internal/lsp: fix builds and tests for go1.12+

Seems we've drifted a bit from go1.12 support, mostly due to error
wrapping.

Fix this, as well as some assorted other failures.

I haven't tested 1.12 interactively.

For golang/go#39146

Change-Id: Id347ead2a13e89b76d2ae0047750e6b6b49911eb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/250941
Run-TryBot: Robert Findley <rfindley@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>

internal/lsp/cache/view.go

@@ -717,7 +717,7 @@ func (v *View) maybeReinitialize() {
 
 func (v *View) setBuildInformation(ctx context.Context, folder span.URI, options source.Options) error {
 	if err := checkPathCase(folder.Filename()); err != nil {
-		return fmt.Errorf("invalid workspace configuration: %w", err)
+		return errors.Errorf("invalid workspace configuration: %w", err)
 	}
 	// Make sure to get the `go env` before continuing with initialization.
 	modFile, err := v.setGoEnv(ctx, options.Env)

internal/lsp/cmd/prepare_rename.go

@@ -6,13 +6,13 @@ package cmd
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/span"
 	"golang.org/x/tools/internal/tool"
+	errors "golang.org/x/xerrors"
 )
 
 // prepareRename implements the prepare_rename verb for gopls.
@@ -68,7 +68,7 @@ func (r *prepareRename) Run(ctx context.Context, args ...string) error {
 	}
 	result, err := conn.PrepareRename(ctx, &p)
 	if err != nil {
-		return fmt.Errorf("prepare_rename failed: %w", err)
+		return errors.Errorf("prepare_rename failed: %w", err)
 	}
 	if result == nil {
 		return ErrInvalidRenamePosition

internal/lsp/cmd/serve.go

@@ -6,7 +6,6 @@ package cmd
 
 import (
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"io"
@@ -22,6 +21,7 @@ import (
 	"golang.org/x/tools/internal/lsp/lsprpc"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/tool"
+	errors "golang.org/x/xerrors"
 )
 
 // Serve is a struct that exposes the configurable parts of the LSP server as

internal/lsp/debug/serve.go

@@ -37,7 +37,7 @@ import (
 	"golang.org/x/tools/internal/lsp/debug/tag"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
-	"golang.org/x/xerrors"
+	errors "golang.org/x/xerrors"
 )
 
 type instanceKeyType int
@@ -151,7 +151,7 @@ func (st *State) Clients() []*Client {
 	return clients
 }
 
-// View returns the View that matches the supplied id.
+// Client returns the Client matching the supplied id.
 func (st *State) Client(id string) *Client {
 	for _, c := range st.Clients() {
 		if c.Session.ID() == id {
@@ -338,7 +338,7 @@ func (i *Instance) SetLogFile(logfile string, isDaemon bool) (func(), error) {
 		}
 		f, err := os.Create(logfile)
 		if err != nil {
-			return nil, fmt.Errorf("unable to create log file: %w", err)
+			return nil, errors.Errorf("unable to create log file: %w", err)
 		}
 		closeLog = func() {
 			defer f.Close()
@@ -480,7 +480,7 @@ func makeGlobalExporter(stderr io.Writer) event.Exporter {
 
 		if event.IsLog(ev) {
 			// Don't log context cancellation errors.
-			if err := keys.Err.Get(ev); xerrors.Is(err, context.Canceled) {
+			if err := keys.Err.Get(ev); errors.Is(err, context.Canceled) {
 				return ctx
 			}
 			// Make sure any log messages without an instance go to stderr.

internal/lsp/fake/editor.go

@@ -7,7 +7,6 @@ package fake
 import (
 	"bufio"
 	"context"
-	"errors"
 	"fmt"
 	"path/filepath"
 	"regexp"
@@ -18,6 +17,7 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 // Editor is a fake editor client.  It keeps track of client state and can be
@@ -118,7 +118,7 @@ func (e *Editor) Connect(ctx context.Context, conn jsonrpc2.Conn, hooks ClientHo
 func (e *Editor) Shutdown(ctx context.Context) error {
 	if e.Server != nil {
 		if err := e.Server.Shutdown(ctx); err != nil {
-			return fmt.Errorf("Shutdown: %w", err)
+			return errors.Errorf("Shutdown: %w", err)
 		}
 	}
 	return nil
@@ -130,7 +130,7 @@ func (e *Editor) Exit(ctx context.Context) error {
 		// Not all LSP clients issue the exit RPC, but we do so here to ensure that
 		// we gracefully handle it on multi-session servers.
 		if err := e.Server.Exit(ctx); err != nil {
-			return fmt.Errorf("Exit: %w", err)
+			return errors.Errorf("Exit: %w", err)
 		}
 	}
 	return nil
@@ -150,7 +150,7 @@ func (e *Editor) Close(ctx context.Context) error {
 		// connection closed itself
 		return nil
 	case <-ctx.Done():
-		return fmt.Errorf("connection not closed: %w", ctx.Err())
+		return errors.Errorf("connection not closed: %w", ctx.Err())
 	}
 }
 
