[INFO] cloning repository https://github.com/max6cn/Kaleidoscope.rs
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/max6cn/Kaleidoscope.rs" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmax6cn%2FKaleidoscope.rs", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmax6cn%2FKaleidoscope.rs'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] ec1a36388ba41c058fed98dc358fe4a130e866ab
[INFO] checking max6cn/Kaleidoscope.rs against master#bca37a20bd376ce3fd138e7cdee7fe704e0f8814 for pr-139493-3
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmax6cn%2FKaleidoscope.rs" "/workspace/builds/worker-2-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/max6cn/Kaleidoscope.rs
[INFO] finished tweaking git repo https://github.com/max6cn/Kaleidoscope.rs
[INFO] tweaked toml for git repo https://github.com/max6cn/Kaleidoscope.rs written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/max6cn/Kaleidoscope.rs on toolchain bca37a20bd376ce3fd138e7cdee7fe704e0f8814
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+bca37a20bd376ce3fd138e7cdee7fe704e0f8814" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/max6cn/Kaleidoscope.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" "+bca37a20bd376ce3fd138e7cdee7fe704e0f8814" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr] warning: no edition set: defaulting to the 2015 edition while the latest is 2024
[INFO] [stderr]     Updating git repository `https://github.com/TheDan64/inkwell`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded serde_derive v1.0.99
[INFO] [stderr]   Downloaded cargo_toml v0.6.4
[INFO] [stderr]   Downloaded enum-methods v0.0.8
[INFO] [stderr]   Downloaded cc v1.0.40
[INFO] [stderr]   Downloaded proc-macro2 v1.0.1
[INFO] [stderr]   Downloaded llvm-sys v80.1.1
[INFO] [stderr]   Downloaded regex-syntax v0.6.11
[INFO] [stderr]   Downloaded serde v1.0.99
[INFO] [stderr]   Downloaded syn v1.0.3
[INFO] [stderr]   Downloaded regex v1.2.1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:aa71247004a7fa38d13ec170f48f06cdedf5bc50b2a8645e56ed7e992e6fa513" "/opt/rustwide/cargo-home/bin/cargo" "+bca37a20bd376ce3fd138e7cdee7fe704e0f8814" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 878298d216e8f00d1c0272ae244ade3bef71f2caa613c6fb49583d87350aafb4
[INFO] running `Command { std: "docker" "start" "-a" "878298d216e8f00d1c0272ae244ade3bef71f2caa613c6fb49583d87350aafb4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "878298d216e8f00d1c0272ae244ade3bef71f2caa613c6fb49583d87350aafb4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "878298d216e8f00d1c0272ae244ade3bef71f2caa613c6fb49583d87350aafb4", kill_on_drop: false }`
[INFO] [stdout] 878298d216e8f00d1c0272ae244ade3bef71f2caa613c6fb49583d87350aafb4
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-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:aa71247004a7fa38d13ec170f48f06cdedf5bc50b2a8645e56ed7e992e6fa513" "/opt/rustwide/cargo-home/bin/cargo" "+bca37a20bd376ce3fd138e7cdee7fe704e0f8814" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 8c2d3d2ff3e7db539c4f9568f9131858dacd5e2851d182db6c33701323cb018a
[INFO] running `Command { std: "docker" "start" "-a" "8c2d3d2ff3e7db539c4f9568f9131858dacd5e2851d182db6c33701323cb018a", kill_on_drop: false }`
[INFO] [stderr] warning: no edition set: defaulting to the 2015 edition while the latest is 2024
[INFO] [stderr]    Compiling proc-macro2 v1.0.1
[INFO] [stderr]    Compiling syn v1.0.3
[INFO] [stderr]    Compiling serde v1.0.99
[INFO] [stderr]    Compiling memchr v2.2.1
[INFO] [stderr]    Compiling lazy_static v1.3.0
[INFO] [stderr]    Compiling libc v0.2.62
[INFO] [stderr]    Compiling regex-syntax v0.6.11
[INFO] [stderr]    Compiling cc v1.0.40
