[INFO] cloning repository https://github.com/Little-Captain/dive-into-rust-of-fcc
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/Little-Captain/dive-into-rust-of-fcc" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLittle-Captain%2Fdive-into-rust-of-fcc", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLittle-Captain%2Fdive-into-rust-of-fcc'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 36807d3bef5728e0c2894fbf31cb03c86bc02ce6
[INFO] checking Little-Captain/dive-into-rust-of-fcc against try#8a2f6fe57adadb246778b8d41925d3dc46d468cb for pr-158320
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLittle-Captain%2Fdive-into-rust-of-fcc" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/Little-Captain/dive-into-rust-of-fcc
[INFO] finished tweaking git repo https://github.com/Little-Captain/dive-into-rust-of-fcc
[INFO] tweaked toml for git repo https://github.com/Little-Captain/dive-into-rust-of-fcc written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/Little-Captain/dive-into-rust-of-fcc on toolchain 8a2f6fe57adadb246778b8d41925d3dc46d468cb
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+8a2f6fe57adadb246778b8d41925d3dc46d468cb" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/Little-Captain/dive-into-rust-of-fcc 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" "+8a2f6fe57adadb246778b8d41925d3dc46d468cb" "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-3-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,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" "-m" "1610612736" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:3a6becf2bc8dde7f3fa57ede90e4f284e72d296796fc446bbb1e2c7cc0530151" "sleep" "infinity", kill_on_drop: false }`
[INFO] [stdout] 21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14
[INFO] running `Command { std: "docker" "start" "21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "exec" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-w" "/opt/rustwide/workdir" "--user" "0:0" "21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14" "/opt/rustwide/cargo-home/bin/cargo" "+8a2f6fe57adadb246778b8d41925d3dc46d468cb" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "exec" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-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" "-w" "/opt/rustwide/workdir" "--user" "0:0" "21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14" "/opt/rustwide/cargo-home/bin/cargo" "+8a2f6fe57adadb246778b8d41925d3dc46d468cb" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr]     Checking dive-into-rust-of-fcc v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unnecessary parentheses around assigned value
[INFO] [stdout]   --> src/ch02/third.rs:11:13
[INFO] [stdout]    |
[INFO] [stdout] 11 |     let b = (0);
[INFO] [stdout]    |             ^ ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_parens)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 11 -     let b = (0);
[INFO] [stdout] 11 +     let b = 0;
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `dog` should have an upper camel case name
[INFO] [stdout]    --> src/ch02/third.rs:213:9
[INFO] [stdout]     |
[INFO] [stdout] 213 |         dog = 1,
[INFO] [stdout]     |         ^^^ help: convert the identifier to upper camel case: `Dog`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(non_camel_case_types)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `cat` should have an upper camel case name
[INFO] [stdout]    --> src/ch02/third.rs:214:9
[INFO] [stdout]     |
[INFO] [stdout] 214 |         cat = 200,
[INFO] [stdout]     |         ^^^ help: convert the identifier to upper camel case (notice the capitalization): `Cat`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `tiger` should have an upper camel case name
[INFO] [stdout]    --> src/ch02/third.rs:215:9
[INFO] [stdout]     |
[INFO] [stdout] 215 |         tiger,
[INFO] [stdout]     |         ^^^^^ help: convert the identifier to upper camel case: `Tiger`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused label
[INFO] [stdout]   --> src/ch03/second.rs:72:13
[INFO] [stdout]    |
[INFO] [stdout] 72 |             'b: loop {
[INFO] [stdout]    |             ^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_labels)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary trailing semicolon
[INFO] [stdout]   --> src/ch09/first.rs:65:47
[INFO] [stdout]    |
[INFO] [stdout] 65 |                 $( map.insert($key, $val); ) *;
[INFO] [stdout]    |                                               ^
[INFO] [stdout] ...
[INFO] [stdout] 70 |     let counts = hashmap!['A' => 0, 'C' => 0, 'G' => 0, 'T' => 0];
[INFO] [stdout]    |                  ------------------------------------------------ in this macro invocation
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(redundant_semicolons)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout]    = note: this warning originates in the macro `hashmap` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Int`
[INFO] [stdout]   --> src/ch13/first.rs:87:32
[INFO] [stdout]    |
[INFO] [stdout] 87 |         use StringOrInt::{Str, Int};
[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: `BorrowError`, `BorrowMutError`, `Cell`, and `RefMut`
[INFO] [stdout]   --> src/ch15/first.rs:17:17
[INFO] [stdout]    |
[INFO] [stdout] 17 | use std::cell::{BorrowError, RefMut, BorrowMutError, Cell};
[INFO] [stdout]    |                 ^^^^^^^^^^^  ^^^^^^  ^^^^^^^^^^^^^^  ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary parentheses around assigned value
[INFO] [stdout]   --> src/ch02/third.rs:11:13
[INFO] [stdout]    |
[INFO] [stdout] 11 |     let b = (0);
[INFO] [stdout]    |             ^ ^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_parens)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] help: remove these parentheses
[INFO] [stdout]    |
[INFO] [stdout] 11 -     let b = (0);
[INFO] [stdout] 11 +     let b = 0;
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `dog` should have an upper camel case name
[INFO] [stdout]    --> src/ch02/third.rs:213:9
[INFO] [stdout]     |
[INFO] [stdout] 213 |         dog = 1,
[INFO] [stdout]     |         ^^^ help: convert the identifier to upper camel case: `Dog`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(non_camel_case_types)]` (part of `#[warn(nonstandard_style)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `cat` should have an upper camel case name
[INFO] [stdout]    --> src/ch02/third.rs:214:9
[INFO] [stdout]     |
[INFO] [stdout] 214 |         cat = 200,
[INFO] [stdout]     |         ^^^ help: convert the identifier to upper camel case (notice the capitalization): `Cat`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `tiger` should have an upper camel case name
[INFO] [stdout]    --> src/ch02/third.rs:215:9
[INFO] [stdout]     |
[INFO] [stdout] 215 |         tiger,
[INFO] [stdout]     |         ^^^^^ help: convert the identifier to upper camel case: `Tiger`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused label
[INFO] [stdout]   --> src/ch03/second.rs:72:13
[INFO] [stdout]    |
[INFO] [stdout] 72 |             'b: loop {
[INFO] [stdout]    |             ^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_labels)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unnecessary trailing semicolon
[INFO] [stdout]   --> src/ch09/first.rs:65:47
[INFO] [stdout]    |
[INFO] [stdout] 65 |                 $( map.insert($key, $val); ) *;
[INFO] [stdout]    |                                               ^
[INFO] [stdout] ...
