Add language_server_workspace_configuration to extension API (#10212)

This PR adds the ability for extensions to implement
`language_server_workspace_configuration` to provide workspace
configuration to the language server.

We've used the Dart extension as a motivating example for this, pulling
it out into an extension in the process.

Release Notes:

- Removed built-in support for Dart, in favor of making it available as
an extension. The Dart extension will be suggested for download when you
open a `.dart` file.

---------

Co-authored-by: Max <max@zed.dev>
Co-authored-by: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/extension/src/extension_lsp_adapter.rs

@@ -12,6 +12,7 @@ use language::{
 };
 use lsp::LanguageServerBinary;
 use serde::Serialize;
+use serde_json::Value;
 use std::ops::Range;
 use std::{
     any::Any,
@@ -181,6 +182,42 @@ impl LspAdapter for ExtensionLspAdapter {
         })
     }
 
+    async fn workspace_configuration(
+        self: Arc<Self>,
+        delegate: &Arc<dyn LspAdapterDelegate>,
+        _cx: &mut AsyncAppContext,
+    ) -> Result<Value> {
+        let delegate = delegate.clone();
+        let json_options: Option<String> = self
+            .extension
+            .call({
+                let this = self.clone();
+                |extension, store| {
+                    async move {
+                        let resource = store.data_mut().table().push(delegate)?;
+                        let options = extension
+                            .call_language_server_workspace_configuration(
+                                store,
+                                &this.language_server_id,
+                                resource,
+                            )
+                            .await?
+                            .map_err(|e| anyhow!("{}", e))?;
+                        anyhow::Ok(options)
+                    }
+                    .boxed()
+                }
+            })
+            .await?;
+        Ok(if let Some(json_options) = json_options {
+            serde_json::from_str(&json_options).with_context(|| {
+                format!("failed to parse initialization_options from extension: {json_options}")
+            })?
+        } else {
+            serde_json::json!({})
+        })
+    }
+
     async fn labels_for_completions(
         self: Arc<Self>,
         completions: &[lsp::CompletionItem],

crates/extension/src/extension_store.rs

@@ -237,6 +237,7 @@ impl ExtensionStore {
                 node_runtime,
                 language_registry.clone(),
                 work_dir,
+                cx,
             ),
             wasm_extensions: Vec::new(),
             fs,

crates/extension/src/wasm_host.rs

@@ -3,6 +3,7 @@ pub(crate) mod wit;
 use crate::ExtensionManifest;
 use anyhow::{anyhow, bail, Context as _, Result};
 use fs::{normalize_path, Fs};
+use futures::future::LocalBoxFuture;
 use futures::{
     channel::{
         mpsc::{self, UnboundedSender},
@@ -11,7 +12,7 @@ use futures::{
     future::BoxFuture,
     Future, FutureExt, StreamExt as _,
 };
-use gpui::BackgroundExecutor;
+use gpui::{AppContext, AsyncAppContext, BackgroundExecutor, Task};
 use language::LanguageRegistry;
 use node_runtime::NodeRuntime;
 use semantic_version::SemanticVersion;
@@ -34,6 +35,8 @@ pub(crate) struct WasmHost {
     pub(crate) language_registry: Arc<LanguageRegistry>,
     fs: Arc<dyn Fs>,
     pub(crate) work_dir: PathBuf,
+    _main_thread_message_task: Task<()>,
+    main_thread_message_tx: mpsc::UnboundedSender<MainThreadCall>,
 }
 
 #[derive(Clone)]
@@ -51,6 +54,9 @@ pub(crate) struct WasmState {
     pub(crate) host: Arc<WasmHost>,
 }
 
+type MainThreadCall =
+    Box<dyn Send + for<'a> FnOnce(&'a mut AsyncAppContext) -> LocalBoxFuture<'a, ()>>;
+
 type ExtensionCall = Box<
     dyn Send + for<'a> FnOnce(&'a mut Extension, &'a mut Store<WasmState>) -> BoxFuture<'a, ()>,
 >;
@@ -75,7 +81,14 @@ impl WasmHost {
         node_runtime: Arc<dyn NodeRuntime>,
         language_registry: Arc<LanguageRegistry>,
         work_dir: PathBuf,
+        cx: &mut AppContext,
     ) -> Arc<Self> {
+        let (tx, mut rx) = mpsc::unbounded::<MainThreadCall>();
+        let task = cx.spawn(|mut cx| async move {
+            while let Some(message) = rx.next().await {
+                message(&mut cx).await;
+            }
+        });
         Arc::new(Self {
             engine: wasm_engine(),
             fs,
@@ -83,6 +96,8 @@ impl WasmHost {
             http_client,
             node_runtime,
             language_registry,
+            _main_thread_message_task: task,
+            main_thread_message_tx: tx,
         })
     }
 
