[chore] update dependencies (#4422)

- github.com/jackc/pgx/v5 v5.7.5 -> v5.7.6
- github.com/ncruces/go-sqlite3 v0.28.0 -> v0.29.0
- github.com/tdewolff/minify/v2 v2.24.2 -> v2.24.3
- golang.org/x/oauth2 v0.30.0 -> v0.31.0
- golang.org/x/sys v0.35.0 -> v0.36.0
- golang.org/x/text v0.28.0 -> v0.29.0

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4422
Co-authored-by: kim <grufwub@gmail.com>
Co-committed-by: kim <grufwub@gmail.com>

vendor/golang.org/x/tools/go/ast/astutil/enclosing.go

@@ -113,7 +113,7 @@ func PathEnclosingInterval(root *ast.File, start, end token.Pos) (path []ast.Nod
 				// childrenOf elides the FuncType node beneath FuncDecl.
 				// Add it back here for TypeParams, Params, Results,
 				// all FieldLists). But we don't add it back for the "func" token
-				// even though it is is the tree at FuncDecl.Type.Func.
+				// even though it is the tree at FuncDecl.Type.Func.
 				if decl, ok := node.(*ast.FuncDecl); ok {
 					if fields, ok := child.(*ast.FieldList); ok && fields != decl.Recv {
 						path = append(path, decl.Type)

vendor/golang.org/x/tools/go/packages/doc.go

@@ -76,6 +76,8 @@ uninterpreted to Load, so that it can interpret them
 according to the conventions of the underlying build system.
 
 See the Example function for typical usage.
+See also [golang.org/x/tools/go/packages/internal/linecount]
+for an example application.
 
 # The driver protocol
 

vendor/golang.org/x/tools/internal/imports/source_modindex.go

@@ -15,6 +15,10 @@ import (
 // This code is here rather than in the modindex package
 // to avoid import loops
 
+// TODO(adonovan): this code is only used by a test in this package.
+// Can we delete it? Or is there a plan to call NewIndexSource from
+// cmd/goimports?
+
 // implements Source using modindex, so only for module cache.
 //
 // this is perhaps over-engineered. A new Index is read at first use.
@@ -22,8 +26,8 @@ import (
 // is read if the index changed. It is not clear the Mutex is needed.
 type IndexSource struct {
 	modcachedir string
-	mutex       sync.Mutex
-	ix          *modindex.Index
+	mu          sync.Mutex
+	index       *modindex.Index // (access via getIndex)
 	expires     time.Time
 }
 
@@ -39,13 +43,14 @@ func (s *IndexSource) LoadPackageNames(ctx context.Context, srcDir string, paths
 }
 
 func (s *IndexSource) ResolveReferences(ctx context.Context, filename string, missing References) ([]*Result, error) {
-	if err := s.maybeReadIndex(); err != nil {
+	index, err := s.getIndex()
+	if err != nil {
 		return nil, err
 	}
 	var cs []modindex.Candidate
 	for pkg, nms := range missing {
 		for nm := range nms {
-			x := s.ix.Lookup(pkg, nm, false)
+			x := index.Lookup(pkg, nm, false)
 			cs = append(cs, x...)
 		}
 	}
@@ -74,30 +79,22 @@ func (s *IndexSource) ResolveReferences(ctx context.Context, filename string, mi
 	return ans, nil
 }
 
-func (s *IndexSource) maybeReadIndex() error {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
+func (s *IndexSource) getIndex() (*modindex.Index, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
 
-	var readIndex bool
-	if time.Now().After(s.expires) {
-		ok, err := modindex.Update(s.modcachedir)
+	// (s.index = nil => s.expires is zero,
+	// so the first condition is strictly redundant.
+	// But it makes the postcondition very clear.)
+	if s.index == nil || time.Now().After(s.expires) {
+		index, err := modindex.Update(s.modcachedir)
 		if err != nil {
-			return err
-		}
-		if ok {
-			readIndex = true
+			return nil, err
 		}
+		s.index = index
+		s.expires = index.ValidAt.Add(15 * time.Minute) // (refresh period)
 	}
+	// Inv: s.index != nil
 
-	if readIndex || s.ix == nil {
-		ix, err := modindex.ReadIndex(s.modcachedir)
-		if err != nil {
-			return err
-		}
-		s.ix = ix
-		// for now refresh every 15 minutes
-		s.expires = time.Now().Add(time.Minute * 15)
-	}
-
-	return nil
+	return s.index, nil
 }

vendor/golang.org/x/tools/internal/modindex/directories.go

@@ -10,7 +10,6 @@ import (
 	"os"
 	"path/filepath"
 	"regexp"
-	"slices"
 	"strings"
 	"sync"
 	"time"
@@ -20,50 +19,48 @@ import (
 )
 
 type directory struct {
-	path       Relpath
+	path       string // relative to GOMODCACHE
 	importPath string
 	version    string // semantic version
-	syms       []symbol
 }
 
