Initialize module and dependencies

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

@@ -0,0 +1,131 @@
+// 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 (
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"sync"
+	"time"
+
+	"golang.org/x/mod/semver"
+	"golang.org/x/tools/internal/gopathwalk"
+)
+
+type directory struct {
+	path       string // relative to GOMODCACHE
+	importPath string
+	version    string // semantic version
+}
+
+// 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
+		}
+		new := directory{
+			path:       dir,
+			importPath: importPath,
+			version:    version,
+		}
+		if old, ok := dirsByPath[importPath]; !ok || compareDirectory(new, old) < 0 {
+			dirsByPath[importPath] = new
+		}
+	}
+	return dirsByPath, nil
+}
+
+// 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
+// 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)
+	// m[3] is the rest of the package path
+	if len(m) != 4 {
+		return "", "", fmt.Errorf("bad dir %s", dir)
+	}
+	if !semver.IsValid(m[2]) {
+		return "", "", fmt.Errorf("bad semantic version %s", m[2])
+	}
+	// ToSlash is required to convert Windows file paths
+	// into Go package import paths.
+	return filepath.ToSlash(m[1] + m[3]), m[2], nil
+}
+
+// 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
+	)
+
+	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}}
+	gopathwalk.WalkSkip(roots, addDir, skipDir, gopathwalk.Options{
+		ModulesEnabled: true,
+		Concurrency:    1, // TODO(pjw): adjust concurrency
+		// Logf: log.Printf,
+	})
+
+	return res
+}

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

@@ -0,0 +1,292 @@
+// 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 (
+	"bufio"
+	"crypto/sha256"
+	"encoding/csv"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+)
+
+/*
+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.)
+Following the header are sections of lines, one section for each
+import path. These sections are sorted by package name.
+The first line of each section, marked by a leading :, contains
+the package name, the import path, the name of the directory relative
+to GOMODCACHE, and its semantic version.
+The rest of each section consists of one line per exported symbol.
+The lines are sorted by the symbol's name and contain the name,
+an indication of its lexical type (C, T, V, F), and if it is the
+name of a function, information about the signature.
+
+The fields in the section header lines are separated by commas, and
+in the unlikely event this would be confusing, the csv package is used
+to write (and read) them.
+
+In the lines containing exported names, C=const, V=var, T=type, F=func.
+If it is a func, the next field is the number of returned values,
+followed by pairs consisting of formal parameter names and types.
+All these fields are separated by spaces. Any spaces in a type
+(e.g., chan struct{}) are replaced by $s on the disk. The $s are
+turned back into spaces when read.
+
+Here is an index header (the comments are not part of the index):
+0                                      // version (of the index format)
+/usr/local/google/home/pjw/go/pkg/mod  // GOMODCACHE
+2024-09-11 18:55:09                    // validity date of the index
+
+Here is an index section:
+:yaml,gopkg.in/yaml.v1,gopkg.in/yaml.v1@v1.0.0-20140924161607-9f9df34309c0,v1.0.0-20140924161607-9f9df34309c0
+Getter T
+Marshal F 2 in interface{}
+Setter T
+Unmarshal F 1 in []byte out interface{}
+
+The package name is yaml, the import path is gopkg.in/yaml.v1.
+Getter and Setter are types, and Marshal and Unmarshal are functions.
+The latter returns one value and has two arguments, 'in' and 'out'
+whose types are []byte and interface{}.
+*/
+
+// CurrentVersion tells readers about the format of the index.
+const CurrentVersion int = 0
+
+// Index is returned by [Read].
+type Index struct {
+	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        string // package directory relative to GOMODCACHE; uses OS path separator
+	ImportPath string
+	PkgName    string
+	Version    string
+	Names      []string // exported names and information
+}
+
+// IndexDir is where the module index is stored.
