chore: Release

move_semantics5: change to fix misleading compiler error

.github/workflows/rust.yml

@@ -18,25 +18,26 @@ jobs:
   fmt:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@stable
-        with:
-          components: rustfmt
-      - uses: DavidAnson/markdownlint-cli2-action@v9
+      - uses: actions/checkout@v4
+      - uses: DavidAnson/markdownlint-cli2-action@v16
         with:
           globs: "exercises/**/*.md"
       - name: Run cargo fmt
-        run: |
-          cargo fmt --all -- --check
+        run: cargo fmt --all -- --check
   test:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macOS-latest]
     steps:
-      - uses: actions/checkout@v3
-      - uses: dtolnay/rust-toolchain@stable
+      - uses: actions/checkout@v4
       - uses: swatinem/rust-cache@v2
       - name: Run cargo test
-        run: |
-          cargo test
+        run: cargo test
+  dev-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: swatinem/rust-cache@v2
+      - name: Run rustlings dev check
+        run: cargo run -- dev check --require-solutions

.github/workflows/web.yml

@@ -54,10 +54,9 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       # Setup
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0
-      - uses: dtolnay/rust-toolchain@stable
       - uses: swatinem/rust-cache@v2
 
       # If you use any mdbook plugins, here's the place to install them!

CHANGELOG.md

@@ -1,3 +1,10 @@
+<a name="6.0.1"></a>
+
+## 6.0.1 (2024-07-04)
+
+Small exercise improvements and fixes.
+Most importantly, fixed that the exercise `clippy1` was already solved 😅
+
 <a name="6.0.0"></a>
 
 ## 6.0.0 (2024-07-03)

Cargo.lock

@@ -136,9 +136,9 @@ checksum = "df8670b8c7b9dae1793364eafadf7239c40d669904660c5960d74cfd80b46a53"
 
 [[package]]
 name = "castaway"
-version = "0.2.2"
+version = "0.2.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a17ed5635fc8536268e5d4de1e22e81ac34419e5f052d4d51f4e01dcc263fcc"
+checksum = "0abae9be0aaf9ea96a3b1b8b1b55c602ca751eba1b1500220cea4ecbafe7c0d5"
 dependencies = [
  "rustversion",
 ]
@@ -527,7 +527,7 @@ dependencies = [
  "libc",
  "redox_syscall 0.5.2",
  "smallvec",
- "windows-targets 0.52.5",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -654,7 +654,7 @@ checksum = "7a66a03ae7c801facd77a29370b4faec201768915ac14a721ba36f20bc9c209b"
 
 [[package]]
 name = "rustlings"
-version = "6.0.0"
+version = "6.0.1"
 dependencies = [
  "anyhow",
  "assert_cmd",
@@ -673,7 +673,7 @@ dependencies = [
 
 [[package]]
 name = "rustlings-macros"
-version = "6.0.0"
+version = "6.0.1"
 dependencies = [
  "quote",
  "serde",
@@ -977,7 +977,7 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets 0.52.5",
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -997,18 +997,18 @@ dependencies = [
 
 [[package]]
 name = "windows-targets"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6f0713a46559409d202e70e28227288446bf7841d3211583a4b53e3f6d96e7eb"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm 0.52.5",
- "windows_aarch64_msvc 0.52.5",
- "windows_i686_gnu 0.52.5",
+ "windows_aarch64_gnullvm 0.52.6",
+ "windows_aarch64_msvc 0.52.6",
+ "windows_i686_gnu 0.52.6",
  "windows_i686_gnullvm",
- "windows_i686_msvc 0.52.5",
- "windows_x86_64_gnu 0.52.5",
- "windows_x86_64_gnullvm 0.52.5",
- "windows_x86_64_msvc 0.52.5",
+ "windows_i686_msvc 0.52.6",
+ "windows_x86_64_gnu 0.52.6",
+ "windows_x86_64_gnullvm 0.52.6",
+ "windows_x86_64_msvc 0.52.6",
 ]
 
