Enable clippy linting in repo (#1114)

Branched from #1113 
Closes #1104 

- On CI. Config taken from
https://github.com/astral-sh/ruff/blob/56eb6b62936142c6ab2bdf0d7b864e32399e02a8/.github/workflows/ci.yaml#L243-L263

- In IDEs via rust-analyzer's `check` config.

I'm a bit hesitant enabling it in rust-analyser because of this (from
#1104 (comment)):

One UX downside to be aware of: After each edits, clippy runs longer
checks on the repo, which locks other gestures requiring compilation
(running tests etc).

<img width="584" height="142" alt="Image"
src="https://github.com/user-attachments/assets/8f6246c3-95a3-4331-a5f2-5d69d6a7f532"
/>

But I guess we can override in our personal configs if we want a
different workflow (check with clippy before sending PR).

Author: lionel-

.github/workflows/check-rust.yml

@@ -20,6 +20,29 @@ jobs:
       - name: "Check formatting"
         run: cargo +nightly fmt --all --check
 
+  clippy:
+    name: "Check clippy"
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: Swatinem/rust-cache@v2
+        with:
+          save-if: ${{ github.ref == 'refs/heads/main' }}
+
+      - name: "Install clippy"
+        run: rustup component add clippy
+
+      - name: Toolchain versions
+        run: |
+          rustc -Vv
+          cargo -V
+          cargo clippy -V
+
+      - name: "Check clippy"
+        run: cargo clippy --all-targets --all-features --locked -- -D warnings
+
   dependencies:
     name: "Check only workspace dependencies"
     runs-on: ubuntu-latest

.vscode/settings.json

@@ -13,6 +13,7 @@
     "rust-analyzer.imports.granularity.group": "item",
     "rust-analyzer.imports.granularity.enforce": true,
     "rust-analyzer.showUnlinkedFileNotification": false,
+    "rust-analyzer.check.command": "clippy",
     "rust-analyzer.check.extraArgs": [
         "--target-dir", "${workspaceFolder}/target/check"
     ],

.zed/settings.json

@@ -2,6 +2,9 @@
     "lsp": {
         "rust-analyzer": {
             "initialization_options": {
+                "check": {
+                    "command": "clippy"
+                },
                 "rustfmt": {
                     "extraArgs": ["+nightly"]
                 }

AGENTS.md

@@ -57,6 +57,12 @@ just test <test_name>
 just test -p ark
 ```
 
+### Running Clippy
+
+```sh
+just clippy
+```
+
 ### Kernel and DAP Test Infrastructure
 
 Integration tests for the kernel and DAP server live in `crates/ark/tests/` and use the test utilities from `crates/ark_test/`.

Cargo.toml

@@ -19,7 +19,7 @@ members = [
 ]
 
 [workspace.package]
-rust-version = "1.89"
+rust-version = "1.94"
 edition = "2021"
 license = "MIT"
 authors = ["Posit Software, PBC"]

crates/amalthea/src/kernel_dirs.rs

@@ -30,23 +30,12 @@ pub fn jupyter_dir() -> Option<PathBuf> {
 #[cfg(not(target_os = "macos"))]
 fn jupyter_xdg_dir() -> Option<PathBuf> {
     // On Windows/Linux, the path is XDG_DATA_DIR/jupyter
-    if let Some(path) = dirs::data_dir() {
-        Some(path.join("jupyter"))
-    } else {
-        None
-    }
+    dirs::data_dir().map(|path| path.join("jupyter"))
 }
 
 #[cfg(target_os = "macos")]
 fn jupyter_xdg_dir() -> Option<PathBuf> {
     // On MacOS, XDG_DATA_DIR is ~/Library/Application Support, but Jupyter
     // looks in ~/Library/Jupyter.
-    if let Some(path) = dirs::data_dir() {
-        if let Some(parent) = path.parent() {
-            return Some(parent.join("Jupyter"));
-        } else {
-            return None;
-        }
-    }
-    None
+    dirs::data_dir().and_then(|path| path.parent().map(|parent| parent.join("Jupyter")))
 }

crates/ark/src/repos.rs

@@ -278,14 +278,14 @@ fn get_ppm_linux_repo(repo_url: Option<url::Url>, linux_name: String) -> anyhow:
 fn get_p3m_linux_codename(id: String, version: String, version_codename: String) -> String {
     // For Debian and Ubuntu, we can just use the codename
     if id == "debian" || id == "ubuntu" || id == "pop" {
-        return version_codename.to_string();
+        version_codename.to_string()
     } else if id == "rhel" {
         // For RHEL, we use the id and major version number
         let parts: Vec<&str> = version.split('.').collect();
         if parts.len() > 1 {
-            return format!("{}{}", id, parts[0]);
+            format!("{}{}", id, parts[0])
         } else {
-            return format!("{}{}", id, version);
+            format!("{}{}", id, version)
         }
     } else if id == "sles" || id.starts_with("opensuse") {
         // For sles and opensuse we use the id and major and minor version number
@@ -294,12 +294,12 @@ fn get_p3m_linux_codename(id: String, version: String, version_codename: String)
 
         let parts: Vec<&str> = version.split('.').collect();
         if parts.len() > 1 {
-            return format!("{}{}{}", distro_id, parts[0], parts[1]);
+            format!("{}{}{}", distro_id, parts[0], parts[1])
         } else {
-            return format!("{}{}", distro_id, version);
+            format!("{}{}", distro_id, version)
         }
     } else {
-        return String::new();
+        String::new()
     }
 }
 
@@ -322,7 +322,7 @@ fn get_ppm_binary_package_repo(repo_url: Option<url::Url>) -> String {
         if let Ok(file) = File::open("/etc/os-release") {
             let reader = BufReader::new(file);
 
-            for line in reader.lines().flatten() {
+            for line in reader.lines().map_while(Result::ok) {
                 if version_codename.is_empty() && line.starts_with(version_codename_key) {
                     version_codename = line[version_codename_key.len()..].to_string();
                 } else if id.is_empty() && line.starts_with(id_key) {

crates/ark/tests/dap_breakpoints_symlink.rs

@@ -13,6 +13,7 @@ use amalthea::wire::execute_request::JupyterPositronLocation;
 use amalthea::wire::execute_request::JupyterPositronPosition;
 use amalthea::wire::execute_request::JupyterPositronRange;
 use ark_test::DummyArkFrontend;
+#[cfg(target_os = "macos")]
 use ark_test::SourceFile;
 use url::Url;
 

justfile

@@ -11,3 +11,7 @@ test-verbose:
 # Run the insta tests in update mode
 test-insta:
   cargo insta test --test-runner nextest
+
+# Run clippy
+clippy:
+  cargo clippy --workspace --all-targets --all-features -- -D warnings

rust-toolchain.toml

@@ -0,0 +1,2 @@
+[toolchain]
+channel = "1.94"