internal/lsp: reorganize the generated Go code for the lsp protocol

Code generation has been unified, so that tsprotocol.go and tsserver.go are produced by the same program. tsprotocol.go is about 900 lines shorter, partly from removing boilerplate comments that golint no longer requires. (And partly by generating fewer unneeded types.) The choice made for a union type is commented with the set of types. There is no Go equivalent for union types, but making themn all interface{} would replace type checking at unmarshalling with checking runtime conversions. Intersection types (A&B) are sometimes embedded (struct{A;B;}, and sometimes expanded, as they have to be if A and B have fields with the same names. There are fewer embedded structs, which had been verbose and confusing to initialize. They have been replaced by types whose names end in Gn. Essentially all the generated *structs have been removed. This makes no difference in what the client sends, and the server may send a {} where it previously might have sent nothing. The benefit is that some nil tests can be removed. Thus 'omitempty' in json tags is just documentation that the element is optional in the protocol. The files that generate this code will be submitted later, but soon. Change-Id: I52b997d9c58de3d733fc8c6ce061e47ce2bdb100 Reviewed-on: https://go-review.googlesource.com/c/tools/+/207598 Run-TryBot: Peter Weinberger <pjw@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Cottrell <iancottrell@google.com>
2024-11-18 15:04:44 -07:00 · 2019-11-17 14:29:15 -05:00 · 2019-11-17 14:29:15 -05:00 · 5091d647ee
commit 5091d647ee
parent 5a76f03bc7
18 changed files with 1396 additions and 2274 deletions
--- a/internal/lsp/cmd/cmd.go
+++ b/internal/lsp/cmd/cmd.go
@ -204,10 +204,10 @@ func (app *Application) connect(ctx context.Context) (*connection, error) {
 }

 func (c *connection) initialize(ctx context.Context) error {
-	params := &protocol.ParamInitia{}
+	params := &protocol.ParamInitialize{}
 	params.RootURI = string(span.FileURI(c.Client.app.wd))
 	params.Capabilities.Workspace.Configuration = true
-	params.Capabilities.TextDocument.Hover = &protocol.HoverClientCapabilities{
+	params.Capabilities.TextDocument.Hover = protocol.HoverClientCapabilities{
 		ContentFormat: []protocol.MarkupKind{protocol.PlainText},
 	}
 	if _, err := c.Server.Initialize(ctx, params); err != nil {
@ -295,7 +295,7 @@ func (c *cmdClient) WorkspaceFolders(ctx context.Context) ([]protocol.WorkspaceF
 	return nil, nil
 }

-func (c *cmdClient) Configuration(ctx context.Context, p *protocol.ParamConfig) ([]interface{}, error) {
+func (c *cmdClient) Configuration(ctx context.Context, p *protocol.ParamConfiguration) ([]interface{}, error) {
 	results := make([]interface{}, len(p.Items))
 	for i, item := range p.Items {
 		if item.Section != "gopls" {
--- a/internal/lsp/cmd/imports.go
+++ b/internal/lsp/cmd/imports.go
@ -69,7 +69,11 @@ func (t *imports) Run(ctx context.Context, args ...string) error {
 		return errors.Errorf("%v: %v", from, err)
 	}
 	var edits []protocol.TextEdit
-	for _, a := range actions {
+	v, ok := actions.([]protocol.CodeAction)
+	if !ok {
+		return errors.Errorf("expected CodeAction, got %T", actions)
+	}
+	for _, a := range v {
 		if a.Title != "Organize Imports" {
 			continue
 		}
--- a/internal/lsp/cmd/suggested_fix.go
+++ b/internal/lsp/cmd/suggested_fix.go
@ -87,7 +87,11 @@ func (s *suggestedfix) Run(ctx context.Context, args ...string) error {
 		return errors.Errorf("%v: %v", from, err)
 	}
 	var edits []protocol.TextEdit
-	for _, a := range actions {
+	v, ok := actions.([]protocol.CodeAction)
+	if !ok {
+		return errors.Errorf("expected CodeAction, got %T", actions)
+	}
+	for _, a := range v {
 		if !a.IsPreferred && !s.All {
 			continue
 		}
--- a/internal/lsp/cmd/symbols.go
+++ b/internal/lsp/cmd/symbols.go
@ -52,7 +52,6 @@ func (r *symbols) Run(ctx context.Context, args ...string) error {
 	if err != nil {
 		return err
 	}
-
 	for _, s := range symbols {
 		fmt.Println(symbolToString(s))
 		// Sort children for consistency
--- a/internal/lsp/code_action.go
+++ b/internal/lsp/code_action.go
@ -63,7 +63,7 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 		codeActions = append(codeActions, protocol.CodeAction{
 			Title: "Tidy",
 			Kind:  protocol.SourceOrganizeImports,
-			Command: &protocol.Command{
+			Command: protocol.Command{
 				Title:   "Tidy",
 				Command: "tidy",
 				Arguments: []interface{}{
@ -94,7 +94,7 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 						codeActions = append(codeActions, protocol.CodeAction{
 							Title: importFixTitle(importFix.Fix),
 							Kind:  protocol.QuickFix,
-							Edit: &protocol.WorkspaceEdit{
+							Edit: protocol.WorkspaceEdit{
 								DocumentChanges: documentChanges(fh, importFix.Edits),
 							},
 							Diagnostics: fixDiagnostics,
@ -107,7 +107,7 @@ func (s *Server) codeAction(ctx context.Context, params *protocol.CodeActionPara
 			codeActions = append(codeActions, protocol.CodeAction{
 				Title: "Organize Imports",
 				Kind:  protocol.SourceOrganizeImports,
-				Edit: &protocol.WorkspaceEdit{
+				Edit: protocol.WorkspaceEdit{
 					DocumentChanges: documentChanges(fh, edits),
 				},
 			})
@ -226,7 +226,7 @@ func quickFixes(ctx context.Context, s source.Snapshot, f source.File, diagnosti
 				Title:       fix.Title,
 				Kind:        protocol.QuickFix,
 				Diagnostics: []protocol.Diagnostic{diag},
-				Edit:        &protocol.WorkspaceEdit{},
+				Edit:        protocol.WorkspaceEdit{},
 			}
 			for uri, edits := range fix.Edits {
 				f, err := s.View().GetFile(ctx, uri)
--- a/internal/lsp/completion.go
+++ b/internal/lsp/completion.go
@ -104,7 +104,7 @@ func toProtocolCompletionItems(candidates []source.CompletionItem, rng protocol.
 			Label:  candidate.Label,
 			Detail: candidate.Detail,
 			Kind:   candidate.Kind,
-			TextEdit: &protocol.TextEdit{
+			TextEdit: protocol.TextEdit{
 				NewText: insertText,
 				Range:   rng,
 			},
@ -123,7 +123,7 @@ func toProtocolCompletionItems(candidates []source.CompletionItem, rng protocol.
 		// since we show return types as well.
 		switch item.Kind {
 		case protocol.FunctionCompletion, protocol.MethodCompletion:
-			item.Command = &protocol.Command{
+			item.Command = protocol.Command{
 				Command: "editor.action.triggerParameterHints",
 			}
 		}
--- a/internal/lsp/general.go
+++ b/internal/lsp/general.go
@ -20,7 +20,7 @@ import (
 	errors "golang.org/x/xerrors"
 )

