Add support for the experimental Next LS for Elixir (#3024)

This is a PR I built for a friend of a friend at StrangeLoop, who is
making a much better LSP for elixir that elixir folks want to experiment
with. This PR also improves the our debug log viewer to handle LSP
restarts.

TODO:
- [ ] Make sure NextLS binary loading works.

Release Notes:

- Added support for the experimental Next LS for Elxir, to enable it add
the following field to your settings to enable:

```json
"elixir": {
    "next": "on"
}
```

Cargo.lock

@@ -9875,12 +9875,14 @@ dependencies = [
  "rpc",
  "rsa",
  "rust-embed",
+ "schemars",
  "search",
  "semantic_index",
  "serde",
  "serde_derive",
  "serde_json",
  "settings",
+ "shellexpand",
  "simplelog",
  "smallvec",
  "smol",

assets/settings/default.json

@@ -372,6 +372,27 @@
   "semantic_index": {
     "enabled": false
   },
+  // Settings specific to our elixir integration
+  "elixir": {
+    // Set Zed to use the experimental Next LS LSP server.
+    // Note that changing this setting requires a restart of Zed
+    // to take effect.
+    //
+    // May take 3 values:
+    //  1. Use the standard elixir-ls LSP server
+    //         "next": "off"
+    //  2. Use a bundled version of the next Next LS LSP server
+    //         "next": "on",
+    //  3. Use a local build of the next Next LS LSP server:
+    //         "next": {
+    //           "local": {
+    //             "path": "~/next-ls/bin/start",
+    //             "arguments": ["--stdio"]
+    //            }
+    //          },
+    //
+    "next": "off"
+  },
   // Different settings for specific languages.
   "languages": {
     "Plain Text": {

crates/language_tools/src/lsp_log.rs

@@ -8,8 +8,8 @@ use gpui::{
         ParentElement, Stack,
     },
     platform::{CursorStyle, MouseButton},
-    AnyElement, AppContext, Element, Entity, ModelContext, ModelHandle, View, ViewContext,
-    ViewHandle, WeakModelHandle,
+    AnyElement, AppContext, Element, Entity, ModelContext, ModelHandle, Subscription, View,
+    ViewContext, ViewHandle, WeakModelHandle,
 };
 use language::{Buffer, LanguageServerId, LanguageServerName};
 use lsp::IoKind;
@@ -53,10 +53,12 @@ pub struct LspLogView {
     current_server_id: Option<LanguageServerId>,
     is_showing_rpc_trace: bool,
     project: ModelHandle<Project>,
+    _log_store_subscription: Subscription,
 }
 
 pub struct LspLogToolbarItemView {
     log_view: Option<ViewHandle<LspLogView>>,
+    _log_view_subscription: Option<Subscription>,
     menu_open: bool,
 }
 
