feat(language_server): support fmt.configPath configuration

crates/oxc_language_server/README.md

@@ -28,6 +28,7 @@ These options can be passed with [initialize](#initialize), [workspace/didChange
 | `typeAware`               | `true` \| `false`              | `false`    | Enables type-aware linting                                                                                                                             |
 | `flags`                   | `Map<string, string>`          | `<empty>`  | Special oxc language server flags, currently only one flag key is supported: `disable_nested_config`                                                   |
 | `fmt.experimental`        | `true` \| `false`              | `false`    | Enables experimental formatting with `oxc_formatter`                                                                                                   |
+| `fmt.configPath`          | `<string>` \| `null`           | `null`     | Path to a oxfmt configuration file, when `null` is passed, the server will use `.oxfmtrc.json` and the workspace root                                  |
 
 ## Supported LSP Specifications from Server
 
@@ -47,7 +48,8 @@ The client can pass the workspace options like following:
       "unusedDisableDirectives": "allow",
       "typeAware": false,
       "flags": {},
-      "fmt.experimental": false
+      "fmt.experimental": false,
+      "fmt.configPath": null
     }
   }]
 }
@@ -84,7 +86,8 @@ The client can pass the workspace options like following:
       "unusedDisableDirectives": "allow",
       "typeAware": false,
       "flags": {},
-      "fmt.experimental": false
+      "fmt.experimental": false,
+      "fmt.configPath": null
     }
   }]
 }
@@ -178,6 +181,7 @@ The client can return a response like:
   "unusedDisableDirectives": "allow",
   "typeAware": false,
   "flags": {},
-  "fmt.experimental": false
+  "fmt.experimental": false,
+  "fmt.configPath": null
 }]
 ```

crates/oxc_language_server/fixtures/formatter/custom_config_path/format.json

@@ -0,0 +1,3 @@
+{
+  "semicolons": "as-needed"
+}

crates/oxc_language_server/fixtures/formatter/custom_config_path/semicolons-as-needed.ts

@@ -0,0 +1,2 @@
+// semicolon is on character 8-9, which will be removed
+debugger;

crates/oxc_language_server/src/formatter/options.rs

@@ -1,10 +1,11 @@
 use serde::{Deserialize, Deserializer, Serialize, de::Error};
 use serde_json::Value;
 
-#[derive(Debug, Default, Serialize, Clone)]
+#[derive(Debug, Default, Serialize, Clone, PartialEq, Eq)]
 #[serde(rename_all = "camelCase")]
 pub struct FormatOptions {
     pub experimental: bool,
+    pub config_path: Option<String>,
 }
 
 impl<'de> Deserialize<'de> for FormatOptions {
@@ -29,6 +30,9 @@ impl TryFrom<Value> for FormatOptions {
             experimental: object
                 .get("fmt.experimental")
                 .is_some_and(|run| serde_json::from_value::<bool>(run.clone()).unwrap_or_default()),
+            config_path: object
+                .get("fmt.configPath")
+                .and_then(|config_path| serde_json::from_value::<String>(config_path.clone()).ok()),
         })
     }
 }
@@ -43,10 +47,12 @@ mod test {
     fn test_valid_options_json() {
         let json = json!({
             "fmt.experimental": true,
+            "fmt.configPath": "./.oxfmtrc.json"
         });
 
         let options = FormatOptions::try_from(json).unwrap();
         assert!(options.experimental);
+        assert_eq!(options.config_path.unwrap(), "./.oxfmtrc.json");
     }
 
     #[test]
@@ -55,15 +61,18 @@ mod test {
 
         let options = FormatOptions::try_from(json).unwrap();
         assert!(!options.experimental);
+        assert!(options.config_path.is_none());
     }
 
     #[test]