+// 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
+	if testing.Testing() {
+		dir = os.TempDir()
+	} else {
+		var err error
+		dir, err = os.UserCacheDir()
+		// shouldn't happen, but TempDir is better than
+		// creating ./goimports
+		if err != nil {
+			dir = os.TempDir()
+		}
+	}
+	dir = filepath.Join(dir, "goimports")
+	if err := os.MkdirAll(dir, 0777); err != nil {
+		dir = "" // #75505, people complain about the error message
+	}
+	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
+	}
+	if IndexDir == "" {
+		return nil, os.ErrNotExist
+	}
+
+	// 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))
+}
+
+func readIndexFrom(gomodcache string, r io.Reader) (*Index, error) {
+	scan := bufio.NewScanner(r)
+
+	// version
+	if !scan.Scan() {
+		return nil, fmt.Errorf("unexpected scan error: %v", scan.Err())
+	}
+	version, err := strconv.Atoi(scan.Text())
+	if err != nil {
+		return nil, err
+	}
+	if version != CurrentVersion {
+		return nil, fmt.Errorf("got version %d, expected %d", version, CurrentVersion)
+	}
+
+	// gomodcache
+	if !scan.Scan() {
+		return nil, fmt.Errorf("scanner error reading module cache dir: %v", scan.Err())
+	}
+	// TODO(pjw): need to check that this is the expected cache dir
+	// so the tag should be passed in to this function
+	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
+	}
+
+	// entries
+	var (
+		curEntry *Entry
+		entries  []Entry
+	)
+	for scan.Scan() {
+		v := scan.Text()
+		if v[0] == ':' {
+			if curEntry != nil {
+				entries = append(entries, *curEntry)
+			}
+			// as directories may contain commas and quotes, they need to be read as csv.
+			rdr := strings.NewReader(v[1:])
+			cs := csv.NewReader(rdr)
+			flds, err := cs.Read()
+			if err != nil {
+				return nil, err
+			}
+			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:        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 {
+		entries = append(entries, *curEntry)
+	}
+
+	return &Index{
+		Version:    version,
+		GOMODCACHE: gomodcache,
+		ValidAt:    changed,
+		Entries:    entries,
+	}, nil
+}
+
+// write writes the index file and updates the index directory to refer to it.
+func write(gomodcache string, ix *Index) error {
+	if IndexDir == "" {
+		return os.ErrNotExist
+	}
+	// 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 // e.g. disk full, or index dir deleted
+	}
+	if err := writeIndexToFile(ix, bufio.NewWriter(f)); err != nil {
+		_ = f.Close() // ignore error
+		return err
+	}
+	if err := f.Close(); err != nil {
+		return err
+	}
+
+	// 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, w *bufio.Writer) error {
+	fmt.Fprintf(w, "%d\n", x.Version)
+	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 == "" {
+			continue // shouldn't happen
+		}
+		// PJW: maybe always write these headers as csv?
+		if strings.ContainsAny(string(e.Dir), ",\"") {
+			cw := csv.NewWriter(w)
+			cw.Write([]string{":" + e.PkgName, e.ImportPath, string(e.Dir), e.Version})
+			cw.Flush()
+		} else {
+			fmt.Fprintf(w, ":%s,%s,%s,%s\n", e.PkgName, e.ImportPath, e.Dir, e.Version)
+		}
+		for _, x := range e.Names {
+			fmt.Fprintf(w, "%s\n", x)
+		}
+	}
+	return w.Flush()
+}
+
+// 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/lookup.go

@@ -0,0 +1,184 @@
+// 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 (
+	"slices"
+	"strconv"
+	"strings"
+
+	"golang.org/x/mod/module"
+)
+
+type Candidate struct {
+	PkgName    string
+	Name       string
+	Dir        string
+	ImportPath string
+	Type       LexType
+	Deprecated bool
+	// information for Funcs
+	Results int16   // how many results
+	Sig     []Field // arg names and types
+}
+
+type Field struct {
+	Arg, Type string
+}
+
+type LexType int8
+
+const (
+	Const LexType = iota
+	Var
+	Type
+	Func
+)
+
+// LookupAll only returns those Candidates whose import path
+// finds all the names.