[INFO] [stdout] 70 |     let counts = hashmap!['A' => 0, 'C' => 0, 'G' => 0, 'T' => 0];
[INFO] [stdout]    |                  ------------------------------------------------ in this macro invocation
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(redundant_semicolons)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout]    = note: this warning originates in the macro `hashmap` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Int`
[INFO] [stdout]   --> src/ch13/first.rs:87:32
[INFO] [stdout]    |
[INFO] [stdout] 87 |         use StringOrInt::{Str, Int};
[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: `BorrowError`, `BorrowMutError`, `Cell`, and `RefMut`
[INFO] [stdout]   --> src/ch15/first.rs:17:17
[INFO] [stdout]    |
[INFO] [stdout] 17 | use std::cell::{BorrowError, RefMut, BorrowMutError, Cell};
[INFO] [stdout]    |                 ^^^^^^^^^^^  ^^^^^^  ^^^^^^^^^^^^^^  ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unreachable statement
[INFO] [stdout]   --> src/ch04/first.rs:67:5
[INFO] [stdout]    |
[INFO] [stdout] 66 |     let x: i32 = diverges();
[INFO] [stdout]    |                  ---------- any code following this expression is unreachable
[INFO] [stdout] 67 |     let y: String = diverges();
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unreachable statement
[INFO] [stdout]   --> src/ch04/first.rs:67:5
[INFO] [stdout]    |
[INFO] [stdout] 66 |     let x: i32 = diverges();
[INFO] [stdout]    |                  ---------- any code following this expression is unreachable
[INFO] [stdout] 67 |     let y: String = diverges();
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^ unreachable statement
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unreachable_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io::Read`
[INFO] [stdout]  --> src/ch11/third.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io::Read;
[INFO] [stdout]   |     ^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `x` is never read
[INFO] [stdout]  --> src/ch02/first.rs:8:17
[INFO] [stdout]   |
[INFO] [stdout] 8 |     let mut x = 5;
[INFO] [stdout]   |                 ^ this value is reassigned later and never used
[INFO] [stdout] 9 |     x = 10;
[INFO] [stdout]   |     ------ `x` is overwritten here before the previous value is read
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_assignments)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `a` is never read
[INFO] [stdout]   --> src/ch02/first.rs:12:10
[INFO] [stdout]    |
[INFO] [stdout] 12 |     let (mut a, mut b) = (1, 2);
[INFO] [stdout]    |          ^^^^^ this value is reassigned later and never used
[INFO] [stdout] 13 |     a = 12;
[INFO] [stdout]    |     ------ `a` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `b` is never read
[INFO] [stdout]   --> src/ch02/first.rs:12:17
[INFO] [stdout]    |
[INFO] [stdout] 12 |     let (mut a, mut b) = (1, 2);
[INFO] [stdout]    |                 ^^^^^ this value is reassigned later and never used
[INFO] [stdout] 13 |     a = 12;
[INFO] [stdout] 14 |     b = 13;
[INFO] [stdout]    |     ------ `b` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `m`
[INFO] [stdout]   --> src/ch02/second.rs:98:9
[INFO] [stdout]    |
[INFO] [stdout] 98 |     let m: i8 = 123;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_m`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `n`
[INFO] [stdout]   --> src/ch02/second.rs:99:9
[INFO] [stdout]    |
[INFO] [stdout] 99 |     let n: i8 = 113;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_n`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `var2`
[INFO] [stdout]    --> src/ch02/second.rs:189:9
[INFO] [stdout]     |
[INFO] [stdout] 189 |     let var2: i16 = var1 as i16;
[INFO] [stdout]     |         ^^^^ help: if this is intentional, prefix it with an underscore: `_var2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]    --> src/ch02/second.rs:191:9
[INFO] [stdout]     |
[INFO] [stdout] 191 |     let a = "some string";
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `value`
[INFO] [stdout]    --> src/ch02/third.rs:132:11
[INFO] [stdout]     |
[INFO] [stdout] 132 |     fn f1(value: Inches) {}
[INFO] [stdout]     |           ^^^^^ help: if this is intentional, prefix it with an underscore: `_value`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `value`
[INFO] [stdout]    --> src/ch02/third.rs:133:11
[INFO] [stdout]     |
[INFO] [stdout] 133 |     fn f2(value: i32) {}
[INFO] [stdout]     |           ^^^^^ help: if this is intentional, prefix it with an underscore: `_value`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch02/third.rs:203:9
[INFO] [stdout]     |
[INFO] [stdout] 203 |     let x: Message = Message::Move { x: 3, y: 4 };
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]    --> src/ch02/third.rs:210:9
[INFO] [stdout]     |
[INFO] [stdout] 210 |     let y: BoardGameTurn = BoardGameTurn::Move { squares: 1 };
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `x` is never read
[INFO] [stdout]   --> src/ch03/first.rs:60:22
[INFO] [stdout]    |
[INFO] [stdout] 60 |     let mut x: i32 = 1;
[INFO] [stdout]    |                      ^ this value is reassigned later and never used
[INFO] [stdout] 61 |     x = 2;
[INFO] [stdout]    |     ----- `x` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `func` is assigned to, but never used