@@ -373,12 +375,49 @@ impl LspLogView {
             .get(&project.downgrade())
             .and_then(|project| project.servers.keys().copied().next());
         let buffer = cx.add_model(|cx| Buffer::new(0, cx.model_id() as u64, ""));
+        let _log_store_subscription = cx.observe(&log_store, |this, store, cx| {
+            (|| -> Option<()> {
+                let project_state = store.read(cx).projects.get(&this.project.downgrade())?;
+                if let Some(current_lsp) = this.current_server_id {
+                    if !project_state.servers.contains_key(&current_lsp) {
+                        if let Some(server) = project_state.servers.iter().next() {
+                            if this.is_showing_rpc_trace {
+                                this.show_rpc_trace_for_server(*server.0, cx)
+                            } else {
+                                this.show_logs_for_server(*server.0, cx)
+                            }
+                        } else {
+                            this.current_server_id = None;
+                            this.editor.update(cx, |editor, cx| {
+                                editor.set_read_only(false);
+                                editor.clear(cx);
+                                editor.set_read_only(true);
+                            });
+                            cx.notify();
+                        }
+                    }
+                } else {
+                    if let Some(server) = project_state.servers.iter().next() {
+                        if this.is_showing_rpc_trace {
+                            this.show_rpc_trace_for_server(*server.0, cx)
+                        } else {
+                            this.show_logs_for_server(*server.0, cx)
+                        }
+                    }
+                }
+
+                Some(())
+            })();
+
+            cx.notify();
+        });
         let mut this = Self {
             editor: Self::editor_for_buffer(project.clone(), buffer, cx),
             project,
             log_store,
             current_server_id: None,
             is_showing_rpc_trace: false,
+            _log_store_subscription,
         };
         if let Some(server_id) = server_id {
             this.show_logs_for_server(server_id, cx);
@@ -601,18 +640,22 @@ impl ToolbarItemView for LspLogToolbarItemView {
     fn set_active_pane_item(
         &mut self,
         active_pane_item: Option<&dyn ItemHandle>,
-        _: &mut ViewContext<Self>,
+        cx: &mut ViewContext<Self>,
     ) -> workspace::ToolbarItemLocation {
         self.menu_open = false;
         if let Some(item) = active_pane_item {
             if let Some(log_view) = item.downcast::<LspLogView>() {
                 self.log_view = Some(log_view.clone());
+                self._log_view_subscription = Some(cx.observe(&log_view, |_, _, cx| {
+                    cx.notify();
+                }));
                 return ToolbarItemLocation::PrimaryLeft {
                     flex: Some((1., false)),
                 };
             }
         }
         self.log_view = None;
+        self._log_view_subscription = None;
         ToolbarItemLocation::Hidden
     }
 }
@@ -743,6 +786,7 @@ impl LspLogToolbarItemView {
         Self {
             menu_open: false,
             log_view: None,
+            _log_view_subscription: None,
         }
     }
 

crates/lsp/src/lsp.rs

@@ -716,11 +716,11 @@ impl LanguageServer {
         }
     }
 
-    pub fn name<'a>(self: &'a Arc<Self>) -> &'a str {
+    pub fn name(&self) -> &str {
         &self.name
     }
 
-    pub fn capabilities<'a>(self: &'a Arc<Self>) -> &'a ServerCapabilities {
+    pub fn capabilities(&self) -> &ServerCapabilities {
         &self.capabilities
     }
 

crates/project/src/project.rs

@@ -2280,11 +2280,13 @@ impl Project {
                 };
 
                 for (_, _, server) in self.language_servers_for_worktree(worktree_id) {
+                    let text = include_text(server.as_ref()).then(|| buffer.read(cx).text());
+
                     server
                         .notify::<lsp::notification::DidSaveTextDocument>(
                             lsp::DidSaveTextDocumentParams {
                                 text_document: text_document.clone(),
-                                text: None,
+                                text,
                             },
                         )
                         .log_err();
@@ -8325,3 +8327,19 @@ async fn wait_for_loading_buffer(
         receiver.next().await;
     }
 }
+
+fn include_text(server: &lsp::LanguageServer) -> bool {
+    server
+        .capabilities()
+        .text_document_sync
+        .as_ref()
+        .and_then(|sync| match sync {
+            lsp::TextDocumentSyncCapability::Kind(_) => None,
+            lsp::TextDocumentSyncCapability::Options(options) => options.save.as_ref(),
+        })
+        .and_then(|save_options| match save_options {
+            lsp::TextDocumentSyncSaveOptions::Supported(_) => None,
+            lsp::TextDocumentSyncSaveOptions::SaveOptions(options) => options.include_text,
+        })
+        .unwrap_or(false)
+}

crates/project_symbols/src/project_symbols.rs

@@ -69,7 +69,7 @@ impl ProjectSymbolsDelegate {
             &self.external_match_candidates,
             query,
             false,
-            MAX_MATCHES - visible_matches.len(),
+            MAX_MATCHES - visible_matches.len().min(MAX_MATCHES),
             &Default::default(),
             cx.background().clone(),
         ));

crates/semantic_index/examples/eval.rs

@@ -456,7 +456,7 @@ fn main() {
         let languages = Arc::new(languages);
 
         let node_runtime = RealNodeRuntime::new(http.clone());
-        languages::init(languages.clone(), node_runtime.clone());
+        languages::init(languages.clone(), node_runtime.clone(), cx);
         language::init(cx);
 
         project::Project::init(&client, cx);

