[INFO] cloning repository https://github.com/frostie614/cards
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/frostie614/cards" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffrostie614%2Fcards", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffrostie614%2Fcards'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 6c0f920240c260881a84e2cbb2b22baeae50cebc
[INFO] checking frostie614/cards against try#f47dd4da3ae8c32c9e65d307bfe640b143e674df for pr-77526
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffrostie614%2Fcards" "/workspace/builds/worker-0/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/frostie614/cards on toolchain f47dd4da3ae8c32c9e65d307bfe640b143e674df
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/frostie614/cards
[INFO] finished tweaking git repo https://github.com/frostie614/cards
[INFO] tweaked toml for git repo https://github.com/frostie614/cards written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] crate git repo https://github.com/frostie614/cards already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 3be7d61b298a1b29ec4524efe0808b3a11367a26d204f40fffc185af84cf30ac
[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" "3be7d61b298a1b29ec4524efe0808b3a11367a26d204f40fffc185af84cf30ac", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "3be7d61b298a1b29ec4524efe0808b3a11367a26d204f40fffc185af84cf30ac", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3be7d61b298a1b29ec4524efe0808b3a11367a26d204f40fffc185af84cf30ac", kill_on_drop: false }`
[INFO] [stdout] 3be7d61b298a1b29ec4524efe0808b3a11367a26d204f40fffc185af84cf30ac
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 226f578457f10981da0f25320fd64937121f01724e54e72e058e3c8c94e57e6c
[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" "226f578457f10981da0f25320fd64937121f01724e54e72e058e3c8c94e57e6c", kill_on_drop: false }`
[INFO] [stderr]     Checking libc v0.2.36
[INFO] [stderr]     Checking rand v0.4.2
[INFO] [stderr]     Checking cards v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variant is never constructed: `Hearts`
[INFO] [stdout]   --> src/main.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |            ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/main.rs:1:9
[INFO] [stdout]    |
[INFO] [stdout] 1  | #![warn(dead_code)]
[INFO] [stdout]    |         ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Hearts`
[INFO] [stdout]   --> src/main.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |            ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/main.rs:1:9
[INFO] [stdout]    |
[INFO] [stdout] 1  | #![warn(dead_code)]
[INFO] [stdout]    |         ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Diamonds`
[INFO] [stdout]   --> src/main.rs:24:20
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |                    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Spades`
[INFO] [stdout]   --> src/main.rs:24:30
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |                              ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Clubs`
[INFO] [stdout]   --> src/main.rs:24:38
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |                                      ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Ace`
[INFO] [stdout]   --> src/main.rs:27:10
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |          ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Two`
[INFO] [stdout]   --> src/main.rs:27:15
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |               ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Three`
[INFO] [stdout]   --> src/main.rs:27:20
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                    ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Four`
[INFO] [stdout]   --> src/main.rs:27:27
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                           ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Five`
[INFO] [stdout]   --> src/main.rs:27:33
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                 ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Six`
[INFO] [stdout]   --> src/main.rs:27:39
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                       ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Seven`
[INFO] [stdout]   --> src/main.rs:27:44
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                            ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Eight`
[INFO] [stdout]   --> src/main.rs:27:51
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                   ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Nine`
[INFO] [stdout]   --> src/main.rs:27:58
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                          ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Ten`
[INFO] [stdout]   --> src/main.rs:27:64
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Jack`
[INFO] [stdout]   --> src/main.rs:27:69
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Queen`
[INFO] [stdout]   --> src/main.rs:27:75
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                           ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `King`
[INFO] [stdout]   --> src/main.rs:27:82
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                                  ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `new`
[INFO] [stdout]   --> src/main.rs:47:5
[INFO] [stdout]    |
[INFO] [stdout] 47 |     fn new()-> Deck{
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `deal`
[INFO] [stdout]   --> src/main.rs:57:5
[INFO] [stdout]    |
[INFO] [stdout] 57 |     fn deal(&mut self) -> Option<Card>{