     fn test_invalid_options_json() {
         let json = json!({
             "fmt.experimental": "what", // should be bool
+            "fmt.configPath": "./.oxfmtrc.json"
         });
 
         let options = FormatOptions::try_from(json).unwrap();
         assert!(!options.experimental);
+        assert_eq!(options.config_path.unwrap(), "./.oxfmtrc.json");
     }
 }

crates/oxc_language_server/src/formatter/server_formatter.rs

@@ -10,17 +10,17 @@ use tower_lsp_server::{
     lsp_types::{Position, Range, TextEdit, Uri},
 };
 
-use crate::FORMAT_CONFIG_FILE;
-
+use crate::formatter::options::FormatOptions as LSPFormatOptions;
+use crate::{FORMAT_CONFIG_FILE, utils::normalize_path};
 pub struct ServerFormatter {
     options: FormatOptions,
 }
 
 impl ServerFormatter {
-    pub fn new(root_uri: &Uri) -> Self {
+    pub fn new(root_uri: &Uri, options: &LSPFormatOptions) -> Self {
         let root_path = root_uri.to_file_path().unwrap();
 
-        Self { options: Self::get_format_options(&root_path) }
+        Self { options: Self::get_format_options(&root_path, options.config_path.as_ref()) }
     }
 
     pub fn run_single(&self, uri: &Uri, content: Option<String>) -> Option<Vec<TextEdit>> {
@@ -75,9 +75,9 @@ impl ServerFormatter {
         )])
     }
 
-    fn get_format_options(root_path: &Path) -> FormatOptions {
-        let config_path = FORMAT_CONFIG_FILE;
-        let config = root_path.join(config_path); // normalize_path when supporting `oxc.fmt.configPath`
+    fn get_format_options(root_path: &Path, config_path: Option<&String>) -> FormatOptions {
+        let config_path = config_path.map_or(FORMAT_CONFIG_FILE, |v| v);
+        let config = normalize_path(root_path.join(config_path));
         let oxfmtrc = if config.try_exists().is_ok_and(|exists| exists) {
             if let Ok(oxfmtrc) = Oxfmtrc::from_file(&config) {
                 oxfmtrc
@@ -232,13 +232,31 @@ mod tests {
 
     #[test]
     fn test_formatter() {
-        Tester::new("fixtures/formatter/basic", Some(FormatOptions { experimental: true }))
-            .format_and_snapshot_single_file("basic.ts");
+        Tester::new(
+            "fixtures/formatter/basic",
+            Some(FormatOptions { experimental: true, ..Default::default() }),
+        )
+        .format_and_snapshot_single_file("basic.ts");
     }
 
     #[test]
     fn test_root_config_detection() {
-        Tester::new("fixtures/formatter/root_config", Some(FormatOptions { experimental: true }))
-            .format_and_snapshot_single_file("semicolons-as-needed.ts");
+        Tester::new(
+            "fixtures/formatter/root_config",
+            Some(FormatOptions { experimental: true, ..Default::default() }),
+        )
+        .format_and_snapshot_single_file("semicolons-as-needed.ts");
+    }
+
+    #[test]
+    fn test_custom_config_path() {
+        Tester::new(
+            "fixtures/formatter/custom_config_path",
+            Some(FormatOptions {
+                experimental: true,
+                config_path: Some("./format.json".to_string()),
+            }),
+        )
+        .format_and_snapshot_single_file("semicolons-as-needed.ts");
     }
 }

crates/oxc_language_server/src/linter/server_linter.rs

@@ -1,4 +1,4 @@
-use std::path::{Component, Path, PathBuf};
+use std::path::{Path, PathBuf};
 use std::str::FromStr;
 use std::sync::Arc;
 
@@ -21,6 +21,7 @@ use crate::linter::{
     options::{LintOptions as LSPLintOptions, Run},
     tsgo_linter::TsgoLinter,
 };
+use crate::utils::normalize_path;
 use crate::{ConcurrentHashMap, LINT_CONFIG_FILE};
 
 use super::config_walker::ConfigWalker;
@@ -377,31 +378,6 @@ impl ServerLinter {
     }
 }
 
-/// Normalize a path by removing `.` and resolving `..` components,
-/// without touching the filesystem.