crates/zed/Cargo.toml

@@ -62,6 +62,7 @@ rpc = { path = "../rpc" }
 settings = { path = "../settings" }
 feature_flags = { path = "../feature_flags" }
 sum_tree = { path = "../sum_tree" }
+shellexpand = "2.1.0"
 text = { path = "../text" }
 terminal_view = { path = "../terminal_view" }
 theme = { path = "../theme" }
@@ -99,6 +100,7 @@ rust-embed.workspace = true
 serde.workspace = true
 serde_derive.workspace = true
 serde_json.workspace = true
+schemars.workspace = true
 simplelog = "0.9"
 smallvec.workspace = true
 smol.workspace = true

crates/zed/src/languages.rs

@@ -1,13 +1,17 @@
 use anyhow::Context;
+use gpui::AppContext;
 pub use language::*;
 use node_runtime::NodeRuntime;
 use rust_embed::RustEmbed;
 use std::{borrow::Cow, str, sync::Arc};
 use util::asset_str;
 
+use self::elixir_next::ElixirSettings;
+
 mod c;
 mod css;
 mod elixir;
+mod elixir_next;
 mod go;
 mod html;
 mod json;
@@ -37,7 +41,13 @@ mod yaml;
 #[exclude = "*.rs"]
 struct LanguageDir;
 
-pub fn init(languages: Arc<LanguageRegistry>, node_runtime: Arc<dyn NodeRuntime>) {
+pub fn init(
+    languages: Arc<LanguageRegistry>,
+    node_runtime: Arc<dyn NodeRuntime>,
+    cx: &mut AppContext,
+) {
+    settings::register::<elixir_next::ElixirSettings>(cx);
+
     let language = |name, grammar, adapters| {
         languages.register(name, load_config(name), grammar, adapters, load_queries)
     };
@@ -61,11 +71,28 @@ pub fn init(languages: Arc<LanguageRegistry>, node_runtime: Arc<dyn NodeRuntime>
             Arc::new(tailwind::TailwindLspAdapter::new(node_runtime.clone())),
         ],
     );
-    language(
-        "elixir",
-        tree_sitter_elixir::language(),
-        vec![Arc::new(elixir::ElixirLspAdapter)],
-    );
+
+    match &settings::get::<ElixirSettings>(cx).next {
+        elixir_next::ElixirNextSetting::Off => language(
+            "elixir",
+            tree_sitter_elixir::language(),
+            vec![Arc::new(elixir::ElixirLspAdapter)],
+        ),
+        elixir_next::ElixirNextSetting::On => language(
+            "elixir",
+            tree_sitter_elixir::language(),
+            vec![Arc::new(elixir_next::NextLspAdapter)],
+        ),
+        elixir_next::ElixirNextSetting::Local { path, arguments } => language(
+            "elixir",
+            tree_sitter_elixir::language(),
+            vec![Arc::new(elixir_next::LocalNextLspAdapter {
+                path: path.clone(),
+                arguments: arguments.clone(),
+            })],
+        ),
+    }
+
     language(
         "go",
         tree_sitter_go::language(),

