[INFO] cloning repository https://github.com/vimhash/number-to-letter-converter
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/vimhash/number-to-letter-converter" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvimhash%2Fnumber-to-letter-converter", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvimhash%2Fnumber-to-letter-converter'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 89b8b4ea6d357b14a1a346ecaf2a374cbb05375b
[INFO] testing vimhash/number-to-letter-converter against 1.86.0 for beta-1.87-3
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fvimhash%2Fnumber-to-letter-converter" "/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/vimhash/number-to-letter-converter on toolchain 1.86.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.86.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/vimhash/number-to-letter-converter
[INFO] finished tweaking git repo https://github.com/vimhash/number-to-letter-converter
[INFO] tweaked toml for git repo https://github.com/vimhash/number-to-letter-converter written to /workspace/builds/worker-0-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/vimhash/number-to-letter-converter 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" "+1.86.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded quote v1.0.9
[INFO] [stderr]   Downloaded modifier v0.1.0
[INFO] [stderr]   Downloaded plugin v0.2.6
[INFO] [stderr]   Downloaded unicase v1.4.2
[INFO] [stderr]   Downloaded typemap v0.3.3
[INFO] [stderr]   Downloaded matches v0.1.8
[INFO] [stderr]   Downloaded groupable v0.2.0
[INFO] [stderr]   Downloaded mime v0.2.6
[INFO] [stderr]   Downloaded safemem v0.3.3
[INFO] [stderr]   Downloaded traitobject v0.1.0
[INFO] [stderr]   Downloaded typeable v0.1.2
[INFO] [stderr]   Downloaded percent-encoding v1.0.1
[INFO] [stderr]   Downloaded unicode-xid v0.2.1
[INFO] [stderr]   Downloaded cfg-if v1.0.0
[INFO] [stderr]   Downloaded unsafe-any v0.4.2
[INFO] [stderr]   Downloaded serde_derive v1.0.123
[INFO] [stderr]   Downloaded byteorder v1.4.2
[INFO] [stderr]   Downloaded language-tags v0.2.2
[INFO] [stderr]   Downloaded version_check v0.1.5
[INFO] [stderr]   Downloaded log v0.3.9
[INFO] [stderr]   Downloaded httparse v1.3.5
[INFO] [stderr]   Downloaded base64 v0.9.3
[INFO] [stderr]   Downloaded num_cpus v1.13.0
[INFO] [stderr]   Downloaded mustache v0.9.0
[INFO] [stderr]   Downloaded url v1.7.2
[INFO] [stderr]   Downloaded ryu v1.0.5
[INFO] [stderr]   Downloaded unicode-normalization v0.1.17
[INFO] [stderr]   Downloaded hyper v0.10.16
[INFO] [stderr]   Downloaded aho-corasick v0.7.15
[INFO] [stderr]   Downloaded serde_json v1.0.62
[INFO] [stderr]   Downloaded serde v1.0.123
[INFO] [stderr]   Downloaded nickel v0.11.0
[INFO] [stderr]   Downloaded syn v1.0.60
[INFO] [stderr]   Downloaded idna v0.1.5
[INFO] [stderr]   Downloaded regex v1.4.3
[INFO] [stderr]   Downloaded regex-syntax v0.6.22
[INFO] [stderr]   Downloaded proc-macro2 v1.0.24
[INFO] [stderr]   Downloaded once_cell v1.5.2
[INFO] [stderr]   Downloaded wasi v0.10.0+wasi-snapshot-preview1
[INFO] [stderr]   Downloaded unicode-bidi v0.3.4
[INFO] [stderr]   Downloaded lazy_static v1.4.0
[INFO] [stderr]   Downloaded log v0.4.14
[INFO] [stderr]   Downloaded memchr v2.3.4
[INFO] [stderr]   Downloaded time v0.1.44
[INFO] [stderr]   Downloaded tinyvec v1.1.1
[INFO] [stderr]   Downloaded libc v0.2.86
[INFO] [stderr]   Downloaded hermit-abi v0.1.18
[INFO] [stderr]   Downloaded thread_local v1.1.3
[INFO] [stderr]   Downloaded itoa v0.4.7
[INFO] [stderr]   Downloaded winapi v0.3.9
[INFO] [stderr]   Downloaded winapi-i686-pc-windows-gnu v0.4.0
[INFO] [stderr]   Downloaded winapi-x86_64-pc-windows-gnu v0.4.0
[INFO] [stderr]   Downloaded tinyvec_macros v0.1.0
[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:b0b074c097205a61b89e8ad263052f976b2b332c4dc5f02aef1fe52501660d6e" "/opt/rustwide/cargo-home/bin/cargo" "+1.86.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 83a48a025c90433789fa2d82f6bc9d65faa6a6edebe47a2a5682a3d7ec04f8e4
[INFO] running `Command { std: "docker" "start" "-a" "83a48a025c90433789fa2d82f6bc9d65faa6a6edebe47a2a5682a3d7ec04f8e4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "83a48a025c90433789fa2d82f6bc9d65faa6a6edebe47a2a5682a3d7ec04f8e4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "83a48a025c90433789fa2d82f6bc9d65faa6a6edebe47a2a5682a3d7ec04f8e4", kill_on_drop: false }`
[INFO] [stdout] 83a48a025c90433789fa2d82f6bc9d65faa6a6edebe47a2a5682a3d7ec04f8e4
[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=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-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:b0b074c097205a61b89e8ad263052f976b2b332c4dc5f02aef1fe52501660d6e" "/opt/rustwide/cargo-home/bin/cargo" "+1.86.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 164240b79e4bfda190c4f329a5224e0dbb4071b24e4a126b3263c5b80de564b2