[INFO] [stdout]   --> src/ch04/first.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let mut func: fn((i32, i32)) -> i32 = add1;
[INFO] [stdout]    |         ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_func` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `func` is never read
[INFO] [stdout]   --> src/ch04/first.rs:28:5
[INFO] [stdout]    |
[INFO] [stdout] 28 |     func = add2;
[INFO] [stdout]    |     ^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ch04/first.rs:66:9
[INFO] [stdout]    |
[INFO] [stdout] 66 |     let x: i32 = diverges();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]   --> src/ch05/first.rs:79:9
[INFO] [stdout]    |
[INFO] [stdout] 79 |     let c = Circle { radius: 2f64 };
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]    --> src/ch05/first.rs:104:9
[INFO] [stdout]     |
[INFO] [stdout] 104 |     let c = Circle { radius: 2f64 };
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `ys`
[INFO] [stdout]   --> src/ch06/first.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let ys: [i32; 500] = [0; 500];
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_ys`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `xs` is never read
[INFO] [stdout]   --> src/ch06/first.rs:21:28
[INFO] [stdout]    |
[INFO] [stdout] 21 |     let mut xs: [i32; 5] = [1, 2, 3, 4, 5];
[INFO] [stdout]    |                            ^^^^^^^^^^^^^^^ this value is reassigned later and never used
[INFO] [stdout] 22 |     let ys: [i32; 5] = [6, 7, 8, 9, 10];
[INFO] [stdout] 23 |     xs = ys;
[INFO] [stdout]    |     ------- `xs` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io::Read`
[INFO] [stdout]  --> src/ch11/third.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io::Read;
[INFO] [stdout]   |     ^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `x` is never read
[INFO] [stdout]  --> src/ch02/first.rs:8:17
[INFO] [stdout]   |
[INFO] [stdout] 8 |     let mut x = 5;
[INFO] [stdout]   |                 ^ this value is reassigned later and never used
[INFO] [stdout] 9 |     x = 10;
[INFO] [stdout]   |     ------ `x` is overwritten here before the previous value is read
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_assignments)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `a` is never read
[INFO] [stdout]   --> src/ch02/first.rs:12:10
[INFO] [stdout]    |
[INFO] [stdout] 12 |     let (mut a, mut b) = (1, 2);
[INFO] [stdout]    |          ^^^^^ this value is reassigned later and never used
[INFO] [stdout] 13 |     a = 12;
[INFO] [stdout]    |     ------ `a` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `b` is never read
[INFO] [stdout]   --> src/ch02/first.rs:12:17
[INFO] [stdout]    |
[INFO] [stdout] 12 |     let (mut a, mut b) = (1, 2);
[INFO] [stdout]    |                 ^^^^^ this value is reassigned later and never used
[INFO] [stdout] 13 |     a = 12;
[INFO] [stdout] 14 |     b = 13;
[INFO] [stdout]    |     ------ `b` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:253:9
[INFO] [stdout]     |
[INFO] [stdout] 253 |     let x = 5_i32; // i32
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:254:9
[INFO] [stdout]     |
[INFO] [stdout] 254 |     let x = &5_i32; // &i32
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:255:9
[INFO] [stdout]     |
[INFO] [stdout] 255 |     let ref x = 5_i32; // &i32
[INFO] [stdout]     |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:257:9
[INFO] [stdout]     |
[INFO] [stdout] 257 |     let ref x = &5_i32; // &&i32
[INFO] [stdout]     |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:277:9
[INFO] [stdout]     |
[INFO] [stdout] 277 |     let mut x: &mut i32;
[INFO] [stdout]     |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `m`
[INFO] [stdout]   --> src/ch02/second.rs:98:9
[INFO] [stdout]    |
[INFO] [stdout] 98 |     let m: i8 = 123;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_m`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `n`
[INFO] [stdout]   --> src/ch02/second.rs:99:9
[INFO] [stdout]    |
[INFO] [stdout] 99 |     let n: i8 = 113;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_n`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `var2`
[INFO] [stdout]    --> src/ch02/second.rs:189:9
[INFO] [stdout]     |
[INFO] [stdout] 189 |     let var2: i16 = var1 as i16;
[INFO] [stdout]     |         ^^^^ help: if this is intentional, prefix it with an underscore: `_var2`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ch08/first.rs:78:13
[INFO] [stdout]    |
[INFO] [stdout] 78 |         let x: i32 = if cond { 1 } else { continue; };
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]    --> src/ch02/second.rs:191:9
[INFO] [stdout]     |
[INFO] [stdout] 191 |     let a = "some string";
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `tt`
[INFO] [stdout]    --> src/ch08/first.rs:107:13
[INFO] [stdout]     |
[INFO] [stdout] 107 |         let tt = t.join().unwrap();
[INFO] [stdout]     |             ^^ help: if this is intentional, prefix it with an underscore: `_tt`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `value`
[INFO] [stdout]    --> src/ch02/third.rs:132:11
[INFO] [stdout]     |
[INFO] [stdout] 132 |     fn f1(value: Inches) {}
[INFO] [stdout]     |           ^^^^^ help: if this is intentional, prefix it with an underscore: `_value`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `value`
[INFO] [stdout]    --> src/ch02/third.rs:133:11
[INFO] [stdout]     |
