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// Copyright 2021 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 internal
import (
// LatestModuleVersions describes the latest versions of a module. It also holds the
// go.mod file of the raw latest version, which establishes whether the module
// is deprecated, and what versions are retracted.
type LatestModuleVersions struct {
ModulePath string
RawVersion string // ignoring retractions
CookedVersion string // considering retractions
GoodVersion string // successfully processed
GoModFile *modfile.File // of raw
Deprecated bool
deprecationComment string
func NewLatestModuleVersions(modulePath, raw, cooked, good string, modBytes []byte) (*LatestModuleVersions, error) {
modFile, err := modfile.ParseLax(fmt.Sprintf("%s@%s/go.mod", modulePath, raw), modBytes, nil)
if err != nil {
return nil, err
dep, comment := isDeprecated(modFile)
return &LatestModuleVersions{
ModulePath: modulePath,
RawVersion: raw,
CookedVersion: cooked,
GoodVersion: good,
GoModFile: modFile,
Deprecated: dep,
deprecationComment: comment,
}, nil
// isDeprecated reports whether the go.mod deprecates this module.
// It looks for "Deprecated" comments in the line comments before and next to
// the module declaration. If it finds one, it returns true along with the text
// after "Deprecated:". Otherwise it returns false, "".
func isDeprecated(mf *modfile.File) (bool, string) {
const prefix = "Deprecated:"
if mf.Module == nil {
return false, ""
for _, comment := range append(mf.Module.Syntax.Before, mf.Module.Syntax.Suffix...) {
text := strings.TrimSpace(strings.TrimPrefix(comment.Token, "//"))
if strings.HasPrefix(text, prefix) {
return true, strings.TrimSpace(text[len(prefix):])
return false, ""
// PopulateModuleInfo uses the LatestModuleVersions to populate fields of the given module.
func (li *LatestModuleVersions) PopulateModuleInfo(mi *ModuleInfo) {
mi.Deprecated = li.Deprecated
mi.DeprecationComment = li.deprecationComment
mi.Retracted, mi.RetractionRationale = isRetracted(li.GoModFile, mi.Version)
// IsRetracted reports whether the version is retracted according to the go.mod
// file in the receiver.
func (li *LatestModuleVersions) IsRetracted(version string) bool {
r, _ := isRetracted(li.GoModFile, version)
return r
// isRetracted reports whether the go.mod file retracts the version.
// If so, it returns true along with the rationale for the retraction.
func isRetracted(mf *modfile.File, resolvedVersion string) (bool, string) {
for _, r := range mf.Retract {
if semver.Compare(resolvedVersion, r.Low) >= 0 && semver.Compare(resolvedVersion, r.High) <= 0 {
return true, r.Rationale
return false, ""