@@ -222,14 +222,14 @@ func (e *Editor) initialize(ctx context.Context, withoutWorkspaceFolders bool, e
 	if e.Server != nil {
 		resp, err := e.Server.Initialize(ctx, params)
 		if err != nil {
-			return fmt.Errorf("initialize: %w", err)
+			return errors.Errorf("initialize: %w", err)
 		}
 		e.mu.Lock()
 		e.serverCapabilities = resp.Capabilities
 		e.mu.Unlock()
 
 		if err := e.Server.Initialized(ctx, &protocol.InitializedParams{}); err != nil {
-			return fmt.Errorf("initialized: %w", err)
+			return errors.Errorf("initialized: %w", err)
 		}
 	}
 	// TODO: await initial configuration here, or expect gopls to manage that?
@@ -271,7 +271,7 @@ func (e *Editor) OpenFileWithContent(ctx context.Context, path, content string)
 		if err := e.Server.DidOpen(ctx, &protocol.DidOpenTextDocumentParams{
 			TextDocument: item,
 		}); err != nil {
-			return fmt.Errorf("DidOpen: %w", err)
+			return errors.Errorf("DidOpen: %w", err)
 		}
 	}
 	return nil
@@ -313,7 +313,7 @@ func (e *Editor) CreateBuffer(ctx context.Context, path, content string) error {
 		if err := e.Server.DidOpen(ctx, &protocol.DidOpenTextDocumentParams{
 			TextDocument: item,
 		}); err != nil {
-			return fmt.Errorf("DidOpen: %w", err)
+			return errors.Errorf("DidOpen: %w", err)
 		}
 	}
 	return nil
@@ -334,7 +334,7 @@ func (e *Editor) CloseBuffer(ctx context.Context, path string) error {
 		if err := e.Server.DidClose(ctx, &protocol.DidCloseTextDocumentParams{
 			TextDocument: e.textDocumentIdentifier(path),
 		}); err != nil {
-			return fmt.Errorf("DidClose: %w", err)
+			return errors.Errorf("DidClose: %w", err)
 		}
 	}
 	return nil
@@ -350,10 +350,10 @@ func (e *Editor) textDocumentIdentifier(path string) protocol.TextDocumentIdenti
 // the filesystem.
 func (e *Editor) SaveBuffer(ctx context.Context, path string) error {
 	if err := e.OrganizeImports(ctx, path); err != nil {
-		return fmt.Errorf("organizing imports before save: %w", err)
+		return errors.Errorf("organizing imports before save: %w", err)
 	}
 	if err := e.FormatBuffer(ctx, path); err != nil {
-		return fmt.Errorf("formatting before save: %w", err)
+		return errors.Errorf("formatting before save: %w", err)
 	}
 	return e.SaveBufferWithoutActions(ctx, path)
 }
@@ -379,11 +379,11 @@ func (e *Editor) SaveBufferWithoutActions(ctx context.Context, path string) erro
 			TextDocument: docID,
 			Reason:       protocol.Manual,
 		}); err != nil {
-			return fmt.Errorf("WillSave: %w", err)
+			return errors.Errorf("WillSave: %w", err)
 		}
 	}
 	if err := e.sandbox.Workdir.WriteFile(ctx, path, content); err != nil {
-		return fmt.Errorf("writing %q: %w", path, err)
+		return errors.Errorf("writing %q: %w", path, err)
 	}
 	if e.Server != nil {
 		params := &protocol.DidSaveTextDocumentParams{
@@ -396,7 +396,7 @@ func (e *Editor) SaveBufferWithoutActions(ctx context.Context, path string) erro
 			params.Text = &content
 		}
 		if err := e.Server.DidSave(ctx, params); err != nil {
-			return fmt.Errorf("DidSave: %w", err)
+			return errors.Errorf("DidSave: %w", err)
 		}
 	}
 	return nil
@@ -417,7 +417,7 @@ func contentPosition(content string, offset int) (Pos, error) {
 		line++
 	}
 	if err := scanner.Err(); err != nil {
-		return Pos{}, fmt.Errorf("scanning content: %w", err)
+		return Pos{}, errors.Errorf("scanning content: %w", err)
 	}
 	// Scan() will drop the last line if it is empty. Correct for this.
 	if strings.HasSuffix(content, "\n") && offset == start {
@@ -565,7 +565,7 @@ func (e *Editor) editBufferLocked(ctx context.Context, path string, edits []Edit
 	}
 	if e.Server != nil {
 		if err := e.Server.DidChange(ctx, params); err != nil {
-			return fmt.Errorf("DidChange: %w", err)
+			return errors.Errorf("DidChange: %w", err)
 		}
 	}
 	return nil
@@ -583,7 +583,7 @@ func (e *Editor) GoToDefinition(ctx context.Context, path string, pos Pos) (stri
 
 	resp, err := e.Server.Definition(ctx, params)
 	if err != nil {
-		return "", Pos{}, fmt.Errorf("definition: %w", err)
+		return "", Pos{}, errors.Errorf("definition: %w", err)
 	}
 	if len(resp) == 0 {
 		return "", Pos{}, nil
@@ -591,7 +591,7 @@ func (e *Editor) GoToDefinition(ctx context.Context, path string, pos Pos) (stri
 	newPath := e.sandbox.Workdir.URIToPath(resp[0].URI)
 	newPos := fromProtocolPosition(resp[0].Range.Start)
 	if err := e.OpenFile(ctx, newPath); err != nil {
-		return "", Pos{}, fmt.Errorf("OpenFile: %w", err)
+		return "", Pos{}, errors.Errorf("OpenFile: %w", err)
 	}
 	return newPath, newPos, nil
 }
@@ -603,7 +603,7 @@ func (e *Editor) Symbol(ctx context.Context, query string) ([]SymbolInformation,
 
