[INFO] cloning repository https://github.com/eda3/rust_by_example
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/eda3/rust_by_example" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feda3%2Frust_by_example", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feda3%2Frust_by_example'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 6a6ce944bf302d0525297dbb34073341a008778a
[INFO] checking eda3/rust_by_example against try#de39175d9e0f63ff8967b81f9639ba28d11ae6ef for pr-135331
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feda3%2Frust_by_example" "/workspace/builds/worker-5-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/eda3/rust_by_example on toolchain de39175d9e0f63ff8967b81f9639ba28d11ae6ef
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+de39175d9e0f63ff8967b81f9639ba28d11ae6ef" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/eda3/rust_by_example
[INFO] finished tweaking git repo https://github.com/eda3/rust_by_example
[INFO] tweaked toml for git repo https://github.com/eda3/rust_by_example written to /workspace/builds/worker-5-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/eda3/rust_by_example 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" "+de39175d9e0f63ff8967b81f9639ba28d11ae6ef" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[INFO] checking eda3/rust_by_example against try#de39175d9e0f63ff8967b81f9639ba28d11ae6ef for pr-135331
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Feda3%2Frust_by_example" "/workspace/builds/worker-5-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/eda3/rust_by_example on toolchain de39175d9e0f63ff8967b81f9639ba28d11ae6ef
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+de39175d9e0f63ff8967b81f9639ba28d11ae6ef" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/eda3/rust_by_example
[INFO] finished tweaking git repo https://github.com/eda3/rust_by_example
[INFO] tweaked toml for git repo https://github.com/eda3/rust_by_example written to /workspace/builds/worker-5-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/eda3/rust_by_example 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" "+de39175d9e0f63ff8967b81f9639ba28d11ae6ef" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/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" "+de39175d9e0f63ff8967b81f9639ba28d11ae6ef" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2fadde3bd3815bd96fa8923c59c0d0d691c520fd5c09593c2e59e391c190bdd5
[INFO] running `Command { std: "docker" "start" "-a" "2fadde3bd3815bd96fa8923c59c0d0d691c520fd5c09593c2e59e391c190bdd5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2fadde3bd3815bd96fa8923c59c0d0d691c520fd5c09593c2e59e391c190bdd5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2fadde3bd3815bd96fa8923c59c0d0d691c520fd5c09593c2e59e391c190bdd5", kill_on_drop: false }`
[INFO] [stdout] 2fadde3bd3815bd96fa8923c59c0d0d691c520fd5c09593c2e59e391c190bdd5
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc2/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" "+de39175d9e0f63ff8967b81f9639ba28d11ae6ef" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 0bab64cb7ad0dd22fd74766a93eb84d3241ead015ed7fcb2116bd9c12bb60f25
[INFO] running `Command { std: "docker" "start" "-a" "0bab64cb7ad0dd22fd74766a93eb84d3241ead015ed7fcb2116bd9c12bb60f25", kill_on_drop: false }`
[INFO] [stderr]     Checking rust_by_example v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `short_lived_binding`
[INFO] [stdout]  --> src/bin/04-2-0_scope.rs:8:9
[INFO] [stdout]   |
[INFO] [stdout] 8 |     let short_lived_binding = 2;
[INFO] [stdout]   |         ^^^^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_short_lived_binding`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `S` is never constructed
[INFO] [stdout]  --> src/bin/14-2-0_impl.rs:1:8
[INFO] [stdout]   |
[INFO] [stdout] 1 | struct S; // 具象型`S`
[INFO] [stdout]   |        ^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `GenericVal` is never constructed
[INFO] [stdout]  --> src/bin/14-2-0_impl.rs:3:8
[INFO] [stdout]   |
[INFO] [stdout] 3 | struct GenericVal<T>(T); // ジェネリック型`GenericVal`
[INFO] [stdout]   |        ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `UnPrintable` is never constructed
[INFO] [stdout]  --> src/bin/01-2-1-0_print_debug.rs:2:8
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct UnPrintable(i32); // -> printデバッグできない
[INFO] [stdout]   |        ^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/bin/01-2-1-0_print_debug.rs:7:23
[INFO] [stdout]   |
[INFO] [stdout] 7 | struct DebugPrintable(i32); // -> printデバッグできる
[INFO] [stdout]   |        -------------- ^^^
[INFO] [stdout]   |        |
[INFO] [stdout]   |        field in this struct