@@ -238,6 +253,26 @@ impl WasmExtension {
 }
 
 impl WasmState {
+    fn on_main_thread<T, Fn>(&self, f: Fn) -> impl 'static + Future<Output = T>
+    where
+        T: 'static + Send,
+        Fn: 'static + Send + for<'a> FnOnce(&'a mut AsyncAppContext) -> LocalBoxFuture<'a, T>,
+    {
+        let (return_tx, return_rx) = oneshot::channel();
+        self.host
+            .main_thread_message_tx
+            .clone()
+            .unbounded_send(Box::new(move |cx| {
+                async {
+                    let result = f(cx).await;
+                    return_tx.send(result).ok();
+                }
+                .boxed_local()
+            }))
+            .expect("main thread message channel should not be closed yet");
+        async move { return_rx.await.expect("main thread message channel") }
+    }
+
     fn work_dir(&self) -> PathBuf {
         self.host.work_dir.join(self.manifest.id.as_ref())
     }

crates/extension/src/wasm_host/wit.rs

@@ -148,6 +148,25 @@ impl Extension {
         }
     }
 
+    pub async fn call_language_server_workspace_configuration(
+        &self,
+        store: &mut Store<WasmState>,
+        language_server_id: &LanguageServerName,
+        resource: Resource<Arc<dyn LspAdapterDelegate>>,
+    ) -> Result<Result<Option<String>, String>> {
+        match self {
+            Extension::V006(ext) => {
+                ext.call_language_server_workspace_configuration(
+                    store,
+                    &language_server_id.0,
+                    resource,
+                )
+                .await
+            }
+            Extension::V004(_) | Extension::V001(_) => Ok(Ok(None)),
+        }
+    }
+
     pub async fn call_labels_for_completions(
         &self,
         store: &mut Store<WasmState>,

crates/extension/src/wasm_host/wit/since_v0_0_6.rs

@@ -1,16 +1,18 @@
 use crate::wasm_host::wit::ToWasmtimeResult;
 use crate::wasm_host::WasmState;
-use anyhow::{anyhow, Result};
+use ::settings::Settings;
+use anyhow::{anyhow, bail, Result};
 use async_compression::futures::bufread::GzipDecoder;
 use async_tar::Archive;
 use async_trait::async_trait;
-use futures::io::BufReader;
+use futures::{io::BufReader, FutureExt as _};
+use language::language_settings::AllLanguageSettings;
 use language::{LanguageServerBinaryStatus, LspAdapterDelegate};
+use project::project_settings::ProjectSettings;
 use semantic_version::SemanticVersion;
-use std::path::Path;
 use std::{
     env,
-    path::PathBuf,
+    path::{Path, PathBuf},
     sync::{Arc, OnceLock},
 };
 use util::maybe;
@@ -27,6 +29,10 @@ wasmtime::component::bindgen!({
     },
 });
 
+mod settings {
+    include!("../../../../extension_api/wit/since_v0.0.6/settings.rs");
+}
+
 pub type ExtensionWorktree = Arc<dyn LspAdapterDelegate>;
 
 pub fn linker() -> &'static Linker<WasmState> {
@@ -36,6 +42,22 @@ pub fn linker() -> &'static Linker<WasmState> {
 
 #[async_trait]
 impl HostWorktree for WasmState {
+    async fn id(
+        &mut self,
+        delegate: Resource<Arc<dyn LspAdapterDelegate>>,
+    ) -> wasmtime::Result<u64> {
+        let delegate = self.table.get(&delegate)?;
+        Ok(delegate.worktree_id())
+    }
+
+    async fn root_path(
+        &mut self,
+        delegate: Resource<Arc<dyn LspAdapterDelegate>>,
+    ) -> wasmtime::Result<String> {
+        let delegate = self.table.get(&delegate)?;
+        Ok(delegate.worktree_root_path().to_string_lossy().to_string())
+    }
+
     async fn read_text_file(
         &mut self,
         delegate: Resource<Arc<dyn LspAdapterDelegate>>,
@@ -78,6 +100,58 @@ impl self::zed::extension::lsp::Host for WasmState {}
 
 #[async_trait]
 impl ExtensionImports for WasmState {
+    async fn get_settings(
+        &mut self,
+        location: Option<self::SettingsLocation>,
+        category: String,
+        key: Option<String>,
+    ) -> wasmtime::Result<Result<String, String>> {
+        self.on_main_thread(|cx| {
+            async move {
+                let location = location
+                    .as_ref()
+                    .map(|location| ::settings::SettingsLocation {
+                        worktree_id: location.worktree_id as usize,
+                        path: Path::new(&location.path),
+                    });
+
+                cx.update(|cx| match category.as_str() {
+                    "language" => {
+                        let settings =
+                            AllLanguageSettings::get(location, cx).language(key.as_deref());
+                        Ok(serde_json::to_string(&settings::LanguageSettings {
+                            tab_size: settings.tab_size,
+                        })?)
+                    }
+                    "lsp" => {
+                        let settings = key
+                            .and_then(|key| {
+                                ProjectSettings::get_global(cx)
+                                    .lsp
+                                    .get(&Arc::<str>::from(key))
+                            })
+                            .cloned()
+                            .unwrap_or_default();
+                        Ok(serde_json::to_string(&settings::LspSettings {
+                            binary: settings.binary.map(|binary| settings::BinarySettings {
+                                path: binary.path,
+                                arguments: binary.arguments,
+                            }),
+                            settings: settings.settings,
+                            initialization_options: settings.initialization_options,
+                        })?)
+                    }
+                    _ => {
+                        bail!("Unknown settings category: {}", category);
+                    }
+                })
+            }
+            .boxed_local()
+        })
+        .await?
+        .to_wasmtime_result()
+    }
+
     async fn node_binary_path(&mut self) -> wasmtime::Result<Result<String, String>> {
         self.host
             .node_runtime