 	resp, err := e.Server.Symbol(ctx, params)
 	if err != nil {
-		return nil, fmt.Errorf("symbol: %w", err)
+		return nil, errors.Errorf("symbol: %w", err)
 	}
 	var res []SymbolInformation
 	for _, si := range resp {
@@ -658,7 +658,7 @@ func (e *Editor) codeAction(ctx context.Context, path string, rng *protocol.Rang
 	}
 	actions, err := e.Server.CodeAction(ctx, params)
 	if err != nil {
-		return fmt.Errorf("textDocument/codeAction: %w", err)
+		return errors.Errorf("textDocument/codeAction: %w", err)
 	}
 	for _, action := range actions {
 		var match bool
@@ -679,7 +679,7 @@ func (e *Editor) codeAction(ctx context.Context, path string, rng *protocol.Rang
 			}
 			edits := convertEdits(change.Edits)
 			if err := e.EditBuffer(ctx, path, edits); err != nil {
-				return fmt.Errorf("editing buffer %q: %w", path, err)
+				return errors.Errorf("editing buffer %q: %w", path, err)
 			}
 		}
 		// Execute any commands. The specification says that commands are
@@ -716,7 +716,7 @@ func (e *Editor) FormatBuffer(ctx context.Context, path string) error {
 	params.TextDocument.URI = e.sandbox.Workdir.URI(path)
 	resp, err := e.Server.Formatting(ctx, params)
 	if err != nil {
-		return fmt.Errorf("textDocument/formatting: %w", err)
+		return errors.Errorf("textDocument/formatting: %w", err)
 	}
 	e.mu.Lock()
 	defer e.mu.Unlock()
@@ -850,7 +850,7 @@ func (e *Editor) Hover(ctx context.Context, path string, pos Pos) (*protocol.Mar
 
 	resp, err := e.Server.Hover(ctx, params)
 	if err != nil {
-		return nil, Pos{}, fmt.Errorf("hover: %w", err)
+		return nil, Pos{}, errors.Errorf("hover: %w", err)
 	}
 	if resp == nil {
 		return nil, Pos{}, nil

internal/lsp/fake/sandbox.go

@@ -15,6 +15,7 @@ import (
 	"golang.org/x/tools/internal/gocommand"
 	"golang.org/x/tools/internal/testenv"
 	"golang.org/x/tools/txtar"
+	errors "golang.org/x/xerrors"
 )
 
 // Sandbox holds a collection of temporary resources to use for working with Go
@@ -203,7 +204,7 @@ func (sb *Sandbox) RunGoCommand(ctx context.Context, verb string, args ...string
 	// check if we need to send any any "watched" file events.
 	if sb.Workdir != nil {
 		if err := sb.Workdir.CheckForFileChanges(ctx); err != nil {
-			return fmt.Errorf("checking for file changes: %w", err)
+			return errors.Errorf("checking for file changes: %w", err)
 		}
 	}
 	return nil
@@ -213,9 +214,7 @@ func (sb *Sandbox) RunGoCommand(ctx context.Context, verb string, args ...string
 func (sb *Sandbox) Close() error {
 	var goCleanErr error
 	if sb.gopath != "" {
-		if err := sb.RunGoCommand(context.Background(), "clean", "-modcache"); err != nil {
+		goCleanErr = sb.RunGoCommand(context.Background(), "clean", "-modcache")
-			goCleanErr = fmt.Errorf("cleaning modcache: %v", err)
-		}
 	}
 	err := os.RemoveAll(sb.basedir)
 	if err != nil || goCleanErr != nil {

internal/lsp/fake/workdir.go

@@ -6,7 +6,6 @@ package fake
 
 import (
 	"context"
-	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -16,6 +15,7 @@ import (
 
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 // FileEvent wraps the protocol.FileEvent so that it can be associated with a
@@ -48,12 +48,12 @@ func (w *Workdir) WriteInitialFiles(txt string) error {
 	files := unpackTxt(txt)
 	for name, data := range files {
 		if err := w.writeFileData(name, string(data)); err != nil {
-			return fmt.Errorf("writing to workdir: %w", err)
+			return errors.Errorf("writing to workdir: %w", err)
 		}
 	}
 	// Poll to capture the current file state.
 	if _, err := w.pollFiles(); err != nil {
-		return fmt.Errorf("polling files: %w", err)
+		return errors.Errorf("polling files: %w", err)
 	}
 	return nil
 }
@@ -134,7 +134,7 @@ func (w *Workdir) ChangeFilesOnDisk(ctx context.Context, events []FileEvent) err
 		case protocol.Deleted:
 			fp := w.filePath(e.Path)
 			if err := os.Remove(fp); err != nil {
-				return fmt.Errorf("removing %q: %w", e.Path, err)
+				return errors.Errorf("removing %q: %w", e.Path, err)
 			}
 		case protocol.Changed, protocol.Created:
 			if _, err := w.writeFile(ctx, e.Path, e.Content); err != nil {
@@ -150,7 +150,7 @@ func (w *Workdir) ChangeFilesOnDisk(ctx context.Context, events []FileEvent) err
 func (w *Workdir) RemoveFile(ctx context.Context, path string) error {
 	fp := w.filePath(path)
 	if err := os.Remove(fp); err != nil {
-		return fmt.Errorf("removing %q: %w", path, err)
+		return errors.Errorf("removing %q: %w", path, err)
 	}
 	evts := []FileEvent{{
 		Path: path,
@@ -205,7 +205,7 @@ func (w *Workdir) writeFile(ctx context.Context, path, content string) (FileEven
 	fp := w.filePath(path)
 	_, err := os.Stat(fp)
 	if err != nil && !os.IsNotExist(err) {
-		return FileEvent{}, fmt.Errorf("checking if %q exists: %w", path, err)
+		return FileEvent{}, errors.Errorf("checking if %q exists: %w", path, err)
 	}
 	var changeType protocol.FileChangeType
 	if os.IsNotExist(err) {
@@ -228,10 +228,10 @@ func (w *Workdir) writeFile(ctx context.Context, path, content string) (FileEven
 func (w *Workdir) writeFileData(path string, content string) error {
 	fp := w.filePath(path)
 	if err := os.MkdirAll(filepath.Dir(fp), 0755); err != nil {
-		return fmt.Errorf("creating nested directory: %w", err)
+		return errors.Errorf("creating nested directory: %w", err)
 	}
 	if err := ioutil.WriteFile(fp, []byte(content), 0644); err != nil {
-		return fmt.Errorf("writing %q: %w", path, err)
+		return errors.Errorf("writing %q: %w", path, err)
 	}
 	return nil
 }