 [[package]]
@@ -1019,9 +1019,9 @@ checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
 
 [[package]]
 name = "windows_aarch64_gnullvm"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7088eed71e8b8dda258ecc8bac5fb1153c5cffaf2578fc8ff5d61e23578d3263"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
 [[package]]
 name = "windows_aarch64_msvc"
@@ -1031,9 +1031,9 @@ checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
 
 [[package]]
 name = "windows_aarch64_msvc"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9985fd1504e250c615ca5f281c3f7a6da76213ebd5ccc9561496568a2752afb6"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
 [[package]]
 name = "windows_i686_gnu"
@@ -1043,15 +1043,15 @@ checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "88ba073cf16d5372720ec942a8ccbf61626074c6d4dd2e745299726ce8b89670"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
 
 [[package]]
 name = "windows_i686_gnullvm"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "87f4261229030a858f36b459e748ae97545d6f1ec60e5e0d6a3d32e0dc232ee9"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
 [[package]]
 name = "windows_i686_msvc"
@@ -1061,9 +1061,9 @@ checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "db3c2bf3d13d5b658be73463284eaf12830ac9a26a90c717b7f771dfe97487bf"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
 [[package]]
 name = "windows_x86_64_gnu"
@@ -1073,9 +1073,9 @@ checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4e4246f76bdeff09eb48875a0fd3e2af6aada79d409d33011886d3e1581517d9"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
@@ -1085,9 +1085,9 @@ checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "852298e482cd67c356ddd9570386e2862b5673c85bd5f88df9ab6802b334c596"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
 [[package]]
 name = "windows_x86_64_msvc"
@@ -1097,9 +1097,9 @@ checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.52.5"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bec47e5bfd1bff0eeaf6d8b485cc1074891a197ab4225d504cb7a1ab88b02bf0"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
 [[package]]
 name = "winnow"

Cargo.toml

@@ -8,7 +8,7 @@ exclude = [
 ]
 
 [workspace.package]
-version = "6.0.0"
+version = "6.0.1"
 authors = [
   "Liv <mokou@fastmail.com>",
   "Mo Bitar <mo8it@proton.me>",
@@ -53,7 +53,7 @@ hashbrown = "0.14.5"
 notify-debouncer-mini = { version = "0.4.1", default-features = false }
 os_pipe = "1.2.0"
 ratatui = { version = "0.27.0", default-features = false, features = ["crossterm"] }
-rustlings-macros = { path = "rustlings-macros", version = "=6.0.0" }
+rustlings-macros = { path = "rustlings-macros", version = "=6.0.1" }
 serde_json = "1.0.120"
 serde.workspace = true
 toml_edit.workspace = true

exercises/00_intro/intro1.rs

@@ -3,8 +3,7 @@
 // ready for the next exercise, enter `n` in the terminal.
 //
 // The exercise file will be reloaded when you change one of the lines below!
-// Try adding a new `println!`.
-// Try removing a semicolon and see what happens in the terminal!
+// Try adding a new `println!` and check the updated output in the terminal.
 
 fn main() {
     println!("Hello and");

exercises/06_move_semantics/move_semantics5.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::ptr_arg)]
+
 // TODO: Fix the compiler errors without changing anything except adding or
 // removing references (the character `&`).
 
@@ -16,7 +18,7 @@ fn get_char(data: String) -> char {
 
 // Should take ownership
 fn string_uppercase(mut data: &String) {
-    data = &data.to_uppercase();
+    data = data.to_uppercase();
 
     println!("{data}");
 }

exercises/08_enums/enums2.rs

@@ -1,3 +1,4 @@
+#[allow(dead_code)]
 #[derive(Debug)]
 enum Message {
     // TODO: Define the different variants used below.
@@ -5,7 +6,7 @@ enum Message {
 
 impl Message {
     fn call(&self) {
-        println!("{:?}", self);
+        println!("{self:?}");
     }
 }
 

exercises/10_modules/modules2.rs

@@ -1,6 +1,7 @@
 // You can bring module paths into scopes and provide new names for them with
 // the `use` and `as` keywords.
 
