[INFO] cloning repository https://github.com/eric556/chip-8-rs
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/eric556/chip-8-rs" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feric556%2Fchip-8-rs", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feric556%2Fchip-8-rs'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] bfb377b5db047c077680e49088d36b50a6445ee7
[INFO] checking eric556/chip-8-rs against master#09a371361240e42b0d69438fd1179efcf212e576 for pr-157814-crater-rollup
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feric556%2Fchip-8-rs" "/workspace/builds/worker-6-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/eric556/chip-8-rs
[INFO] finished tweaking git repo https://github.com/eric556/chip-8-rs
[INFO] tweaked toml for git repo https://github.com/eric556/chip-8-rs written to /workspace/builds/worker-6-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/eric556/chip-8-rs on toolchain 09a371361240e42b0d69438fd1179efcf212e576
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+09a371361240e42b0d69438fd1179efcf212e576" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/eric556/chip-8-rs already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+09a371361240e42b0d69438fd1179efcf212e576" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded csfml-window-sys v0.4.0
[INFO] [stderr]   Downloaded sfml-build v0.2.0
[INFO] [stderr]   Downloaded csfml-graphics-sys v0.4.0
[INFO] [stderr]   Downloaded csfml-system-sys v0.4.0
[INFO] [stderr]   Downloaded rand_chacha v0.2.0
[INFO] [stderr]   Downloaded csfml-audio-sys v0.4.0
[INFO] [stderr]   Downloaded c2-chacha v0.2.2
[INFO] [stderr]   Downloaded ppv-lite86 v0.2.5
[INFO] [stderr]   Downloaded rand_core v0.5.0
[INFO] [stderr]   Downloaded getrandom v0.1.6
[INFO] [stderr]   Downloaded rand v0.7.0
[INFO] [stderr]   Downloaded sfml v0.14.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6-tc1/target:/opt/rustwide/target:rw,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" "-m" "1610612736" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:7cf07dcec6eec8f91d8fcff9552b5c74122c05467aaf1800be6da9d6f61e2ab2" "sleep" "infinity", kill_on_drop: false }`
[INFO] [stdout] 2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2
[INFO] running `Command { std: "docker" "start" "2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "exec" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-w" "/opt/rustwide/workdir" "--user" "0:0" "2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2" "/opt/rustwide/cargo-home/bin/cargo" "+09a371361240e42b0d69438fd1179efcf212e576" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "exec" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-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" "-w" "/opt/rustwide/workdir" "--user" "0:0" "2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2" "/opt/rustwide/cargo-home/bin/cargo" "+09a371361240e42b0d69438fd1179efcf212e576" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr]    Compiling sfml-build v0.2.0
[INFO] [stderr]     Checking spin v0.5.0
[INFO] [stderr]    Compiling libc v0.2.60
[INFO] [stderr]    Compiling autocfg v0.1.5
[INFO] [stderr]     Checking ppv-lite86 v0.2.5
[INFO] [stderr]     Checking lazy_static v1.3.0
[INFO] [stderr]    Compiling csfml-system-sys v0.4.0
[INFO] [stderr]    Compiling csfml-window-sys v0.4.0
[INFO] [stderr]    Compiling csfml-audio-sys v0.4.0
[INFO] [stderr]    Compiling csfml-graphics-sys v0.4.0
[INFO] [stderr]    Compiling rand_chacha v0.2.0
[INFO] [stderr]     Checking c2-chacha v0.2.2
[INFO] [stderr]     Checking getrandom v0.1.6
[INFO] [stderr]     Checking rand_core v0.5.0
[INFO] [stderr]     Checking sfml v0.14.0
[INFO] [stderr]     Checking rand v0.7.0
[INFO] [stderr]     Checking chip_8 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `sfml::system::*`
[INFO] [stdout]  --> src/main.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use sfml::system::*;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:160:62
[INFO] [stdout]     |
[INFO] [stdout] 160 |     fn skip_immediate(&mut self, x: usize, byte: u16, comp: &Fn(u16, u16) -> bool) {
[INFO] [stdout]     |                                                              ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]     = note: `#[warn(bare_trait_objects)]` (part of `#[warn(rust_2021_compatibility)]`) on by default
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 160 |     fn skip_immediate(&mut self, x: usize, byte: u16, comp: &dyn Fn(u16, u16) -> bool) {
[INFO] [stdout]     |                                                              +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:168:60
[INFO] [stdout]     |
[INFO] [stdout] 168 |     fn skip_register(&mut self, x: usize, y: usize, comp: &Fn(u8, u8) -> bool) {
[INFO] [stdout]     |                                                            ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 168 |     fn skip_register(&mut self, x: usize, y: usize, comp: &dyn Fn(u8, u8) -> bool) {
[INFO] [stdout]     |                                                            +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:176:58
[INFO] [stdout]     |
[INFO] [stdout] 176 |     fn op_immediate(&mut self, x: usize, byte: u16, op: &Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                          ^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 176 |     fn op_immediate(&mut self, x: usize, byte: u16, op: &dyn Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                          +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:181:56
[INFO] [stdout]     |
[INFO] [stdout] 181 |     fn op_register(&mut self, x: usize, y: usize, op: &Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                        ^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 181 |     fn op_register(&mut self, x: usize, y: usize, op: &dyn Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                        +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:186:62
[INFO] [stdout]     |
[INFO] [stdout] 186 |     fn op_register_carry(&mut self, x: usize, y: usize, op: &Fn(u16, u16) -> (u8, u16)) {
[INFO] [stdout]     |                                                              ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 186 |     fn op_register_carry(&mut self, x: usize, y: usize, op: &dyn Fn(u16, u16) -> (u8, u16)) {
[INFO] [stdout]     |                                                              +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `sfml::system::*`