-func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitia) (*protocol.InitializeResult, error) {
+func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitialize) (*protocol.InitializeResult, error) {
 	s.stateMu.Lock()
 	state := s.state
 	s.stateMu.Unlock()
@ -53,8 +53,7 @@ func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitia) (
 	}

 	var codeActionProvider interface{}
-	if ca := params.Capabilities.TextDocument.CodeAction; ca != nil && ca.CodeActionLiteralSupport != nil &&
-		len(ca.CodeActionLiteralSupport.CodeActionKind.ValueSet) > 0 {
+	if ca := params.Capabilities.TextDocument.CodeAction; len(ca.CodeActionLiteralSupport.CodeActionKind.ValueSet) > 0 {
 		// If the client has specified CodeActionLiteralSupport,
 		// send the code actions we support.
 		//
@ -65,18 +64,16 @@ func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitia) (
 	} else {
 		codeActionProvider = true
 	}
-	var renameOpts interface{}
-	if r := params.Capabilities.TextDocument.Rename; r != nil {
-		renameOpts = &protocol.RenameOptions{
-			PrepareProvider: r.PrepareSupport,
-		}
-	} else {
-		renameOpts = true
+	// This used to be interface{}, when r could be nil
+	var renameOpts protocol.RenameOptions
+	r := params.Capabilities.TextDocument.Rename
+	renameOpts = protocol.RenameOptions{
+		PrepareProvider: r.PrepareSupport,
 	}
 	return &protocol.InitializeResult{
 		Capabilities: protocol.ServerCapabilities{
 			CodeActionProvider: codeActionProvider,
-			CompletionProvider: &protocol.CompletionOptions{
+			CompletionProvider: protocol.CompletionOptions{
 				TriggerCharacters: []string{"."},
 			},
 			DefinitionProvider:         true,
@ -84,35 +81,27 @@ func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitia) (
 			ImplementationProvider:     true,
 			DocumentFormattingProvider: true,
 			DocumentSymbolProvider:     true,
-			ExecuteCommandProvider: &protocol.ExecuteCommandOptions{
+			ExecuteCommandProvider: protocol.ExecuteCommandOptions{
 				Commands: options.SupportedCommands,
 			},
 			FoldingRangeProvider:      true,
 			HoverProvider:             true,
 			DocumentHighlightProvider: true,
-			DocumentLinkProvider:      &protocol.DocumentLinkOptions{},
+			DocumentLinkProvider:      protocol.DocumentLinkOptions{},
 			ReferencesProvider:        true,
 			RenameProvider:            renameOpts,
-			SignatureHelpProvider: &protocol.SignatureHelpOptions{
+			SignatureHelpProvider: protocol.SignatureHelpOptions{
 				TriggerCharacters: []string{"(", ","},
 			},
 			TextDocumentSync: &protocol.TextDocumentSyncOptions{
 				Change:    options.TextDocumentSyncKind,
 				OpenClose: true,
-				Save: &protocol.SaveOptions{
+				Save: protocol.SaveOptions{
 					IncludeText: false,
 				},
 			},
-			Workspace: &struct {
-				WorkspaceFolders *struct {
-					Supported           bool   "json:\"supported,omitempty\""
-					ChangeNotifications string "json:\"changeNotifications,omitempty\""
-				} "json:\"workspaceFolders,omitempty\""
-			}{
-				WorkspaceFolders: &struct {
-					Supported           bool   "json:\"supported,omitempty\""
-					ChangeNotifications string "json:\"changeNotifications,omitempty\""
-				}{
+			Workspace: protocol.WorkspaceGn{
+				protocol.WorkspaceFoldersGn{
 					Supported:           true,
 					ChangeNotifications: "workspace/didChangeWorkspaceFolders",
 				},
@ -192,7 +181,7 @@ func (s *Server) fetchConfig(ctx context.Context, name string, folder span.URI,
 	if !s.session.Options().ConfigurationSupported {
 		return nil
 	}
-	v := protocol.ParamConfig{
+	v := protocol.ParamConfiguration{
 		ConfigurationParams: protocol.ConfigurationParams{
 			Items: []protocol.ConfigurationItem{{
 				ScopeURI: protocol.NewURI(folder),
--- a/internal/lsp/highlight.go
+++ b/internal/lsp/highlight.go
@ -32,7 +32,7 @@ func toProtocolHighlight(rngs []protocol.Range) []protocol.DocumentHighlight {
 	kind := protocol.Text
 	for _, rng := range rngs {
 		result = append(result, protocol.DocumentHighlight{
-			Kind:  &kind,
+			Kind:  kind,
 			Range: rng,
 		})
 	}
--- a/internal/lsp/hover.go
+++ b/internal/lsp/hover.go
@ -40,7 +40,7 @@ func (s *Server) hover(ctx context.Context, params *protocol.HoverParams) (*prot
 	contents := s.toProtocolHoverContents(ctx, hover, view.Options())
 	return &protocol.Hover{
 		Contents: contents,
-		Range:    &rng,
+		Range:    rng,
 	}, nil
 }