-// byImportPath groups the directories by import path,
-// sorting the ones with the same import path by semantic version,
-// most recent first.
-func byImportPath(dirs []Relpath) (map[string][]*directory, error) {
-	ans := make(map[string][]*directory) // key is import path
-	for _, d := range dirs {
-		ip, sv, err := DirToImportPathVersion(d)
+// bestDirByImportPath returns the best directory for each import
+// path, where "best" means most recent semantic version. These import
+// paths are inferred from the GOMODCACHE-relative dir names in dirs.
+func bestDirByImportPath(dirs []string) (map[string]directory, error) {
+	dirsByPath := make(map[string]directory)
+	for _, dir := range dirs {
+		importPath, version, err := dirToImportPathVersion(dir)
 		if err != nil {
 			return nil, err
 		}
-		ans[ip] = append(ans[ip], &directory{
-			path:       d,
-			importPath: ip,
-			version:    sv,
-		})
+		new := directory{
+			path:       dir,
+			importPath: importPath,
+			version:    version,
+		}
+		if old, ok := dirsByPath[importPath]; !ok || compareDirectory(new, old) < 0 {
+			dirsByPath[importPath] = new
+		}
 	}
-	for k, v := range ans {
-		semanticSort(v)
-		ans[k] = v
-	}
-	return ans, nil
+	return dirsByPath, nil
 }
 
-// sort the directories by semantic version, latest first
-func semanticSort(v []*directory) {
-	slices.SortFunc(v, func(l, r *directory) int {
-		if n := semver.Compare(l.version, r.version); n != 0 {
-			return -n // latest first
-		}
-		return strings.Compare(string(l.path), string(r.path))
-	})
+// compareDirectory defines an ordering of path@version directories,
+// by descending version, then by ascending path.
+func compareDirectory(x, y directory) int {
+	if sign := -semver.Compare(x.version, y.version); sign != 0 {
+		return sign // latest first
+	}
+	return strings.Compare(string(x.path), string(y.path))
 }
 
 // modCacheRegexp splits a relpathpath into module, module version, and package.
 var modCacheRegexp = regexp.MustCompile(`(.*)@([^/\\]*)(.*)`)
 
-// DirToImportPathVersion computes import path and semantic version
-func DirToImportPathVersion(dir Relpath) (string, string, error) {
+// dirToImportPathVersion computes import path and semantic version
+// from a GOMODCACHE-relative directory name.
+func dirToImportPathVersion(dir string) (string, string, error) {
 	m := modCacheRegexp.FindStringSubmatch(string(dir))
 	// m[1] is the module path
 	// m[2] is the version major.minor.patch(-<pre release identifier)
@@ -74,62 +71,61 @@ func DirToImportPathVersion(dir Relpath) (string, string, error) {
 	if !semver.IsValid(m[2]) {
 		return "", "", fmt.Errorf("bad semantic version %s", m[2])
 	}
-	// ToSlash is required for Windows.
+	// ToSlash is required to convert Windows file paths
+	// into Go package import paths.
 	return filepath.ToSlash(m[1] + m[3]), m[2], nil
 }
 
-// a region controls what directories to look at, for
-// updating the index incrementally, and for testing that.
-// (for testing one builds an index as of A, incrementally
-// updates it to B, and compares the result to an index build
-// as of B.)
-type region struct {
-	onlyAfter, onlyBefore time.Time
-	sync.Mutex
-	ans []Relpath
-}
+// findDirs returns an unordered list of relevant package directories,
+// relative to the specified module cache root. The result includes only
+// module dirs whose mtime is within (start, end).
+func findDirs(root string, start, end time.Time) []string {
+	var (
+		resMu sync.Mutex
+		res   []string
+	)
 
