internal/lsp/cache/mod.go - tools - Git at Google

 // Copyright 2019 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 package cache

 import (
 	"context"
 	"encoding/json"
 	"fmt"
 	"io"
 	"os"
 	"path/filepath"
 	"regexp"
 	"strconv"
 	"strings"
 	"unicode"

 	"golang.org/x/mod/modfile"
 	"golang.org/x/mod/module"
 	"golang.org/x/tools/internal/event"
 	"golang.org/x/tools/internal/gocommand"
 	"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/tools/internal/memoize"
 	"golang.org/x/tools/internal/span"
 	errors "golang.org/x/xerrors"
 )

 const (
 	SyntaxError = "syntax"
 )

 type parseModHandle struct {
 	handle *memoize.Handle
 }

 type parseModData struct {
 	parsed *source.ParsedModule

 	// err is any error encountered while parsing the file.
 	err error
 }

 func (mh *parseModHandle) parse(ctx context.Context, snapshot *snapshot) (*source.ParsedModule, error) {
 	v, err := mh.handle.Get(ctx, snapshot.generation, snapshot)
 	if err != nil {
 		return nil, err
 	}
 	data := v.(*parseModData)
 	return data.parsed, data.err
 }

 func (s *snapshot) ParseMod(ctx context.Context, modFH source.FileHandle) (*source.ParsedModule, error) {
 	if handle := s.getParseModHandle(modFH.URI()); handle != nil {
 		return handle.parse(ctx, s)
 	}
 	h := s.generation.Bind(modFH.FileIdentity(), func(ctx context.Context, _ memoize.Arg) interface{} {
 		_, done := event.Start(ctx, "cache.ParseModHandle", tag.URI.Of(modFH.URI()))
 		defer done()

 		contents, err := modFH.Read()
 		if err != nil {
 			return &parseModData{err: err}
 		}
 		m := &protocol.ColumnMapper{
 			URI:       modFH.URI(),
 			Converter: span.NewContentConverter(modFH.URI().Filename(), contents),
 			Content:   contents,
 		}
 		data := &parseModData{
 			parsed: &source.ParsedModule{
 				Mapper: m,
 			},
 		}
 		data.parsed.File, data.err = modfile.Parse(modFH.URI().Filename(), contents, nil)
 		if data.err != nil {
 			// Attempt to convert the error to a standardized parse error.
 			if parseErr, extractErr := extractModParseErrors(modFH.URI(), m, data.err, contents); extractErr == nil {
 				data.parsed.ParseErrors = []source.Error{*parseErr}
 			}
 			// If the file was still parsed, we don't want to treat this as a
 			// fatal error. Note: This currently cannot happen as modfile.Parse
 			// always returns an error when the file is nil.
 			if data.parsed.File != nil {
 				data.err = nil
 			}
 		}
 		return data
 	}, nil)

 	pmh := &parseModHandle{handle: h}
 	s.mu.Lock()
 	s.parseModHandles[modFH.URI()] = pmh
 	s.mu.Unlock()

 	return pmh.parse(ctx, s)
 }

 // goSum reads the go.sum file for the go.mod file at modURI, if it exists. If
 // it doesn't exist, it returns nil.
 func (s *snapshot) goSum(ctx context.Context, modURI span.URI) []byte {
 	// Get the go.sum file, either from the snapshot or directly from the
 	// cache. Avoid (*snapshot).GetFile here, as we don't want to add
 	// nonexistent file handles to the snapshot if the file does not exist.
 	sumURI := span.URIFromPath(sumFilename(modURI))
 	var sumFH source.FileHandle = s.FindFile(sumURI)
 	if sumFH == nil {
 		var err error
 		sumFH, err = s.view.session.cache.getFile(ctx, sumURI)
 		if err != nil {
 			return nil
 		}
 	}
 	content, err := sumFH.Read()
 	if err != nil {
 		return nil
 	}
 	return content
 }

 func sumFilename(modURI span.URI) string {
 	return strings.TrimSuffix(modURI.Filename(), ".mod") + ".sum"
 }