--- a/internal/lsp/lsp_test.go
+++ b/internal/lsp/lsp_test.go
@ -314,8 +314,9 @@ func (r *runner) Import(t *testing.T, spn span.Span) {
 		t.Fatal(err)
 	}
 	got := string(m.Content)
-	if len(actions) > 0 {
-		res, err := applyWorkspaceEdits(r, actions[0].Edit)
+	xact := actions.([]protocol.CodeAction)
+	if len(xact) > 0 {
+		res, err := applyWorkspaceEdits(r, xact[0].Edit)
 		if err != nil {
 			t.Fatal(err)
 		}
@ -354,10 +355,11 @@ func (r *runner) SuggestedFix(t *testing.T, spn span.Span) {
 		t.Fatal(err)
 	}
 	// TODO: This test should probably be able to handle multiple code actions.
-	if len(actions) > 1 {
+	xact := actions.([]protocol.CodeAction)
+	if len(xact) > 1 {
 		t.Fatal("expected only 1 code action")
 	}
-	res, err := applyWorkspaceEdits(r, actions[0].Edit)
+	res, err := applyWorkspaceEdits(r, xact[0].Edit)
 	if err != nil {
 		t.Fatal(err)
 	}
@ -575,7 +577,7 @@ func (r *runner) Rename(t *testing.T, spn span.Span, newText string) {
 		}
 		return
 	}
-	res, err := applyWorkspaceEdits(r, wedit)
+	res, err := applyWorkspaceEdits(r, *wedit)
 	if err != nil {
 		t.Fatal(err)
 	}
@ -628,18 +630,23 @@ func (r *runner) PrepareRename(t *testing.T, src span.Span, want *source.Prepare
 		t.Errorf("prepare rename failed for %v: got error: %v", src, err)
 		return
 	}
-	if got == nil {
+	// we all love typed nils
+	if got == nil || got.(*protocol.Range) == nil {
 		if want.Text != "" { // expected an ident.
 			t.Errorf("prepare rename failed for %v: got nil", src)
 		}
 		return
 	}
-	if protocol.CompareRange(*got, want.Range) != 0 {
-		t.Errorf("prepare rename failed: incorrect range got %v want %v", *got, want.Range)
+	xx, ok := got.(*protocol.Range)
+	if !ok {
+		t.Fatalf("got %T, wanted Range", got)
+	}
+	if protocol.CompareRange(*xx, want.Range) != 0 {
+		t.Errorf("prepare rename failed: incorrect range got %v want %v", *xx, want.Range)
 	}
 }

-func applyWorkspaceEdits(r *runner, wedit *protocol.WorkspaceEdit) (map[span.URI]string, error) {
+func applyWorkspaceEdits(r *runner, wedit protocol.WorkspaceEdit) (map[span.URI]string, error) {
 	res := map[span.URI]string{}
 	for _, docEdits := range wedit.DocumentChanges {
 		uri := span.URI(docEdits.TextDocument.URI)
@ -682,7 +689,6 @@ func (r *runner) Symbols(t *testing.T, uri span.URI, expectedSymbols []protocol.
 	if err != nil {
 		t.Fatal(err)
 	}
-
 	if len(symbols) != len(expectedSymbols) {
 		t.Errorf("want %d top-level symbols in %v, got %d", len(expectedSymbols), uri, len(symbols))
 		return
--- a/internal/lsp/protocol/protocol.go
+++ b/internal/lsp/protocol/protocol.go
@ -7,6 +7,7 @@ package protocol
 import (
 	"context"
 	"encoding/json"
+	"fmt"

 	"golang.org/x/tools/internal/jsonrpc2"
 	"golang.org/x/tools/internal/telemetry/log"
@ -39,7 +40,16 @@ func (canceller) Request(ctx context.Context, conn *jsonrpc2.Conn, direction jso
 		if err := json.Unmarshal(*r.Params, &params); err != nil {
 			log.Error(ctx, "", err)
 		} else {
-			conn.Cancel(params.ID)
+			v := jsonrpc2.ID{}
+			if n, ok := params.ID.(float64); ok {
+				v.Number = int64(n)
+			} else if s, ok := params.ID.(string); ok {
+				v.Name = s
+			} else {
+				log.Error(ctx, fmt.Sprintf("Request ID %v malformed", params.ID), nil)
+				return ctx
+			}
+			conn.Cancel(v)
 		}
 	}
 	return ctx
--- a/internal/lsp/protocol/tsclient.go
+++ b/internal/lsp/protocol/tsclient.go
@ -1,5 +1,10 @@
 package protocol

+// Package protocol contains data types and code for LSP jsonrpcs
+// generated automatically from vscode-languageserver-node
+// commit: 635ab1fe6f8c57ce9402e573d007f24d6d290fd3
+// last fetched Sun Oct 13 2019 10:14:32 GMT-0400 (Eastern Daylight Time)
+
 // Code generated (see typescript/README.md) DO NOT EDIT.

 import (
@ -16,11 +21,11 @@ type Client interface {
 	LogMessage(context.Context, *LogMessageParams) error
 	Event(context.Context, *interface{}) error
 	PublishDiagnostics(context.Context, *PublishDiagnosticsParams) error
-	WorkspaceFolders(context.Context) ([]WorkspaceFolder, error)
-	Configuration(context.Context, *ParamConfig) ([]interface{}, error)
+	WorkspaceFolders(context.Context) ([]WorkspaceFolder /*WorkspaceFolder[] | null*/, error)
+	Configuration(context.Context, *ParamConfiguration) ([]interface{}, error)
 	RegisterCapability(context.Context, *RegistrationParams) error
 	UnregisterCapability(context.Context, *UnregistrationParams) error
-	ShowMessageRequest(context.Context, *ShowMessageRequestParams) (*MessageActionItem, error)
+	ShowMessageRequest(context.Context, *ShowMessageRequestParams) (*MessageActionItem /*MessageActionItem | null*/, error)
 	ApplyEdit(context.Context, *ApplyWorkspaceEditParams) (*ApplyWorkspaceEditResponse, error)
 }