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider removing this field
[INFO] [stdout]   = note: `DebugPrintable` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `name` and `age` are never read
[INFO] [stdout]   --> src/bin/01-2-1-0_print_debug.rs:12:3
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Person<'a> {
[INFO] [stdout]    |        ------ fields in this struct
[INFO] [stdout] 12 |   name: &'a str,
[INFO] [stdout]    |   ^^^^
[INFO] [stdout] 13 |   age: u8,
[INFO] [stdout]    |   ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Person` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `value` is never read
[INFO] [stdout]   --> src/bin/06-1-0_from_into.rs:24:3
[INFO] [stdout]    |
[INFO] [stdout] 23 | struct Number {
[INFO] [stdout]    |        ------ field in this struct
[INFO] [stdout] 24 |   value: i32,
[INFO] [stdout]    |   ^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Number` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `name` and `age` are never read
[INFO] [stdout]  --> src/bin/03-1-0_structs.rs:4:3
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct Person<'a> {
[INFO] [stdout]   |        ------ fields in this struct
[INFO] [stdout] 3 |   // 'a はライフタイムの設定
[INFO] [stdout] 4 |   name: &'a str,
[INFO] [stdout]   |   ^^^^
[INFO] [stdout] 5 |   age: u8,
[INFO] [stdout]   |   ^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `Person` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `printer` is never used
[INFO] [stdout]  --> src/bin/14-4-0_bounds.rs:8:4
[INFO] [stdout]   |
[INFO] [stdout] 8 | fn printer<T: Display>(t: T) {
[INFO] [stdout]   |    ^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `length` and `height` are never read
[INFO] [stdout]   --> src/bin/14-4-0_bounds.rs:30:3
[INFO] [stdout]    |
[INFO] [stdout] 29 | struct Triangle {
[INFO] [stdout]    |        -------- fields in this struct
[INFO] [stdout] 30 |   length: f64,
[INFO] [stdout]    |   ^^^^^^
[INFO] [stdout] 31 |   height: f64,
[INFO] [stdout]    |   ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Triangle` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/bin/03-2-0_enum.rs:64:7
[INFO] [stdout]    |
[INFO] [stdout] 64 |   let x = Operations::Add;
[INFO] [stdout]    |       ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `Subtract` is never constructed
[INFO] [stdout]   --> src/bin/03-2-0_enum.rs:29:3
[INFO] [stdout]    |
[INFO] [stdout] 27 | enum VeriVerboseEnumOfThingsToDoWithNumbers {
[INFO] [stdout]    |      -------------------------------------- variant in this enum
[INFO] [stdout] 28 |   Add,
[INFO] [stdout] 29 |   Subtract,
[INFO] [stdout]    |   ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `run` is never used
[INFO] [stdout]   --> src/bin/03-2-0_enum.rs:36:6
[INFO] [stdout]    |
[INFO] [stdout] 35 | impl Operations {
[INFO] [stdout]    | --------------- method in this implementation
[INFO] [stdout] 36 |   fn run(&self, x: i32, y: i32) -> i32 {
[INFO] [stdout]    |      ^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: path statement with no effect
[INFO] [stdout]  --> src/bin/07-0_expression.rs:6:3
[INFO] [stdout]   |
[INFO] [stdout] 6 |   x;
[INFO] [stdout]   |   ^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(path_statements)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused arithmetic operation that must be used
[INFO] [stdout]  --> src/bin/07-0_expression.rs:7:3
[INFO] [stdout]   |
[INFO] [stdout] 7 |   x + 1;
[INFO] [stdout]   |   ^^^^^ the arithmetic operation produces a value
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]   |
[INFO] [stdout] 7 |   let _ = x + 1;
[INFO] [stdout]   |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused arithmetic operation that must be used
[INFO] [stdout]   --> src/bin/07-0_expression.rs:22:5
[INFO] [stdout]    |
[INFO] [stdout] 22 |     2 * x;
[INFO] [stdout]    |     ^^^^^ the arithmetic operation produces a value
[INFO] [stdout]    |
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]    |
[INFO] [stdout] 22 |     let _ = 2 * x;
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0425]: cannot find value `integer` in this scope
[INFO] [stdout]   --> src/bin/02-0_primitives.rs:13:17
[INFO] [stdout]    |
[INFO] [stdout] 13 |   let default = integer = 7; // i32
[INFO] [stdout]    |                 ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] help: you might have meant to introduce a new binding
[INFO] [stdout]    |
[INFO] [stdout] 13 |   let default = let integer = 7; // i32
[INFO] [stdout]    |                 +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `rust_by_example` (bin "02-0_primitives") due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] warning: struct `UnPrintable` is never constructed