internal/lsp/general.go

@@ -22,13 +22,14 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 func (s *Server) initialize(ctx context.Context, params *protocol.ParamInitialize) (*protocol.InitializeResult, error) {
 	s.stateMu.Lock()
 	if s.state >= serverInitializing {
 		defer s.stateMu.Unlock()
-		return nil, fmt.Errorf("%w: initialize called while server in %v state", jsonrpc2.ErrInvalidRequest, s.state)
+		return nil, errors.Errorf("%w: initialize called while server in %v state", jsonrpc2.ErrInvalidRequest, s.state)
 	}
 	s.state = serverInitializing
 	s.stateMu.Unlock()
@@ -142,7 +143,7 @@ func (s *Server) initialized(ctx context.Context, params *protocol.InitializedPa
 	s.stateMu.Lock()
 	if s.state >= serverInitialized {
 		defer s.stateMu.Unlock()
-		return fmt.Errorf("%w: initalized called while server in %v state", jsonrpc2.ErrInvalidRequest, s.state)
+		return errors.Errorf("%w: initalized called while server in %v state", jsonrpc2.ErrInvalidRequest, s.state)
 	}
 	s.state = serverInitialized
 	s.stateMu.Unlock()

internal/lsp/lsprpc/autostart_default.go

@@ -5,8 +5,9 @@
 package lsprpc
 
 import (
-	"fmt"
 	"os/exec"
+
+	errors "golang.org/x/xerrors"
 )
 
 var (
@@ -18,7 +19,7 @@ var (
 func startRemoteDefault(goplsPath string, args ...string) error {
 	cmd := exec.Command(goplsPath, args...)
 	if err := cmd.Start(); err != nil {
-		return fmt.Errorf("starting remote gopls: %w", err)
+		return errors.Errorf("starting remote gopls: %w", err)
 	}
 	return nil
 }

internal/lsp/lsprpc/autostart_posix.go

@@ -17,6 +17,8 @@ import (
 	"path/filepath"
 	"strconv"
 	"syscall"
+
+	"golang.org/x/xerrors"
 )
 
 func init() {
@@ -31,7 +33,7 @@ func startRemotePosix(goplsPath string, args ...string) error {
 		Setsid: true,
 	}
 	if err := cmd.Start(); err != nil {
-		return fmt.Errorf("starting remote gopls: %w", err)
+		return xerrors.Errorf("starting remote gopls: %w", err)
 	}
 	return nil
 }
@@ -78,7 +80,7 @@ func verifyRemoteOwnershipPosix(network, address string) (bool, error) {
 		if os.IsNotExist(err) {
 			return true, nil
 		}
-		return false, fmt.Errorf("checking socket owner: %w", err)
+		return false, xerrors.Errorf("checking socket owner: %w", err)
 	}
 	stat, ok := fi.Sys().(*syscall.Stat_t)
 	if !ok {
@@ -86,11 +88,11 @@ func verifyRemoteOwnershipPosix(network, address string) (bool, error) {
 	}
 	user, err := user.Current()
 	if err != nil {
-		return false, fmt.Errorf("checking current user: %w", err)
+		return false, xerrors.Errorf("checking current user: %w", err)
 	}
 	uid, err := strconv.ParseUint(user.Uid, 10, 32)
 	if err != nil {
-		return false, fmt.Errorf("parsing current UID: %w", err)
+		return false, xerrors.Errorf("parsing current UID: %w", err)
 	}
 	return stat.Uid == uint32(uid), nil
 }

internal/lsp/lsprpc/lsprpc.go

@@ -25,6 +25,7 @@ import (
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/lsp/debug/tag"
 	"golang.org/x/tools/internal/lsp/protocol"
+	errors "golang.org/x/xerrors"
 )
 