@ -85,7 +90,7 @@ func (h clientHandler) Deliver(ctx context.Context, r *jsonrpc2.Request, deliver
 		}
 		return true
 	case "workspace/configuration": // req
-		var params ParamConfig
+		var params ParamConfiguration
 		if err := json.Unmarshal(*r.Params, &params); err != nil {
 			sendParseError(ctx, r, err)
 			return true
@ -164,15 +169,15 @@ func (s *clientDispatcher) Event(ctx context.Context, params *interface{}) error
 func (s *clientDispatcher) PublishDiagnostics(ctx context.Context, params *PublishDiagnosticsParams) error {
 	return s.Conn.Notify(ctx, "textDocument/publishDiagnostics", params)
 }
-func (s *clientDispatcher) WorkspaceFolders(ctx context.Context) ([]WorkspaceFolder, error) {
-	var result []WorkspaceFolder
+func (s *clientDispatcher) WorkspaceFolders(ctx context.Context) ([]WorkspaceFolder /*WorkspaceFolder[] | null*/, error) {
+	var result []WorkspaceFolder /*WorkspaceFolder[] | null*/
 	if err := s.Conn.Call(ctx, "workspace/workspaceFolders", nil, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *clientDispatcher) Configuration(ctx context.Context, params *ParamConfig) ([]interface{}, error) {
+func (s *clientDispatcher) Configuration(ctx context.Context, params *ParamConfiguration) ([]interface{}, error) {
 	var result []interface{}
 	if err := s.Conn.Call(ctx, "workspace/configuration", params, &result); err != nil {
 		return nil, err
@ -188,8 +193,8 @@ func (s *clientDispatcher) UnregisterCapability(ctx context.Context, params *Unr
 	return s.Conn.Call(ctx, "client/unregisterCapability", params, nil) // Call, not Notify
 }

-func (s *clientDispatcher) ShowMessageRequest(ctx context.Context, params *ShowMessageRequestParams) (*MessageActionItem, error) {
-	var result MessageActionItem
+func (s *clientDispatcher) ShowMessageRequest(ctx context.Context, params *ShowMessageRequestParams) (*MessageActionItem /*MessageActionItem | null*/, error) {
+	var result MessageActionItem /*MessageActionItem | null*/
 	if err := s.Conn.Call(ctx, "window/showMessageRequest", params, &result); err != nil {
 		return nil, err
 	}
@ -203,9 +208,3 @@ func (s *clientDispatcher) ApplyEdit(ctx context.Context, params *ApplyWorkspace
 	}
 	return &result, nil
 }
-
-// Types constructed to avoid structs as formal argument types
-type ParamConfig struct {
-	ConfigurationParams
-	PartialResultParams
-}
--- a/internal/lsp/protocol/tsprotocol.go
+++ b/internal/lsp/protocol/tsprotocol.go
--- a/internal/lsp/protocol/tsserver.go
+++ b/internal/lsp/protocol/tsserver.go
@ -1,5 +1,10 @@
 package protocol

+// Package protocol contains data types and code for LSP jsonrpcs
+// generated automatically from vscode-languageserver-node
+// commit: 635ab1fe6f8c57ce9402e573d007f24d6d290fd3
+// last fetched Sun Oct 13 2019 10:14:32 GMT-0400 (Eastern Daylight Time)
+
 // Code generated (see typescript/README.md) DO NOT EDIT.