+#[allow(dead_code)]
 mod delicious_snacks {
     // TODO: Add the following two `use` statements after fixing them.
     // use self::fruits::PEAR as ???;

exercises/12_options/options1.rs

@@ -19,7 +19,8 @@ mod tests {
         // TODO: Fix this test. How do you get the value contained in the
         // Option?
         let icecreams = maybe_icecream(12);
-        assert_eq!(icecreams, 5);
+
+        assert_eq!(icecreams, 5); // Don't change this line.
     }
 
     #[test]

exercises/13_error_handling/errors2.rs

@@ -5,11 +5,11 @@
 // the player typed in the quantity, we get it as a string. They might have
 // typed anything, not just numbers!
 //
-// Right now, this function isn't handling the error case at all (and isn't
-// handling the success case properly either). What we want to do is: If we call
-// the `total_cost` function on a string that is not a number, that function
-// will return a `ParseIntError`. In that case, we want to immediately return
-// that error from our function and not try to multiply and add.
+// Right now, this function isn't handling the error case at all. What we want
+// to do is: If we call the `total_cost` function on a string that is not a
+// number, that function will return a `ParseIntError`. In that case, we want to
+// immediately return that error from our function and not try to multiply and
+// add.
 //
 // There are at least two ways to implement this that are both correct. But one
 // is a lot shorter!

exercises/13_error_handling/errors4.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::comparison_chain)]
+
 #[derive(PartialEq, Debug)]
 enum CreationError {
     Negative,

exercises/13_error_handling/errors6.rs

@@ -35,7 +35,7 @@ impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<Self, CreationError> {
         match value {
             x if x < 0 => Err(CreationError::Negative),
-            x if x == 0 => Err(CreationError::Zero),
+            0 => Err(CreationError::Zero),
             x => Ok(Self(x as u64)),
         }
     }
@@ -55,7 +55,6 @@ fn main() {
 #[cfg(test)]
 mod test {
     use super::*;
-    use std::num::IntErrorKind;
 
     #[test]
     fn test_parse_error() {

exercises/15_traits/traits3.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 trait Licensed {
     // TODO: Add a default implementation for `licensing_info` so that
     // implementors like the two structs below can share that default behavior

exercises/18_iterators/iterators3.rs

@@ -54,7 +54,7 @@ mod tests {
 
     #[test]
     fn test_result_with_list() {
-        assert_eq!(result_with_list().unwarp(), [1, 11, 1426, 3]);
+        assert_eq!(result_with_list().unwrap(), [1, 11, 1426, 3]);
     }
 
     #[test]

exercises/19_smart_pointers/arc1.rs

@@ -1,4 +1,4 @@
-// In this exercise, we are given a `Vec` of u32 called `numbers` with values
+// In this exercise, we are given a `Vec` of `u32` called `numbers` with values
 // ranging from 0 to 99. We would like to use this set of numbers within 8
 // different threads simultaneously. Each thread is going to get the sum of
 // every eighth value with an offset.
@@ -9,8 +9,11 @@
 // …
 // The eighth thread (offset 7), will sum 7, 15, 23, …
 //
-// Because we are using threads, our values need to be thread-safe. Therefore,
-// we are using `Arc`.
+// Each thread should own a reference-counting pointer to the vector of
+// numbers. But `Rc` isn't thread-safe. Therefore, we need to use `Arc`.
+//
+// Don't get distracted by how threads are spawned and joined. We will practice
+// that later in the exercises about threads.
 
 // Don't change the lines below.
 #![forbid(unused_imports)]

exercises/19_smart_pointers/rc1.rs

@@ -8,6 +8,7 @@ use std::rc::Rc;
 #[derive(Debug)]
 struct Sun;
 
+#[allow(dead_code)]
 #[derive(Debug)]
 enum Planet {
     Mercury(Rc<Sun>),

exercises/22_clippy/clippy1.rs

@@ -4,11 +4,9 @@
 // For these exercises, the code will fail to compile when there are Clippy
 // warnings. Check Clippy's suggestions from the output to solve the exercise.
 