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `shuffle`
[INFO] [stdout]   --> src/main.rs:61:5
[INFO] [stdout]    |
[INFO] [stdout] 61 |     fn shuffle(&mut self){
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `new`
[INFO] [stdout]   --> src/main.rs:68:5
[INFO] [stdout]    |
[INFO] [stdout] 68 |     fn new(suit:Suit, pip:Pip) -> Card{
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `value`
[INFO] [stdout]   --> src/main.rs:72:5
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn value(&self) -> u8 {
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Diamonds`
[INFO] [stdout]   --> src/main.rs:24:20
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |                    ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Spades`
[INFO] [stdout]   --> src/main.rs:24:30
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |                              ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Clubs`
[INFO] [stdout]   --> src/main.rs:24:38
[INFO] [stdout]    |
[INFO] [stdout] 24 | enum Suit {Hearts, Diamonds, Spades, Clubs}
[INFO] [stdout]    |                                      ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Ace`
[INFO] [stdout]   --> src/main.rs:27:10
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |          ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Two`
[INFO] [stdout]   --> src/main.rs:27:15
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |               ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Three`
[INFO] [stdout]   --> src/main.rs:27:20
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                    ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Four`
[INFO] [stdout]   --> src/main.rs:27:27
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                           ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Five`
[INFO] [stdout]   --> src/main.rs:27:33
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                 ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Six`
[INFO] [stdout]   --> src/main.rs:27:39
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                       ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Seven`
[INFO] [stdout]   --> src/main.rs:27:44
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                            ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Eight`
[INFO] [stdout]   --> src/main.rs:27:51
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                   ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Nine`
[INFO] [stdout]   --> src/main.rs:27:58
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                          ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Ten`
[INFO] [stdout]   --> src/main.rs:27:64
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Jack`
[INFO] [stdout]   --> src/main.rs:27:69
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                     ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `Queen`
[INFO] [stdout]   --> src/main.rs:27:75
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                           ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant is never constructed: `King`
[INFO] [stdout]   --> src/main.rs:27:82
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum Pip{Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King}
[INFO] [stdout]    |                                                                                  ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `new`
[INFO] [stdout]   --> src/main.rs:47:5
[INFO] [stdout]    |
[INFO] [stdout] 47 |     fn new()-> Deck{
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `deal`
[INFO] [stdout]   --> src/main.rs:57:5
[INFO] [stdout]    |
[INFO] [stdout] 57 |     fn deal(&mut self) -> Option<Card>{
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `shuffle`
[INFO] [stdout]   --> src/main.rs:61:5
[INFO] [stdout]    |
[INFO] [stdout] 61 |     fn shuffle(&mut self){
[INFO] [stdout]    |        ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `new`
[INFO] [stdout]   --> src/main.rs:68:5
[INFO] [stdout]    |
[INFO] [stdout] 68 |     fn new(suit:Suit, pip:Pip) -> Card{
[INFO] [stdout]    |        ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: associated function is never used: `value`
[INFO] [stdout]   --> src/main.rs:72:5
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn value(&self) -> u8 {
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `std::result::Result` that must be used
[INFO] [stdout]   --> src/main.rs:38:13
[INFO] [stdout]    |
[INFO] [stdout] 38 |             writeln!(f, "{}", card);
[INFO] [stdout]    |             ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]    = note: this warning originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 23 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `std::result::Result` that must be used
[INFO] [stdout]   --> src/main.rs:38:13
[INFO] [stdout]    |
[INFO] [stdout] 38 |             writeln!(f, "{}", card);
[INFO] [stdout]    |             ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]    = note: this warning originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 23 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 2.64s
[INFO] running `Command { std: "docker" "inspect" "226f578457f10981da0f25320fd64937121f01724e54e72e058e3c8c94e57e6c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "226f578457f10981da0f25320fd64937121f01724e54e72e058e3c8c94e57e6c", kill_on_drop: false }`
[INFO] [stdout] 226f578457f10981da0f25320fd64937121f01724e54e72e058e3c8c94e57e6c