stdout] 61 | let _ = &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | +++++++ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: unused borrow that must be used [INFO] [stdout] --> src/chain/block.rs:61:9 [INFO] [stdout] | [INFO] [stdout] 61 | &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value [INFO] [stdout] | [INFO] [stdout] = note: `#[warn(unused_must_use)]` on by default [INFO] [stdout] help: use `let _ = ...` to ignore the resulting value [INFO] [stdout] | [INFO] [stdout] 61 | let _ = &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stdout] | +++++++ [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stdout] warning: 2 warnings emitted [INFO] [stdout] [INFO] [stdout] [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 4.57s [INFO] running `Command { std: "docker" "inspect" "a93f6a3efb86f586d860cea70ec1c036b0c3586e2c37000e4879a7c2ffbeedc1", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "a93f6a3efb86f586d860cea70ec1c036b0c3586e2c37000e4879a7c2ffbeedc1", kill_on_drop: false }` [INFO] [stdout] a93f6a3efb86f586d860cea70ec1c036b0c3586e2c37000e4879a7c2ffbeedc1 [INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-58/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "test" "--frozen", kill_on_drop: false }` [INFO] [stdout] 9a56c09de76ec43be974183a39df4287466cc97131d8e0ca7da2eab5a99fe1c0 [INFO] running `Command { std: "docker" "start" "-a" "9a56c09de76ec43be974183a39df4287466cc97131d8e0ca7da2eab5a99fe1c0", kill_on_drop: false }` [INFO] [stderr] Blocking waiting for file lock on package cache [INFO] [stderr] warning: trait objects without an explicit `dyn` are deprecated [INFO] [stderr] --> src/consensus/node.rs:40:19 [INFO] [stderr] | [INFO] [stderr] 40 | (self as &fmt::Display).fmt(f) [INFO] [stderr] | ^^^^^^^^^^^^ help: use `dyn`: `dyn fmt::Display` [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(bare_trait_objects)]` on by default [INFO] [stderr] = warning: this is accepted in the current edition (Rust 2018) but is a hard error in Rust 2021! [INFO] [stderr] = note: for more information, see [INFO] [stderr] [INFO] [stderr] warning: unused borrow that must be used [INFO] [stderr] --> src/chain/block.rs:61:9 [INFO] [stderr] | [INFO] [stderr] 61 | &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stderr] | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the borrow produces a value [INFO] [stderr] | [INFO] [stderr] = note: `#[warn(unused_must_use)]` on by default [INFO] [stderr] help: use `let _ = ...` to ignore the resulting value [INFO] [stderr] | [INFO] [stderr] 61 | let _ = &self.transactions.retain(|trans| trans.verify(&blockchain)); [INFO] [stderr] | +++++++ [INFO] [stderr] [INFO] [stderr] warning: `blockchain` (lib) generated 2 warnings [INFO] [stderr] warning: `blockchain` (lib test) generated 2 warnings (2 duplicates) [INFO] [stderr] warning: `blockchain` (bin "main" test) generated 2 warnings (2 duplicates) [INFO] [stderr] Finished test [unoptimized + debuginfo] target(s) in 1.12s [INFO] [stderr] Running unittests (/opt/rustwide/target/debug/deps/blockchain-7adfd6b4a44be5f1) [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] [stderr] Running unittests (/opt/rustwide/target/debug/deps/main-09dab6e332f2e3d3) [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] [stderr] Running unittests (/opt/rustwide/target/debug/deps/wallet-d4cd71bb6d04bce9) [INFO] [stdout] [INFO] [stderr] Doc-tests blockchain [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] [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" "9a56c09de76ec43be974183a39df4287466cc97131d8e0ca7da2eab5a99fe1c0", kill_on_drop: false }` [INFO] running `Command { std: "docker" "rm" "-f" "9a56c09de76ec43be974183a39df4287466cc97131d8e0ca7da2eab5a99fe1c0", kill_on_drop: false }` [INFO] [stdout] 9a56c09de76ec43be974183a39df4287466cc97131d8e0ca7da2eab5a99fe1c0