+func (ix *Index) LookupAll(pkgName string, names ...string) map[string][]Candidate {
+	// this can be made faster when benchmarks show that it needs to be
+	names = uniquify(names)
+	byImpPath := make(map[string][]Candidate)
+	for _, nm := range names {
+		cands := ix.Lookup(pkgName, nm, false)
+		for _, c := range cands {
+			byImpPath[c.ImportPath] = append(byImpPath[c.ImportPath], c)
+		}
+	}
+	for k, v := range byImpPath {
+		if len(v) != len(names) {
+			delete(byImpPath, k)
+		}
+	}
+	return byImpPath
+}
+
+// remove duplicates
+func uniquify(in []string) []string {
+	if len(in) == 0 {
+		return in
+	}
+	in = slices.Clone(in)
+	slices.Sort(in)
+	return slices.Compact(in)
+}
+
+// Lookup finds all the symbols in the index with the given PkgName and name.
+// If prefix is true, it finds all of these with name as a prefix.
+func (ix *Index) Lookup(pkgName, name string, prefix bool) []Candidate {
+	loc, ok := slices.BinarySearchFunc(ix.Entries, pkgName, func(e Entry, pkg string) int {
+		return strings.Compare(e.PkgName, pkgName)
+	})
+	if !ok {
+		return nil // didn't find the package
+	}
+	var ans []Candidate
+	// loc is the first entry for this package name, but there may be several
+	for i := loc; i < len(ix.Entries); i++ {
+		e := ix.Entries[i]
+		if e.PkgName != pkgName {
+			break // end of sorted package names
+		}
+		nloc, ok := slices.BinarySearchFunc(e.Names, name, func(s string, name string) int {
+			if strings.HasPrefix(s, name) {
+				return 0
+			}
+			if s < name {
+				return -1
+			}
+			return 1
+		})
+		if !ok {
+			continue // didn't find the name, nor any symbols with name as a prefix
+		}
+		for j := nloc; j < len(e.Names); j++ {
+			nstr := e.Names[j]
+			// benchmarks show this makes a difference when there are a lot of Possibilities
+			flds := fastSplit(nstr)
+			if !(flds[0] == name || prefix && strings.HasPrefix(flds[0], name)) {
+				// past range of matching Names
+				break
+			}
+			if len(flds) < 2 {
+				continue // should never happen
+			}
+			impPath, err := module.UnescapePath(e.ImportPath)
+			if err != nil {
+				continue
+			}
+			px := Candidate{
+				PkgName:    pkgName,
+				Name:       flds[0],
+				Dir:        string(e.Dir),
+				ImportPath: impPath,
+				Type:       asLexType(flds[1][0]),
+				Deprecated: len(flds[1]) > 1 && flds[1][1] == 'D',
+			}
+			if px.Type == Func {
+				n, err := strconv.Atoi(flds[2])
+				if err != nil {
+					continue // should never happen
+				}
+				px.Results = int16(n)
+				if len(flds) >= 4 {
+					sig := strings.Split(flds[3], " ")
+					for i := range sig {
+						// $ cannot otherwise occur. removing the spaces
+						// almost works, but for chan struct{}, e.g.