-use std::f32::consts::PI;
-
 fn main() {
-    // Use the more accurate `PI` constant.
-    let pi = PI;
+    // TODO: Fix the Clippy lint in this line.
+    let pi = 3.14;
     let radius: f32 = 5.0;
 
     let area = pi * radius.powi(2);

exercises/quizzes/quiz1.rs

@@ -6,8 +6,8 @@
 // Mary is buying apples. The price of an apple is calculated as follows:
 // - An apple costs 2 rustbucks.
 // - If Mary buys more than 40 apples, each apple only costs 1 rustbuck!
-// Write a function that calculates the price of an order of apples given the
-// quantity bought.
+// TODO: Write a function that calculates the price of an order of apples given
+// the quantity bought.
 
 // Put your function here!
 // fn calculate_price_of_apples(???) -> ??? {

oranda.json

@@ -9,16 +9,5 @@
         "domain": "rustlings.cool"
       }
     }
-  },
-  "components": {
-    "artifacts": {
-      "auto": true,
-      "package_managers": {
-        "preferred": {
-          "macos/linux/unix": "curl -L https://raw.githubusercontent.com/rust-lang/rustlings/main/install.sh | bash",
-          "windows": "Start-BitsTransfer -Source https://raw.githubusercontent.com/rust-lang/rustlings/main/install.ps1 -Destination $env:TMP/install_rustlings.ps1; Unblock-File $env:TMP/install_rustlings.ps1; Invoke-Expression $env:TMP/install_rustlings.ps1"
-        }
-      }
-    }
   }
 }

rustlings-macros/info.toml

@@ -16,16 +16,14 @@ get started, here are some notes about how Rustlings operates:
 3. If you're stuck on an exercise, enter `h` to show a hint.
 4. If an exercise doesn't make sense to you, feel free to open an issue on GitHub!
    (https://github.com/rust-lang/rustlings). We look at every issue, and sometimes,
-   other learners do too so you can help each other out!
-"""
+   other learners do too so you can help each other out!"""
 
 final_message = """We hope you enjoyed learning about the various aspects of Rust!
 If you noticed any issues, don't hesitate to report them on Github.
 You can also contribute your own exercises to help the greater community!
 
 Before reporting an issue or contributing, please read our guidelines:
-https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md
-"""
+https://github.com/rust-lang/rustlings/blob/main/CONTRIBUTING.md"""
 
 # INTRO
 
@@ -130,8 +128,7 @@ The type of Constants must always be annotated.
 
 Read more about constants and the differences between variables and constants
 under 'Constants' in the book's section 'Variables and Mutability':
-https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#constants
-"""
+https://doc.rust-lang.org/book/ch03-01-variables-and-mutability.html#constants"""
 
 # FUNCTIONS
 
@@ -312,8 +309,7 @@ In Rust, there are two ways to define a Vector.
    the initial values.
 
 Check this chapter: https://doc.rust-lang.org/stable/book/ch08-01-vectors.html
-of the Rust book to learn more.
-"""
+of the Rust book to learn more."""
 
 [[exercises]]
 name = "vecs2"
@@ -327,8 +323,7 @@ In the second function, we map the values of the input and collect them into a v
 After you've completed both functions, decide for yourself which approach you
 like better.
 
-What do you think is the more commonly used pattern under Rust developers?
-"""
+What do you think is the more commonly used pattern under Rust developers?"""
 
 # MOVE SEMANTICS
 
@@ -355,8 +350,7 @@ We call this "moving" a variable. When we pass `vec0` into `fill_vec`, it's
 being "moved" into `vec1`, meaning we can't access `vec0` anymore.
 
 You could make another, separate version of the data that's in `vec0` and
-pass it to `fill_vec` instead.
-"""
+pass it to `fill_vec` instead."""
 