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling inkwell v0.1.0 (https://github.com/TheDan64/inkwell?branch=llvm8-0#bbe67cca)
[INFO] [stderr]     Checking log v0.4.8
[INFO] [stderr]    Compiling enum-methods v0.0.8
[INFO] [stderr]     Checking humantime v1.2.0
[INFO] [stderr]     Checking termcolor v1.0.5
[INFO] [stderr]     Checking either v1.5.2
[INFO] [stderr]    Compiling thread_local v0.3.6
[INFO] [stderr]    Compiling aho-corasick v0.7.6
[INFO] [stderr]    Compiling quote v1.0.2
[INFO] [stderr]     Checking atty v0.2.13
[INFO] [stderr]     Checking regex v1.2.1
[INFO] [stderr]    Compiling serde_derive v1.0.99
[INFO] [stderr]     Checking env_logger v0.6.2
[INFO] [stderr]    Compiling toml v0.4.10
[INFO] [stderr]    Compiling llvm-sys v80.1.1
[INFO] [stderr]    Compiling cargo_toml v0.6.4
[INFO] [stderr]    Compiling inkwell_internal_macros v0.1.0 (https://github.com/TheDan64/inkwell?branch=llvm8-0#bbe67cca)
[INFO] [stderr]     Checking Kaleidoscope v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `inkwell::FloatPredicate`
[INFO] [stdout]  --> src/lib/codegen.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use inkwell::FloatPredicate;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `Parser` and `Token`
[INFO] [stdout]  --> src/lib/codegen.rs:8:6
[INFO] [stdout]   |
[INFO] [stdout] 8 | use {Parser, Token};
[INFO] [stdout]   |      ^^^^^^  ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `codegen::*`
[INFO] [stdout]  --> src/lib/parser.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 7 | use codegen::*;
[INFO] [stdout]   |     ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `inkwell::FloatPredicate`
[INFO] [stdout]  --> src/lib/codegen.rs:6:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | use inkwell::FloatPredicate;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `Parser` and `Token`
[INFO] [stdout]  --> src/lib/codegen.rs:8:6
[INFO] [stdout]   |
[INFO] [stdout] 8 | use {Parser, Token};
[INFO] [stdout]   |      ^^^^^^  ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Token`
[INFO] [stdout]    --> src/lib/codegen.rs:106:18
[INFO] [stdout]     |
[INFO] [stdout] 106 |     use {Parser, Token};
[INFO] [stdout]     |                  ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `codegen::*`
[INFO] [stdout]  --> src/lib/parser.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 7 | use codegen::*;
[INFO] [stdout]   |     ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `llvm`
[INFO] [stdout]   --> src/lib/codegen.rs:82:23
[INFO] [stdout]    |
[INFO] [stdout] 82 |     fn codegen(&self, llvm: &LLVM) -> Result<FloatValue, &'static str> {
[INFO] [stdout]    |                       ^^^^ help: if this is intentional, prefix it with an underscore: `_llvm`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `llvm`
[INFO] [stdout]   --> src/lib/codegen.rs:88:23
[INFO] [stdout]    |
[INFO] [stdout] 88 |     fn codegen(&self, llvm: &LLVM) -> Result<FloatValue, &'static str> {
[INFO] [stdout]    |                       ^^^^ help: if this is intentional, prefix it with an underscore: `_llvm`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `llvm`
[INFO] [stdout]   --> src/lib/codegen.rs:93:23
[INFO] [stdout]    |
[INFO] [stdout] 93 |     fn codegen(&self, llvm: &LLVM) -> Result<FloatValue, &'static str> {
[INFO] [stdout]    |                       ^^^^ help: if this is intentional, prefix it with an underscore: `_llvm`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `module` is never read
[INFO] [stdout]   --> src/lib/codegen.rs:14:5
[INFO] [stdout]    |
[INFO] [stdout] 11 | pub struct LLVM {
[INFO] [stdout]    |            ---- field in this struct
[INFO] [stdout] ...