 // AutoNetwork is the pseudo network type used to signal that gopls should use
@@ -173,19 +174,19 @@ func QueryServerState(ctx context.Context, network, address string) (*ServerStat
 	if network == AutoNetwork {
 		gp, err := os.Executable()
 		if err != nil {
-			return nil, fmt.Errorf("getting gopls path: %w", err)
+			return nil, errors.Errorf("getting gopls path: %w", err)
 		}
 		network, address = autoNetworkAddress(gp, address)
 	}
 	netConn, err := net.DialTimeout(network, address, 5*time.Second)
 	if err != nil {
-		return nil, fmt.Errorf("dialing remote: %w", err)
+		return nil, errors.Errorf("dialing remote: %w", err)
 	}
 	serverConn := jsonrpc2.NewConn(jsonrpc2.NewHeaderStream(netConn))
 	serverConn.Go(ctx, jsonrpc2.MethodNotFound)
 	var state ServerState
 	if err := protocol.Call(ctx, serverConn, sessionsMethod, nil, &state); err != nil {
-		return nil, fmt.Errorf("querying server state: %w", err)
+		return nil, errors.Errorf("querying server state: %w", err)
 	}
 	return &state, nil
 }
@@ -197,7 +198,7 @@ func (f *Forwarder) ServeStream(ctx context.Context, clientConn jsonrpc2.Conn) e
 
 	netConn, err := f.connectToRemote(ctx)
 	if err != nil {
-		return fmt.Errorf("forwarder: connecting to remote: %w", err)
+		return errors.Errorf("forwarder: connecting to remote: %w", err)
 	}
 	serverConn := jsonrpc2.NewConn(jsonrpc2.NewHeaderStream(netConn))
 	server := protocol.ServerDispatcher(serverConn)
@@ -320,7 +321,7 @@ func connectToRemote(ctx context.Context, inNetwork, inAddr, goplsPath string, r
 			// instances are simultaneously starting up.
 			if _, err := os.Stat(address); err == nil {
 				if err := os.Remove(address); err != nil {
-					return nil, fmt.Errorf("removing remote socket file: %w", err)
+					return nil, errors.Errorf("removing remote socket file: %w", err)
 				}
 			}
 		}
@@ -335,7 +336,7 @@ func connectToRemote(ctx context.Context, inNetwork, inAddr, goplsPath string, r
 			args = append(args, "-debug", rcfg.debug)
 		}
 		if err := startRemote(goplsPath, args...); err != nil {
-			return nil, fmt.Errorf("startRemote(%q, %v): %w", goplsPath, args, err)
+			return nil, errors.Errorf("startRemote(%q, %v): %w", goplsPath, args, err)
 		}
 	}
 
@@ -355,7 +356,7 @@ func connectToRemote(ctx context.Context, inNetwork, inAddr, goplsPath string, r
 			time.Sleep(dialTimeout - time.Since(startDial))
 		}
 	}
-	return nil, fmt.Errorf("dialing remote: %w", err)
+	return nil, errors.Errorf("dialing remote: %w", err)
 }
 
 // forwarderHandler intercepts 'exit' messages to prevent the shared gopls
@@ -555,7 +556,7 @@ func handshaker(session *cache.Session, goplsPath string, logHandshakes bool, ha
 }
 
 func sendError(ctx context.Context, reply jsonrpc2.Replier, err error) {
-	err = fmt.Errorf("%w: %v", jsonrpc2.ErrParse, err)
+	err = errors.Errorf("%v: %w", err, jsonrpc2.ErrParse)
 	if err := reply(ctx, nil, err); err != nil {
 		event.Error(ctx, "", err)
 	}

internal/lsp/lsprpc/lsprpc_test.go

@@ -18,6 +18,7 @@ import (
 	"golang.org/x/tools/internal/lsp/debug"
 	"golang.org/x/tools/internal/lsp/fake"
 	"golang.org/x/tools/internal/lsp/protocol"
+	"golang.org/x/tools/internal/testenv"
 )
 
 type fakeClient struct {
@@ -288,6 +289,7 @@ func (s *initServer) Initialize(ctx context.Context, params *protocol.ParamIniti
 }
 
 func TestEnvForwarding(t *testing.T) {
+	testenv.NeedsGo1Point(t, 13)
 	server := &initServer{}
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()

internal/lsp/mod/code_lens.go

@@ -95,7 +95,7 @@ func CodeLens(ctx context.Context, snapshot source.Snapshot, uri span.URI) ([]pr
 	if err != nil && err != source.ErrTmpModfileUnsupported {
 		return nil, err
 	}
-	if len(tidied.Errors) > 0 {
+	if tidied != nil && len(tidied.Errors) > 0 {
 		codelens = append(codelens, protocol.CodeLens{
 			Range: rng,
 			Command: protocol.Command{

internal/lsp/mod/hover.go

@@ -12,6 +12,7 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 func Hover(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle, position protocol.Position) (*protocol.Hover, error) {
@@ -28,15 +29,15 @@ func Hover(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle,
 	// Get the position of the cursor.
 	pm, err := snapshot.ParseMod(ctx, fh)
 	if err != nil {
-		return nil, fmt.Errorf("getting modfile handle: %w", err)
+		return nil, errors.Errorf("getting modfile handle: %w", err)
 	}
 	spn, err := pm.Mapper.PointSpan(position)
 	if err != nil {
-		return nil, fmt.Errorf("computing cursor position: %w", err)
+		return nil, errors.Errorf("computing cursor position: %w", err)
 	}
 	hoverRng, err := spn.Range(pm.Mapper.Converter)
 	if err != nil {
-		return nil, fmt.Errorf("computing hover range: %w", err)
+		return nil, errors.Errorf("computing hover range: %w", err)
 	}
 