 [[exercises]]
 name = "move_semantics3"
@@ -375,8 +369,7 @@ Carefully reason about the range in which each mutable reference is in
 scope. Does it help to update the value of `x` immediately after
 the mutable reference is taken?
 Read more about 'Mutable References' in the book's section 'References and Borrowing':
-https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html#mutable-references.
-"""
+https://doc.rust-lang.org/book/ch04-02-references-and-borrowing.html#mutable-references."""
 
 [[exercises]]
 name = "move_semantics5"
@@ -517,8 +510,7 @@ Example:
 `placeholder("blue");`
 should become
 `string_slice("blue");`
-because "blue" is `&str`, not `String`.
-"""
+because "blue" is `&str`, not `String`."""
 
 # MODULES
 
@@ -620,8 +612,7 @@ Remember that `Option`s can be nested in if-let and while-let statements.
 
 For example: `if let Some(Some(x)) = y`
 
-Also see `Option::flatten`
-"""
+Also see `Option::flatten`"""
 
 [[exercises]]
 name = "options3"
@@ -813,8 +804,7 @@ Here is how to specify a trait bound for an implementation block:
 `impl<T: Trait1 + Trait2 + …> for Foo<T> { … }`
 
 You may need this:
-`use std::fmt::Display;`
-"""
+`use std::fmt::Display;`"""
 
 # LIFETIMES
 

solutions/01_variables/variables3.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::needless_late_init)]
+
 fn main() {
     // Reading uninitialized variables isn't allowed in Rust!
     // Therefore, we need to assign a value first.
@@ -5,7 +7,7 @@ fn main() {
 
     println!("Number {x}");
 
-    // It possible to declare a variable and initialize it later.
+    // It is possible to declare a variable and initialize it later.
     // But it can't be used before initialization.
     let y: i32;
     y = 42;

solutions/06_move_semantics/move_semantics5.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::ptr_arg)]
+
 fn main() {
     let data = "Rust is great!".to_string();
 

solutions/08_enums/enums2.rs

@@ -1,3 +1,4 @@
+#[allow(dead_code)]
 #[derive(Debug)]
 enum Message {
     Move { x: i64, y: i64 },
@@ -8,7 +9,7 @@ enum Message {
 
 impl Message {
     fn call(&self) {
-        println!("{:?}", self);
+        println!("{self:?}");
     }
 }
 

solutions/10_modules/modules2.rs

@@ -1,3 +1,4 @@
+#[allow(dead_code)]
 mod delicious_snacks {
     // Added `pub` and used the expected alias after `as`.
     pub use self::fruits::PEAR as fruit;

solutions/11_hashmaps/hashmaps3.rs

@@ -28,13 +28,13 @@ fn build_scores_table(results: &str) -> HashMap<&str, Team> {
         let team_2_score: u8 = split_iterator.next().unwrap().parse().unwrap();
 
         // Insert the default with zeros if a team doesn't exist yet.
-        let mut team_1 = scores.entry(team_1_name).or_insert_with(|| Team::default());
+        let team_1 = scores.entry(team_1_name).or_insert_with(Team::default);
         // Update the values.
         team_1.goals_scored += team_1_score;
         team_1.goals_conceded += team_2_score;
 
         // Similarely for the second team.
-        let mut team_2 = scores.entry(team_2_name).or_insert_with(|| Team::default());
+        let team_2 = scores.entry(team_2_name).or_insert_with(Team::default);
         team_2.goals_scored += team_2_score;
         team_2.goals_conceded += team_1_score;
     }

solutions/12_options/options1.rs

@@ -4,8 +4,8 @@
 // `hour_of_day` is higher than 23.
 fn maybe_icecream(hour_of_day: u16) -> Option<u16> {
     match hour_of_day {
-        0..22 => Some(5),
-        22..24 => Some(0),
+        0..=21 => Some(5),
+        22..=23 => Some(0),
         _ => None,
     }
 }
@@ -22,6 +22,7 @@ mod tests {
     fn raw_value() {
         // Using `unwrap` is fine in a test.
         let icecreams = maybe_icecream(12).unwrap();
+
         assert_eq!(icecreams, 5);
     }
 