 import (
@ -22,39 +27,40 @@ type Server interface {
 	DidSave(context.Context, *DidSaveTextDocumentParams) error
 	WillSave(context.Context, *WillSaveTextDocumentParams) error
 	DidChangeWatchedFiles(context.Context, *DidChangeWatchedFilesParams) error
+	CancelRequest(context.Context, *CancelParams) error
 	Progress(context.Context, *ProgressParams) error
 	SetTraceNotification(context.Context, *SetTraceParams) error
 	LogTraceNotification(context.Context, *LogTraceParams) error
-	Implementation(context.Context, *ImplementationParams) ([]Location, error)
-	TypeDefinition(context.Context, *TypeDefinitionParams) ([]Location, error)
+	Implementation(context.Context, *ImplementationParams) (Definition /*Definition | DefinitionLink[] | null*/, error)
+	TypeDefinition(context.Context, *TypeDefinitionParams) (Definition /*Definition | DefinitionLink[] | null*/, error)
 	DocumentColor(context.Context, *DocumentColorParams) ([]ColorInformation, error)
 	ColorPresentation(context.Context, *ColorPresentationParams) ([]ColorPresentation, error)
-	FoldingRange(context.Context, *FoldingRangeParams) ([]FoldingRange, error)
-	Declaration(context.Context, *DeclarationParams) ([]DeclarationLink, error)
-	SelectionRange(context.Context, *SelectionRangeParams) ([]SelectionRange, error)
-	Initialize(context.Context, *ParamInitia) (*InitializeResult, error)
+	FoldingRange(context.Context, *FoldingRangeParams) ([]FoldingRange /*FoldingRange[] | null*/, error)
+	Declaration(context.Context, *DeclarationParams) (Declaration /*Declaration | DeclarationLink[] | null*/, error)
+	SelectionRange(context.Context, *SelectionRangeParams) ([]SelectionRange /*SelectionRange[] | null*/, error)
+	Initialize(context.Context, *ParamInitialize) (*InitializeResult, error)
 	Shutdown(context.Context) error
-	WillSaveWaitUntil(context.Context, *WillSaveTextDocumentParams) ([]TextEdit, error)
-	Completion(context.Context, *CompletionParams) (*CompletionList, error)
+	WillSaveWaitUntil(context.Context, *WillSaveTextDocumentParams) ([]TextEdit /*TextEdit[] | null*/, error)
+	Completion(context.Context, *CompletionParams) (*CompletionList /*CompletionItem[] | CompletionList | null*/, error)
 	Resolve(context.Context, *CompletionItem) (*CompletionItem, error)
-	Hover(context.Context, *HoverParams) (*Hover, error)
-	SignatureHelp(context.Context, *SignatureHelpParams) (*SignatureHelp, error)
-	Definition(context.Context, *DefinitionParams) ([]Location, error)
-	References(context.Context, *ReferenceParams) ([]Location, error)
-	DocumentHighlight(context.Context, *DocumentHighlightParams) ([]DocumentHighlight, error)
-	DocumentSymbol(context.Context, *DocumentSymbolParams) ([]DocumentSymbol, error)
-	CodeAction(context.Context, *CodeActionParams) ([]CodeAction, error)
-	Symbol(context.Context, *WorkspaceSymbolParams) ([]SymbolInformation, error)
-	CodeLens(context.Context, *CodeLensParams) ([]CodeLens, error)
+	Hover(context.Context, *HoverParams) (*Hover /*Hover | null*/, error)
+	SignatureHelp(context.Context, *SignatureHelpParams) (*SignatureHelp /*SignatureHelp | null*/, error)
+	Definition(context.Context, *DefinitionParams) (Definition /*Definition | DefinitionLink[] | null*/, error)
+	References(context.Context, *ReferenceParams) ([]Location /*Location[] | null*/, error)
+	DocumentHighlight(context.Context, *DocumentHighlightParams) ([]DocumentHighlight /*DocumentHighlight[] | null*/, error)
+	DocumentSymbol(context.Context, *DocumentSymbolParams) ([]DocumentSymbol /*SymbolInformation[] | DocumentSymbol[] | null*/, error)
+	CodeAction(context.Context, *CodeActionParams) (interface{} /*Command | CodeAction*/ /*(Command | CodeAction)[] | null*/, error)
+	Symbol(context.Context, *WorkspaceSymbolParams) ([]SymbolInformation /*SymbolInformation[] | null*/, error)
+	CodeLens(context.Context, *CodeLensParams) ([]CodeLens /*CodeLens[] | null*/, error)
 	ResolveCodeLens(context.Context, *CodeLens) (*CodeLens, error)
-	DocumentLink(context.Context, *DocumentLinkParams) ([]DocumentLink, error)
+	DocumentLink(context.Context, *DocumentLinkParams) ([]DocumentLink /*DocumentLink[] | null*/, error)
 	ResolveDocumentLink(context.Context, *DocumentLink) (*DocumentLink, error)
-	Formatting(context.Context, *DocumentFormattingParams) ([]TextEdit, error)
-	RangeFormatting(context.Context, *DocumentRangeFormattingParams) ([]TextEdit, error)
-	OnTypeFormatting(context.Context, *DocumentOnTypeFormattingParams) ([]TextEdit, error)
-	Rename(context.Context, *RenameParams) (*WorkspaceEdit, error)
-	PrepareRename(context.Context, *PrepareRenameParams) (*Range, error)
-	ExecuteCommand(context.Context, *ExecuteCommandParams) (interface{}, error)
+	Formatting(context.Context, *DocumentFormattingParams) ([]TextEdit /*TextEdit[] | null*/, error)
+	RangeFormatting(context.Context, *DocumentRangeFormattingParams) ([]TextEdit /*TextEdit[] | null*/, error)
+	OnTypeFormatting(context.Context, *DocumentOnTypeFormattingParams) ([]TextEdit /*TextEdit[] | null*/, error)
+	Rename(context.Context, *RenameParams) (*WorkspaceEdit /*WorkspaceEdit | null*/, error)
+	PrepareRename(context.Context, *PrepareRenameParams) (interface{} /* Range | struct{;  Range Range`json:"range"`;  Placeholder string`json:"placeholder"`; } | nil*/, error)
+	ExecuteCommand(context.Context, *ExecuteCommandParams) (interface{} /*any | null*/, error)
 }

 func (h serverHandler) Deliver(ctx context.Context, r *jsonrpc2.Request, delivered bool) bool {
@ -162,6 +168,16 @@ func (h serverHandler) Deliver(ctx context.Context, r *jsonrpc2.Request, deliver
 			log.Error(ctx, "", err)
 		}
 		return true
+	case "$/cancelRequest": // notif
+		var params CancelParams
+		if err := json.Unmarshal(*r.Params, &params); err != nil {
+			sendParseError(ctx, r, err)
+			return true
+		}
+		if err := h.server.CancelRequest(ctx, &params); err != nil {
+			log.Error(ctx, "", err)
+		}
+		return true
 	case "$/progress": // notif
 		var params ProgressParams
 		if err := json.Unmarshal(*r.Params, &params); err != nil {
@ -270,7 +286,7 @@ func (h serverHandler) Deliver(ctx context.Context, r *jsonrpc2.Request, deliver
 		}
 		return true
 	case "initialize": // req
-		var params ParamInitia
+		var params ParamInitialize
 		if err := json.Unmarshal(*r.Params, &params); err != nil {
 			sendParseError(ctx, r, err)
 			return true
@ -571,6 +587,10 @@ func (s *serverDispatcher) DidChangeWatchedFiles(ctx context.Context, params *Di
 	return s.Conn.Notify(ctx, "workspace/didChangeWatchedFiles", params)
 }