 	// Confirm that the cursor is at the position of a require statement.

internal/lsp/protocol/protocol.go

@@ -12,6 +12,7 @@ import (
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/jsonrpc2"
 	"golang.org/x/tools/internal/xcontext"
+	errors "golang.org/x/xerrors"
 )
 
 var (
@@ -133,5 +134,5 @@ func cancelCall(ctx context.Context, conn jsonrpc2.Conn, id jsonrpc2.ID) {
 }
 
 func sendParseError(ctx context.Context, reply jsonrpc2.Replier, err error) error {
-	return reply(ctx, nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err))
+	return reply(ctx, nil, errors.Errorf("%w: %s", jsonrpc2.ErrParse, err))
 }

internal/lsp/protocol/tsclient.go

@@ -3,16 +3,16 @@ package protocol
 // Package protocol contains data types and code for LSP jsonrpcs
 // generated automatically from vscode-languageserver-node
 // commit: 399de64448129835b53c7efe8962de91681d6cde
-// last fetched Tue Jul 28 2020 09:32:20 GMT-0400 (Eastern Daylight Time)
+// last fetched Wed Aug 26 2020 20:34:24 GMT-0400 (Eastern Daylight Time)
 
 // Code generated (see typescript/README.md) DO NOT EDIT.
 
 import (
 	"context"
 	"encoding/json"
-	"fmt"
 
 	"golang.org/x/tools/internal/jsonrpc2"
+	errors "golang.org/x/xerrors"
 )
 
 type Client interface {
@@ -69,7 +69,7 @@ func clientDispatch(ctx context.Context, client Client, reply jsonrpc2.Replier,
 		return true, reply(ctx, nil, err)
 	case "workspace/workspaceFolders": // req
 		if len(r.Params()) > 0 {
-			return true, reply(ctx, nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
+			return true, reply(ctx, nil, errors.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
 		}
 		resp, err := client.WorkspaceFolders(ctx)
 		return true, reply(ctx, resp, err)

internal/lsp/protocol/tsprotocol.go

@@ -1,7 +1,7 @@
 // Package protocol contains data types and code for LSP jsonrpcs
 // generated automatically from vscode-languageserver-node
 // commit: 399de64448129835b53c7efe8962de91681d6cde
-// last fetched Tue Jul 28 2020 09:32:20 GMT-0400 (Eastern Daylight Time)
+// last fetched Wed Aug 26 2020 20:34:24 GMT-0400 (Eastern Daylight Time)
 package protocol
 
 // Code generated (see typescript/README.md) DO NOT EDIT.

internal/lsp/protocol/tsserver.go

@@ -3,16 +3,16 @@ package protocol
 // Package protocol contains data types and code for LSP jsonrpcs
 // generated automatically from vscode-languageserver-node
 // commit: 399de64448129835b53c7efe8962de91681d6cde
-// last fetched Tue Jul 28 2020 09:32:20 GMT-0400 (Eastern Daylight Time)
+// last fetched Wed Aug 26 2020 20:34:24 GMT-0400 (Eastern Daylight Time)
 
 // Code generated (see typescript/README.md) DO NOT EDIT.
 
 import (
 	"context"
 	"encoding/json"
-	"fmt"
 
 	"golang.org/x/tools/internal/jsonrpc2"
+	errors "golang.org/x/xerrors"
 )
 
 type Server interface {
@@ -236,7 +236,7 @@ func serverDispatch(ctx context.Context, server Server, reply jsonrpc2.Replier,
 		return true, reply(ctx, resp, err)
 	case "shutdown": // req
 		if len(r.Params()) > 0 {
-			return true, reply(ctx, nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
+			return true, reply(ctx, nil, errors.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
 		}
 		err := server.Shutdown(ctx)
 		return true, reply(ctx, nil, err)

internal/lsp/protocol/typescript/code.ts

@@ -915,7 +915,7 @@ let server: side = {
 
 // commonly used output
 const notNil = `if len(r.Params()) > 0 {
-  return true, reply(ctx, nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
+  return true, reply(ctx, nil, errors.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
 }`;
 
 // Go code for notifications. Side is client or server, m is the request
@@ -1078,9 +1078,9 @@ function output(side: side) {
         import (
           "context"
           "encoding/json"
-          "fmt"
 
           "golang.org/x/tools/internal/jsonrpc2"
+          errors "golang.org/x/xerrors"
         )
         `);
   const a = side.name[0].toUpperCase() + side.name.substring(1)

internal/lsp/regtest/codelens_test.go

@@ -134,6 +134,7 @@ require golang.org/x/hello v1.3.3
 }
 
 func TestUnusedDependenciesCodelens(t *testing.T) {
+	testenv.NeedsGo1Point(t, 14)
 	const proxy = `
 -- golang.org/x/hello@v1.0.0/go.mod --
 module golang.org/x/hello

internal/lsp/regtest/link_test.go

@@ -7,9 +7,12 @@ package regtest
 import (
 	"strings"
 	"testing"
+
+	"golang.org/x/tools/internal/testenv"
 )
 
 func TestHoverAndDocumentLink(t *testing.T) {
+	testenv.NeedsGo1Point(t, 13)
 	const program = `
 -- go.mod --
 module mod.test

internal/lsp/regtest/reg_test.go

@@ -14,6 +14,7 @@ import (
 	"time"
 
