Update go dependencies

vendor/k8s.io/gengo/args/args.go

@@ -112,7 +112,7 @@ func (g *GeneratorArgs) LoadGoBoilerplate() ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	b = bytes.Replace(b, []byte("YEAR"), []byte(strconv.Itoa(time.Now().Year())), -1)
+	b = bytes.Replace(b, []byte("YEAR"), []byte(strconv.Itoa(time.Now().UTC().Year())), -1)
 
 	if g.GeneratedByCommentTemplate != "" {
 		if len(b) != 0 {
@@ -159,6 +159,9 @@ func (g *GeneratorArgs) InputIncludes(p *types.Package) bool {
 		if strings.HasSuffix(d, "...") {
 			d = strings.TrimSuffix(d, "...")
 		}
+		if strings.HasPrefix(d, "./vendor/") {
+			d = strings.TrimPrefix(d, "./vendor/")
+		}
 		if strings.HasPrefix(p.Path, d) {
 			return true
 		}

vendor/k8s.io/gengo/examples/defaulter-gen/generators/defaulter.go

@@ -248,7 +248,11 @@ func Packages(context *generator.Context, arguments *args.GeneratorArgs) generat
 		shouldCreateObjectDefaulterFn := func(t *types.Type) bool {
 			if defaults, ok := existingDefaulters[t]; ok && defaults.object != nil {
 				// A default generator is defined
-				klog.V(5).Infof("  an object defaulter already exists as %s", defaults.base.Name)
+				baseTypeName := "<unknown>"
+				if defaults.base != nil {
+					baseTypeName = defaults.base.Name.String()
+				}
+				klog.V(5).Infof("  an object defaulter already exists as %s", baseTypeName)
 				return false
 			}
 			// opt-out

vendor/k8s.io/gengo/examples/import-boss/generators/import_restrict.go

@@ -33,11 +33,13 @@ import (
 	"k8s.io/gengo/generator"
 	"k8s.io/gengo/namer"
 	"k8s.io/gengo/types"
+	"sigs.k8s.io/yaml"
 
 	"k8s.io/klog"
 )
 
 const (
+	goModFile          = "go.mod"
 	importBossFileType = "import-boss"
 )
 
@@ -58,7 +60,7 @@ func DefaultNameSystem() string {
 func Packages(c *generator.Context, arguments *args.GeneratorArgs) generator.Packages {
 	pkgs := generator.Packages{}
 	c.FileTypes = map[string]generator.FileType{
-		importBossFileType: importRuleFile{},
+		importBossFileType: importRuleFile{c},
 	}
 
 	for _, p := range c.Universe {
@@ -70,6 +72,7 @@ func Packages(c *generator.Context, arguments *args.GeneratorArgs) generator.Pac
 		pkgs = append(pkgs, &generator.DefaultPackage{
 			PackageName: p.Name,
 			PackagePath: p.Path,
+			Source:      p.SourcePath,
 			// GeneratorFunc returns a list of generators. Each generator makes a
 			// single file.
 			GeneratorFunc: func(c *generator.Context) (generators []generator.Generator) {
@@ -96,10 +99,19 @@ type Rule struct {
 	ForbiddenPrefixes []string
 }
 
+type InverseRule struct {
+	Rule
+	// True if the rule is to be applied to transitive imports.
+	Transitive bool
+}
+
 type fileFormat struct {
 	CurrentImports []string
 
-	Rules []Rule
+	Rules        []Rule
+	InverseRules []InverseRule
+
+	path string
 }
 
 func readFile(path string) (*fileFormat, error) {
@@ -109,10 +121,11 @@ func readFile(path string) (*fileFormat, error) {
 	}
 
 	var current fileFormat
-	err = json.Unmarshal(currentBytes, &current)
+	err = yaml.Unmarshal(currentBytes, &current)
 	if err != nil {
 		return nil, fmt.Errorf("couldn't unmarshal %v: %v", path, err)
 	}
+	current.path = path
 	return &current, nil
 }
 
@@ -131,10 +144,12 @@ func writeFile(path string, ff *fileFormat) error {
 }
 
 // This does the actual checking, since it knows the literal destination file.
-type importRuleFile struct{}
+type importRuleFile struct {
+	context *generator.Context
+}
 
-func (importRuleFile) AssembleFile(f *generator.File, path string) error {
-	return nil
+func (irf importRuleFile) AssembleFile(f *generator.File, path string) error {
+	return irf.VerifyFile(f, path)
 }
 