crates/zed/src/languages/elixir_next.rs

@@ -0,0 +1,266 @@
+use anyhow::{anyhow, bail, Result};
+
+use async_trait::async_trait;
+pub use language::*;
+use lsp::{LanguageServerBinary, SymbolKind};
+use schemars::JsonSchema;
+use serde_derive::{Deserialize, Serialize};
+use settings::Setting;
+use smol::{fs, stream::StreamExt};
+use std::{any::Any, env::consts, ops::Deref, path::PathBuf, sync::Arc};
+use util::{
+    async_iife,
+    github::{latest_github_release, GitHubLspBinaryVersion},
+    ResultExt,
+};
+
+#[derive(Clone, Serialize, Deserialize, JsonSchema)]
+pub struct ElixirSettings {
+    pub next: ElixirNextSetting,
+}
+
+#[derive(Clone, Serialize, Deserialize, JsonSchema)]
+#[serde(rename_all = "snake_case")]
+pub enum ElixirNextSetting {
+    Off,
+    On,
+    Local {
+        path: String,
+        arguments: Vec<String>,
+    },
+}
+
+#[derive(Clone, Serialize, Default, Deserialize, JsonSchema)]
+pub struct ElixirSettingsContent {
+    next: Option<ElixirNextSetting>,
+}
+
+impl Setting for ElixirSettings {
+    const KEY: Option<&'static str> = Some("elixir");
+
+    type FileContent = ElixirSettingsContent;
+
+    fn load(
+        default_value: &Self::FileContent,
+        user_values: &[&Self::FileContent],
+        _: &gpui::AppContext,
+    ) -> Result<Self>
+    where
+        Self: Sized,
+    {
+        Self::load_via_json_merge(default_value, user_values)
+    }
+}
+
+pub struct NextLspAdapter;
+
+#[async_trait]
+impl LspAdapter for NextLspAdapter {
+    async fn name(&self) -> LanguageServerName {
+        LanguageServerName("next-ls".into())
+    }
+
+    fn short_name(&self) -> &'static str {
+        "next-ls"
+    }
+
+    async fn fetch_latest_server_version(
+        &self,
+        delegate: &dyn LspAdapterDelegate,
+    ) -> Result<Box<dyn 'static + Send + Any>> {
+        let release =
+            latest_github_release("elixir-tools/next-ls", false, delegate.http_client()).await?;
+        let version = release.name.clone();
+        let platform = match consts::ARCH {
+            "x86_64" => "darwin_arm64",
+            "aarch64" => "darwin_amd64",
+            other => bail!("Running on unsupported platform: {other}"),
+        };
+        let asset_name = format!("next_ls_{}", platform);
+        let asset = release
+            .assets
+            .iter()
+            .find(|asset| asset.name == asset_name)
+            .ok_or_else(|| anyhow!("no asset found matching {:?}", asset_name))?;
+        let version = GitHubLspBinaryVersion {
+            name: version,
+            url: asset.browser_download_url.clone(),
+        };
+        Ok(Box::new(version) as Box<_>)
+    }
+
+    async fn fetch_server_binary(
+        &self,
+        version: Box<dyn 'static + Send + Any>,
+        container_dir: PathBuf,
+        delegate: &dyn LspAdapterDelegate,
+    ) -> Result<LanguageServerBinary> {
+        let version = version.downcast::<GitHubLspBinaryVersion>().unwrap();
+
+        let binary_path = container_dir.join("next-ls");
+
+        if fs::metadata(&binary_path).await.is_err() {
+            let mut response = delegate
+                .http_client()
+                .get(&version.url, Default::default(), true)
+                .await
+                .map_err(|err| anyhow!("error downloading release: {}", err))?;
+
+            let mut file = smol::fs::File::create(&binary_path).await?;
+            if !response.status().is_success() {
+                Err(anyhow!(
+                    "download failed with status {}",
+                    response.status().to_string()
+                ))?;
+            }
+            futures::io::copy(response.body_mut(), &mut file).await?;
+
+            fs::set_permissions(
+                &binary_path,
+                <fs::Permissions as fs::unix::PermissionsExt>::from_mode(0o755),
+            )
+            .await?;
+        }
+
+        Ok(LanguageServerBinary {
+            path: binary_path,
+            arguments: vec!["--stdio".into()],
+        })
+    }
+
+    async fn cached_server_binary(
+        &self,
+        container_dir: PathBuf,
+        _: &dyn LspAdapterDelegate,
+    ) -> Option<LanguageServerBinary> {
+        get_cached_server_binary(container_dir)
+            .await
+            .map(|mut binary| {
+                binary.arguments = vec!["--stdio".into()];
+                binary
+            })
+    }
+
+    async fn installation_test_binary(
+        &self,
+        container_dir: PathBuf,
+    ) -> Option<LanguageServerBinary> {
+        get_cached_server_binary(container_dir)
+            .await