-func findDirs(root string, onlyAfter, onlyBefore time.Time) []Relpath {
+	addDir := func(root gopathwalk.Root, dir string) {
+		// TODO(pjw): do we need to check times?
+		resMu.Lock()
+		defer resMu.Unlock()
+		res = append(res, relative(root.Path, dir))
+	}
+
+	skipDir := func(_ gopathwalk.Root, dir string) bool {
+		// The cache directory is already ignored in gopathwalk.
+		if filepath.Base(dir) == "internal" {
+			return true
+		}
+
+		// Skip toolchains.
+		if strings.Contains(dir, "toolchain@") {
+			return true
+		}
+
+		// Don't look inside @ directories that are too old/new.
+		if strings.Contains(filepath.Base(dir), "@") {
+			st, err := os.Stat(dir)
+			if err != nil {
+				log.Printf("can't stat dir %s %v", dir, err)
+				return true
+			}
+			mtime := st.ModTime()
+			return mtime.Before(start) || mtime.After(end)
+		}
+
+		return false
+	}
+
+	// TODO(adonovan): parallelize this. Even with a hot buffer cache,
+	//   find $(go env GOMODCACHE) -type d
+	// can easily take up a minute.
 	roots := []gopathwalk.Root{{Path: root, Type: gopathwalk.RootModuleCache}}
-	// TODO(PJW): adjust concurrency
-	opts := gopathwalk.Options{ModulesEnabled: true, Concurrency: 1 /* ,Logf: log.Printf*/}
-	betw := &region{
-		onlyAfter:  onlyAfter,
-		onlyBefore: onlyBefore,
-	}
-	gopathwalk.WalkSkip(roots, betw.addDir, betw.skipDir, opts)
-	return betw.ans
-}
+	gopathwalk.WalkSkip(roots, addDir, skipDir, gopathwalk.Options{
+		ModulesEnabled: true,
+		Concurrency:    1, // TODO(pjw): adjust concurrency
+		// Logf: log.Printf,
+	})
 
-func (r *region) addDir(rt gopathwalk.Root, dir string) {
-	// do we need to check times?
-	r.Lock()
-	defer r.Unlock()
-	x := filepath.ToSlash(string(toRelpath(Abspath(rt.Path), dir)))
-	r.ans = append(r.ans, toRelpath(Abspath(rt.Path), x))
-}
-
-func (r *region) skipDir(_ gopathwalk.Root, dir string) bool {
-	// The cache directory is already ignored in gopathwalk\
-	if filepath.Base(dir) == "internal" {
-		return true
-	}
-	if strings.Contains(dir, "toolchain@") {
-		return true
-	}
-	// don't look inside @ directories that are too old
-	if strings.Contains(filepath.Base(dir), "@") {
-		st, err := os.Stat(dir)
-		if err != nil {
-			log.Printf("can't stat dir %s %v", dir, err)
-			return true
-		}
-		if st.ModTime().Before(r.onlyAfter) {
-			return true
-		}
-		if st.ModTime().After(r.onlyBefore) {
-			return true
-		}
-	}
-	return false
+	return res
 }

vendor/golang.org/x/tools/internal/modindex/index.go

@@ -6,12 +6,10 @@ package modindex
 
 import (
 	"bufio"
+	"crypto/sha256"
 	"encoding/csv"
-	"errors"
 	"fmt"
-	"hash/crc64"
 	"io"
-	"io/fs"
 	"log"
 	"os"
 	"path/filepath"
@@ -22,7 +20,7 @@ import (
 )
 
 /*
-The on-disk index is a text file.
+The on-disk index ("payload") is a text file.
 The first 3 lines are header information containing CurrentVersion,
 the value of GOMODCACHE, and the validity date of the index.
 (This is when the code started building the index.)
@@ -68,34 +66,45 @@ whose types are []byte and interface{}.
 // CurrentVersion tells readers about the format of the index.
 const CurrentVersion int = 0
 
-// Index is returned by ReadIndex().
+// Index is returned by [Read].
 type Index struct {
-	Version  int
-	Cachedir Abspath   // The directory containing the module cache
-	Changed  time.Time // The index is up to date as of Changed
-	Entries  []Entry
+	Version    int
+	GOMODCACHE string    // absolute path of Go module cache dir
+	ValidAt    time.Time // moment at which the index was up to date
+	Entries    []Entry
+}
+
+func (ix *Index) String() string {
+	return fmt.Sprintf("Index(%s v%d has %d entries at %v)",
+		ix.GOMODCACHE, ix.Version, len(ix.Entries), ix.ValidAt)
 }
 
 // An Entry contains information for an import path.
 type Entry struct {
-	Dir        Relpath // directory in modcache
+	Dir        string // package directory relative to GOMODCACHE; uses OS path separator
 	ImportPath string
 	PkgName    string
 	Version    string
-	//ModTime    STime    // is this useful?
-	Names []string // exported names and information
+	Names      []string // exported names and information
 }
 