 // extractModParseErrors processes the raw errors returned by modfile.Parse,
 // extracting the filenames and line numbers that correspond to the errors.
 func extractModParseErrors(uri span.URI, m *protocol.ColumnMapper, parseErr error, content []byte) (*source.Error, error) {
 	re := regexp.MustCompile(`.*:([\d]+): (.+)`)
 	matches := re.FindStringSubmatch(strings.TrimSpace(parseErr.Error()))
 	if len(matches) < 3 {
 		return nil, errors.Errorf("could not parse go.mod error message: %s", parseErr)
 	}
 	line, err := strconv.Atoi(matches[1])
 	if err != nil {
 		return nil, err
 	}
 	lines := strings.Split(string(content), "\n")
 	if line > len(lines) {
 		return nil, errors.Errorf("could not parse go.mod error message %q, line number %v out of range", content, line)
 	}
 	// The error returned from the modfile package only returns a line number,
 	// so we assume that the diagnostic should be for the entire line.
 	endOfLine := len(lines[line-1])
 	sOffset, err := m.Converter.ToOffset(line, 0)
 	if err != nil {
 		return nil, err
 	}
 	eOffset, err := m.Converter.ToOffset(line, endOfLine)
 	if err != nil {
 		return nil, err
 	}
 	spn := span.New(uri, span.NewPoint(line, 0, sOffset), span.NewPoint(line, endOfLine, eOffset))
 	rng, err := m.Range(spn)
 	if err != nil {
 		return nil, err
 	}
 	return &source.Error{
 		Category: SyntaxError,
 		Message:  matches[2],
 		Range:    rng,
 		URI:      uri,
 	}, nil
 }

 // modKey is uniquely identifies cached data for `go mod why` or dependencies
 // to upgrade.
 type modKey struct {
 	sessionID, env, view string
 	mod                  source.FileIdentity
 	verb                 modAction
 }

 type modAction int

 const (
 	why modAction = iota
 	upgrade
 )

 type modWhyHandle struct {
 	handle *memoize.Handle
 }

 type modWhyData struct {
 	// why keeps track of the `go mod why` results for each require statement
 	// in the go.mod file.
 	why map[string]string

 	err error
 }

 func (mwh *modWhyHandle) why(ctx context.Context, snapshot *snapshot) (map[string]string, error) {
 	v, err := mwh.handle.Get(ctx, snapshot.generation, snapshot)
 	if err != nil {
 		return nil, err
 	}
 	data := v.(*modWhyData)
 	return data.why, data.err
 }

 func (s *snapshot) ModWhy(ctx context.Context, fh source.FileHandle) (map[string]string, error) {
 	if fh.Kind() != source.Mod {
 		return nil, fmt.Errorf("%s is not a go.mod file", fh.URI())
 	}
 	if handle := s.getModWhyHandle(fh.URI()); handle != nil {
 		return handle.why(ctx, s)
 	}
 	key := modKey{
 		sessionID: s.view.session.id,
 		env:       hashEnv(s),
 		mod:       fh.FileIdentity(),
 		view:      s.view.rootURI.Filename(),
 		verb:      why,
 	}
 	h := s.generation.Bind(key, func(ctx context.Context, arg memoize.Arg) interface{} {
 		ctx, done := event.Start(ctx, "cache.ModWhyHandle", tag.URI.Of(fh.URI()))
 		defer done()

 		snapshot := arg.(*snapshot)

 		pm, err := snapshot.ParseMod(ctx, fh)
 		if err != nil {
 			return &modWhyData{err: err}
 		}
 		// No requires to explain.
 		if len(pm.File.Require) == 0 {
 			return &modWhyData{}
 		}
 		// Run `go mod why` on all the dependencies.
 		inv := &gocommand.Invocation{
 			Verb:       "mod",
 			Args:       []string{"why", "-m"},
 			WorkingDir: filepath.Dir(fh.URI().Filename()),
 		}
 		for _, req := range pm.File.Require {
 			inv.Args = append(inv.Args, req.Mod.Path)
 		}
 		stdout, err := snapshot.RunGoCommandDirect(ctx, source.Normal, inv)
 		if err != nil {
 			return &modWhyData{err: err}
 		}
 		whyList := strings.Split(stdout.String(), "\n\n")
 		if len(whyList) != len(pm.File.Require) {
 			return &modWhyData{
 				err: fmt.Errorf("mismatched number of results: got %v, want %v", len(whyList), len(pm.File.Require)),
 			}
 		}
 		why := make(map[string]string, len(pm.File.Require))
 		for i, req := range pm.File.Require {
 			why[req.Mod.Path] = whyList[i]
 		}
 		return &modWhyData{why: why}
 	}, nil)