+						sig[i] = strings.Replace(sig[i], "$", " ", -1)
+					}
+					px.Sig = toFields(sig)
+				}
+			}
+			ans = append(ans, px)
+		}
+	}
+	return ans
+}
+
+func toFields(sig []string) []Field {
+	ans := make([]Field, len(sig)/2)
+	for i := range ans {
+		ans[i] = Field{Arg: sig[2*i], Type: sig[2*i+1]}
+	}
+	return ans
+}
+
+// benchmarks show this is measurably better than strings.Split
+// split into first 4 fields separated by single space
+func fastSplit(x string) []string {
+	ans := make([]string, 0, 4)
+	nxt := 0
+	start := 0
+	for i := 0; i < len(x); i++ {
+		if x[i] != ' ' {
+			continue
+		}
+		ans = append(ans, x[start:i])
+		nxt++
+		start = i + 1
+		if nxt >= 3 {
+			break
+		}
+	}
+	ans = append(ans, x[start:])
+	return ans
+}
+
+func asLexType(c byte) LexType {
+	switch c {
+	case 'C':
+		return Const
+	case 'V':
+		return Var
+	case 'T':
+		return Type
+	case 'F':
+		return Func
+	}
+	return -1
+}

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

@@ -0,0 +1,119 @@
+// 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 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.
+// [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.)
+
+import (
+	"maps"
+	"os"
+	"path/filepath"
+	"slices"
+	"strings"
+	"time"
+
+	"golang.org/x/mod/semver"
+)
+
+// 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 {
+		if !os.IsNotExist(err) {
+			return nil, err
+		}
+		prev = nil
+	}
+	return update(gomodcache, prev)
+}
+
+// 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 nil, err
+	}
+	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)
+			}
+		}
+	}
+
+	// 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(x.ImportPath, y.ImportPath)
+	})
+
+	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

@@ -0,0 +1,244 @@
+// 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 (
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"go/types"
+	"iter"
+	"os"
+	"path/filepath"
+	"runtime"
+	"slices"
+	"strings"
+	"sync"
+
+	"golang.org/x/sync/errgroup"
+)
+
+// The name of a symbol contains information about the symbol:
+// <name> T for types, TD if the type is deprecated
+// <name> C for consts, CD if the const is deprecated
+// <name> V for vars, VD if the var is deprecated
+// and for funcs: <name> F <num of return values> (<arg-name> <arg-type>)*
+// any spaces in <arg-type> are replaced by $s so that the fields
+// of the name are space separated. F is replaced by FD if the func
+// is deprecated.
+type symbol struct {
+	pkg  string // name of the symbols's package
+	name string // declared name
+	kind string // T, C, V, or F, followed by D if deprecated
+	sig  string // signature information, for F
+}
+
+// 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 dir := range dirs {
+		g.Go(func() error {
+			thedir := filepath.Join(cwd, string(dir.path))
+			mode := parser.SkipObjectResolution | parser.ParseComments
+
+			// Parse all Go files in dir and extract symbols.
+			dirents, err := os.ReadDir(thedir)
+			if err != nil {
+				return nil // log this someday?
+			}
+			var syms []symbol
+			for _, dirent := range dirents {
+				if !strings.HasSuffix(dirent.Name(), ".go") ||
+					strings.HasSuffix(dirent.Name(), "_test.go") {
+					continue
+				}
+				fname := filepath.Join(thedir, dirent.Name())
+				tr, err := parser.ParseFile(token.NewFileSet(), fname, nil, mode)
+				if err != nil {
+					continue // ignore errors, someday log them?
+				}
+				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() // ignore error
+
+	return entries
+}
+
+func getFileExports(f *ast.File) []symbol {
+	pkg := f.Name.Name
+	if pkg == "main" || pkg == "" {
+		return nil
+	}
+	var ans []symbol
+	// should we look for //go:build ignore?
+	for _, decl := range f.Decls {
+		switch decl := decl.(type) {
+		case *ast.FuncDecl:
+			if decl.Recv != nil {
+				// ignore methods, as we are completing package selections
+				continue
+			}
+			name := decl.Name.Name
+			dtype := decl.Type
+			// not looking at dtype.TypeParams. That is, treating
+			// generic functions just like non-generic ones.