 // IndexDir is where the module index is stored.
-var IndexDir string
-
-// Set IndexDir
-func init() {
+// Each logical index entry consists of a pair of files:
+//
+//   - the "payload" (index-VERSION-XXX), whose name is
+//     randomized, holds the actual index; and
+//   - the "link" (index-name-VERSION-HASH),
+//     whose name is predictable, contains the
+//     name of the payload file.
+//
+// Since the link file is small (<512B),
+// reads and writes to it may be assumed atomic.
+var IndexDir string = func() string {
 	var dir string
-	var err error
 	if testing.Testing() {
 		dir = os.TempDir()
 	} else {
+		var err error
 		dir, err = os.UserCacheDir()
 		// shouldn't happen, but TempDir is better than
 		// creating ./go/imports
@@ -103,81 +112,83 @@ func init() {
 			dir = os.TempDir()
 		}
 	}
-	dir = filepath.Join(dir, "go", "imports")
-	os.MkdirAll(dir, 0777)
-	IndexDir = dir
+	dir = filepath.Join(dir, "goimports")
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		log.Printf("failed to create modcache index dir: %v", err)
+	}
+	return dir
+}()
+
+// Read reads the latest version of the on-disk index
+// for the specified Go module cache directory.
+// If there is no index, it returns a nil Index and an fs.ErrNotExist error.
+func Read(gomodcache string) (*Index, error) {
+	gomodcache, err := filepath.Abs(gomodcache)
+	if err != nil {
+		return nil, err
+	}
+
+	// Read the "link" file for the specified gomodcache directory.
+	// It names the payload file.
+	content, err := os.ReadFile(filepath.Join(IndexDir, linkFileBasename(gomodcache)))
+	if err != nil {
+		return nil, err
+	}
+	payloadFile := filepath.Join(IndexDir, string(content))
+
+	// Read the index out of the payload file.
+	f, err := os.Open(payloadFile)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return readIndexFrom(gomodcache, bufio.NewReader(f))
 }
 
-// ReadIndex reads the latest version of the on-disk index
-// for the cache directory cd.
-// It returns (nil, nil) if there is no index, but returns
-// a non-nil error if the index exists but could not be read.
-func ReadIndex(cachedir string) (*Index, error) {
-	cachedir, err := filepath.Abs(cachedir)
-	if err != nil {
-		return nil, err
-	}
-	cd := Abspath(cachedir)
-	dir := IndexDir
-	base := indexNameBase(cd)
-	iname := filepath.Join(dir, base)
-	buf, err := os.ReadFile(iname)
-	if err != nil {
-		if errors.Is(err, fs.ErrNotExist) {
-			return nil, nil
-		}
-		return nil, fmt.Errorf("cannot read %s: %w", iname, err)
-	}
-	fname := filepath.Join(dir, string(buf))
-	fd, err := os.Open(fname)
-	if err != nil {
-		return nil, err
-	}
-	defer fd.Close()
-	r := bufio.NewReader(fd)
-	ix, err := readIndexFrom(cd, r)
-	if err != nil {
-		return nil, err
-	}
-	return ix, nil
-}
+func readIndexFrom(gomodcache string, r io.Reader) (*Index, error) {
+	scan := bufio.NewScanner(r)
 
-func readIndexFrom(cd Abspath, bx io.Reader) (*Index, error) {
-	b := bufio.NewScanner(bx)
-	var ans Index
-	// header
-	ok := b.Scan()
-	if !ok {
-		return nil, fmt.Errorf("unexpected scan error")
+	// version
+	if !scan.Scan() {
+		return nil, fmt.Errorf("unexpected scan error: %v", scan.Err())
 	}
-	l := b.Text()
-	var err error
-	ans.Version, err = strconv.Atoi(l)
+	version, err := strconv.Atoi(scan.Text())
 	if err != nil {
 		return nil, err
 	}
-	if ans.Version != CurrentVersion {
-		return nil, fmt.Errorf("got version %d, expected %d", ans.Version, CurrentVersion)
+	if version != CurrentVersion {
+		return nil, fmt.Errorf("got version %d, expected %d", version, CurrentVersion)
 	}
-	if ok := b.Scan(); !ok {
-		return nil, fmt.Errorf("scanner error reading cachedir")
+
+	// gomodcache
+	if !scan.Scan() {
+		return nil, fmt.Errorf("scanner error reading module cache dir: %v", scan.Err())
 	}
-	ans.Cachedir = Abspath(b.Text())
-	if ok := b.Scan(); !ok {
-		return nil, fmt.Errorf("scanner error reading index creation time")
-	}
-	// TODO(pjw): need to check that this is the expected cachedir
+	// TODO(pjw): need to check that this is the expected cache dir
 	// so the tag should be passed in to this function
-	ans.Changed, err = time.ParseInLocation(time.DateTime, b.Text(), time.Local)
+	if dir := string(scan.Text()); dir != gomodcache {
+		return nil, fmt.Errorf("index file GOMODCACHE mismatch: got %q, want %q", dir, gomodcache)
+	}
+
+	// changed
+	if !scan.Scan() {
+		return nil, fmt.Errorf("scanner error reading index creation time: %v", scan.Err())
+	}
+	changed, err := time.ParseInLocation(time.DateTime, scan.Text(), time.Local)
 	if err != nil {
 		return nil, err
 	}
-	var curEntry *Entry
-	for b.Scan() {
-		v := b.Text()
+
+	// entries
+	var (
+		curEntry *Entry
+		entries  []Entry
+	)
+	for scan.Scan() {
+		v := scan.Text()
 		if v[0] == ':' {
 			if curEntry != nil {
-				ans.Entries = append(ans.Entries, *curEntry)
+				entries = append(entries, *curEntry)
 			}
 			// as directories may contain commas and quotes, they need to be read as csv.
 			rdr := strings.NewReader(v[1:])
@@ -189,49 +200,56 @@ func readIndexFrom(cd Abspath, bx io.Reader) (*Index, error) {
 			if len(flds) != 4 {
 				return nil, fmt.Errorf("header contains %d fields, not 4: %q", len(v), v)
 			}
-			curEntry = &Entry{PkgName: flds[0], ImportPath: flds[1], Dir: toRelpath(cd, flds[2]), Version: flds[3]}
+			curEntry = &Entry{
+				PkgName:    flds[0],
+				ImportPath: flds[1],
+				Dir:        relative(gomodcache, flds[2]),
+				Version:    flds[3],
+			}
 			continue
 		}
 		curEntry.Names = append(curEntry.Names, v)
 	}
+	if err := scan.Err(); err != nil {
+		return nil, fmt.Errorf("scanner failed while reading modindex entry: %v", err)
+	}
 	if curEntry != nil {
-		ans.Entries = append(ans.Entries, *curEntry)
+		entries = append(entries, *curEntry)
 	}
-	if err := b.Err(); err != nil {
-		return nil, fmt.Errorf("scanner failed %v", err)
-	}
-	return &ans, nil
+
+	return &Index{
+		Version:    version,
+		GOMODCACHE: gomodcache,
+		ValidAt:    changed,
+		Entries:    entries,
+	}, nil
 }
 