 	mwh := &modWhyHandle{handle: h}
 	s.mu.Lock()
 	s.modWhyHandles[fh.URI()] = mwh
 	s.mu.Unlock()

 	return mwh.why(ctx, s)
 }

 type modUpgradeHandle struct {
 	handle *memoize.Handle
 }

 type modUpgradeData struct {
 	// upgrades maps modules to their latest versions.
 	upgrades map[string]string

 	err error
 }

 func (muh *modUpgradeHandle) upgrades(ctx context.Context, snapshot *snapshot) (map[string]string, error) {
 	v, err := muh.handle.Get(ctx, snapshot.generation, snapshot)
 	if v == nil {
 		return nil, err
 	}
 	data := v.(*modUpgradeData)
 	return data.upgrades, data.err
 }

 // moduleUpgrade describes a module that can be upgraded to a particular
 // version.
 type moduleUpgrade struct {
 	Path   string
 	Update struct {
 		Version string
 	}
 }

 func (s *snapshot) ModUpgrade(ctx context.Context, fh source.FileHandle) (map[string]string, error) {
 	if fh.Kind() != source.Mod {
 		return nil, fmt.Errorf("%s is not a go.mod file", fh.URI())
 	}
 	if handle := s.getModUpgradeHandle(fh.URI()); handle != nil {
 		return handle.upgrades(ctx, s)
 	}
 	key := modKey{
 		sessionID: s.view.session.id,
 		env:       hashEnv(s),
 		mod:       fh.FileIdentity(),
 		view:      s.view.rootURI.Filename(),
 		verb:      upgrade,
 	}
 	h := s.generation.Bind(key, func(ctx context.Context, arg memoize.Arg) interface{} {
 		ctx, done := event.Start(ctx, "cache.ModUpgradeHandle", tag.URI.Of(fh.URI()))
 		defer done()

 		snapshot := arg.(*snapshot)

 		pm, err := snapshot.ParseMod(ctx, fh)
 		if err != nil {
 			return &modUpgradeData{err: err}
 		}

 		// No requires to upgrade.
 		if len(pm.File.Require) == 0 {
 			return &modUpgradeData{}
 		}
 		// Run "go list -mod readonly -u -m all" to be able to see which deps can be
 		// upgraded without modifying mod file.
 		inv := &gocommand.Invocation{
 			Verb:       "list",
 			Args:       []string{"-u", "-m", "-json", "all"},
 			WorkingDir: filepath.Dir(fh.URI().Filename()),
 		}
 		if s.workspaceMode()&tempModfile == 0 || containsVendor(fh.URI()) {
 			// Use -mod=readonly if the module contains a vendor directory
 			// (see golang/go#38711).
 			inv.ModFlag = "readonly"
 		}
 		stdout, err := snapshot.RunGoCommandDirect(ctx, source.Normal, inv)
 		if err != nil {
 			return &modUpgradeData{err: err}
 		}
 		var upgradeList []moduleUpgrade
 		dec := json.NewDecoder(stdout)
 		for {
 			var m moduleUpgrade
 			if err := dec.Decode(&m); err == io.EOF {
 				break
 			} else if err != nil {
 				return &modUpgradeData{err: err}
 			}
 			upgradeList = append(upgradeList, m)
 		}
 		if len(upgradeList) <= 1 {
 			return &modUpgradeData{}
 		}
 		upgrades := make(map[string]string)
 		for _, upgrade := range upgradeList[1:] {
 			if upgrade.Update.Version == "" {
 				continue
 			}
 			upgrades[upgrade.Path] = upgrade.Update.Version
 		}
 		return &modUpgradeData{
 			upgrades: upgrades,
 		}
 	}, nil)
 	muh := &modUpgradeHandle{handle: h}
 	s.mu.Lock()
 	s.modUpgradeHandles[fh.URI()] = muh
 	s.mu.Unlock()

 	return muh.upgrades(ctx, s)
 }

 // containsVendor reports whether the module has a vendor folder.
 func containsVendor(modURI span.URI) bool {
 	dir := filepath.Dir(modURI.Filename())
 	f, err := os.Stat(filepath.Join(dir, "vendor"))
 	if err != nil {
 		return false
 	}
 	return f.IsDir()
 }

 var moduleAtVersionRe = regexp.MustCompile(`^(?P<module>.*)@(?P<version>.*)$`)