+func (s *serverDispatcher) CancelRequest(ctx context.Context, params *CancelParams) error {
+	return s.Conn.Notify(ctx, "$/cancelRequest", params)
+}
+
 func (s *serverDispatcher) Progress(ctx context.Context, params *ProgressParams) error {
 	return s.Conn.Notify(ctx, "$/progress", params)
 }
@ -582,16 +602,16 @@ func (s *serverDispatcher) SetTraceNotification(ctx context.Context, params *Set
 func (s *serverDispatcher) LogTraceNotification(ctx context.Context, params *LogTraceParams) error {
 	return s.Conn.Notify(ctx, "$/logTraceNotification", params)
 }
-func (s *serverDispatcher) Implementation(ctx context.Context, params *ImplementationParams) ([]Location, error) {
-	var result []Location
+func (s *serverDispatcher) Implementation(ctx context.Context, params *ImplementationParams) (Definition /*Definition | DefinitionLink[] | null*/, error) {
+	var result Definition /*Definition | DefinitionLink[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/implementation", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) TypeDefinition(ctx context.Context, params *TypeDefinitionParams) ([]Location, error) {
-	var result []Location
+func (s *serverDispatcher) TypeDefinition(ctx context.Context, params *TypeDefinitionParams) (Definition /*Definition | DefinitionLink[] | null*/, error) {
+	var result Definition /*Definition | DefinitionLink[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/typeDefinition", params, &result); err != nil {
 		return nil, err
 	}
@ -614,31 +634,31 @@ func (s *serverDispatcher) ColorPresentation(ctx context.Context, params *ColorP
 	return result, nil
 }

-func (s *serverDispatcher) FoldingRange(ctx context.Context, params *FoldingRangeParams) ([]FoldingRange, error) {
-	var result []FoldingRange
+func (s *serverDispatcher) FoldingRange(ctx context.Context, params *FoldingRangeParams) ([]FoldingRange /*FoldingRange[] | null*/, error) {
+	var result []FoldingRange /*FoldingRange[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/foldingRange", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) Declaration(ctx context.Context, params *DeclarationParams) ([]DeclarationLink, error) {
-	var result []DeclarationLink
+func (s *serverDispatcher) Declaration(ctx context.Context, params *DeclarationParams) (Declaration /*Declaration | DeclarationLink[] | null*/, error) {
+	var result Declaration /*Declaration | DeclarationLink[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/declaration", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) SelectionRange(ctx context.Context, params *SelectionRangeParams) ([]SelectionRange, error) {
-	var result []SelectionRange
+func (s *serverDispatcher) SelectionRange(ctx context.Context, params *SelectionRangeParams) ([]SelectionRange /*SelectionRange[] | null*/, error) {
+	var result []SelectionRange /*SelectionRange[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/selectionRange", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) Initialize(ctx context.Context, params *ParamInitia) (*InitializeResult, error) {
+func (s *serverDispatcher) Initialize(ctx context.Context, params *ParamInitialize) (*InitializeResult, error) {
 	var result InitializeResult
 	if err := s.Conn.Call(ctx, "initialize", params, &result); err != nil {
 		return nil, err
@ -650,16 +670,16 @@ func (s *serverDispatcher) Shutdown(ctx context.Context) error {
 	return s.Conn.Call(ctx, "shutdown", nil, nil)
 }

-func (s *serverDispatcher) WillSaveWaitUntil(ctx context.Context, params *WillSaveTextDocumentParams) ([]TextEdit, error) {
-	var result []TextEdit
+func (s *serverDispatcher) WillSaveWaitUntil(ctx context.Context, params *WillSaveTextDocumentParams) ([]TextEdit /*TextEdit[] | null*/, error) {
+	var result []TextEdit /*TextEdit[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/willSaveWaitUntil", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) Completion(ctx context.Context, params *CompletionParams) (*CompletionList, error) {
-	var result CompletionList
+func (s *serverDispatcher) Completion(ctx context.Context, params *CompletionParams) (*CompletionList /*CompletionItem[] | CompletionList | null*/, error) {
+	var result CompletionList /*CompletionItem[] | CompletionList | null*/
 	if err := s.Conn.Call(ctx, "textDocument/completion", params, &result); err != nil {
 		return nil, err
 	}
@ -674,72 +694,72 @@ func (s *serverDispatcher) Resolve(ctx context.Context, params *CompletionItem)
 	return &result, nil
 }

-func (s *serverDispatcher) Hover(ctx context.Context, params *HoverParams) (*Hover, error) {
-	var result Hover
+func (s *serverDispatcher) Hover(ctx context.Context, params *HoverParams) (*Hover /*Hover | null*/, error) {
+	var result Hover /*Hover | null*/
 	if err := s.Conn.Call(ctx, "textDocument/hover", params, &result); err != nil {
 		return nil, err
 	}
 	return &result, nil
 }

-func (s *serverDispatcher) SignatureHelp(ctx context.Context, params *SignatureHelpParams) (*SignatureHelp, error) {
-	var result SignatureHelp
+func (s *serverDispatcher) SignatureHelp(ctx context.Context, params *SignatureHelpParams) (*SignatureHelp /*SignatureHelp | null*/, error) {
+	var result SignatureHelp /*SignatureHelp | null*/
 	if err := s.Conn.Call(ctx, "textDocument/signatureHelp", params, &result); err != nil {
 		return nil, err
 	}
 	return &result, nil
 }