-pub fn normalize_path<P: AsRef<Path>>(path: P) -> PathBuf {
-    let mut result = PathBuf::new();
-
-    for component in path.as_ref().components() {
-        match component {
-            Component::ParentDir => {
-                result.pop();
-            }
-            Component::CurDir => {
-                // Skip current directory component
-            }
-            Component::Normal(c) => {
-                result.push(c);
-            }
-            Component::RootDir | Component::Prefix(_) => {
-                result.push(component.as_os_str());
-            }
-        }
-    }
-
-    result
-}
-
 #[cfg(test)]
 mod test {
     use std::path::{Path, PathBuf};
@@ -411,20 +387,12 @@ mod test {
         linter::{
             error_with_position::DiagnosticReport,
             options::{LintOptions, Run, UnusedDisableDirectives},
-            server_linter::{ServerLinter, ServerLinterDiagnostics, normalize_path},
+            server_linter::{ServerLinter, ServerLinterDiagnostics},
         },
         tester::{Tester, get_file_path},
     };
     use rustc_hash::FxHashMap;
 
-    #[test]
-    fn test_normalize_path() {
-        assert_eq!(
-            normalize_path(Path::new("/root/directory/./.oxlintrc.json")),
-            Path::new("/root/directory/.oxlintrc.json")
-        );
-    }
-
     #[test]
     fn test_create_nested_configs_with_disabled_nested_configs() {
         let mut flags = FxHashMap::default();

crates/oxc_language_server/src/main.rs

@@ -11,6 +11,7 @@ mod linter;
 mod options;
 #[cfg(test)]
 mod tester;
+mod utils;
 mod worker;
 
 use crate::backend::Backend;

crates/oxc_language_server/src/snapshots/fixtures_formatter_custom_config_path@semicolons-as-needed.ts.snap

@@ -0,0 +1,16 @@
+---
+source: crates/oxc_language_server/src/formatter/tester.rs
+---
+========================================
+File: fixtures/formatter/custom_config_path/semicolons-as-needed.ts
+========================================
+Range: Range {
+    start: Position {
+        line: 1,
+        character: 8,
+    },
+    end: Position {
+        line: 1,
+        character: 9,
+    },
+}

crates/oxc_language_server/src/utils.rs

@@ -0,0 +1,41 @@
+use std::path::{Component, Path, PathBuf};
+
+/// Normalize a path by removing `.` and resolving `..` components,
+/// without touching the filesystem.
+pub fn normalize_path<P: AsRef<Path>>(path: P) -> PathBuf {
+    let mut result = PathBuf::new();
+
+    for component in path.as_ref().components() {
+        match component {
+            Component::ParentDir => {
+                result.pop();
+            }
+            Component::CurDir => {
+                // Skip current directory component
+            }
+            Component::Normal(c) => {
+                result.push(c);
+            }
+            Component::RootDir | Component::Prefix(_) => {
+                result.push(component.as_os_str());
+            }
+        }
+    }
+
+    result
+}
+
+#[cfg(test)]
+mod test {
+    use std::path::Path;
+
+    use crate::utils::normalize_path;
+
+    #[test]
+    fn test_normalize_path() {
+        assert_eq!(
+            normalize_path(Path::new("/root/directory/./.oxlintrc.json")),
+            Path::new("/root/directory/.oxlintrc.json")
+        );
+    }
+}

crates/oxc_language_server/src/worker.rs

@@ -16,9 +16,10 @@ use crate::{
     formatter::server_formatter::ServerFormatter,
     linter::{
         error_with_position::DiagnosticReport,
-        server_linter::{ServerLinter, ServerLinterRun, normalize_path},
+        server_linter::{ServerLinter, ServerLinterRun},
     },
     options::Options,
+    utils::normalize_path,
 };
 
 /// A worker that manages the individual tools for a specific workspace
@@ -71,7 +72,8 @@ impl WorkspaceWorker {
         *self.server_linter.write().await = Some(ServerLinter::new(&self.root_uri, &options.lint));
         if options.format.experimental {
             debug!("experimental formatter enabled");
-            *self.server_formatter.write().await = Some(ServerFormatter::new(&self.root_uri));
+            *self.server_formatter.write().await =
+                Some(ServerFormatter::new(&self.root_uri, &options.format));
         }
     }
 
@@ -338,10 +340,12 @@ impl WorkspaceWorker {
         }
 
         let mut formatting = false;
-        if current_option.format.experimental != changed_options.format.experimental {
+        if current_option.format != changed_options.format {
             if changed_options.format.experimental {
-                debug!("experimental formatter enabled");
-                *self.server_formatter.write().await = Some(ServerFormatter::new(&self.root_uri));
+                debug!("experimental formatter enabled/restarted");
+                // restart the formatter
+                *self.server_formatter.write().await =
+                    Some(ServerFormatter::new(&self.root_uri, &changed_options.format));
                 formatting = true;
             } else {
                 debug!("experimental formatter disabled");