 // ExtractGoCommandError tries to parse errors that come from the go command
 // and shape them into go.mod diagnostics.
 func extractGoCommandError(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle, loadErr error) *source.Error {
 	// We try to match module versions in error messages. Some examples:
 	//
 	//  example.com@v1.2.2: reading example.com/@v/v1.2.2.mod: no such file or directory
 	//  go: github.com/cockroachdb/apd/v2@v2.0.72: reading github.com/cockroachdb/apd/go.mod at revision v2.0.72: unknown revision v2.0.72
 	//  go: example.com@v1.2.3 requires\n\trandom.org@v1.2.3: parsing go.mod:\n\tmodule declares its path as: bob.org\n\tbut was required as: random.org
 	//
 	// We split on colons and whitespace, and attempt to match on something
 	// that matches module@version. If we're able to find a match, we try to
 	// find anything that matches it in the go.mod file.
 	var v module.Version
 	fields := strings.FieldsFunc(loadErr.Error(), func(r rune) bool {
 		return unicode.IsSpace(r) || r == ':'
 	})
 	for _, s := range fields {
 		s = strings.TrimSpace(s)
 		match := moduleAtVersionRe.FindStringSubmatch(s)
 		if match == nil || len(match) < 3 {
 			continue
 		}
 		path, version := match[1], match[2]
 		// Any module versions that come from the workspace module should not
 		// be shown to the user.
 		if source.IsWorkspaceModuleVersion(version) {
 			continue
 		}
 		if err := module.Check(path, version); err != nil {
 			continue
 		}
 		v.Path, v.Version = path, version
 		break
 	}
 	pm, err := snapshot.ParseMod(ctx, fh)
 	if err != nil {
 		return nil
 	}
 	toSourceError := func(line *modfile.Line) *source.Error {
 		rng, err := rangeFromPositions(pm.Mapper, line.Start, line.End)
 		if err != nil {
 			return nil
 		}
 		return &source.Error{
 			Message: loadErr.Error(),
 			Range:   rng,
 			URI:     fh.URI(),
 		}
 	}
 	// Check if there are any require, exclude, or replace statements that
 	// match this module version.
 	for _, req := range pm.File.Require {
 		if req.Mod != v {
 			continue
 		}
 		return toSourceError(req.Syntax)
 	}
 	for _, ex := range pm.File.Exclude {
 		if ex.Mod != v {
 			continue
 		}
 		return toSourceError(ex.Syntax)
 	}
 	for _, rep := range pm.File.Replace {
 		if rep.New != v && rep.Old != v {
 			continue
 		}
 		return toSourceError(rep.Syntax)
 	}
 	// No match for the module path was found in the go.mod file.
 	// Show the error on the module declaration, if one exists.
 	if pm.File.Module == nil {
 		return nil
 	}
 	return toSourceError(pm.File.Module.Syntax)
 }
	// Copyright 2019 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	package cache

	import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"unicode"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/gocommand"
	"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/tools/internal/memoize"
	"golang.org/x/tools/internal/span"
	errors "golang.org/x/xerrors"
	)

	const (
	SyntaxError = "syntax"
	)

	type parseModHandle struct {
	handle *memoize.Handle
	}

	type parseModData struct {
	parsed *source.ParsedModule

	// err is any error encountered while parsing the file.
	err error
	}

	func (mh parseModHandle) parse(ctx context.Context, snapshot snapshot) (*source.ParsedModule, error) {
	v, err := mh.handle.Get(ctx, snapshot.generation, snapshot)
	if err != nil {
	return nil, err
	}
	data := v.(*parseModData)
	return data.parsed, data.err
	}

	func (s snapshot) ParseMod(ctx context.Context, modFH source.FileHandle) (source.ParsedModule, error) {
	if handle := s.getParseModHandle(modFH.URI()); handle != nil {
	return handle.parse(ctx, s)
	}
	h := s.generation.Bind(modFH.FileIdentity(), func(ctx context.Context, _ memoize.Arg) interface{} {
	_, done := event.Start(ctx, "cache.ParseModHandle", tag.URI.Of(modFH.URI()))
	defer done()

