[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] error: copy-fd: write returned: No space left on device
[INFO] [stderr] fatal: cannot copy '/usr/share/git-core/templates/info/exclude' to '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust/info/exclude': No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 1)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 2)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 3)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 4)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 5)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 6)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 7)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 8)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 9)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 10)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 11)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 12)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] [stderr] /workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust: No space left on device
[WARN] Retrying crate fetch in 3 seconds (attempt 13)
[INFO] cloning repository https://github.com/matvey-tytarenko/calculator-Rust
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/matvey-tytarenko/calculator-Rust" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 295c13ccdb05d8d5537f8b443ae92b798b0684a2
[INFO] checking matvey-tytarenko/calculator-Rust against master#336209eef13882bd1e211b24779584cb7ef911eb for pr-129249
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatvey-tytarenko%2Fcalculator-Rust" "/workspace/builds/worker-0-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/matvey-tytarenko/calculator-Rust on toolchain 336209eef13882bd1e211b24779584cb7ef911eb
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+336209eef13882bd1e211b24779584cb7ef911eb" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/matvey-tytarenko/calculator-Rust
[INFO] finished tweaking git repo https://github.com/matvey-tytarenko/calculator-Rust
[INFO] tweaked toml for git repo https://github.com/matvey-tytarenko/calculator-Rust written to /workspace/builds/worker-0-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/matvey-tytarenko/calculator-Rust 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" "+336209eef13882bd1e211b24779584cb7ef911eb" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:f3a9d4ad9d972b27faf3965f35b62e55ba32bbce8f20bc8fe909558a86702fde" "/opt/rustwide/cargo-home/bin/cargo" "+336209eef13882bd1e211b24779584cb7ef911eb" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 8aa946fc58e0c55fbd438ecc3dfa4c925055c5a96fd6ed54a6334b86170d7fa7
[INFO] running `Command { std: "docker" "start" "-a" "8aa946fc58e0c55fbd438ecc3dfa4c925055c5a96fd6ed54a6334b86170d7fa7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8aa946fc58e0c55fbd438ecc3dfa4c925055c5a96fd6ed54a6334b86170d7fa7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8aa946fc58e0c55fbd438ecc3dfa4c925055c5a96fd6ed54a6334b86170d7fa7", kill_on_drop: false }`
[INFO] [stdout] 8aa946fc58e0c55fbd438ecc3dfa4c925055c5a96fd6ed54a6334b86170d7fa7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=forbid" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:f3a9d4ad9d972b27faf3965f35b62e55ba32bbce8f20bc8fe909558a86702fde" "/opt/rustwide/cargo-home/bin/cargo" "+336209eef13882bd1e211b24779584cb7ef911eb" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] a570ba2f61200320116373d2dce2dfbc2f6f87e13b4151a69d1a3a355de61e01
[INFO] running `Command { std: "docker" "start" "-a" "a570ba2f61200320116373d2dce2dfbc2f6f87e13b4151a69d1a3a355de61e01", kill_on_drop: false }`
[INFO] [stderr]     Checking calculator_2 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: named argument `num_first` is not used by name
[INFO] [stdout]   --> src/main.rs:40:31
[INFO] [stdout]    |
[INFO] [stdout] 40 |         "=" => println!("{}", num_first = num_second),
[INFO] [stdout]    |                          --   ^^^^^^^^^ this named argument is referred to by position in formatting string
[INFO] [stdout]    |                          |
[INFO] [stdout]    |                          this formatting argument uses named argument `num_first` by position
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(named_arguments_used_positionally)]` on by default
[INFO] [stdout] help: use the named argument by name to avoid ambiguity
[INFO] [stdout]    |
[INFO] [stdout] 40 |         "=" => println!("{num_first}", num_first = num_second),
[INFO] [stdout]    |                           +++++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: named argument `num_first` is not used by name
[INFO] [stdout]   --> src/main.rs:40:31
[INFO] [stdout]    |
[INFO] [stdout] 40 |         "=" => println!("{}", num_first = num_second),
[INFO] [stdout]    |                          --   ^^^^^^^^^ this named argument is referred to by position in formatting string
[INFO] [stdout]    |                          |
[INFO] [stdout]    |                          this formatting argument uses named argument `num_first` by position
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(named_arguments_used_positionally)]` on by default
[INFO] [stdout] help: use the named argument by name to avoid ambiguity
[INFO] [stdout]    |
[INFO] [stdout] 40 |         "=" => println!("{num_first}", num_first = num_second),
[INFO] [stdout]    |                           +++++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:10:5
[INFO] [stdout]    |
[INFO] [stdout] 10 |     input.read_line(&mut num_a);
[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)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let _ = input.read_line(&mut num_a);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:13:5
[INFO] [stdout]    |
[INFO] [stdout] 13 |     input.read_line(&mut num_b);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let _ = input.read_line(&mut num_b);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:16:5
[INFO] [stdout]    |
[INFO] [stdout] 16 |     input.read_line(&mut operator);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let _ = input.read_line(&mut operator);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:53:5
[INFO] [stdout]    |
[INFO] [stdout] 53 |     input.read_line(&mut exit);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 53 |     let _ = input.read_line(&mut exit);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:10:5
[INFO] [stdout]    |
[INFO] [stdout] 10 |     input.read_line(&mut num_a);
[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)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 10 |     let _ = input.read_line(&mut num_a);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:13:5
[INFO] [stdout]    |
[INFO] [stdout] 13 |     input.read_line(&mut num_b);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let _ = input.read_line(&mut num_b);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:16:5
[INFO] [stdout]    |
[INFO] [stdout] 16 |     input.read_line(&mut operator);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 16 |     let _ = input.read_line(&mut operator);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/main.rs:53:5
[INFO] [stdout]    |
[INFO] [stdout] 53 |     input.read_line(&mut exit);
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 53 |     let _ = input.read_line(&mut exit);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.08s
[INFO] running `Command { std: "docker" "inspect" "a570ba2f61200320116373d2dce2dfbc2f6f87e13b4151a69d1a3a355de61e01", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a570ba2f61200320116373d2dce2dfbc2f6f87e13b4151a69d1a3a355de61e01", kill_on_drop: false }`
[INFO] [stdout] a570ba2f61200320116373d2dce2dfbc2f6f87e13b4151a69d1a3a355de61e01