 // TODO: make a flag to enable this, or expose this information in some other way.
@@ -169,62 +184,99 @@ func removeLastDir(path string) (newPath, removedDir string) {
 	return filepath.Join(filepath.Dir(dir), file), filepath.Base(dir)
 }
 
-// Keep going up a directory until we find an .import-restrictions file.
-func recursiveRead(path string) (*fileFormat, string, error) {
+// isGoModRoot checks if a directory is the root directory for a package
+// by checking for the existence of a 'go.mod' file in that directory.
+func isGoModRoot(path string) bool {
+	_, err := os.Stat(filepath.Join(filepath.Dir(path), goModFile))
+	return err == nil
+}
+
+// recursiveRead collects all '.import-restriction' files, between the current directory,
+// and the package root when Go modules are enabled, or $GOPATH/src when they are not.
+func recursiveRead(path string) ([]*fileFormat, error) {
+	restrictionFiles := make([]*fileFormat, 0)
+
 	for {
 		if _, err := os.Stat(path); err == nil {
-			ff, err := readFile(path)
-			return ff, path, err
+			rules, err := readFile(path)
+			if err != nil {
+				return nil, err
+			}
+
+			restrictionFiles = append(restrictionFiles, rules)
 		}
 
 		nextPath, removedDir := removeLastDir(path)
-		if nextPath == path || removedDir == "src" {
+		if nextPath == path || isGoModRoot(path) || removedDir == "src" {
 			break
 		}
+
 		path = nextPath
 	}
-	return nil, "", nil
+
+	return restrictionFiles, nil
 }
 
-func (importRuleFile) VerifyFile(f *generator.File, path string) error {
-	rules, actualPath, err := recursiveRead(path)
+func (irf importRuleFile) VerifyFile(f *generator.File, path string) error {
+	restrictionFiles, err := recursiveRead(filepath.Join(f.PackageSourcePath, f.Name))
 	if err != nil {
 		return fmt.Errorf("error finding rules file: %v", err)
 	}
 
-	if rules == nil {
-		// No restrictions on this directory.
-		return nil
+	if err := irf.verifyRules(restrictionFiles, f); err != nil {
+		return err
+	}
+
+	return irf.verifyInverseRules(restrictionFiles, f)
+}
+
+func (irf importRuleFile) verifyRules(restrictionFiles []*fileFormat, f *generator.File) error {
+	selectors := make([][]*regexp.Regexp, len(restrictionFiles))
+	for i, restrictionFile := range restrictionFiles {
+		for _, r := range restrictionFile.Rules {
+			re, err := regexp.Compile(r.SelectorRegexp)
+			if err != nil {
+				return fmt.Errorf("regexp `%s` in file %q doesn't compile: %v", r.SelectorRegexp, restrictionFile.path, err)
+			}
+
+			selectors[i] = append(selectors[i], re)
+		}
 	}
 