	contents, err := modFH.Read()
	if err != nil {
	return &parseModData{err: err}
	}
	m := &protocol.ColumnMapper{
	URI: modFH.URI(),
	Converter: span.NewContentConverter(modFH.URI().Filename(), contents),
	Content: contents,
	}
	data := &parseModData{
	parsed: &source.ParsedModule{
	Mapper: m,
	},
	}
	data.parsed.File, data.err = modfile.Parse(modFH.URI().Filename(), contents, nil)
	if data.err != nil {
	// Attempt to convert the error to a standardized parse error.
	if parseErr, extractErr := extractModParseErrors(modFH.URI(), m, data.err, contents); extractErr == nil {
	data.parsed.ParseErrors = []source.Error{*parseErr}
	}
	// If the file was still parsed, we don't want to treat this as a
	// fatal error. Note: This currently cannot happen as modfile.Parse
	// always returns an error when the file is nil.
	if data.parsed.File != nil {
	data.err = nil
	}
	}
	return data
	}, nil)

	pmh := &parseModHandle{handle: h}
	s.mu.Lock()
	s.parseModHandles[modFH.URI()] = pmh
	s.mu.Unlock()

	return pmh.parse(ctx, s)
	}

	// goSum reads the go.sum file for the go.mod file at modURI, if it exists. If
	// it doesn't exist, it returns nil.
	func (s *snapshot) goSum(ctx context.Context, modURI span.URI) []byte {
	// Get the go.sum file, either from the snapshot or directly from the
	// cache. Avoid (*snapshot).GetFile here, as we don't want to add
	// nonexistent file handles to the snapshot if the file does not exist.
	sumURI := span.URIFromPath(sumFilename(modURI))
	var sumFH source.FileHandle = s.FindFile(sumURI)
	if sumFH == nil {
	var err error
	sumFH, err = s.view.session.cache.getFile(ctx, sumURI)
	if err != nil {
	return nil
	}
	}
	content, err := sumFH.Read()
	if err != nil {
	return nil
	}
	return content
	}

	func sumFilename(modURI span.URI) string {
	return strings.TrimSuffix(modURI.Filename(), ".mod") + ".sum"
	}

	// extractModParseErrors processes the raw errors returned by modfile.Parse,
	// extracting the filenames and line numbers that correspond to the errors.
	func extractModParseErrors(uri span.URI, m protocol.ColumnMapper, parseErr error, content []byte) (source.Error, error) {
	re := regexp.MustCompile(`.*:([\d]+): (.+)`)
	matches := re.FindStringSubmatch(strings.TrimSpace(parseErr.Error()))
	if len(matches) < 3 {
	return nil, errors.Errorf("could not parse go.mod error message: %s", parseErr)
	}
	line, err := strconv.Atoi(matches[1])
	if err != nil {
	return nil, err
	}
	lines := strings.Split(string(content), "\n")
	if line > len(lines) {
	return nil, errors.Errorf("could not parse go.mod error message %q, line number %v out of range", content, line)
	}
	// The error returned from the modfile package only returns a line number,
	// so we assume that the diagnostic should be for the entire line.
	endOfLine := len(lines[line-1])
	sOffset, err := m.Converter.ToOffset(line, 0)
	if err != nil {
	return nil, err
	}
	eOffset, err := m.Converter.ToOffset(line, endOfLine)
	if err != nil {
	return nil, err
	}
	spn := span.New(uri, span.NewPoint(line, 0, sOffset), span.NewPoint(line, endOfLine, eOffset))
	rng, err := m.Range(spn)
	if err != nil {
	return nil, err
	}
	return &source.Error{
	Category: SyntaxError,
	Message: matches[2],
	Range: rng,
	URI: uri,
	}, nil
	}

	// modKey is uniquely identifies cached data for `go mod why` or dependencies
	// to upgrade.
	type modKey struct {
	sessionID, env, view string
	mod source.FileIdentity
	verb modAction
	}

	type modAction int

	const (
	why modAction = iota
	upgrade
	)

	type modWhyHandle struct {
	handle *memoize.Handle
	}

	type modWhyData struct {
	// why keeps track of the `go mod why` results for each require statement
	// in the go.mod file.
	why map[string]string

	err error
	}

	func (mwh modWhyHandle) why(ctx context.Context, snapshot snapshot) (map[string]string, error) {
	v, err := mwh.handle.Get(ctx, snapshot.generation, snapshot)
	if err != nil {
	return nil, err
	}
	data := v.(*modWhyData)
	return data.why, data.err
	}