[INFO] running `Command { std: "docker" "start" "-a" "164240b79e4bfda190c4f329a5224e0dbb4071b24e4a126b3263c5b80de564b2", kill_on_drop: false }`
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling tinyvec_macros v0.1.0
[INFO] [stderr]    Compiling libc v0.2.86
[INFO] [stderr]    Compiling serde v1.0.123
[INFO] [stderr]    Compiling proc-macro2 v1.0.24
[INFO] [stderr]    Compiling memchr v2.3.4
[INFO] [stderr]    Compiling unicode-xid v0.2.1
[INFO] [stderr]    Compiling httparse v1.3.5
[INFO] [stderr]    Compiling tinyvec v1.1.1
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling safemem v0.3.3
[INFO] [stderr]    Compiling log v0.3.9
[INFO] [stderr]    Compiling byteorder v1.4.2
[INFO] [stderr]    Compiling once_cell v1.5.2
[INFO] [stderr]    Compiling serde_json v1.0.62
[INFO] [stderr]    Compiling syn v1.0.60
[INFO] [stderr]    Compiling base64 v0.9.3
[INFO] [stderr]    Compiling thread_local v1.1.3
[INFO] [stderr]    Compiling aho-corasick v0.7.15
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling unicode-normalization v0.1.17
[INFO] [stderr]    Compiling time v0.1.44
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling mime v0.2.6
[INFO] [stderr]    Compiling serde_derive v1.0.123
[INFO] [stderr]    Compiling regex-syntax v0.6.22
[INFO] [stderr]    Compiling itoa v0.4.7
[INFO] [stderr]    Compiling groupable v0.2.0
[INFO] [stderr]    Compiling idna v0.1.5
[INFO] [stderr]    Compiling url v1.7.2
[INFO] [stderr]    Compiling hyper v0.10.16
[INFO] [stderr]    Compiling regex v1.4.3
[INFO] [stderr]    Compiling mustache v0.9.0
[INFO] [stderr]    Compiling nickel v0.11.0
[INFO] [stderr]    Compiling numbers_to_letters2 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]  --> src/control/cardinals.rs:2:13
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let mut result = String::from("");
[INFO] [stdout]   |             ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: maybe it is overwritten before being read?
[INFO] [stdout]   = note: `#[warn(unused_assignments)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]   --> src/control/cardinals.rs:20:13
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let mut result = String::from("");
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]  --> src/control.rs:5:13
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut result = String::from("");
[INFO] [stdout]   |             ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> src/control.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 9 |     let mut number_len = number_string.len();
[INFO] [stdout]   |         ----^^^^^^^^^^
[INFO] [stdout]   |         |
[INFO] [stdout]   |         help: remove this `mut`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]  --> src/cardinals.rs:2:13
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let mut result = String::from("");
[INFO] [stdout]   |             ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]   --> src/cardinals.rs:20:13
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let mut result = String::from("");
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 30.09s
[INFO] [stderr] warning: the following packages contain code that will be rejected by a future version of Rust: traitobject v0.1.0, typemap v0.3.3
[INFO] [stderr] note: to see what the problems were, use the option `--future-incompat-report`, or run `cargo report future-incompatibilities --id 3`
[INFO] running `Command { std: "docker" "inspect" "164240b79e4bfda190c4f329a5224e0dbb4071b24e4a126b3263c5b80de564b2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "164240b79e4bfda190c4f329a5224e0dbb4071b24e4a126b3263c5b80de564b2", kill_on_drop: false }`
[INFO] [stdout] 164240b79e4bfda190c4f329a5224e0dbb4071b24e4a126b3263c5b80de564b2
[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=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-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:b0b074c097205a61b89e8ad263052f976b2b332c4dc5f02aef1fe52501660d6e" "/opt/rustwide/cargo-home/bin/cargo" "+1.86.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 1654014d3d820a5956c8861f6c998638df4d6ff0c19b5b64eed9f40e9ee0adbd
[INFO] running `Command { std: "docker" "start" "-a" "1654014d3d820a5956c8861f6c998638df4d6ff0c19b5b64eed9f40e9ee0adbd", kill_on_drop: false }`
[INFO] [stderr]    Compiling numbers_to_letters2 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]  --> src/control/cardinals.rs:2:13
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let mut result = String::from("");
[INFO] [stdout]   |             ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: maybe it is overwritten before being read?