[INFO] [stdout] 133 |     fn f2(value: i32) {}
[INFO] [stdout]     |           ^^^^^ help: if this is intentional, prefix it with an underscore: `_value`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch02/third.rs:203:9
[INFO] [stdout]     |
[INFO] [stdout] 203 |     let x: Message = Message::Move { x: 3, y: 4 };
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `y`
[INFO] [stdout]    --> src/ch02/third.rs:210:9
[INFO] [stdout]     |
[INFO] [stdout] 210 |     let y: BoardGameTurn = BoardGameTurn::Move { squares: 1 };
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_y`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch11/third.rs:110:13
[INFO] [stdout]     |
[INFO] [stdout] 110 |         let x = D(1);
[INFO] [stdout]     |             ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch11/third.rs:112:13
[INFO] [stdout]     |
[INFO] [stdout] 112 |         let x = D(2);
[INFO] [stdout]     |             ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `x` is never read
[INFO] [stdout]   --> src/ch03/first.rs:60:22
[INFO] [stdout]    |
[INFO] [stdout] 60 |     let mut x: i32 = 1;
[INFO] [stdout]    |                      ^ this value is reassigned later and never used
[INFO] [stdout] 61 |     x = 2;
[INFO] [stdout]    |     ----- `x` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `p2` is assigned to, but never used
[INFO] [stdout]   --> src/ch12/first.rs:52:17
[INFO] [stdout]    |
[INFO] [stdout] 52 |             let mut p2 = &var;
[INFO] [stdout]    |                 ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_p2` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `p2` is never read
[INFO] [stdout]   --> src/ch12/first.rs:53:13
[INFO] [stdout]    |
[INFO] [stdout] 53 |             p2 = &temp;
[INFO] [stdout]    |             ^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `p3` is never read
[INFO] [stdout]   --> src/ch12/first.rs:61:13
[INFO] [stdout]    |
[INFO] [stdout] 61 |             p3 = &mut temp;
[INFO] [stdout]    |             ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `func` is assigned to, but never used
[INFO] [stdout]   --> src/ch04/first.rs:27:9
[INFO] [stdout]    |
[INFO] [stdout] 27 |     let mut func: fn((i32, i32)) -> i32 = add1;
[INFO] [stdout]    |         ^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_func` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `func` is never read
[INFO] [stdout]   --> src/ch04/first.rs:28:5
[INFO] [stdout]    |
[INFO] [stdout] 28 |     func = add2;
[INFO] [stdout]    |     ^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ch04/first.rs:66:9
[INFO] [stdout]    |
[INFO] [stdout] 66 |     let x: i32 = diverges();
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `v`
[INFO] [stdout]    --> src/ch12/first.rs:129:13
[INFO] [stdout]     |
[INFO] [stdout] 129 |         let v = x.into_bytes();
[INFO] [stdout]     |             ^ help: if this is intentional, prefix it with an underscore: `_v`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]    --> src/ch12/first.rs:243:32
[INFO] [stdout]     |
[INFO] [stdout] 243 |             fn test<'a>(&self, s: &'a str) {}
[INFO] [stdout]     |                                ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/ch13/first.rs:88:13
[INFO] [stdout]    |
[INFO] [stdout] 88 |         let mut x = Str("Hello World".to_string());
[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: unused variable: `x`
[INFO] [stdout]   --> src/ch13/first.rs:88:13
[INFO] [stdout]    |
[INFO] [stdout] 88 |         let mut x = Str("Hello World".to_string());
[INFO] [stdout]    |             ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]   --> src/ch05/first.rs:79:9
[INFO] [stdout]    |
[INFO] [stdout] 79 |     let c = Circle { radius: 2f64 };
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/ch13/first.rs:106:13
[INFO] [stdout]     |
[INFO] [stdout] 106 |         let mut arr = vec!["ABC", "DEF", "GHI"];
[INFO] [stdout]     |             ----^^^
[INFO] [stdout]     |             |
[INFO] [stdout]     |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `c`
[INFO] [stdout]    --> src/ch05/first.rs:104:9
[INFO] [stdout]     |
[INFO] [stdout] 104 |     let c = Circle { radius: 2f64 };
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_c`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `ys`
[INFO] [stdout]   --> src/ch06/first.rs:13:9
[INFO] [stdout]    |
[INFO] [stdout] 13 |     let ys: [i32; 500] = [0; 500];
[INFO] [stdout]    |         ^^ help: if this is intentional, prefix it with an underscore: `_ys`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `xs` is never read
[INFO] [stdout]   --> src/ch06/first.rs:21:28
[INFO] [stdout]    |
[INFO] [stdout] 21 |     let mut xs: [i32; 5] = [1, 2, 3, 4, 5];
[INFO] [stdout]    |                            ^^^^^^^^^^^^^^^ this value is reassigned later and never used
[INFO] [stdout] 22 |     let ys: [i32; 5] = [6, 7, 8, 9, 10];
[INFO] [stdout] 23 |     xs = ys;
[INFO] [stdout]    |     ------- `xs` is overwritten here before the previous value is read
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s1`
[INFO] [stdout]    --> src/ch16/first.rs:167:13
[INFO] [stdout]     |
[INFO] [stdout] 167 |         let s1 = s.clone();
[INFO] [stdout]     |             ^^ help: if this is intentional, prefix it with an underscore: `_s1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `ps1`