 	forbiddenImports := map[string]string{}
 	allowedMismatchedImports := []string{}
-	for _, r := range rules.Rules {
-		re, err := regexp.Compile(r.SelectorRegexp)
-		if err != nil {
-			return fmt.Errorf("regexp `%s` in file %q doesn't compile: %v", r.SelectorRegexp, actualPath, err)
-		}
-		for v := range f.Imports {
-			klog.V(4).Infof("Checking %v matches %v: %v\n", r.SelectorRegexp, v, re.MatchString(v))
-			if !re.MatchString(v) {
-				continue
-			}
-			for _, forbidden := range r.ForbiddenPrefixes {
-				klog.V(4).Infof("Checking %v against %v\n", v, forbidden)
-				if strings.HasPrefix(v, forbidden) {
-					forbiddenImports[v] = forbidden
+
+	for v := range f.Imports {
+		explicitlyAllowed := false
+
+	NextRestrictionFiles:
+		for i, rules := range restrictionFiles {
+			for j, r := range rules.Rules {
+				matching := selectors[i][j].MatchString(v)
+				klog.V(5).Infof("Checking %v matches %v: %v\n", r.SelectorRegexp, v, matching)
+				if !matching {
+					continue
 				}
-			}
-			found := false
-			for _, allowed := range r.AllowedPrefixes {
-				klog.V(4).Infof("Checking %v against %v\n", v, allowed)
-				if strings.HasPrefix(v, allowed) {
-					found = true
-					break
+				for _, forbidden := range r.ForbiddenPrefixes {
+					klog.V(4).Infof("Checking %v against %v\n", v, forbidden)
+					if strings.HasPrefix(v, forbidden) {
+						forbiddenImports[v] = forbidden
+					}
+				}
+				for _, allowed := range r.AllowedPrefixes {
+					klog.V(4).Infof("Checking %v against %v\n", v, allowed)
+					if strings.HasPrefix(v, allowed) {
+						explicitlyAllowed = true
+						break
+					}
+				}
+
+				if !explicitlyAllowed {
+					allowedMismatchedImports = append(allowedMismatchedImports, v)
+				} else {
+					klog.V(2).Infof("%v importing %v allowed by %v\n", f.PackagePath, v, restrictionFiles[i].path)
+					break NextRestrictionFiles
 				}
-			}
-			if !found {
-				allowedMismatchedImports = append(allowedMismatchedImports, v)
 			}
 		}
 	}
@@ -243,8 +295,85 @@ func (importRuleFile) VerifyFile(f *generator.File, path string) error {
 		}
 		return errors.New(errorBuilder.String())
 	}
-	if len(rules.Rules) > 0 {
-		klog.V(2).Infof("%v passes rules found in %v\n", path, actualPath)
+
+	return nil
+}
+
+// verifyInverseRules checks that all packages that import a package are allowed to import it.
+func (irf importRuleFile) verifyInverseRules(restrictionFiles []*fileFormat, f *generator.File) error {
+	// compile all Selector regex in all restriction files
+	selectors := make([][]*regexp.Regexp, len(restrictionFiles))
+	for i, restrictionFile := range restrictionFiles {
+		for _, r := range restrictionFile.InverseRules {
+			re, err := regexp.Compile(r.SelectorRegexp)
+			if err != nil {
+				return fmt.Errorf("regexp `%s` in file %q doesn't compile: %v", r.SelectorRegexp, restrictionFile.path, err)
+			}
+
+			selectors[i] = append(selectors[i], re)
+		}
+	}
+
+	directImport := map[string]bool{}
+	for _, imp := range irf.context.IncomingImports()[f.PackagePath] {
+		directImport[imp] = true
+	}
+
+	forbiddenImports := map[string]string{}
+	allowedMismatchedImports := []string{}
+
+	for _, v := range irf.context.TransitiveIncomingImports()[f.PackagePath] {
+		explicitlyAllowed := false
+
+	NextRestrictionFiles:
+		for i, rules := range restrictionFiles {
+			for j, r := range rules.InverseRules {
+				if !r.Transitive && !directImport[v] {
+					continue
+				}
+
+				re := selectors[i][j]
+				matching := re.MatchString(v)
+				klog.V(4).Infof("Checking %v matches %v (importing %v: %v\n", r.SelectorRegexp, v, f.PackagePath, matching)
+				if !matching {
+					continue
+				}
+				for _, forbidden := range r.ForbiddenPrefixes {
+					klog.V(4).Infof("Checking %v against %v\n", v, forbidden)
+					if strings.HasPrefix(v, forbidden) {
+						forbiddenImports[v] = forbidden
+					}
+				}
+				for _, allowed := range r.AllowedPrefixes {
+					klog.V(4).Infof("Checking %v against %v\n", v, allowed)
+					if strings.HasPrefix(v, allowed) {
+						explicitlyAllowed = true
+						break
+					}
+				}
+				if !explicitlyAllowed {
+					allowedMismatchedImports = append(allowedMismatchedImports, v)
+				} else {
+					klog.V(2).Infof("%v importing %v allowed by %v\n", v, f.PackagePath, restrictionFiles[i].path)
+					break NextRestrictionFiles
+				}
+			}
+		}
+	}
+
+	if len(forbiddenImports) > 0 || len(allowedMismatchedImports) > 0 {
+		var errorBuilder strings.Builder
+		for i, f := range forbiddenImports {
+			fmt.Fprintf(&errorBuilder, "(inverse): import %v has forbidden prefix %v\n", i, f)
+		}
+		if len(allowedMismatchedImports) > 0 {
+			sort.Sort(sort.StringSlice(allowedMismatchedImports))
+			fmt.Fprintf(&errorBuilder, "(inverse): the following imports did not match any allowed prefix:\n")
+			for _, i := range allowedMismatchedImports {
+				fmt.Fprintf(&errorBuilder, "  %v\n", i)
+			}
+		}
+		return errors.New(errorBuilder.String())
 	}
 
 	return nil

vendor/k8s.io/gengo/generator/default_package.go

@@ -26,6 +26,8 @@ type DefaultPackage struct {
 	PackageName string
 	// Import path of the package, and the location on disk of the package.
 	PackagePath string
+	// The location of the package on disk.
+	Source string
 