-func (s *serverDispatcher) Definition(ctx context.Context, params *DefinitionParams) ([]Location, error) {
-	var result []Location
+func (s *serverDispatcher) Definition(ctx context.Context, params *DefinitionParams) (Definition /*Definition | DefinitionLink[] | null*/, error) {
+	var result Definition /*Definition | DefinitionLink[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/definition", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) References(ctx context.Context, params *ReferenceParams) ([]Location, error) {
-	var result []Location
+func (s *serverDispatcher) References(ctx context.Context, params *ReferenceParams) ([]Location /*Location[] | null*/, error) {
+	var result []Location /*Location[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/references", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) DocumentHighlight(ctx context.Context, params *DocumentHighlightParams) ([]DocumentHighlight, error) {
-	var result []DocumentHighlight
+func (s *serverDispatcher) DocumentHighlight(ctx context.Context, params *DocumentHighlightParams) ([]DocumentHighlight /*DocumentHighlight[] | null*/, error) {
+	var result []DocumentHighlight /*DocumentHighlight[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/documentHighlight", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) DocumentSymbol(ctx context.Context, params *DocumentSymbolParams) ([]DocumentSymbol, error) {
-	var result []DocumentSymbol
+func (s *serverDispatcher) DocumentSymbol(ctx context.Context, params *DocumentSymbolParams) ([]DocumentSymbol /*SymbolInformation[] | DocumentSymbol[] | null*/, error) {
+	var result []DocumentSymbol /*SymbolInformation[] | DocumentSymbol[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/documentSymbol", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) CodeAction(ctx context.Context, params *CodeActionParams) ([]CodeAction, error) {
-	var result []CodeAction
+func (s *serverDispatcher) CodeAction(ctx context.Context, params *CodeActionParams) (interface{} /*Command | CodeAction*/ /*(Command | CodeAction)[] | null*/, error) {
+	var result interface{} /*Command | CodeAction*/ /*(Command | CodeAction)[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/codeAction", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) Symbol(ctx context.Context, params *WorkspaceSymbolParams) ([]SymbolInformation, error) {
-	var result []SymbolInformation
+func (s *serverDispatcher) Symbol(ctx context.Context, params *WorkspaceSymbolParams) ([]SymbolInformation /*SymbolInformation[] | null*/, error) {
+	var result []SymbolInformation /*SymbolInformation[] | null*/
 	if err := s.Conn.Call(ctx, "workspace/symbol", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) CodeLens(ctx context.Context, params *CodeLensParams) ([]CodeLens, error) {
-	var result []CodeLens
+func (s *serverDispatcher) CodeLens(ctx context.Context, params *CodeLensParams) ([]CodeLens /*CodeLens[] | null*/, error) {
+	var result []CodeLens /*CodeLens[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/codeLens", params, &result); err != nil {
 		return nil, err
 	}
@ -754,8 +774,8 @@ func (s *serverDispatcher) ResolveCodeLens(ctx context.Context, params *CodeLens
 	return &result, nil
 }

-func (s *serverDispatcher) DocumentLink(ctx context.Context, params *DocumentLinkParams) ([]DocumentLink, error) {
-	var result []DocumentLink
+func (s *serverDispatcher) DocumentLink(ctx context.Context, params *DocumentLinkParams) ([]DocumentLink /*DocumentLink[] | null*/, error) {
+	var result []DocumentLink /*DocumentLink[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/documentLink", params, &result); err != nil {
 		return nil, err
 	}
@ -770,63 +790,50 @@ func (s *serverDispatcher) ResolveDocumentLink(ctx context.Context, params *Docu
 	return &result, nil
 }

-func (s *serverDispatcher) Formatting(ctx context.Context, params *DocumentFormattingParams) ([]TextEdit, error) {
-	var result []TextEdit
+func (s *serverDispatcher) Formatting(ctx context.Context, params *DocumentFormattingParams) ([]TextEdit /*TextEdit[] | null*/, error) {
+	var result []TextEdit /*TextEdit[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/formatting", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) RangeFormatting(ctx context.Context, params *DocumentRangeFormattingParams) ([]TextEdit, error) {
-	var result []TextEdit
+func (s *serverDispatcher) RangeFormatting(ctx context.Context, params *DocumentRangeFormattingParams) ([]TextEdit /*TextEdit[] | null*/, error) {
+	var result []TextEdit /*TextEdit[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/rangeFormatting", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) OnTypeFormatting(ctx context.Context, params *DocumentOnTypeFormattingParams) ([]TextEdit, error) {
-	var result []TextEdit
+func (s *serverDispatcher) OnTypeFormatting(ctx context.Context, params *DocumentOnTypeFormattingParams) ([]TextEdit /*TextEdit[] | null*/, error) {
+	var result []TextEdit /*TextEdit[] | null*/
 	if err := s.Conn.Call(ctx, "textDocument/onTypeFormatting", params, &result); err != nil {
 		return nil, err
 	}
 	return result, nil
 }

-func (s *serverDispatcher) Rename(ctx context.Context, params *RenameParams) (*WorkspaceEdit, error) {
-	var result WorkspaceEdit
+func (s *serverDispatcher) Rename(ctx context.Context, params *RenameParams) (*WorkspaceEdit /*WorkspaceEdit | null*/, error) {
+	var result WorkspaceEdit /*WorkspaceEdit | null*/
 	if err := s.Conn.Call(ctx, "textDocument/rename", params, &result); err != nil {
 		return nil, err
 	}
 	return &result, nil
 }

-func (s *serverDispatcher) PrepareRename(ctx context.Context, params *PrepareRenameParams) (*Range, error) {
-	var result Range
+func (s *serverDispatcher) PrepareRename(ctx context.Context, params *PrepareRenameParams) (interface{} /* Range | struct{;  Range Range`json:"range"`;  Placeholder string`json:"placeholder"`; } | nil*/, error) {
+	var result interface{} /* Range | struct{;  Range Range`json:"range"`;  Placeholder string`json:"placeholder"`; } | nil*/
 	if err := s.Conn.Call(ctx, "textDocument/prepareRename", params, &result); err != nil {
 		return nil, err
 	}
-	return &result, nil
-}
-
-func (s *serverDispatcher) ExecuteCommand(ctx context.Context, params *ExecuteCommandParams) (interface{}, error) {
-	var result interface{}
-	if err := s.Conn.Call(ctx, "workspace/executeCommand", params, &result); err != nil {
-		return nil, err
-	}
 	return result, nil
 }

-type CancelParams struct {
-	/**
-	 * The request id to cancel.
-	 */
-	ID jsonrpc2.ID `json:"id"`
-}
-
-// Types constructed to avoid structs as formal argument types
-type ParamInitia struct {
-	InitializeParams
-	WorkDoneProgressParams
+func (s *serverDispatcher) ExecuteCommand(ctx context.Context, params *ExecuteCommandParams) (interface{} /*any | null*/, error) {
+	var result interface{} /*any | null*/
+	if err := s.Conn.Call(ctx, "workspace/executeCommand", params, &result); err != nil {
+		return nil, err
+	}
+	return result, nil
 }
--- a/internal/lsp/server.go
+++ b/internal/lsp/server.go
@ -91,7 +91,7 @@ type Server struct {

 // General

-func (s *Server) Initialize(ctx context.Context, params *protocol.ParamInitia) (*protocol.InitializeResult, error) {
+func (s *Server) Initialize(ctx context.Context, params *protocol.ParamInitialize) (*protocol.InitializeResult, error) {
 	return s.initialize(ctx, params)
 }