[INFO] [stdout]    --> src/ch16/first.rs:168:13
[INFO] [stdout]     |
[INFO] [stdout] 168 |         let ps1 = (*s).clone();
[INFO] [stdout]     |             ^^^ help: if this is intentional, prefix it with an underscore: `_ps1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `pps1`
[INFO] [stdout]    --> src/ch16/first.rs:169:13
[INFO] [stdout]     |
[INFO] [stdout] 169 |         let pps1 = (**s).clone();
[INFO] [stdout]     |             ^^^^ help: if this is intentional, prefix it with an underscore: `_pps1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type alias `T1` is never used
[INFO] [stdout]   --> src/ch08/first.rs:19:10
[INFO] [stdout]    |
[INFO] [stdout] 19 |     type T1 = [i32; 2];
[INFO] [stdout]    |          ^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type alias `T2` is never used
[INFO] [stdout]   --> src/ch08/first.rs:20:10
[INFO] [stdout]    |
[INFO] [stdout] 20 |     type T2 = (i32, i32);
[INFO] [stdout]    |          ^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `T3` is never constructed
[INFO] [stdout]   --> src/ch08/first.rs:21:12
[INFO] [stdout]    |
[INFO] [stdout] 21 |     struct T3(i32, i32);
[INFO] [stdout]    |            ^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `T4` is never constructed
[INFO] [stdout]   --> src/ch08/first.rs:22:12
[INFO] [stdout]    |
[INFO] [stdout] 22 |     struct T4 {
[INFO] [stdout]    |            ^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `dive-into-rust-of-fcc` (lib) due to 1 previous error; 74 warnings emitted
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stdout] warning: enum `Direction` is never used
[INFO] [stdout]   --> src/ch08/first.rs:33:10
[INFO] [stdout]    |
[INFO] [stdout] 33 |     enum Direction {
[INFO] [stdout]    |          ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Option` is never used
[INFO] [stdout]   --> src/ch08/first.rs:41:10
[INFO] [stdout]    |
[INFO] [stdout] 41 |     enum Option<T> {
[INFO] [stdout]    |          ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `HashSet` is never constructed
[INFO] [stdout]   --> src/ch08/first.rs:62:16
[INFO] [stdout]    |
[INFO] [stdout] 62 |     pub struct HashSet<T, S = RandomState> {
[INFO] [stdout]    |                ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Never` is never used
[INFO] [stdout]   --> src/ch08/first.rs:67:10
[INFO] [stdout]    |
[INFO] [stdout] 67 |     enum Never {}
[INFO] [stdout]    |          ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `test1` is never used
[INFO] [stdout]   --> src/ch08/first.rs:94:8
[INFO] [stdout]    |
[INFO] [stdout] 94 |     fn test1() {
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `test2` is never used
[INFO] [stdout]    --> src/ch08/first.rs:102:8
[INFO] [stdout]     |
[INFO] [stdout] 102 |     fn test2() {
[INFO] [stdout]     |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `nope` is never used
[INFO] [stdout]    --> src/ch08/first.rs:168:8
[INFO] [stdout]     |
[INFO] [stdout] 168 |     fn nope(_: u32) -> Option<u32> { None }
[INFO] [stdout]     |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `T` is never constructed
[INFO] [stdout]    --> src/ch12/first.rs:238:16
[INFO] [stdout]     |
[INFO] [stdout] 238 |         struct T<'a> {
[INFO] [stdout]     |                ^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `test` is never used
[INFO] [stdout]    --> src/ch12/first.rs:243:16
[INFO] [stdout]     |
[INFO] [stdout] 242 |         impl<'t> T<'t> {
[INFO] [stdout]     |         -------------- method in this implementation
[INFO] [stdout] 243 |             fn test<'a>(&self, s: &'a str) {}
[INFO] [stdout]     |                ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_str` is never used
[INFO] [stdout]    --> src/ch12/first.rs:255:12
[INFO] [stdout]     |
[INFO] [stdout] 255 |         fn get_str(s: &String) -> &str {
[INFO] [stdout]     |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_str_x` is never used
[INFO] [stdout]    --> src/ch12/first.rs:259:12
[INFO] [stdout]     |
[INFO] [stdout] 259 |         fn get_str_x<'a>(s: &'a String) -> &'a str {
[INFO] [stdout]     |            ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]   --> src/ch13/first.rs:82:13
[INFO] [stdout]    |
[INFO] [stdout] 82 |         Str(String),
[INFO] [stdout]    |         --- ^^^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         field in this variant
[INFO] [stdout]    |
[INFO] [stdout]    = note: `StringOrInt` 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] 82 -         Str(String),
[INFO] [stdout] 82 +         Str(()),
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `Int` is never constructed
[INFO] [stdout]   --> src/ch13/first.rs:83:9
[INFO] [stdout]    |
[INFO] [stdout] 81 |     enum StringOrInt {
[INFO] [stdout]    |          ----------- variant in this enum
[INFO] [stdout] 82 |         Str(String),
[INFO] [stdout] 83 |         Int(i64),
[INFO] [stdout]    |         ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `StringOrInt` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `process_or_default` is never used
[INFO] [stdout]   --> src/ch14/first.rs:72:8
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn process_or_default<K, V: Default>(map: &mut HashMap<K, V>, key: K)
[INFO] [stdout]    |        ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_default` is never used