[INFO] [stdout]   = note: `#[warn(unused_assignments)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]   --> src/control/cardinals.rs:20:13
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let mut result = String::from("");
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]  --> src/control.rs:5:13
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut result = String::from("");
[INFO] [stdout]   |             ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> src/control.rs:9:9
[INFO] [stdout]   |
[INFO] [stdout] 9 |     let mut number_len = number_string.len();
[INFO] [stdout]   |         ----^^^^^^^^^^
[INFO] [stdout]   |         |
[INFO] [stdout]   |         help: remove this `mut`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]  --> src/cardinals.rs:2:13
[INFO] [stdout]   |
[INFO] [stdout] 2 |     let mut result = String::from("");
[INFO] [stdout]   |             ^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `result` is never read
[INFO] [stdout]   --> src/cardinals.rs:20:13
[INFO] [stdout]    |
[INFO] [stdout] 20 |     let mut result = String::from("");
[INFO] [stdout]    |             ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 1.05s
[INFO] [stderr] warning: the following packages contain code that will be rejected by a future version of Rust: traitobject v0.1.0, typemap v0.3.3
[INFO] [stderr] note: to see what the problems were, use the option `--future-incompat-report`, or run `cargo report future-incompatibilities --id 3`
[INFO] running `Command { std: "docker" "inspect" "1654014d3d820a5956c8861f6c998638df4d6ff0c19b5b64eed9f40e9ee0adbd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1654014d3d820a5956c8861f6c998638df4d6ff0c19b5b64eed9f40e9ee0adbd", kill_on_drop: false }`
[INFO] [stdout] 1654014d3d820a5956c8861f6c998638df4d6ff0c19b5b64eed9f40e9ee0adbd
[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=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-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:b0b074c097205a61b89e8ad263052f976b2b332c4dc5f02aef1fe52501660d6e" "/opt/rustwide/cargo-home/bin/cargo" "+1.86.0" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 0e4d663e435842eacf8d432508686e4a53cf33e5245793c060179d67ebc225f9
[INFO] running `Command { std: "docker" "start" "-a" "0e4d663e435842eacf8d432508686e4a53cf33e5245793c060179d67ebc225f9", kill_on_drop: false }`
[INFO] [stderr] warning: value assigned to `result` is never read
[INFO] [stderr]  --> src/control/cardinals.rs:2:13
[INFO] [stderr]   |
[INFO] [stderr] 2 |     let mut result = String::from("");
[INFO] [stderr]   |             ^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = help: maybe it is overwritten before being read?
[INFO] [stderr]   = note: `#[warn(unused_assignments)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `result` is never read
[INFO] [stderr]   --> src/control/cardinals.rs:20:13
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let mut result = String::from("");
[INFO] [stderr]    |             ^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `result` is never read
[INFO] [stderr]  --> src/control.rs:5:13
[INFO] [stderr]   |
[INFO] [stderr] 5 |     let mut result = String::from("");
[INFO] [stderr]   |             ^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]  --> src/control.rs:9:9
[INFO] [stderr]   |
[INFO] [stderr] 9 |     let mut number_len = number_string.len();
[INFO] [stderr]   |         ----^^^^^^^^^^
[INFO] [stderr]   |         |
[INFO] [stderr]   |         help: remove this `mut`
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `result` is never read
[INFO] [stderr]  --> src/cardinals.rs:2:13
[INFO] [stderr]   |
[INFO] [stderr] 2 |     let mut result = String::from("");
[INFO] [stderr]   |             ^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: value assigned to `result` is never read
[INFO] [stderr]   --> src/cardinals.rs:20:13
[INFO] [stderr]    |
[INFO] [stderr] 20 |     let mut result = String::from("");
[INFO] [stderr]    |             ^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = help: maybe it is overwritten before being read?
[INFO] [stderr] 
[INFO] [stderr] warning: `numbers_to_letters2` (bin "numbers_to_letters2" test) generated 6 warnings (run `cargo fix --bin "numbers_to_letters2" --tests` to apply 1 suggestion)
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.17s
[INFO] [stderr] warning: the following packages contain code that will be rejected by a future version of Rust: traitobject v0.1.0, typemap v0.3.3
[INFO] [stderr] note: to see what the problems were, use the option `--future-incompat-report`, or run `cargo report future-incompatibilities --id 3`
[INFO] [stderr]      Running unittests src/main.rs (/opt/rustwide/target/debug/deps/numbers_to_letters2-872f15390ec98ced)
[INFO] [stdout] 
[INFO] [stdout] running 1 test
[INFO] [stdout] test tests::test_calc ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "0e4d663e435842eacf8d432508686e4a53cf33e5245793c060179d67ebc225f9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0e4d663e435842eacf8d432508686e4a53cf33e5245793c060179d67ebc225f9", kill_on_drop: false }`
[INFO] [stdout] 0e4d663e435842eacf8d432508686e4a53cf33e5245793c060179d67ebc225f9