 	// Emitted at the top of every file.
 	HeaderText []byte
@@ -43,8 +45,9 @@ type DefaultPackage struct {
 	FilterFunc func(*Context, *types.Type) bool
 }
 
-func (d *DefaultPackage) Name() string { return d.PackageName }
-func (d *DefaultPackage) Path() string { return d.PackagePath }
+func (d *DefaultPackage) Name() string       { return d.PackageName }
+func (d *DefaultPackage) Path() string       { return d.PackagePath }
+func (d *DefaultPackage) SourcePath() string { return d.Source }
 
 func (d *DefaultPackage) Filter(c *Context, t *types.Type) bool {
 	if d.FilterFunc != nil {

vendor/k8s.io/gengo/generator/execute.go

@@ -233,11 +233,13 @@ func (c *Context) ExecutePackage(outDir string, p Package) error {
 		if f == nil {
 			// This is the first generator to reference this file, so start it.
 			f = &File{
-				Name:        g.Filename(),
-				FileType:    fileType,
-				PackageName: p.Name(),
-				Header:      p.Header(g.Filename()),
-				Imports:     map[string]struct{}{},
+				Name:              g.Filename(),
+				FileType:          fileType,
+				PackageName:       p.Name(),
+				PackagePath:       p.Path(),
+				PackageSourcePath: p.SourcePath(),
+				Header:            p.Header(g.Filename()),
+				Imports:           map[string]struct{}{},
 			}
 			files[f.Name] = f
 		} else {

vendor/k8s.io/gengo/generator/generator.go

@@ -31,6 +31,8 @@ type Package interface {
 	Name() string
 	// Path returns the package import path.
 	Path() string
+	// SourcePath returns the location of the package on disk.
+	SourcePath() string
 
 	// Filter should return true if this package cares about this type.
 	// Otherwise, this type will be omitted from the type ordering for
@@ -50,14 +52,16 @@ type Package interface {
 }
 
 type File struct {
-	Name        string
-	FileType    string
-	PackageName string
-	Header      []byte
-	Imports     map[string]struct{}
-	Vars        bytes.Buffer
-	Consts      bytes.Buffer
-	Body        bytes.Buffer
+	Name              string
+	FileType          string
+	PackageName       string
+	Header            []byte
+	PackagePath       string
+	PackageSourcePath string
+	Imports           map[string]struct{}
+	Vars              bytes.Buffer
+	Consts            bytes.Buffer
+	Body              bytes.Buffer
 }
 
 type FileType interface {
@@ -156,6 +160,12 @@ type Context struct {
 	// All the types, in case you want to look up something.
 	Universe types.Universe
 
+	// Incoming imports, i.e. packages importing the given package.
+	incomingImports map[string][]string
+
+	// Incoming transitive imports, i.e. the transitive closure of IncomingImports
+	incomingTransitiveImports map[string][]string
+
 	// All the user-specified packages.  This is after recursive expansion.
 	Inputs []string
 
@@ -203,11 +213,36 @@ func NewContext(b *parser.Builder, nameSystems namer.NameSystems, canonicalOrder
 	return c, nil
 }
 
+// IncomingImports returns the incoming imports for each package. The map is lazily computed.
+func (ctxt *Context) IncomingImports() map[string][]string {
+	if ctxt.incomingImports == nil {
+		incoming := map[string][]string{}
+		for _, pkg := range ctxt.Universe {
+			for imp := range pkg.Imports {
+				incoming[imp] = append(incoming[imp], pkg.Path)
+			}
+		}
+		ctxt.incomingImports = incoming
+	}
+	return ctxt.incomingImports
+}
+
+// TransitiveIncomingImports returns the transitive closure of the incoming imports for each package.
+// The map is lazily computed.
+func (ctxt *Context) TransitiveIncomingImports() map[string][]string {
+	if ctxt.incomingTransitiveImports == nil {
+		ctxt.incomingTransitiveImports = transitiveClosure(ctxt.IncomingImports())
+	}
+	return ctxt.incomingTransitiveImports
+}
+
 // AddDir adds a Go package to the context. The specified path must be a single
 // go package import path.  GOPATH, GOROOT, and the location of your go binary
 // (`which go`) will all be searched, in the normal Go fashion.
 // Deprecated. Please use AddDirectory.
 func (ctxt *Context) AddDir(path string) error {
+	ctxt.incomingImports = nil
+	ctxt.incomingTransitiveImports = nil
 	return ctxt.builder.AddDirTo(path, &ctxt.Universe)
 }
 