[INFO] [stdout]   --> src/ch14/first.rs:81:8
[INFO] [stdout]    |
[INFO] [stdout] 81 |     fn get_default<K, V>(map: &mut HashMap<K, V>, key: K)
[INFO] [stdout]    |        ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `capitalize` is never used
[INFO] [stdout]    --> src/ch14/first.rs:113:8
[INFO] [stdout]     |
[INFO] [stdout] 113 |     fn capitalize(data: &mut [char]) {
[INFO] [stdout]     |        ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `test2` is never used
[INFO] [stdout]    --> src/ch15/first.rs:159:8
[INFO] [stdout]     |
[INFO] [stdout] 159 |     fn test2() {
[INFO] [stdout]     |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait `Deref` is never used
[INFO] [stdout]   --> src/ch16/first.rs:21:15
[INFO] [stdout]    |
[INFO] [stdout] 21 |     pub trait Deref {
[INFO] [stdout]    |               ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait `DerefMut` is never used
[INFO] [stdout]   --> src/ch16/first.rs:26:15
[INFO] [stdout]    |
[INFO] [stdout] 26 |     pub trait DerefMut: Deref {
[INFO] [stdout]    |               ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: creating a shared reference to mutable static
[INFO] [stdout]    --> src/ch02/first.rs:150:24
[INFO] [stdout]     |
[INFO] [stdout] 150 |         println!("{}", G2);
[INFO] [stdout]     |                        ^^ shared reference to mutable static
[INFO] [stdout]     |
[INFO] [stdout]     = note: shared references to mutable statics are dangerous; it's undefined behavior if the static is mutated or if a mutable reference is created for it while the shared reference lives
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2024/static-mut-references.html>
[INFO] [stdout]     = note: `#[warn(static_mut_refs)]` (part of `#[warn(rust_2024_compatibility)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:253:9
[INFO] [stdout]     |
[INFO] [stdout] 253 |     let x = 5_i32; // i32
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:254:9
[INFO] [stdout]     |
[INFO] [stdout] 254 |     let x = &5_i32; // &i32
[INFO] [stdout]     |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:255:9
[INFO] [stdout]     |
[INFO] [stdout] 255 |     let ref x = 5_i32; // &i32
[INFO] [stdout]     |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:257:9
[INFO] [stdout]     |
[INFO] [stdout] 257 |     let ref x = &5_i32; // &&i32
[INFO] [stdout]     |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch07/second.rs:277:9
[INFO] [stdout]     |
[INFO] [stdout] 277 |     let mut x: &mut i32;
[INFO] [stdout]     |         ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing
[INFO] [stdout]   --> src/ch11/third.rs:98:9
[INFO] [stdout]    |
[INFO] [stdout] 98 |         std::mem::drop(x);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^-^
[INFO] [stdout]    |                        |
[INFO] [stdout]    |                        argument has type `i32`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dropping_copy_types)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the expression or result
[INFO] [stdout]    |
[INFO] [stdout] 98 -         std::mem::drop(x);
[INFO] [stdout] 98 +         let _ = x;
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/ch08/first.rs:78:13
[INFO] [stdout]    |
[INFO] [stdout] 78 |         let x: i32 = if cond { 1 } else { continue; };
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
[INFO] [stdout]    --> src/ch15/first.rs:207:21
[INFO] [stdout]     |
[INFO] [stdout] 206 |                     let p = &(self.value) as *const T as *mut T;
[INFO] [stdout]     |                             ----------------------------------- casting happened here
[INFO] [stdout] 207 |                     *p = v;
[INFO] [stdout]     |                     ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
[INFO] [stdout]     = note: `#[deny(invalid_reference_casting)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `tt`
[INFO] [stdout]    --> src/ch08/first.rs:107:13
[INFO] [stdout]     |
[INFO] [stdout] 107 |         let tt = t.join().unwrap();
[INFO] [stdout]     |             ^^ help: if this is intentional, prefix it with an underscore: `_tt`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch11/third.rs:110:13
[INFO] [stdout]     |
[INFO] [stdout] 110 |         let x = D(1);
[INFO] [stdout]     |             ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]    --> src/ch11/third.rs:112:13
[INFO] [stdout]     |
[INFO] [stdout] 112 |         let x = D(2);
[INFO] [stdout]     |             ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable `p2` is assigned to, but never used
[INFO] [stdout]   --> src/ch12/first.rs:52:17
[INFO] [stdout]    |
[INFO] [stdout] 52 |             let mut p2 = &var;
[INFO] [stdout]    |                 ^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: consider using `_p2` instead
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `p2` is never read
[INFO] [stdout]   --> src/ch12/first.rs:53:13
[INFO] [stdout]    |
[INFO] [stdout] 53 |             p2 = &temp;
[INFO] [stdout]    |             ^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: value assigned to `p3` is never read
[INFO] [stdout]   --> src/ch12/first.rs:61:13
[INFO] [stdout]    |
[INFO] [stdout] 61 |             p3 = &mut temp;
[INFO] [stdout]    |             ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = help: maybe it is overwritten before being read?