-// write the index as a text file
-func writeIndex(cachedir Abspath, ix *Index) error {
-	ipat := fmt.Sprintf("index-%d-*", CurrentVersion)
-	fd, err := os.CreateTemp(IndexDir, ipat)
+// write writes the index file and updates the index directory to refer to it.
+func write(gomodcache string, ix *Index) error {
+	// Write the index into a payload file with a fresh name.
+	f, err := os.CreateTemp(IndexDir, fmt.Sprintf("index-%d-*", CurrentVersion))
 	if err != nil {
-		return err // can this happen?
+		return err // e.g. disk full, or index dir deleted
 	}
-	defer fd.Close()
-	if err := writeIndexToFile(ix, fd); err != nil {
+	if err := writeIndexToFile(ix, bufio.NewWriter(f)); err != nil {
+		_ = f.Close() // ignore error
 		return err
 	}
-	content := fd.Name()
-	content = filepath.Base(content)
-	base := indexNameBase(cachedir)
-	nm := filepath.Join(IndexDir, base)
-	err = os.WriteFile(nm, []byte(content), 0666)
-	if err != nil {
+	if err := f.Close(); err != nil {
 		return err
 	}
-	return nil
+
+	// Write the name of the payload file into a link file.
+	indexDirFile := filepath.Join(IndexDir, linkFileBasename(gomodcache))
+	content := []byte(filepath.Base(f.Name()))
+	return os.WriteFile(indexDirFile, content, 0666)
 }
 
-func writeIndexToFile(x *Index, fd *os.File) error {
-	cnt := 0
-	w := bufio.NewWriter(fd)
+func writeIndexToFile(x *Index, w *bufio.Writer) error {
 	fmt.Fprintf(w, "%d\n", x.Version)
-	fmt.Fprintf(w, "%s\n", x.Cachedir)
-	// round the time down
-	tm := x.Changed.Add(-time.Second / 2)
+	fmt.Fprintf(w, "%s\n", x.GOMODCACHE)
+	tm := x.ValidAt.Truncate(time.Second) // round the time down
 	fmt.Fprintf(w, "%s\n", tm.Format(time.DateTime))
 	for _, e := range x.Entries {
 		if e.ImportPath == "" {
@@ -239,7 +257,6 @@ func writeIndexToFile(x *Index, fd *os.File) error {
 		}
 		// PJW: maybe always write these headers as csv?
 		if strings.ContainsAny(string(e.Dir), ",\"") {
-			log.Printf("DIR: %s", e.Dir)
 			cw := csv.NewWriter(w)
 			cw.Write([]string{":" + e.PkgName, e.ImportPath, string(e.Dir), e.Version})
 			cw.Flush()
@@ -248,19 +265,23 @@ func writeIndexToFile(x *Index, fd *os.File) error {
 		}
 		for _, x := range e.Names {
 			fmt.Fprintf(w, "%s\n", x)
-			cnt++
 		}
 	}
-	if err := w.Flush(); err != nil {
-		return err
-	}
-	return nil
+	return w.Flush()
 }
 