	func (s *snapshot) ModWhy(ctx context.Context, fh source.FileHandle) (map[string]string, error) {
	if fh.Kind() != source.Mod {
	return nil, fmt.Errorf("%s is not a go.mod file", fh.URI())
	}
	if handle := s.getModWhyHandle(fh.URI()); handle != nil {
	return handle.why(ctx, s)
	}
	key := modKey{
	sessionID: s.view.session.id,
	env: hashEnv(s),
	mod: fh.FileIdentity(),
	view: s.view.rootURI.Filename(),
	verb: why,
	}
	h := s.generation.Bind(key, func(ctx context.Context, arg memoize.Arg) interface{} {
	ctx, done := event.Start(ctx, "cache.ModWhyHandle", tag.URI.Of(fh.URI()))
	defer done()

	snapshot := arg.(*snapshot)

	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
	return &modWhyData{err: err}
	}
	// No requires to explain.
	if len(pm.File.Require) == 0 {
	return &modWhyData{}
	}
	// Run `go mod why` on all the dependencies.
	inv := &gocommand.Invocation{
	Verb: "mod",
	Args: []string{"why", "-m"},
	WorkingDir: filepath.Dir(fh.URI().Filename()),
	}
	for _, req := range pm.File.Require {
	inv.Args = append(inv.Args, req.Mod.Path)
	}
	stdout, err := snapshot.RunGoCommandDirect(ctx, source.Normal, inv)
	if err != nil {
	return &modWhyData{err: err}
	}
	whyList := strings.Split(stdout.String(), "\n\n")
	if len(whyList) != len(pm.File.Require) {
	return &modWhyData{
	err: fmt.Errorf("mismatched number of results: got %v, want %v", len(whyList), len(pm.File.Require)),
	}
	}
	why := make(map[string]string, len(pm.File.Require))
	for i, req := range pm.File.Require {
	why[req.Mod.Path] = whyList[i]
	}
	return &modWhyData{why: why}
	}, nil)

	mwh := &modWhyHandle{handle: h}
	s.mu.Lock()
	s.modWhyHandles[fh.URI()] = mwh
	s.mu.Unlock()

	return mwh.why(ctx, s)
	}

	type modUpgradeHandle struct {
	handle *memoize.Handle
	}

	type modUpgradeData struct {
	// upgrades maps modules to their latest versions.
	upgrades map[string]string

	err error
	}

	func (muh modUpgradeHandle) upgrades(ctx context.Context, snapshot snapshot) (map[string]string, error) {
	v, err := muh.handle.Get(ctx, snapshot.generation, snapshot)
	if v == nil {
	return nil, err
	}
	data := v.(*modUpgradeData)
	return data.upgrades, data.err
	}

	// moduleUpgrade describes a module that can be upgraded to a particular
	// version.
	type moduleUpgrade struct {
	Path string
	Update struct {
	Version string
	}
	}

	func (s *snapshot) ModUpgrade(ctx context.Context, fh source.FileHandle) (map[string]string, error) {
	if fh.Kind() != source.Mod {
	return nil, fmt.Errorf("%s is not a go.mod file", fh.URI())
	}
	if handle := s.getModUpgradeHandle(fh.URI()); handle != nil {
	return handle.upgrades(ctx, s)
	}
	key := modKey{
	sessionID: s.view.session.id,
	env: hashEnv(s),
	mod: fh.FileIdentity(),
	view: s.view.rootURI.Filename(),
	verb: upgrade,
	}
	h := s.generation.Bind(key, func(ctx context.Context, arg memoize.Arg) interface{} {
	ctx, done := event.Start(ctx, "cache.ModUpgradeHandle", tag.URI.Of(fh.URI()))
	defer done()

	snapshot := arg.(*snapshot)

	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
	return &modUpgradeData{err: err}
	}