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `v`
[INFO] [stdout]    --> src/ch12/first.rs:129:13
[INFO] [stdout]     |
[INFO] [stdout] 129 |         let v = x.into_bytes();
[INFO] [stdout]     |             ^ help: if this is intentional, prefix it with an underscore: `_v`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s`
[INFO] [stdout]    --> src/ch12/first.rs:243:32
[INFO] [stdout]     |
[INFO] [stdout] 243 |             fn test<'a>(&self, s: &'a str) {}
[INFO] [stdout]     |                                ^ help: if this is intentional, prefix it with an underscore: `_s`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/ch13/first.rs:88:13
[INFO] [stdout]    |
[INFO] [stdout] 88 |         let mut x = Str("Hello World".to_string());
[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: unused variable: `x`
[INFO] [stdout]   --> src/ch13/first.rs:88:13
[INFO] [stdout]    |
[INFO] [stdout] 88 |         let mut x = Str("Hello World".to_string());
[INFO] [stdout]    |             ^^^^^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/ch13/first.rs:106:13
[INFO] [stdout]     |
[INFO] [stdout] 106 |         let mut arr = vec!["ABC", "DEF", "GHI"];
[INFO] [stdout]     |             ----^^^
[INFO] [stdout]     |             |
[INFO] [stdout]     |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s1`
[INFO] [stdout]    --> src/ch16/first.rs:167:13
[INFO] [stdout]     |
[INFO] [stdout] 167 |         let s1 = s.clone();
[INFO] [stdout]     |             ^^ help: if this is intentional, prefix it with an underscore: `_s1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `ps1`
[INFO] [stdout]    --> src/ch16/first.rs:168:13
[INFO] [stdout]     |
[INFO] [stdout] 168 |         let ps1 = (*s).clone();
[INFO] [stdout]     |             ^^^ help: if this is intentional, prefix it with an underscore: `_ps1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `pps1`
[INFO] [stdout]    --> src/ch16/first.rs:169:13
[INFO] [stdout]     |
[INFO] [stdout] 169 |         let pps1 = (**s).clone();
[INFO] [stdout]     |             ^^^^ help: if this is intentional, prefix it with an underscore: `_pps1`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type alias `T1` is never used
[INFO] [stdout]   --> src/ch08/first.rs:19:10
[INFO] [stdout]    |
[INFO] [stdout] 19 |     type T1 = [i32; 2];
[INFO] [stdout]    |          ^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: type alias `T2` is never used
[INFO] [stdout]   --> src/ch08/first.rs:20:10
[INFO] [stdout]    |
[INFO] [stdout] 20 |     type T2 = (i32, i32);
[INFO] [stdout]    |          ^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `T3` is never constructed
[INFO] [stdout]   --> src/ch08/first.rs:21:12
[INFO] [stdout]    |
[INFO] [stdout] 21 |     struct T3(i32, i32);
[INFO] [stdout]    |            ^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `T4` is never constructed
[INFO] [stdout]   --> src/ch08/first.rs:22:12
[INFO] [stdout]    |
[INFO] [stdout] 22 |     struct T4 {
[INFO] [stdout]    |            ^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Direction` is never used
[INFO] [stdout]   --> src/ch08/first.rs:33:10
[INFO] [stdout]    |
[INFO] [stdout] 33 |     enum Direction {
[INFO] [stdout]    |          ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Option` is never used
[INFO] [stdout]   --> src/ch08/first.rs:41:10
[INFO] [stdout]    |
[INFO] [stdout] 41 |     enum Option<T> {
[INFO] [stdout]    |          ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `HashSet` is never constructed
[INFO] [stdout]   --> src/ch08/first.rs:62:16
[INFO] [stdout]    |
[INFO] [stdout] 62 |     pub struct HashSet<T, S = RandomState> {
[INFO] [stdout]    |                ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: enum `Never` is never used
[INFO] [stdout]   --> src/ch08/first.rs:67:10
[INFO] [stdout]    |
[INFO] [stdout] 67 |     enum Never {}
[INFO] [stdout]    |          ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `test1` is never used
[INFO] [stdout]   --> src/ch08/first.rs:94:8
[INFO] [stdout]    |
[INFO] [stdout] 94 |     fn test1() {
[INFO] [stdout]    |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `test2` is never used
[INFO] [stdout]    --> src/ch08/first.rs:102:8
[INFO] [stdout]     |
[INFO] [stdout] 102 |     fn test2() {
[INFO] [stdout]     |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `nope` is never used
[INFO] [stdout]    --> src/ch08/first.rs:168:8
[INFO] [stdout]     |
[INFO] [stdout] 168 |     fn nope(_: u32) -> Option<u32> { None }
[INFO] [stdout]     |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `T` is never constructed
[INFO] [stdout]    --> src/ch12/first.rs:238:16
[INFO] [stdout]     |
[INFO] [stdout] 238 |         struct T<'a> {
[INFO] [stdout]     |                ^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: method `test` is never used
[INFO] [stdout]    --> src/ch12/first.rs:243:16
[INFO] [stdout]     |
[INFO] [stdout] 242 |         impl<'t> T<'t> {
[INFO] [stdout]     |         -------------- method in this implementation
[INFO] [stdout] 243 |             fn test<'a>(&self, s: &'a str) {}
[INFO] [stdout]     |                ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_str` is never used
[INFO] [stdout]    --> src/ch12/first.rs:255:12