-// return the base name of the file containing the name of the current index
-func indexNameBase(cachedir Abspath) string {
-	// crc64 is a way to convert path names into 16 hex digits.
-	h := crc64.Checksum([]byte(cachedir), crc64.MakeTable(crc64.ECMA))
-	fname := fmt.Sprintf("index-name-%d-%016x", CurrentVersion, h)
-	return fname
+// linkFileBasename returns the base name of the link file in the
+// index directory that holds the name of the payload file for the
+// specified (absolute) Go module cache dir.
+func linkFileBasename(gomodcache string) string {
+	// Note: coupled to logic in ./gomodindex/cmd.go. TODO: factor.
+	h := sha256.Sum256([]byte(gomodcache)) // collision-resistant hash
+	return fmt.Sprintf("index-name-%d-%032x", CurrentVersion, h)
+}
+
+func relative(base, file string) string {
+	if rel, err := filepath.Rel(base, file); err == nil {
+		return rel
+	}
+	return file
 }

vendor/golang.org/x/tools/internal/modindex/modindex.go

@@ -2,17 +2,21 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Package modindex contains code for building and searching an index to
-// the Go module cache. The directory containing the index, returned by
-// IndexDir(), contains a file index-name-<ver> that contains the name
+// Package modindex contains code for building and searching an
+// [Index] of the Go module cache.
+package modindex
+
+// The directory containing the index, returned by
+// [IndexDir], contains a file index-name-<ver> that contains the name
 // of the current index. We believe writing that short file is atomic.
-// ReadIndex reads that file to get the file name of the index.
+// [Read] reads that file to get the file name of the index.
 // WriteIndex writes an index with a unique name and then
 // writes that name into a new version of index-name-<ver>.
 // (<ver> stands for the CurrentVersion of the index format.)
-package modindex
 
 import (
+	"maps"
+	"os"
 	"path/filepath"
 	"slices"
 	"strings"
@@ -21,144 +25,95 @@ import (
 	"golang.org/x/mod/semver"
 )
 
-// Create always creates a new index for the go module cache that is in cachedir.
-func Create(cachedir string) error {
-	_, err := indexModCache(cachedir, true)
-	return err
-}
-
-// Update the index for the go module cache that is in cachedir,
-// If there is no existing index it will build one.
-// If there are changed directories since the last index, it will
-// write a new one and return true. Otherwise it returns false.
-func Update(cachedir string) (bool, error) {
-	return indexModCache(cachedir, false)
-}
-
-// indexModCache writes an index current as of when it is called.
-// If clear is true the index is constructed from all of GOMODCACHE
-// otherwise the index is constructed from the last previous index
-// and the updates to the cache. It returns true if it wrote an index,
-// false otherwise.
-func indexModCache(cachedir string, clear bool) (bool, error) {
-	cachedir, err := filepath.Abs(cachedir)
+// Update updates the index for the specified Go
+// module cache directory, creating it as needed.
+// On success it returns the current index.
+func Update(gomodcache string) (*Index, error) {
+	prev, err := Read(gomodcache)
 	if err != nil {
-		return false, err
-	}
-	cd := Abspath(cachedir)
-	future := time.Now().Add(24 * time.Hour) // safely in the future
-	ok, err := modindexTimed(future, cd, clear)
-	if err != nil {
-		return false, err
-	}
-	return ok, nil
-}
-
-// modindexTimed writes an index current as of onlyBefore.
-// If clear is true the index is constructed from all of GOMODCACHE
-// otherwise the index is constructed from the last previous index
-// and all the updates to the cache before onlyBefore.
-// It returns true if it wrote a new index, false if it wrote nothing.
-func modindexTimed(onlyBefore time.Time, cachedir Abspath, clear bool) (bool, error) {
-	var curIndex *Index
-	if !clear {
-		var err error
-		curIndex, err = ReadIndex(string(cachedir))
-		if clear && err != nil {
-			return false, err
+		if !os.IsNotExist(err) {
+			return nil, err
 		}
-		// TODO(pjw): check that most of those directories still exist
+		prev = nil
 	}
-	cfg := &work{
-		onlyBefore: onlyBefore,
-		oldIndex:   curIndex,
-		cacheDir:   cachedir,
-	}
-	if curIndex != nil {
-		cfg.onlyAfter = curIndex.Changed
-	}
-	if err := cfg.buildIndex(); err != nil {
-		return false, err
-	}
-	if len(cfg.newIndex.Entries) == 0 && curIndex != nil {
-		// no changes from existing curIndex, don't write a new index
-		return false, nil
-	}
-	if err := cfg.writeIndex(); err != nil {
-		return false, err
-	}
-	return true, nil
+	return update(gomodcache, prev)
 }
 