@@ -215,5 +250,7 @@ func (ctxt *Context) AddDir(path string) error {
 // single go package import path.  GOPATH, GOROOT, and the location of your go
 // binary (`which go`) will all be searched, in the normal Go fashion.
 func (ctxt *Context) AddDirectory(path string) (*types.Package, error) {
+	ctxt.incomingImports = nil
+	ctxt.incomingTransitiveImports = nil
 	return ctxt.builder.AddDirectoryTo(path, &ctxt.Universe)
 }

vendor/k8s.io/gengo/generator/import_tracker.go

@@ -17,6 +17,7 @@ limitations under the License.
 package generator
 
 import (
+	"go/token"
 	"strings"
 
 	"k8s.io/klog"
@@ -58,6 +59,11 @@ func golangTrackerLocalName(tracker namer.ImportTracker, t types.Name) string {
 			// This name collides with some other package
 			continue
 		}
+
+		// If the import name is a Go keyword, prefix with an underscore.
+		if token.Lookup(name).IsKeyword() {
+			name = "_" + name
+		}
 		return name
 	}
 	panic("can't find import for " + path)

vendor/k8s.io/gengo/generator/transitive_closure.go

@@ -0,0 +1,65 @@
+/*
+Copyright 2019 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package generator
+
+import "sort"
+
+type edge struct {
+	from string
+	to   string
+}
+
+func transitiveClosure(in map[string][]string) map[string][]string {
+	adj := make(map[edge]bool)
+	imports := make(map[string]struct{})
+	for from, tos := range in {
+		for _, to := range tos {
+			adj[edge{from, to}] = true
+			imports[to] = struct{}{}
+		}
+	}
+
+	// Warshal's algorithm
+	for k := range in {
+		for i := range in {
+			if !adj[edge{i, k}] {
+				continue
+			}
+			for j := range imports {
+				if adj[edge{i, j}] {
+					continue
+				}
+				if adj[edge{k, j}] {
+					adj[edge{i, j}] = true
+				}
+			}
+		}
+	}
+
+	out := make(map[string][]string, len(in))
+	for i := range in {
+		for j := range imports {
+			if adj[edge{i, j}] {
+				out[i] = append(out[i], j)
+			}
+		}
+
+		sort.Strings(out[i])
+	}
+
+	return out
+}

vendor/k8s.io/gengo/namer/order.go

@@ -43,6 +43,9 @@ func (o *Orderer) OrderUniverse(u types.Universe) []*types.Type {
 		for _, v := range p.Variables {
 			list.types = append(list.types, v)
 		}
+		for _, v := range p.Constants {
+			list.types = append(list.types, v)
+		}
 	}
 	sort.Sort(list)
 	return list.types

vendor/k8s.io/gengo/parser/parse.go

@@ -227,12 +227,16 @@ func (b *Builder) AddDirRecursive(dir string) error {
 		klog.Warningf("Ignoring directory %v: %v", dir, err)
 	}
 