[INFO] [stdout]  --> src/main.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 | use sfml::system::*;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:160:62
[INFO] [stdout]     |
[INFO] [stdout] 160 |     fn skip_immediate(&mut self, x: usize, byte: u16, comp: &Fn(u16, u16) -> bool) {
[INFO] [stdout]     |                                                              ^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout]     = note: `#[warn(bare_trait_objects)]` (part of `#[warn(rust_2021_compatibility)]`) on by default
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 160 |     fn skip_immediate(&mut self, x: usize, byte: u16, comp: &dyn Fn(u16, u16) -> bool) {
[INFO] [stdout]     |                                                              +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:168:60
[INFO] [stdout]     |
[INFO] [stdout] 168 |     fn skip_register(&mut self, x: usize, y: usize, comp: &Fn(u8, u8) -> bool) {
[INFO] [stdout]     |                                                            ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 168 |     fn skip_register(&mut self, x: usize, y: usize, comp: &dyn Fn(u8, u8) -> bool) {
[INFO] [stdout]     |                                                            +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:176:58
[INFO] [stdout]     |
[INFO] [stdout] 176 |     fn op_immediate(&mut self, x: usize, byte: u16, op: &Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                          ^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 176 |     fn op_immediate(&mut self, x: usize, byte: u16, op: &dyn Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                          +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:181:56
[INFO] [stdout]     |
[INFO] [stdout] 181 |     fn op_register(&mut self, x: usize, y: usize, op: &Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                        ^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 181 |     fn op_register(&mut self, x: usize, y: usize, op: &dyn Fn(u8, u8) -> u8) {
[INFO] [stdout]     |                                                        +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait objects without an explicit `dyn` are deprecated
[INFO] [stdout]    --> src/main.rs:186:62
[INFO] [stdout]     |
[INFO] [stdout] 186 |     fn op_register_carry(&mut self, x: usize, y: usize, op: &Fn(u16, u16) -> (u8, u16)) {
[INFO] [stdout]     |                                                              ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[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 <https://doc.rust-lang.org/edition-guide/rust-2021/warnings-promoted-to-error.html>
[INFO] [stdout] help: if this is a dyn-compatible trait, use `dyn`
[INFO] [stdout]     |
[INFO] [stdout] 186 |     fn op_register_carry(&mut self, x: usize, y: usize, op: &dyn Fn(u16, u16) -> (u8, u16)) {
[INFO] [stdout]     |                                                              +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `dump` is never used
[INFO] [stdout]    --> src/main.rs:119:8
[INFO] [stdout]     |
[INFO] [stdout]  94 | impl Chip8 {
[INFO] [stdout]     | ---------- method in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 119 |     fn dump(&self) {
[INFO] [stdout]     |        ^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: static variable `chip8_fontset` should have an upper case name
[INFO] [stdout]   --> src/main.rs:14:8
[INFO] [stdout]    |
[INFO] [stdout] 14 | static chip8_fontset: [u8; 80] = [
[INFO] [stdout]    |        ^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_upper_case_globals)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] help: convert the identifier to upper case
[INFO] [stdout]    |
[INFO] [stdout] 14 - static chip8_fontset: [u8; 80] = [
[INFO] [stdout] 14 + static CHIP8_FONTSET: [u8; 80] = [
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait method `FromBig` should have a snake case name
[INFO] [stdout]   --> src/main.rs:34:8
[INFO] [stdout]    |
[INFO] [stdout] 34 |     fn FromBig(other: T) -> Self;
[INFO] [stdout]    |        ^^^^^^^ help: convert the identifier to snake case: `from_big`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_snake_case)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:502:5
[INFO] [stdout]     |
[INFO] [stdout] 502 |     file.unwrap().read_to_end(&mut rom);
[INFO] [stdout]     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 502 |     let _ = file.unwrap().read_to_end(&mut rom);
[INFO] [stdout]     |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `dump` is never used
[INFO] [stdout]    --> src/main.rs:119:8
[INFO] [stdout]     |
[INFO] [stdout]  94 | impl Chip8 {
[INFO] [stdout]     | ---------- method in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 119 |     fn dump(&self) {
[INFO] [stdout]     |        ^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: static variable `chip8_fontset` should have an upper case name
[INFO] [stdout]   --> src/main.rs:14:8
[INFO] [stdout]    |
[INFO] [stdout] 14 | static chip8_fontset: [u8; 80] = [
[INFO] [stdout]    |        ^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_upper_case_globals)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] help: convert the identifier to upper case
[INFO] [stdout]    |
[INFO] [stdout] 14 - static chip8_fontset: [u8; 80] = [
[INFO] [stdout] 14 + static CHIP8_FONTSET: [u8; 80] = [
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait method `FromBig` should have a snake case name
[INFO] [stdout]   --> src/main.rs:34:8
[INFO] [stdout]    |
[INFO] [stdout] 34 |     fn FromBig(other: T) -> Self;
[INFO] [stdout]    |        ^^^^^^^ help: convert the identifier to snake case: `from_big`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(non_snake_case)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:502:5
[INFO] [stdout]     |
[INFO] [stdout] 502 |     file.unwrap().read_to_end(&mut rom);
[INFO] [stdout]     |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 502 |     let _ = file.unwrap().read_to_end(&mut rom);
[INFO] [stdout]     |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 4.05s
[INFO] running `Command { std: "docker" "inspect" "2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2", kill_on_drop: false }`
[INFO] [stdout] 2351c5a1ebfc65f53217237589871e4819c63d5150e2cbfc2575713c6ddd74a2