-type work struct {
-	onlyBefore time.Time // do not use directories later than this
-	onlyAfter  time.Time // only interested in directories after this
-	// directories from before onlyAfter come from oldIndex
-	oldIndex *Index
-	newIndex *Index
-	cacheDir Abspath
-}
-
-func (w *work) buildIndex() error {
-	// The effective date of the new index should be at least
-	// slightly earlier than when the directories are scanned
-	// so set it now.
-	w.newIndex = &Index{Changed: time.Now(), Cachedir: w.cacheDir}
-	dirs := findDirs(string(w.cacheDir), w.onlyAfter, w.onlyBefore)
-	if len(dirs) == 0 {
-		return nil
-	}
-	newdirs, err := byImportPath(dirs)
+// update builds, writes, and returns the current index.
+//
+// If old is nil, the new index is built from all of GOMODCACHE;
+// otherwise it is built from the old index plus cache updates
+// since the previous index's time.
+func update(gomodcache string, old *Index) (*Index, error) {
+	gomodcache, err := filepath.Abs(gomodcache)
 	if err != nil {
-		return err
+		return nil, err
 	}
-	// for each import path it might occur only in newdirs,
-	// only in w.oldIndex, or in both.
-	// If it occurs in both, use the semantically later one
-	if w.oldIndex != nil {
-		for _, e := range w.oldIndex.Entries {
-			found, ok := newdirs[e.ImportPath]
-			if !ok {
-				w.newIndex.Entries = append(w.newIndex.Entries, e)
-				continue // use this one, there is no new one
-			}
-			if semver.Compare(found[0].version, e.Version) > 0 {
-				// use the new one
-			} else {
-				// use the old one, forget the new one
-				w.newIndex.Entries = append(w.newIndex.Entries, e)
-				delete(newdirs, e.ImportPath)
+	new, changed, err := build(gomodcache, old)
+	if err != nil {
+		return nil, err
+	}
+	if old == nil || changed {
+		if err := write(gomodcache, new); err != nil {
+			return nil, err
+		}
+	}
+	return new, nil
+}
+
+// build returns a new index for the specified Go module cache (an
+// absolute path).
+//
+// If an old index is provided, only directories more recent than it
+// that it are scanned; older directories are provided by the old
+// Index.
+//
+// The boolean result indicates whether new entries were found.
+func build(gomodcache string, old *Index) (*Index, bool, error) {
+	// Set the time window.
+	var start time.Time // = dawn of time
+	if old != nil {
+		start = old.ValidAt
+	}
+	now := time.Now()
+	end := now.Add(24 * time.Hour) // safely in the future
+
+	// Enumerate GOMODCACHE package directories.
+	// Choose the best (latest) package for each import path.
+	pkgDirs := findDirs(gomodcache, start, end)
+	dirByPath, err := bestDirByImportPath(pkgDirs)
+	if err != nil {
+		return nil, false, err
+	}
+
+	// For each import path it might occur only in
+	// dirByPath, only in old, or in both.
+	// If both, use the semantically later one.
+	var entries []Entry
+	if old != nil {
+		for _, entry := range old.Entries {
+			dir, ok := dirByPath[entry.ImportPath]
+			if !ok || semver.Compare(dir.version, entry.Version) <= 0 {
+				// New dir is missing or not more recent; use old entry.
+				entries = append(entries, entry)
+				delete(dirByPath, entry.ImportPath)
 			}
 		}
 	}
-	// get symbol information for all the new diredtories
-	getSymbols(w.cacheDir, newdirs)
-	// assemble the new index entries
-	for k, v := range newdirs {
-		d := v[0]
-		pkg, names := processSyms(d.syms)
-		if pkg == "" {
-			continue // PJW: does this ever happen?
-		}
-		entry := Entry{
-			PkgName:    pkg,
-			Dir:        d.path,
-			ImportPath: k,
-			Version:    d.version,
-			Names:      names,
-		}
-		w.newIndex.Entries = append(w.newIndex.Entries, entry)
-	}
-	// sort the entries in the new index
-	slices.SortFunc(w.newIndex.Entries, func(l, r Entry) int {
-		if n := strings.Compare(l.PkgName, r.PkgName); n != 0 {
+
+	// Extract symbol information for all the new directories.
+	newEntries := extractSymbols(gomodcache, maps.Values(dirByPath))
+	entries = append(entries, newEntries...)
+	slices.SortFunc(entries, func(x, y Entry) int {
+		if n := strings.Compare(x.PkgName, y.PkgName); n != 0 {
 			return n
 		}
-		return strings.Compare(l.ImportPath, r.ImportPath)
+		return strings.Compare(x.ImportPath, y.ImportPath)
 	})
-	return nil
-}
 