+			sig := dtype.Params
+			kind := "F"
+			if isDeprecated(decl.Doc) {
+				kind += "D"
+			}
+			result := []string{fmt.Sprintf("%d", dtype.Results.NumFields())}
+			for _, x := range sig.List {
+				// This code creates a string representing the type.
+				// TODO(pjw): it may be fragile:
+				// 1. x.Type could be nil, perhaps in ill-formed code
+				// 2. ExprString might someday change incompatibly to
+				//    include struct tags, which can be arbitrary strings
+				if x.Type == nil {
+					// Can this happen without a parse error? (Files with parse
+					// errors are ignored in getSymbols)
+					continue // maybe report this someday
+				}
+				tp := types.ExprString(x.Type)
+				if len(tp) == 0 {
+					// Can this happen?
+					continue // maybe report this someday
+				}
+				// This is only safe if ExprString never returns anything with a $
+				// The only place a $ can occur seems to be in a struct tag, which
+				// can be an arbitrary string literal, and ExprString does not presently
+				// print struct tags. So for this to happen the type of a formal parameter
+				// has to be a explicit struct, e.g. foo(x struct{a int "$"}) and ExprString
+				// would have to show the struct tag. Even testing for this case seems
+				// a waste of effort, but let's remember the possibility
+				if strings.Contains(tp, "$") {
+					continue
+				}
+				tp = strings.Replace(tp, " ", "$", -1)
+				if len(x.Names) == 0 {
+					result = append(result, "_")
+					result = append(result, tp)
+				} else {
+					for _, y := range x.Names {
+						result = append(result, y.Name)
+						result = append(result, tp)
+					}
+				}
+			}
+			sigs := strings.Join(result, " ")
+			if s := newsym(pkg, name, kind, sigs); s != nil {
+				ans = append(ans, *s)
+			}
+		case *ast.GenDecl:
+			depr := isDeprecated(decl.Doc)
+			switch decl.Tok {
+			case token.CONST, token.VAR:
+				tp := "V"
+				if decl.Tok == token.CONST {
+					tp = "C"
+				}
+				if depr {
+					tp += "D"
+				}
+				for _, sp := range decl.Specs {
+					for _, x := range sp.(*ast.ValueSpec).Names {
+						if s := newsym(pkg, x.Name, tp, ""); s != nil {
+							ans = append(ans, *s)
+						}
+					}
+				}
+			case token.TYPE:
+				tp := "T"
+				if depr {
+					tp += "D"
+				}
+				for _, sp := range decl.Specs {
+					if s := newsym(pkg, sp.(*ast.TypeSpec).Name.Name, tp, ""); s != nil {
+						ans = append(ans, *s)
+					}
+				}
+			}
+		}
+	}
+	return ans
+}
+
+func newsym(pkg, name, kind, sig string) *symbol {
+	if len(name) == 0 || !ast.IsExported(name) {
+		return nil
+	}
+	sym := symbol{pkg: pkg, name: name, kind: kind, sig: sig}
+	return &sym
+}
+
+func isDeprecated(doc *ast.CommentGroup) bool {
+	if doc == nil {
+		return false
+	}
+	// go.dev/wiki/Deprecated Paragraph starting 'Deprecated:'
+	// This code fails for /* Deprecated: */, but it's the code from
+	// gopls/internal/analysis/deprecated
+	for line := range strings.SplitSeq(doc.Text(), "\n\n") {
+		if strings.HasPrefix(line, "Deprecated:") {
+			return true
+		}
+	}
+	return false
+}
+
+// return the package name and the value for the symbols.
+// if there are multiple packages, choose one arbitrarily
+// the returned slice is sorted lexicographically
+func processSyms(syms []symbol) (string, []string) {
+	if len(syms) == 0 {
+		return "", nil
+	}
+	slices.SortFunc(syms, func(l, r symbol) int {
+		return strings.Compare(l.name, r.name)
+	})
+	pkg := syms[0].pkg
+	var names []string
+	for _, s := range syms {
+		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
+}