[INFO] [stdout]     |
[INFO] [stdout] 255 |         fn get_str(s: &String) -> &str {
[INFO] [stdout]     |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_str_x` is never used
[INFO] [stdout]    --> src/ch12/first.rs:259:12
[INFO] [stdout]     |
[INFO] [stdout] 259 |         fn get_str_x<'a>(s: &'a String) -> &'a str {
[INFO] [stdout]     |            ^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field `0` is never read
[INFO] [stdout]   --> src/ch13/first.rs:82:13
[INFO] [stdout]    |
[INFO] [stdout] 82 |         Str(String),
[INFO] [stdout]    |         --- ^^^^^^
[INFO] [stdout]    |         |
[INFO] [stdout]    |         field in this variant
[INFO] [stdout]    |
[INFO] [stdout]    = note: `StringOrInt` 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] 82 -         Str(String),
[INFO] [stdout] 82 +         Str(()),
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variant `Int` is never constructed
[INFO] [stdout]   --> src/ch13/first.rs:83:9
[INFO] [stdout]    |
[INFO] [stdout] 81 |     enum StringOrInt {
[INFO] [stdout]    |          ----------- variant in this enum
[INFO] [stdout] 82 |         Str(String),
[INFO] [stdout] 83 |         Int(i64),
[INFO] [stdout]    |         ^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `StringOrInt` has a derived impl for the trait `Debug`, but this is intentionally ignored during dead code analysis
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `process_or_default` is never used
[INFO] [stdout]   --> src/ch14/first.rs:72:8
[INFO] [stdout]    |
[INFO] [stdout] 72 |     fn process_or_default<K, V: Default>(map: &mut HashMap<K, V>, key: K)
[INFO] [stdout]    |        ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `get_default` is never used
[INFO] [stdout]   --> src/ch14/first.rs:81:8
[INFO] [stdout]    |
[INFO] [stdout] 81 |     fn get_default<K, V>(map: &mut HashMap<K, V>, key: K)
[INFO] [stdout]    |        ^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `capitalize` is never used
[INFO] [stdout]    --> src/ch14/first.rs:113:8
[INFO] [stdout]     |
[INFO] [stdout] 113 |     fn capitalize(data: &mut [char]) {
[INFO] [stdout]     |        ^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function `test2` is never used
[INFO] [stdout]    --> src/ch15/first.rs:159:8
[INFO] [stdout]     |
[INFO] [stdout] 159 |     fn test2() {
[INFO] [stdout]     |        ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait `Deref` is never used
[INFO] [stdout]   --> src/ch16/first.rs:21:15
[INFO] [stdout]    |
[INFO] [stdout] 21 |     pub trait Deref {
[INFO] [stdout]    |               ^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: trait `DerefMut` is never used
[INFO] [stdout]   --> src/ch16/first.rs:26:15
[INFO] [stdout]    |
[INFO] [stdout] 26 |     pub trait DerefMut: Deref {
[INFO] [stdout]    |               ^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: creating a shared reference to mutable static
[INFO] [stdout]    --> src/ch02/first.rs:150:24
[INFO] [stdout]     |
[INFO] [stdout] 150 |         println!("{}", G2);
[INFO] [stdout]     |                        ^^ shared reference to mutable static
[INFO] [stdout]     |
[INFO] [stdout]     = note: shared references to mutable statics are dangerous; it's undefined behavior if the static is mutated or if a mutable reference is created for it while the shared reference lives
[INFO] [stdout]     = note: for more information, see <https://doc.rust-lang.org/edition-guide/rust-2024/static-mut-references.html>
[INFO] [stdout]     = note: `#[warn(static_mut_refs)]` (part of `#[warn(rust_2024_compatibility)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: calls to `std::mem::drop` with a value that implements `Copy` does nothing
[INFO] [stdout]   --> src/ch11/third.rs:98:9
[INFO] [stdout]    |
[INFO] [stdout] 98 |         std::mem::drop(x);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^-^
[INFO] [stdout]    |                        |
[INFO] [stdout]    |                        argument has type `i32`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dropping_copy_types)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the expression or result
[INFO] [stdout]    |
[INFO] [stdout] 98 -         std::mem::drop(x);
[INFO] [stdout] 98 +         let _ = x;
[INFO] [stdout]    |
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: assigning to `&T` is undefined behavior, consider using an `UnsafeCell`
[INFO] [stdout]    --> src/ch15/first.rs:207:21
[INFO] [stdout]     |
[INFO] [stdout] 206 |                     let p = &(self.value) as *const T as *mut T;
[INFO] [stdout]     |                             ----------------------------------- casting happened here
[INFO] [stdout] 207 |                     *p = v;
[INFO] [stdout]     |                     ^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: for more information, visit <https://doc.rust-lang.org/book/ch15-05-interior-mutability.html>
[INFO] [stdout]     = note: `#[deny(invalid_reference_casting)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `dive-into-rust-of-fcc` (lib test) due to 1 previous error; 74 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14", kill_on_drop: false }`
[INFO] [stdout] 21b6c67339e08491713fe91891b2d4a224cda75592ed0583bc4ca690b616cd14