@ -107,6 +107,10 @@ func (s *Server) Exit(ctx context.Context) error {
 	return s.exit(ctx)
 }

+func (s *Server) CancelRequest(ctx context.Context, params *protocol.CancelParams) error {
+	return s.CancelRequest(ctx, params)
+}
+
 // Workspace

 func (s *Server) DidChangeWorkspaceFolders(ctx context.Context, params *protocol.DidChangeWorkspaceFoldersParams) error {
@ -173,15 +177,15 @@ func (s *Server) SignatureHelp(ctx context.Context, params *protocol.SignatureHe
 	return s.signatureHelp(ctx, params)
 }

-func (s *Server) Definition(ctx context.Context, params *protocol.DefinitionParams) ([]protocol.Location, error) {
+func (s *Server) Definition(ctx context.Context, params *protocol.DefinitionParams) (protocol.Definition, error) {
 	return s.definition(ctx, params)
 }

-func (s *Server) TypeDefinition(ctx context.Context, params *protocol.TypeDefinitionParams) ([]protocol.Location, error) {
+func (s *Server) TypeDefinition(ctx context.Context, params *protocol.TypeDefinitionParams) (protocol.Definition, error) {
 	return s.typeDefinition(ctx, params)
 }

-func (s *Server) Implementation(ctx context.Context, params *protocol.ImplementationParams) ([]protocol.Location, error) {
+func (s *Server) Implementation(ctx context.Context, params *protocol.ImplementationParams) (protocol.Definition, error) {
 	return s.implementation(ctx, params)
 }

@ -197,7 +201,7 @@ func (s *Server) DocumentSymbol(ctx context.Context, params *protocol.DocumentSy
 	return s.documentSymbol(ctx, params)
 }

-func (s *Server) CodeAction(ctx context.Context, params *protocol.CodeActionParams) ([]protocol.CodeAction, error) {
+func (s *Server) CodeAction(ctx context.Context, params *protocol.CodeActionParams) (interface{}, error) {
 	return s.codeAction(ctx, params)
 }

@ -241,7 +245,7 @@ func (s *Server) Rename(ctx context.Context, params *protocol.RenameParams) (*pr
 	return s.rename(ctx, params)
 }

-func (s *Server) Declaration(context.Context, *protocol.DeclarationParams) ([]protocol.DeclarationLink, error) {
+func (s *Server) Declaration(context.Context, *protocol.DeclarationParams) (protocol.Declaration, error) {
 	return nil, notImplemented("Declaration")
 }

@ -253,7 +257,7 @@ func (s *Server) LogTraceNotification(context.Context, *protocol.LogTraceParams)
 	return notImplemented("LogtraceNotification")
 }

-func (s *Server) PrepareRename(ctx context.Context, params *protocol.PrepareRenameParams) (*protocol.Range, error) {
+func (s *Server) PrepareRename(ctx context.Context, params *protocol.PrepareRenameParams) (interface{}, error) {
 	// TODO(suzmue): support sending placeholder text.
 	return s.prepareRename(ctx, params)
 }
--- a/internal/lsp/source/options.go
+++ b/internal/lsp/source/options.go
@ -183,7 +183,7 @@ func SetOptions(options *Options, opts interface{}) OptionResults {

 func (o *Options) ForClientCapabilities(caps protocol.ClientCapabilities) {
 	// Check if the client supports snippets in completion items.
-	if c := caps.TextDocument.Completion; c != nil && c.CompletionItem != nil && c.CompletionItem.SnippetSupport {
+	if c := caps.TextDocument.Completion; c.CompletionItem.SnippetSupport {
 		o.InsertTextFormat = protocol.SnippetTextFormat
 	}
 	// Check if the client supports configuration messages.
@ -192,13 +192,12 @@ func (o *Options) ForClientCapabilities(caps protocol.ClientCapabilities) {
 	o.DynamicWatchedFilesSupported = caps.Workspace.DidChangeWatchedFiles.DynamicRegistration

 	// Check which types of content format are supported by this client.
-	if hover := caps.TextDocument.Hover; hover != nil && len(hover.ContentFormat) > 0 {
+	if hover := caps.TextDocument.Hover; len(hover.ContentFormat) > 0 {
 		o.PreferredContentFormat = hover.ContentFormat[0]
 	}
 	// Check if the client supports only line folding.
-	if fr := caps.TextDocument.FoldingRange; fr != nil {
-		o.LineFoldingOnly = fr.LineFoldingOnly
-	}
+	fr := caps.TextDocument.FoldingRange
+	o.LineFoldingOnly = fr.LineFoldingOnly
 }

 func (o *Options) set(name string, value interface{}) OptionResult {
--- a/internal/lsp/tests/completion.go
+++ b/internal/lsp/tests/completion.go
@ -26,7 +26,7 @@ func ToProtocolCompletionItem(item source.CompletionItem) protocol.CompletionIte
 		Detail:        item.Detail,
 		Documentation: item.Documentation,
 		InsertText:    item.InsertText,
-		TextEdit: &protocol.TextEdit{
+		TextEdit: protocol.TextEdit{
 			NewText: item.Snippet(),
 		},
 		// Negate score so best score has lowest sort text like real API.
--- a/internal/lsp/text_synchronization.go
+++ b/internal/lsp/text_synchronization.go
@ -96,7 +96,7 @@ func fullChange(changes []protocol.TextDocumentContentChangeEvent) (string, bool
 		return "", false
 	}
 	// The length of the changes must be 1 at this point.
-	if changes[0].Range == nil && changes[0].RangeLength == 0 {
+	if changes[0].RangeLength == 0 { // used to check changes[0].Range == nil
 		return changes[0].Text, true
 	}
 	return "", false
@ -116,7 +116,7 @@ func (s *Server) applyChanges(ctx context.Context, uri span.URI, changes []proto
 			Content:   content,
 		}

-		spn, err := m.RangeSpan(*change.Range)
+		spn, err := m.RangeSpan(change.Range)
 		if err != nil {
 			return "", err
 		}