+            .map(|mut binary| {
+                binary.arguments = vec!["--help".into()];
+                binary
+            })
+    }
+
+    async fn label_for_symbol(
+        &self,
+        name: &str,
+        symbol_kind: SymbolKind,
+        language: &Arc<Language>,
+    ) -> Option<CodeLabel> {
+        label_for_symbol_next(name, symbol_kind, language)
+    }
+}
+
+async fn get_cached_server_binary(container_dir: PathBuf) -> Option<LanguageServerBinary> {
+    async_iife!({
+        let mut last_binary_path = None;
+        let mut entries = fs::read_dir(&container_dir).await?;
+        while let Some(entry) = entries.next().await {
+            let entry = entry?;
+            if entry.file_type().await?.is_file()
+                && entry
+                    .file_name()
+                    .to_str()
+                    .map_or(false, |name| name == "next-ls")
+            {
+                last_binary_path = Some(entry.path());
+            }
+        }
+
+        if let Some(path) = last_binary_path {
+            Ok(LanguageServerBinary {
+                path,
+                arguments: Vec::new(),
+            })
+        } else {
+            Err(anyhow!("no cached binary"))
+        }
+    })
+    .await
+    .log_err()
+}
+
+pub struct LocalNextLspAdapter {
+    pub path: String,
+    pub arguments: Vec<String>,
+}
+
+#[async_trait]
+impl LspAdapter for LocalNextLspAdapter {
+    async fn name(&self) -> LanguageServerName {
+        LanguageServerName("local-next-ls".into())
+    }
+
+    fn short_name(&self) -> &'static str {
+        "next-ls"
+    }
+
+    async fn fetch_latest_server_version(
+        &self,
+        _: &dyn LspAdapterDelegate,
+    ) -> Result<Box<dyn 'static + Send + Any>> {
+        Ok(Box::new(()) as Box<_>)
+    }
+
+    async fn fetch_server_binary(
+        &self,
+        _: Box<dyn 'static + Send + Any>,
+        _: PathBuf,
+        _: &dyn LspAdapterDelegate,
+    ) -> Result<LanguageServerBinary> {
+        let path = shellexpand::full(&self.path)?;
+        Ok(LanguageServerBinary {
+            path: PathBuf::from(path.deref()),
+            arguments: self.arguments.iter().map(|arg| arg.into()).collect(),
+        })
+    }
+
+    async fn cached_server_binary(
+        &self,
+        _: PathBuf,
+        _: &dyn LspAdapterDelegate,
+    ) -> Option<LanguageServerBinary> {
+        let path = shellexpand::full(&self.path).ok()?;
+        Some(LanguageServerBinary {
+            path: PathBuf::from(path.deref()),
+            arguments: self.arguments.iter().map(|arg| arg.into()).collect(),
+        })
+    }
+
+    async fn installation_test_binary(&self, _: PathBuf) -> Option<LanguageServerBinary> {
+        let path = shellexpand::full(&self.path).ok()?;
+        Some(LanguageServerBinary {
+            path: PathBuf::from(path.deref()),
+            arguments: self.arguments.iter().map(|arg| arg.into()).collect(),
+        })
+    }
+
+    async fn label_for_symbol(
+        &self,
+        name: &str,
+        symbol: SymbolKind,
+        language: &Arc<Language>,
+    ) -> Option<CodeLabel> {
+        label_for_symbol_next(name, symbol, language)
+    }
+}
+
+fn label_for_symbol_next(name: &str, _: SymbolKind, language: &Arc<Language>) -> Option<CodeLabel> {
+    Some(CodeLabel {
+        runs: language.highlight_text(&name.into(), 0..name.len()),
+        text: name.to_string(),
+        filter_range: 0..name.len(),
+    })
+}

crates/zed/src/main.rs

@@ -135,7 +135,7 @@ fn main() {
         let languages = Arc::new(languages);
         let node_runtime = RealNodeRuntime::new(http.clone());
 
-        languages::init(languages.clone(), node_runtime.clone());
+        languages::init(languages.clone(), node_runtime.clone(), cx);
         let user_store = cx.add_model(|cx| UserStore::new(client.clone(), http.clone(), cx));
         let channel_store =
             cx.add_model(|cx| ChannelStore::new(client.clone(), user_store.clone(), cx));

crates/zed/src/zed.rs

@@ -2388,11 +2388,12 @@ mod tests {
 
     #[gpui::test]
     fn test_bundled_languages(cx: &mut AppContext) {
+        cx.set_global(SettingsStore::test(cx));
         let mut languages = LanguageRegistry::test();
         languages.set_executor(cx.background().clone());
         let languages = Arc::new(languages);
         let node_runtime = node_runtime::FakeNodeRuntime::new();
-        languages::init(languages.clone(), node_runtime);
+        languages::init(languages.clone(), node_runtime, cx);
         for name in languages.language_names() {
             languages.language_for_name(&name);
         }