 	"golang.org/x/tools/internal/lsp/cmd"
+	"golang.org/x/tools/internal/testenv"
 	"golang.org/x/tools/internal/tool"
 )
 
@@ -77,7 +78,13 @@ func TestMain(m *testing.M) {
 	code := m.Run()
 	if err := runner.Close(); err != nil {
 		fmt.Fprintf(os.Stderr, "closing test runner: %v\n", err)
-		os.Exit(1)
+		// Regtest cleanup is broken in go1.12 and earlier, but this is OK
+		// for our CI.
+		//
+		// But fail on go1.13+.
+		if testenv.Go1Point() >= 13 {
+			os.Exit(1)
+		}
 	}
 	os.Exit(code)
 }

internal/lsp/regtest/wrappers.go

@@ -5,12 +5,12 @@
 package regtest
 
 import (
-	"errors"
 	"io"
 	"testing"
 
 	"golang.org/x/tools/internal/lsp/fake"
 	"golang.org/x/tools/internal/lsp/protocol"
+	errors "golang.org/x/xerrors"
 )
 
 func (e *Env) ChangeFilesOnDisk(events []fake.FileEvent) {
@@ -244,7 +244,7 @@ func (e *Env) CodeLens(path string) []protocol.CodeLens {
 	return lens
 }
 
-// ReferencesAtRegexp calls textDocument/references for the given path at the
+// References calls textDocument/references for the given path at the
 // position of the given regexp.
 func (e *Env) References(path string, pos fake.Pos) []protocol.Location {
 	e.T.Helper()

internal/lsp/server.go

@@ -14,6 +14,7 @@ import (
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/lsp/source"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 const concurrentAnalyses = 1
@@ -139,7 +140,7 @@ func (s *Server) nonstandardRequest(ctx context.Context, method string, params i
 }
 
 func notImplemented(method string) error {
-	return fmt.Errorf("%w: %q not yet implemented", jsonrpc2.ErrMethodNotFound, method)
+	return errors.Errorf("%w: %q not yet implemented", jsonrpc2.ErrMethodNotFound, method)
 }
 
 //go:generate helper/helper -d protocol/tsserver.go -o server_gen.go -u .

internal/lsp/source/command.go

@@ -16,6 +16,7 @@ import (
 	"golang.org/x/tools/internal/lsp/analysis/undeclaredname"
 	"golang.org/x/tools/internal/lsp/protocol"
 	"golang.org/x/tools/internal/span"
+	errors "golang.org/x/xerrors"
 )
 
 type Command struct {
@@ -209,7 +210,7 @@ func (c *Command) SuggestedFix(ctx context.Context, snapshot Snapshot, fh Versio
 func getAllSuggestedFixInputs(ctx context.Context, snapshot Snapshot, fh FileHandle, pRng protocol.Range) (*token.FileSet, span.Range, []byte, *ast.File, *protocol.ColumnMapper, *types.Package, *types.Info, error) {
 	pkg, pgf, err := getParsedFile(ctx, snapshot, fh, NarrowestPackage)
 	if err != nil {
-		return nil, span.Range{}, nil, nil, nil, nil, nil, fmt.Errorf("getting file for Identifier: %w", err)
+		return nil, span.Range{}, nil, nil, nil, nil, nil, errors.Errorf("getting file for Identifier: %w", err)
 	}
 	spn, err := pgf.Mapper.RangeSpan(pRng)
 	if err != nil {

internal/lsp/source/completion.go

@@ -6,7 +6,6 @@ package source
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/constant"
 	"go/scanner"
@@ -471,7 +470,7 @@ func Completion(ctx context.Context, snapshot Snapshot, fh FileHandle, protoPos
 
 	pkg, pgf, err := getParsedFile(ctx, snapshot, fh, NarrowestPackage)
 	if err != nil {
-		return nil, nil, fmt.Errorf("getting file for Completion: %w", err)
+		return nil, nil, errors.Errorf("getting file for Completion: %w", err)
 	}
 	spn, err := pgf.Mapper.PointSpan(protoPos)
 	if err != nil {

internal/lsp/source/highlight.go

@@ -24,7 +24,7 @@ func Highlight(ctx context.Context, snapshot Snapshot, fh FileHandle, pos protoc
 
 	pkg, pgf, err := getParsedFile(ctx, snapshot, fh, WidestPackage)
 	if err != nil {
-		return nil, fmt.Errorf("getting file for Highlight: %w", err)
+		return nil, errors.Errorf("getting file for Highlight: %w", err)
 	}
 	spn, err := pgf.Mapper.PointSpan(pos)
 	if err != nil {

internal/lsp/source/implementation.go

@@ -15,6 +15,7 @@ import (
 
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/lsp/protocol"
+	"golang.org/x/xerrors"
 )
 