-func (w *work) writeIndex() error {
-	return writeIndex(w.cacheDir, w.newIndex)
+	return &Index{
+		GOMODCACHE: gomodcache,
+		ValidAt:    now, // time before the directories were scanned
+		Entries:    entries,
+	}, len(newEntries) > 0, nil
 }

vendor/golang.org/x/tools/internal/modindex/symbols.go

@@ -10,11 +10,13 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
+	"iter"
 	"os"
 	"path/filepath"
 	"runtime"
 	"slices"
 	"strings"
+	"sync"
 
 	"golang.org/x/sync/errgroup"
 )
@@ -34,41 +36,65 @@ type symbol struct {
 	sig  string // signature information, for F
 }
 
-// find the symbols for the best directories
-func getSymbols(cd Abspath, dirs map[string][]*directory) {
+// extractSymbols returns a (new, unordered) array of Entries, one for
+// each provided package directory, describing its exported symbols.
+func extractSymbols(cwd string, dirs iter.Seq[directory]) []Entry {
+	var (
+		mu      sync.Mutex
+		entries []Entry
+	)
+
 	var g errgroup.Group
 	g.SetLimit(max(2, runtime.GOMAXPROCS(0)/2))
-	for _, vv := range dirs {
-		// throttling some day?
-		d := vv[0]
+	for dir := range dirs {
 		g.Go(func() error {
-			thedir := filepath.Join(string(cd), string(d.path))
+			thedir := filepath.Join(cwd, string(dir.path))
 			mode := parser.SkipObjectResolution | parser.ParseComments
 
-			fi, err := os.ReadDir(thedir)
+			// Parse all Go files in dir and extract symbols.
+			dirents, err := os.ReadDir(thedir)
 			if err != nil {
 				return nil // log this someday?
 			}
-			for _, fx := range fi {
-				if !strings.HasSuffix(fx.Name(), ".go") || strings.HasSuffix(fx.Name(), "_test.go") {
+			var syms []symbol
+			for _, dirent := range dirents {
+				if !strings.HasSuffix(dirent.Name(), ".go") ||
+					strings.HasSuffix(dirent.Name(), "_test.go") {
 					continue
 				}
-				fname := filepath.Join(thedir, fx.Name())
+				fname := filepath.Join(thedir, dirent.Name())
 				tr, err := parser.ParseFile(token.NewFileSet(), fname, nil, mode)
 				if err != nil {
 					continue // ignore errors, someday log them?
 				}
-				d.syms = append(d.syms, getFileExports(tr)...)
+				syms = append(syms, getFileExports(tr)...)
 			}
+
+			// Create an entry for the package.
+			pkg, names := processSyms(syms)
+			if pkg != "" {
+				mu.Lock()
+				defer mu.Unlock()
+				entries = append(entries, Entry{
+					PkgName:    pkg,
+					Dir:        dir.path,
+					ImportPath: dir.importPath,
+					Version:    dir.version,
+					Names:      names,
+				})
+			}
+
 			return nil
 		})
 	}
-	g.Wait()
+	g.Wait() // ignore error
+
+	return entries
 }
 
 func getFileExports(f *ast.File) []symbol {
 	pkg := f.Name.Name
-	if pkg == "main" {
+	if pkg == "main" || pkg == "" {
 		return nil
 	}
 	var ans []symbol
@@ -202,17 +228,18 @@ func processSyms(syms []symbol) (string, []string) {
 	pkg := syms[0].pkg
 	var names []string
 	for _, s := range syms {
-		var nx string
-		if s.pkg == pkg {
-			if s.sig != "" {
-				nx = fmt.Sprintf("%s %s %s", s.name, s.kind, s.sig)
-			} else {
-				nx = fmt.Sprintf("%s %s", s.name, s.kind)
-			}
-			names = append(names, nx)
-		} else {
-			continue // PJW: do we want to keep track of these?
+		if s.pkg != pkg {
+			// Symbols came from two files in same dir
+			// with different package declarations.
+			continue
 		}
+		var nx string
+		if s.sig != "" {
+			nx = fmt.Sprintf("%s %s %s", s.name, s.kind, s.sig)
+		} else {
+			nx = fmt.Sprintf("%s %s", s.name, s.kind)
+		}
+		names = append(names, nx)
 	}
 	return pkg, names
 }

vendor/golang.org/x/tools/internal/modindex/types.go

@@ -1,25 +0,0 @@
-// Copyright 2024 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 modindex
-
-import (
-	"strings"
-)
-
-// some special types to avoid confusions
-
-// distinguish various types of directory names. It's easy to get confused.
-type Abspath string // absolute paths
-type Relpath string // paths with GOMODCACHE prefix removed
-
-func toRelpath(cachedir Abspath, s string) Relpath {
-	if strings.HasPrefix(s, string(cachedir)) {
-		if s == string(cachedir) {
-			return Relpath("")
-		}
-		return Relpath(s[len(cachedir)+1:])
-	}
-	return Relpath(s)
-}