[INFO] [stdout]  --> src/bin/01-2-1-0_print_debug.rs:2:8
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct UnPrintable(i32); // -> printデバッグできない
[INFO] [stdout]   |        ^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/bin/01-2-1-0_print_debug.rs:7:23
[INFO] [stdout]   |
[INFO] [stdout] 7 | struct DebugPrintable(i32); // -> printデバッグできる
[INFO] [stdout]   |        -------------- ^^^
[INFO] [stdout]   |        |
[INFO] [stdout]   |        field in this struct
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider removing this field
[INFO] [stdout]   = note: `DebugPrintable` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `name` and `age` are never read
[INFO] [stdout]   --> src/bin/01-2-1-0_print_debug.rs:12:3
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct Person<'a> {
[INFO] [stdout]    |        ------ fields in this struct
[INFO] [stdout] 12 |   name: &'a str,
[INFO] [stdout]    |   ^^^^
[INFO] [stdout] 13 |   age: u8,
[INFO] [stdout]    |   ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Person` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/bin/15-4-4_struct.rs:5:21
[INFO] [stdout]   |
[INFO] [stdout] 5 | struct Borrowed<'a>(&'a i32);
[INFO] [stdout]   |        --------     ^^^^^^^
[INFO] [stdout]   |        |
[INFO] [stdout]   |        field in this struct
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider removing this field
[INFO] [stdout]   = note: `Borrowed` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: fields `x` and `y` are never read
[INFO] [stdout]   --> src/bin/15-4-4_struct.rs:10:3
[INFO] [stdout]    |
[INFO] [stdout] 9  | struct NamedBorrowed<'a> {
[INFO] [stdout]    |        ------------- fields in this struct
[INFO] [stdout] 10 |   x: &'a i32,
[INFO] [stdout]    |   ^
[INFO] [stdout] 11 |   y: &'a i32,
[INFO] [stdout]    |   ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `NamedBorrowed` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]   --> src/bin/15-4-4_struct.rs:17:7
[INFO] [stdout]    |
[INFO] [stdout] 17 |   Num(i32),
[INFO] [stdout]    |   --- ^^^
[INFO] [stdout]    |   |
[INFO] [stdout]    |   field in this variant
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Either` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]    |
[INFO] [stdout] 17 |   Num(()),
[INFO] [stdout]    |       ~~
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]   --> src/bin/15-4-4_struct.rs:18:7
[INFO] [stdout]    |
[INFO] [stdout] 18 |   Ref(&'a i32),
[INFO] [stdout]    |   --- ^^^^^^^
[INFO] [stdout]    |   |
[INFO] [stdout]    |   field in this variant
[INFO] [stdout]    |
[INFO] [stdout]    = note: `Either` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] help: consider changing the field to be of unit type to suppress this warning while preserving the field numbering, or remove the field
[INFO] [stdout]    |
[INFO] [stdout] 18 |   Ref(()),
[INFO] [stdout]    |       ~~
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `x` is never read
[INFO] [stdout]  --> src/bin/15-4-5_trait.rs:3:3
[INFO] [stdout]   |
[INFO] [stdout] 2 | struct Borrowed<'a> {
[INFO] [stdout]   |        -------- field in this struct
[INFO] [stdout] 3 |   x: &'a i32,
[INFO] [stdout]   |   ^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `Borrowed` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0425]: cannot find value `integer` in this scope
[INFO] [stdout]   --> src/bin/02-0_primitives.rs:13:17
[INFO] [stdout]    |
[INFO] [stdout] 13 |   let default = integer = 7; // i32
[INFO] [stdout]    |                 ^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] help: you might have meant to introduce a new binding
[INFO] [stdout]    |
[INFO] [stdout] 13 |   let default = let integer = 7; // i32
[INFO] [stdout]    |                 +++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0425`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `rust_by_example` (bin "02-0_primitives" test) due to 1 previous error
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]  --> src/bin/15-4-6_lifetime_bounds.rs:4:23
[INFO] [stdout]   |
[INFO] [stdout] 4 | struct Ref<'a, T: 'a>(&'a T);
[INFO] [stdout]   |        ---            ^^^^^
[INFO] [stdout]   |        |
[INFO] [stdout]   |        field in this struct
[INFO] [stdout]   |
[INFO] [stdout]   = help: consider removing this field
[INFO] [stdout]   = note: `Ref` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "0bab64cb7ad0dd22fd74766a93eb84d3241ead015ed7fcb2116bd9c12bb60f25", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0bab64cb7ad0dd22fd74766a93eb84d3241ead015ed7fcb2116bd9c12bb60f25", kill_on_drop: false }`
[INFO] [stdout] 0bab64cb7ad0dd22fd74766a93eb84d3241ead015ed7fcb2116bd9c12bb60f25