[INFO] [stdout] 14 |     module: Module,
[INFO] [stdout]    |     ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `llvm`
[INFO] [stdout]   --> src/lib/codegen.rs:82:23
[INFO] [stdout]    |
[INFO] [stdout] 82 |     fn codegen(&self, llvm: &LLVM) -> Result<FloatValue, &'static str> {
[INFO] [stdout]    |                       ^^^^ help: if this is intentional, prefix it with an underscore: `_llvm`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `llvm`
[INFO] [stdout]   --> src/lib/codegen.rs:88:23
[INFO] [stdout]    |
[INFO] [stdout] 88 |     fn codegen(&self, llvm: &LLVM) -> Result<FloatValue, &'static str> {
[INFO] [stdout]    |                       ^^^^ help: if this is intentional, prefix it with an underscore: `_llvm`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `llvm`
[INFO] [stdout]   --> src/lib/codegen.rs:93:23
[INFO] [stdout]    |
[INFO] [stdout] 93 |     fn codegen(&self, llvm: &LLVM) -> Result<FloatValue, &'static str> {
[INFO] [stdout]    |                       ^^^^ help: if this is intentional, prefix it with an underscore: `_llvm`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/lib/codegen.rs:134:17
[INFO] [stdout]     |
[INFO] [stdout] 134 |             let mut llvm = LLVM {
[INFO] [stdout]     |                 ----^^^^
[INFO] [stdout]     |                 |
[INFO] [stdout]     |                 help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `module` is never read
[INFO] [stdout]   --> src/lib/codegen.rs:14:5
[INFO] [stdout]    |
[INFO] [stdout] 11 | pub struct LLVM {
[INFO] [stdout]    |            ---- field in this struct
[INFO] [stdout] ...
[INFO] [stdout] 14 |     module: Module,
[INFO] [stdout]    |     ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Write`
[INFO] [stdout]  --> src/bin/main.rs:7:21
[INFO] [stdout]   |
[INFO] [stdout] 7 | use std::io::{Read, Write};
[INFO] [stdout]   |                     ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::str::Chars`
[INFO] [stdout]  --> src/bin/main.rs:8:5
[INFO] [stdout]   |
[INFO] [stdout] 8 | use std::str::Chars;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/main.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let mut line = "".to_owned();
[INFO] [stdout]    |         ----^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/main.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let mut should_quit = false;
[INFO] [stdout]    |         ----^^^^^^^^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `line`
[INFO] [stdout]   --> src/bin/main.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let mut line = "".to_owned();
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_line`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `should_quit`
[INFO] [stdout]   --> src/bin/main.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let mut should_quit = false;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_should_quit`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/main.rs:25:9
[INFO] [stdout]    |
[INFO] [stdout] 25 |         std::io::stdin().read_exact(&mut c);
[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] 25 |         let _ = std::io::stdin().read_exact(&mut c);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/main.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |         tx_char_stream.send(c as char);
[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] 27 |         let _ = tx_char_stream.send(c as char);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Write`
[INFO] [stdout]  --> src/bin/main.rs:7:21
[INFO] [stdout]   |
[INFO] [stdout] 7 | use std::io::{Read, Write};
[INFO] [stdout]   |                     ^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::str::Chars`
[INFO] [stdout]  --> src/bin/main.rs:8:5
[INFO] [stdout]   |
[INFO] [stdout] 8 | use std::str::Chars;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/main.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let mut line = "".to_owned();
[INFO] [stdout]    |         ----^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/main.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let mut should_quit = false;
[INFO] [stdout]    |         ----^^^^^^^^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `line`
[INFO] [stdout]   --> src/bin/main.rs:18:9
[INFO] [stdout]    |
[INFO] [stdout] 18 |     let mut line = "".to_owned();
[INFO] [stdout]    |         ^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_line`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `should_quit`
[INFO] [stdout]   --> src/bin/main.rs:19:9
[INFO] [stdout]    |
[INFO] [stdout] 19 |     let mut should_quit = false;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_should_quit`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/main.rs:25:9
[INFO] [stdout]    |
[INFO] [stdout] 25 |         std::io::stdin().read_exact(&mut c);
[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] 25 |         let _ = std::io::stdin().read_exact(&mut c);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/bin/main.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |         tx_char_stream.send(c as char);
[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] 27 |         let _ = tx_char_stream.send(c as char);
[INFO] [stdout]    |         +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 18.32s
[INFO] running `Command { std: "docker" "inspect" "8c2d3d2ff3e7db539c4f9568f9131858dacd5e2851d182db6c33701323cb018a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8c2d3d2ff3e7db539c4f9568f9131858dacd5e2851d182db6c33701323cb018a", kill_on_drop: false }`
[INFO] [stdout] 8c2d3d2ff3e7db539c4f9568f9131858dacd5e2851d182db6c33701323cb018a