solutions/13_error_handling/errors2.rs

@@ -5,17 +5,18 @@
 // the player typed in the quantity, we get it as a string. They might have
 // typed anything, not just numbers!
 //
-// Right now, this function isn't handling the error case at all (and isn't
-// handling the success case properly either). What we want to do is: If we call
-// the `total_cost` function on a string that is not a number, that function
-// will return a `ParseIntError`. In that case, we want to immediately return
-// that error from our function and not try to multiply and add.
+// Right now, this function isn't handling the error case at all. What we want
+// to do is: If we call the `total_cost` function on a string that is not a
+// number, that function will return a `ParseIntError`. In that case, we want to
+// immediately return that error from our function and not try to multiply and
+// add.
 //
 // There are at least two ways to implement this that are both correct. But one
 // is a lot shorter!
 
 use std::num::ParseIntError;
 
+#[allow(unused_variables)]
 fn total_cost(item_quantity: &str) -> Result<i32, ParseIntError> {
     let processing_fee = 1;
     let cost_per_item = 5;

solutions/13_error_handling/errors4.rs

@@ -1,3 +1,5 @@
+#![allow(clippy::comparison_chain)]
+
 #[derive(PartialEq, Debug)]
 enum CreationError {
     Negative,

solutions/13_error_handling/errors6.rs

@@ -36,7 +36,7 @@ impl PositiveNonzeroInteger {
     fn new(value: i64) -> Result<Self, CreationError> {
         match value {
             x if x < 0 => Err(CreationError::Negative),
-            x if x == 0 => Err(CreationError::Zero),
+            0 => Err(CreationError::Zero),
             x => Ok(Self(x as u64)),
         }
     }
@@ -57,7 +57,6 @@ fn main() {
 #[cfg(test)]
 mod test {
     use super::*;
-    use std::num::IntErrorKind;
 
     #[test]
     fn test_parse_error() {

solutions/15_traits/traits3.rs

@@ -1,3 +1,5 @@
+#![allow(dead_code)]
+
 trait Licensed {
     fn licensing_info(&self) -> String {
         "Default license".to_string()

solutions/19_smart_pointers/arc1.rs

@@ -1,4 +1,4 @@
-// In this exercise, we are given a `Vec` of u32 called `numbers` with values
+// In this exercise, we are given a `Vec` of `u32` called `numbers` with values
 // ranging from 0 to 99. We would like to use this set of numbers within 8
 // different threads simultaneously. Each thread is going to get the sum of
 // every eighth value with an offset.
@@ -9,8 +9,11 @@
 // …
 // The eighth thread (offset 7), will sum 7, 15, 23, …
 //
-// Because we are using threads, our values need to be thread-safe. Therefore,
-// we are using `Arc`.
+// Each thread should own a reference-counting pointer to the vector of
+// numbers. But `Rc` isn't thread-safe. Therefore, we need to use `Arc`.
+//
+// Don't get distracted by how threads are spawned and joined. We will practice
+// that later in the exercises about threads.
 
 // Don't change the lines below.
 #![forbid(unused_imports)]

solutions/19_smart_pointers/rc1.rs

@@ -8,6 +8,7 @@ use std::rc::Rc;
 #[derive(Debug)]
 struct Sun;
 
+#[allow(dead_code)]
 #[derive(Debug)]
 enum Planet {
     Mercury(Rc<Sun>),

solutions/23_conversions/try_from_into.rs

@@ -4,6 +4,7 @@
 // type itself. You can read more about it in the documentation:
 // https://doc.rust-lang.org/std/convert/trait.TryFrom.html
 
+#![allow(clippy::useless_vec)]
 use std::convert::{TryFrom, TryInto};
 
 #[derive(Debug, PartialEq)]