Replace hashbrown with ahash

hashbrown is already used in the standard library, but we want the
improved performance of the different hash algorithm.
Using ahash directly conveys this intent more clearly.

Cargo.lock

@@ -9,6 +9,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e89da841a80418a9b391ebaea17f5c112ffaaa96f621d2c285b5174da76b9011"
 dependencies = [
  "cfg-if",
+ "getrandom",
  "once_cell",
  "version_check",
  "zerocopy",
@@ -246,6 +247,17 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4567c8db10ae91089c99af84c68c38da3ec2f087c3f82960bcdbf3656b6f4d7"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "hashbrown"
 version = "0.14.5"
@@ -517,9 +529,9 @@ dependencies = [
 name = "rustlings"
 version = "6.1.0"
 dependencies = [
+ "ahash",
  "anyhow",
  "clap",
- "hashbrown",
  "notify-debouncer-mini",
  "os_pipe",
  "ratatui",

Cargo.toml

@@ -46,9 +46,9 @@ include = [
 ]
 
 [dependencies]
+ahash = "0.8.11"
 anyhow = "1.0.86"
 clap = { version = "4.5.13", features = ["derive"] }
-hashbrown = "0.14.5"
 notify-debouncer-mini = { version = "0.4.1", default-features = false }
 os_pipe = "1.2.1"
 ratatui = { version = "0.27.0", default-features = false, features = ["crossterm"] }

src/app_state.rs

@@ -1,3 +1,4 @@
+use ahash::{HashSet, HashSetExt};
 use anyhow::{bail, Context, Error, Result};
 use std::{
     fs::{self, File},
@@ -69,7 +70,7 @@ impl AppState {
             return StateFileStatus::NotRead;
         }
 
-        let mut done_exercises = hashbrown::HashSet::with_capacity(self.exercises.len());
+        let mut done_exercises = HashSet::with_capacity(self.exercises.len());
 
         for done_exerise_name in lines {
             if done_exerise_name.is_empty() {

src/dev/check.rs

@@ -1,3 +1,4 @@
+use ahash::{HashSet, HashSetExt};
 use anyhow::{anyhow, bail, Context, Error, Result};
 use std::{
     cmp::Ordering,
@@ -48,9 +49,9 @@ fn check_cargo_toml(
 }
 
 // Check the info of all exercises and return their paths in a set.
-fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<PathBuf>> {
+fn check_info_file_exercises(info_file: &InfoFile) -> Result<HashSet<PathBuf>> {
-    let mut names = hashbrown::HashSet::with_capacity(info_file.exercises.len());
+    let mut names = HashSet::with_capacity(info_file.exercises.len());
-    let mut paths = hashbrown::HashSet::with_capacity(info_file.exercises.len());
+    let mut paths = HashSet::with_capacity(info_file.exercises.len());
 
     let mut file_buf = String::with_capacity(1 << 14);
     for exercise_info in &info_file.exercises {
@@ -111,10 +112,7 @@ fn check_info_file_exercises(info_file: &InfoFile) -> Result<hashbrown::HashSet<
 // Check `dir` for unexpected files.
 // Only Rust files in `allowed_rust_files` and `README.md` files are allowed.
 // Only one level of directory nesting is allowed.
-fn check_unexpected_files(
+fn check_unexpected_files(dir: &str, allowed_rust_files: &HashSet<PathBuf>) -> Result<()> {
-    dir: &str,
-    allowed_rust_files: &hashbrown::HashSet<PathBuf>,
-) -> Result<()> {
     let unexpected_file = |path: &Path| {
         anyhow!("Found the file `{}`. Only `README.md` and Rust files related to an exercise in `info.toml` are allowed in the `{dir}` directory", path.display())
     };
@@ -253,7 +251,7 @@ fn check_solutions(
             })
             .collect::<Vec<_>>();
 
-        let mut sol_paths = hashbrown::HashSet::with_capacity(info_file.exercises.len());
+        let mut sol_paths = HashSet::with_capacity(info_file.exercises.len());
         let mut fmt_cmd = Command::new("rustfmt");
         fmt_cmd
             .arg("--check")