-	// filepath.Walk includes the root dir, but we already did that, so we'll
-	// remove that prefix and rebuild a package import path.
-	prefix := b.buildPackages[dir].Dir
+	// filepath.Walk does not follow symlinks. We therefore evaluate symlinks and use that with
+	// filepath.Walk.
+	realPath, err := filepath.EvalSymlinks(b.buildPackages[dir].Dir)
+	if err != nil {
+		return err
+	}
+
 	fn := func(filePath string, info os.FileInfo, err error) error {
 		if info != nil && info.IsDir() {
-			rel := filepath.ToSlash(strings.TrimPrefix(filePath, prefix))
+			rel := filepath.ToSlash(strings.TrimPrefix(filePath, realPath))
 			if rel != "" {
 				// Make a pkg path.
 				pkg := path.Join(string(canonicalizeImportPath(b.buildPackages[dir].ImportPath)), rel)
@@ -245,7 +249,7 @@ func (b *Builder) AddDirRecursive(dir string) error {
 		}
 		return nil
 	}
-	if err := filepath.Walk(b.buildPackages[dir].Dir, fn); err != nil {
+	if err := filepath.Walk(realPath, fn); err != nil {
 		return err
 	}
 	return nil
@@ -544,6 +548,10 @@ func (b *Builder) findTypesIn(pkgPath importPathString, u *types.Universe) error
 		if ok && !tv.IsField() {
 			b.addVariable(*u, nil, tv)
 		}
+		tconst, ok := obj.(*tc.Const)
+		if ok {
+			b.addConstant(*u, nil, tconst)
+		}
 	}
 
 	importedPkgs := []string{}
@@ -774,7 +782,10 @@ func (b *Builder) walkType(u types.Universe, useName *types.Name, in tc.Type) *t
 				if out.Methods == nil {
 					out.Methods = map[string]*types.Type{}
 				}
-				out.Methods[t.Method(i).Name()] = b.walkType(u, nil, t.Method(i).Type())
+				method := t.Method(i)
+				mt := b.walkType(u, nil, method.Type())
+				mt.CommentLines = splitLines(b.priorCommentLines(method.Pos(), 1).Text())
+				out.Methods[method.Name()] = mt
 			}
 		}
 		return out
@@ -811,6 +822,17 @@ func (b *Builder) addVariable(u types.Universe, useName *types.Name, in *tc.Var)
 	return out
 }
 
+func (b *Builder) addConstant(u types.Universe, useName *types.Name, in *tc.Const) *types.Type {
+	name := tcVarNameToName(in.String())
+	if useName != nil {
+		name = *useName
+	}
+	out := u.Constant(name)
+	out.Kind = types.DeclarationOf
+	out.Underlying = b.walkType(u, nil, in.Type())
+	return out
+}
+
 // canonicalizeImportPath takes an import path and returns the actual package.
 // It doesn't support nested vendoring.
 func canonicalizeImportPath(importPath string) importPathString {

vendor/k8s.io/gengo/types/types.go

@@ -135,6 +135,10 @@ type Package struct {
 	// package name).
 	Variables map[string]*Type
 
+	// Global constants within this package, indexed by their name (*not* including
+	// package name).
+	Constants map[string]*Type
+
 	// Packages imported by this package, indexed by (canonicalized)
 	// package path.
 	Imports map[string]*Package
@@ -193,6 +197,20 @@ func (p *Package) Variable(varName string) *Type {
 	return t
 }
 
+// Constant gets the given constant Type in this Package. If the constant is
+// not already defined, this will add it. If a constant is added, it's the caller's
+// responsibility to finish construction of the constant by setting Underlying
+// to the correct type.
+func (p *Package) Constant(constName string) *Type {
+	if t, ok := p.Constants[constName]; ok {
+		return t
+	}
+	t := &Type{Name: Name{Package: p.Path, Name: constName}}
+	t.Kind = DeclarationOf
+	p.Constants[constName] = t
+	return t
+}
+
 // HasImport returns true if p imports packageName. Package names include the
 // package directory.
 func (p *Package) HasImport(packageName string) bool {
@@ -229,6 +247,14 @@ func (u Universe) Variable(n Name) *Type {
 	return u.Package(n.Package).Variable(n.Name)
 }
 
+// Constant returns the canonical constant for the given fully-qualified name.
+// If a non-existing constant is requested, this will create (a marker for) it.
+// If a marker is created, it's the caller's responsibility to finish
+// construction of the constant by setting Underlying to the correct type.
+func (u Universe) Constant(n Name) *Type {
+	return u.Package(n.Package).Constant(n.Name)
+}
+
 // AddImports registers import lines for packageName. May be called multiple times.
 // You are responsible for canonicalizing all package paths.
 func (u Universe) AddImports(packagePath string, importPaths ...string) {
@@ -251,6 +277,7 @@ func (u Universe) Package(packagePath string) *Package {
 		Types:     map[string]*Type{},
 		Functions: map[string]*Type{},
 		Variables: map[string]*Type{},
+		Constants: map[string]*Type{},
 		Imports:   map[string]*Package{},
 	}
 	u[packagePath] = p