 func Implementation(ctx context.Context, snapshot Snapshot, f FileHandle, pp protocol.Position) ([]protocol.Location, error) {
@@ -239,7 +240,7 @@ func qualifiedObjsAtProtocolPos(ctx context.Context, s Snapshot, fh FileHandle,
 			} else {
 				obj := searchpkg.GetTypesInfo().ObjectOf(leaf)
 				if obj == nil {
-					return nil, fmt.Errorf("%w for %q", errNoObjectFound, leaf.Name)
+					return nil, xerrors.Errorf("%w for %q", errNoObjectFound, leaf.Name)
 				}
 				objs = append(objs, obj)
 			}
@@ -247,7 +248,7 @@ func qualifiedObjsAtProtocolPos(ctx context.Context, s Snapshot, fh FileHandle,
 			// Look up the implicit *types.PkgName.
 			obj := searchpkg.GetTypesInfo().Implicits[leaf]
 			if obj == nil {
-				return nil, fmt.Errorf("%w for import %q", errNoObjectFound, importPath(leaf))
+				return nil, xerrors.Errorf("%w for import %q", errNoObjectFound, importPath(leaf))
 			}
 			objs = append(objs, obj)
 		}
@@ -265,7 +266,7 @@ func qualifiedObjsAtProtocolPos(ctx context.Context, s Snapshot, fh FileHandle,
 		addPkg(searchpkg)
 		for _, obj := range objs {
 			if obj.Parent() == types.Universe {
-				return nil, fmt.Errorf("%w %q", errBuiltin, obj.Name())
+				return nil, xerrors.Errorf("%q: %w", obj.Name(), errBuiltin)
 			}
 			pkg, ok := pkgs[obj.Pkg()]
 			if !ok {

internal/lsp/source/signature_help.go

@@ -6,7 +6,6 @@ package source
 
 import (
 	"context"
-	"fmt"
 	"go/ast"
 	"go/doc"
 	"go/token"
@@ -24,7 +23,7 @@ func SignatureHelp(ctx context.Context, snapshot Snapshot, fh FileHandle, pos pr
 
 	pkg, pgf, err := getParsedFile(ctx, snapshot, fh, NarrowestPackage)
 	if err != nil {
-		return nil, 0, fmt.Errorf("getting file for SignatureHelp: %w", err)
+		return nil, 0, errors.Errorf("getting file for SignatureHelp: %w", err)
 	}
 	spn, err := pgf.Mapper.PointSpan(pos)
 	if err != nil {

internal/lsp/source/symbols.go

@@ -12,6 +12,7 @@ import (
 
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/lsp/protocol"
+	errors "golang.org/x/xerrors"
 )
 
 func DocumentSymbols(ctx context.Context, snapshot Snapshot, fh FileHandle) ([]protocol.DocumentSymbol, error) {
@@ -20,7 +21,7 @@ func DocumentSymbols(ctx context.Context, snapshot Snapshot, fh FileHandle) ([]p
 
 	pkg, pgf, err := getParsedFile(ctx, snapshot, fh, NarrowestPackage)
 	if err != nil {
-		return nil, fmt.Errorf("getting file for DocumentSymbols: %w", err)
+		return nil, errors.Errorf("getting file for DocumentSymbols: %w", err)
 	}
 
 	info := pkg.GetTypesInfo()

internal/lsp/testdata/lsp/primarymod/rename/b/b.go.golden

@@ -75,4 +75,4 @@ Hello description
 func Hello() {} //@rename("Hello", "Goodbye")
 
 -- uint-rename --
-builtin object "int"
+"int": builtin object

internal/lsp/text_synchronization.go

@@ -320,7 +320,7 @@ func (s *Server) wasFirstChange(uri span.URI) bool {
 
 func (s *Server) changedText(ctx context.Context, uri span.URI, changes []protocol.TextDocumentContentChangeEvent) ([]byte, error) {
 	if len(changes) == 0 {
-		return nil, fmt.Errorf("%w: no content changes provided", jsonrpc2.ErrInternal)
+		return nil, errors.Errorf("%w: no content changes provided", jsonrpc2.ErrInternal)
 	}
 
 	// Check if the client sent the full content of the file.
@@ -338,7 +338,7 @@ func (s *Server) applyIncrementalChanges(ctx context.Context, uri span.URI, chan
 	}
 	content, err := fh.Read()
 	if err != nil {
-		return nil, fmt.Errorf("%w: file not found (%v)", jsonrpc2.ErrInternal, err)
+		return nil, errors.Errorf("%w: file not found (%v)", jsonrpc2.ErrInternal, err)
 	}
 	for _, change := range changes {
 		// Make sure to update column mapper along with the content.
@@ -349,18 +349,18 @@ func (s *Server) applyIncrementalChanges(ctx context.Context, uri span.URI, chan
 			Content:   content,
 		}
 		if change.Range == nil {
-			return nil, fmt.Errorf("%w: unexpected nil range for change", jsonrpc2.ErrInternal)
+			return nil, errors.Errorf("%w: unexpected nil range for change", jsonrpc2.ErrInternal)
 		}
 		spn, err := m.RangeSpan(*change.Range)
 		if err != nil {
 			return nil, err
 		}
 		if !spn.HasOffset() {
-			return nil, fmt.Errorf("%w: invalid range for content change", jsonrpc2.ErrInternal)
+			return nil, errors.Errorf("%w: invalid range for content change", jsonrpc2.ErrInternal)
 		}
 		start, end := spn.Start().Offset(), spn.End().Offset()
 		if end < start {
-			return nil, fmt.Errorf("%w: invalid range for content change", jsonrpc2.ErrInternal)
+			return nil, errors.Errorf("%w: invalid range for content change", jsonrpc2.ErrInternal)
 		}
 		var buf bytes.Buffer
 		buf.Write(content[:start])