internal/lsp: initialize CodeActionProvider with supported actions

Send the code action kinds that we support, if codeActionLiteralSupport
is specified. Editors may use the CodeActionKinds that we support to
determine UI layout for example.

Change-Id: Iee368aa02c26f4395bb2894593ef38d84d3283b7
Reviewed-on: https://go-review.googlesource.com/c/tools/+/191620
Run-TryBot: Suzy Mueller <suzmue@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/code_action.go

@@ -7,6 +7,7 @@ package lsp
 import (
 	"context"
 	"fmt"
+	"sort"
 	"strings"
 
 	"golang.org/x/tools/internal/imports"
@@ -18,6 +19,24 @@ import (
 	errors "golang.org/x/xerrors"
 )
 
+func (s *Server) getSupportedCodeActions() []protocol.CodeActionKind {
+	allCodeActionKinds := make(map[protocol.CodeActionKind]struct{})
+	for _, kinds := range s.supportedCodeActions {
+		for kind := range kinds {
+			allCodeActionKinds[kind] = struct{}{}
+		}
+	}
+
+	var result []protocol.CodeActionKind
+	for kind := range allCodeActionKinds {
+		result = append(result, kind)
+	}
+	sort.Slice(result, func(i, j int) bool {
+		return result[i] < result[j]
+	})
+	return result
+}
+
 func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionParams) ([]protocol.CodeAction, error) {
 	uri := span.NewURI(params.TextDocument.URI)
 	view := s.session.ViewOf(uri)

internal/lsp/general.go

@@ -77,9 +77,22 @@ func (s *Server) initialize(ctx context.Context, params *protocol.InitializePara
 			return nil, err
 		}
 	}
+
+	var codeActionProvider interface{}
+	if len(params.Capabilities.TextDocument.CodeAction.CodeActionLiteralSupport.CodeActionKind.ValueSet) > 0 {
+		// If the client has specified CodeActionLiteralSupport,
+		// send the code actions we support.
+		//
+		// Using CodeActionOptions is only valid if codeActionLiteralSupport is set.
+		codeActionProvider = &protocol.CodeActionOptions{
+			CodeActionKinds: s.getSupportedCodeActions(),
+		}
+	} else {
+		codeActionProvider = true
+	}
 	return &protocol.InitializeResult{
 		Capabilities: protocol.ServerCapabilities{
-			CodeActionProvider: true,
+			CodeActionProvider: codeActionProvider,
 			CompletionProvider: &protocol.CompletionOptions{
 				TriggerCharacters: []string{"."},
 			},

internal/lsp/protocol/tsprotocol.go

@@ -1528,7 +1528,7 @@ type ServerCapabilities struct {
 	 * specified if the client states that it supports
 	 * `codeActionLiteralSupport` in its initial `initialize` request.
 	 */
-	CodeActionProvider bool `json:"codeActionProvider,omitempty"` // boolean | CodeActionOptions
+	CodeActionProvider interface{} `json:"codeActionProvider,omitempty"` // boolean | CodeActionOptions
 
 	/*CodeLensProvider defined:
 	 * The server provides code lens.