Send active diagnostics to LSP when requesting code actions. (#2005)

* Send active diagnostics to LSP when requesting code actions.

This allows for e.g. clangd to properly send the quickfix code actions
corresponding to those diagnostics as options.
The LSP spec v3.16.0 introduced an opaque `data` member that would allow
the server to persist arbitrary data between the diagnostic and the code
actions request, but this is not supported yet by this commit.

* Reuse existing range_to_lsp_range functionality

helix-lsp/src/client.rs

@@ -842,11 +842,12 @@ impl Client {
         &self,
         text_document: lsp::TextDocumentIdentifier,
         range: lsp::Range,
+        context: lsp::CodeActionContext,
     ) -> impl Future<Output = Result<Value>> {
         let params = lsp::CodeActionParams {
             text_document,
             range,
-            context: lsp::CodeActionContext::default(),
+            context,
             work_done_progress_params: lsp::WorkDoneProgressParams::default(),
             partial_result_params: lsp::PartialResultParams::default(),
         };

helix-lsp/src/lib.rs

@@ -58,6 +58,36 @@ pub mod util {
     use super::*;
     use helix_core::{Range, Rope, Transaction};
 
+    /// Converts a diagnostic in the document to [`lsp::Diagnostic`].
+    ///
+    /// Panics when [`pos_to_lsp_pos`] would for an invalid range on the diagnostic.
+    pub fn diagnostic_to_lsp_diagnostic(
+        doc: &Rope,
+        diag: &helix_core::diagnostic::Diagnostic,
+        offset_encoding: OffsetEncoding,
+    ) -> lsp::Diagnostic {
+        use helix_core::diagnostic::Severity::*;
+
+        let range = Range::new(diag.range.start, diag.range.end);
+        let severity = diag.severity.map(|s| match s {
+            Hint => lsp::DiagnosticSeverity::HINT,
+            Info => lsp::DiagnosticSeverity::INFORMATION,
+            Warning => lsp::DiagnosticSeverity::WARNING,
+            Error => lsp::DiagnosticSeverity::ERROR,
+        });
+
+        // TODO: add support for Diagnostic.data
+        lsp::Diagnostic::new(
+            range_to_lsp_range(doc, range, offset_encoding),
+            severity,
+            None,
+            None,
+            diag.message.to_owned(),
+            None,
+            None,
+        )
+    }
+
     /// Converts [`lsp::Position`] to a position in the document.
     ///
     /// Returns `None` if position exceeds document length or an operation overflows.

helix-term/src/commands/lsp.rs

@@ -1,6 +1,6 @@
 use helix_lsp::{
     block_on, lsp,
-    util::{lsp_pos_to_pos, lsp_range_to_range, range_to_lsp_range},
+    util::{diagnostic_to_lsp_diagnostic, lsp_pos_to_pos, lsp_range_to_range, range_to_lsp_range},
     OffsetEncoding,
 };
 
@@ -192,15 +192,29 @@ pub fn code_action(cx: &mut Context) {
 
     let language_server = language_server!(cx.editor, doc);
 
-    let range = range_to_lsp_range(
+    let selection_range = doc.selection(view.id).primary();
-        doc.text(),
-        doc.selection(view.id).primary(),
-        language_server.offset_encoding(),
-    );
-
-    let future = language_server.code_actions(doc.identifier(), range);
     let offset_encoding = language_server.offset_encoding();
 
+    let range = range_to_lsp_range(doc.text(), selection_range, offset_encoding);
+
+    let future = language_server.code_actions(
+        doc.identifier(),
+        range,
+        // Filter and convert overlapping diagnostics
+        lsp::CodeActionContext {
+            diagnostics: doc
+                .diagnostics()
+                .iter()
+                .filter(|&diag| {
+                    selection_range
+                        .overlaps(&helix_core::Range::new(diag.range.start, diag.range.end))
+                })
+                .map(|diag| diagnostic_to_lsp_diagnostic(doc.text(), diag, offset_encoding))
+                .collect(),
+            only: None,
+        },
+    );
+
     cx.callback(
         future,
         move |editor, compositor, response: Option<lsp::CodeActionResponse>| {