	// No requires to upgrade.
	if len(pm.File.Require) == 0 {
	return &modUpgradeData{}
	}
	// Run "go list -mod readonly -u -m all" to be able to see which deps can be
	// upgraded without modifying mod file.
	inv := &gocommand.Invocation{
	Verb: "list",
	Args: []string{"-u", "-m", "-json", "all"},
	WorkingDir: filepath.Dir(fh.URI().Filename()),
	}
	if s.workspaceMode()&tempModfile == 0 \|\| containsVendor(fh.URI()) {
	// Use -mod=readonly if the module contains a vendor directory
	// (see golang/go#38711).
	inv.ModFlag = "readonly"
	}
	stdout, err := snapshot.RunGoCommandDirect(ctx, source.Normal, inv)
	if err != nil {
	return &modUpgradeData{err: err}
	}
	var upgradeList []moduleUpgrade
	dec := json.NewDecoder(stdout)
	for {
	var m moduleUpgrade
	if err := dec.Decode(&m); err == io.EOF {
	break
	} else if err != nil {
	return &modUpgradeData{err: err}
	}
	upgradeList = append(upgradeList, m)
	}
	if len(upgradeList) <= 1 {
	return &modUpgradeData{}
	}
	upgrades := make(map[string]string)
	for _, upgrade := range upgradeList[1:] {
	if upgrade.Update.Version == "" {
	continue
	}
	upgrades[upgrade.Path] = upgrade.Update.Version
	}
	return &modUpgradeData{
	upgrades: upgrades,
	}
	}, nil)
	muh := &modUpgradeHandle{handle: h}
	s.mu.Lock()
	s.modUpgradeHandles[fh.URI()] = muh
	s.mu.Unlock()

	return muh.upgrades(ctx, s)
	}

	// containsVendor reports whether the module has a vendor folder.
	func containsVendor(modURI span.URI) bool {
	dir := filepath.Dir(modURI.Filename())
	f, err := os.Stat(filepath.Join(dir, "vendor"))
	if err != nil {
	return false
	}
	return f.IsDir()
	}

	var moduleAtVersionRe = regexp.MustCompile(`^(?P<module>.)@(?P<version>.)$`)

	// ExtractGoCommandError tries to parse errors that come from the go command
	// and shape them into go.mod diagnostics.
	func extractGoCommandError(ctx context.Context, snapshot source.Snapshot, fh source.FileHandle, loadErr error) *source.Error {
	// We try to match module versions in error messages. Some examples:
	//
	// example.com@v1.2.2: reading example.com/@v/v1.2.2.mod: no such file or directory
	// go: github.com/cockroachdb/apd/v2@v2.0.72: reading github.com/cockroachdb/apd/go.mod at revision v2.0.72: unknown revision v2.0.72
	// go: example.com@v1.2.3 requires\n\trandom.org@v1.2.3: parsing go.mod:\n\tmodule declares its path as: bob.org\n\tbut was required as: random.org
	//
	// We split on colons and whitespace, and attempt to match on something
	// that matches module@version. If we're able to find a match, we try to
	// find anything that matches it in the go.mod file.
	var v module.Version
	fields := strings.FieldsFunc(loadErr.Error(), func(r rune) bool {
	return unicode.IsSpace(r) \|\| r == ':'
	})
	for _, s := range fields {
	s = strings.TrimSpace(s)
	match := moduleAtVersionRe.FindStringSubmatch(s)
	if match == nil \|\| len(match) < 3 {
	continue
	}
	path, version := match[1], match[2]
	// Any module versions that come from the workspace module should not
	// be shown to the user.
	if source.IsWorkspaceModuleVersion(version) {
	continue
	}
	if err := module.Check(path, version); err != nil {
	continue
	}
	v.Path, v.Version = path, version
	break
	}
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
	return nil
	}
	toSourceError := func(line modfile.Line) source.Error {
	rng, err := rangeFromPositions(pm.Mapper, line.Start, line.End)
	if err != nil {
	return nil
	}
	return &source.Error{
	Message: loadErr.Error(),
	Range: rng,
	URI: fh.URI(),
	}
	}
	// Check if there are any require, exclude, or replace statements that
	// match this module version.
	for _, req := range pm.File.Require {
	if req.Mod != v {
	continue
	}
	return toSourceError(req.Syntax)
	}
	for _, ex := range pm.File.Exclude {
	if ex.Mod != v {
	continue
	}
	return toSourceError(ex.Syntax)
	}
	for _, rep := range pm.File.Replace {
	if rep.New != v && rep.Old != v {
	continue
	}
	return toSourceError(rep.Syntax)
	}
	// No match for the module path was found in the go.mod file.
	// Show the error on the module declaration, if one exists.
	if pm.File.Module == nil {
	return nil
	}
	return toSourceError(pm.File.Module.Syntax)
	}