@@ -522,21 +522,9 @@ func rewriteDockerfileFrom(dockerfileName string, translator func(reference.Name

 			if err != nil {

 				return nil, nil, err

 			}

-

-			digested := false

-			switch ref.(type) {

-			case reference.NamedTagged:

-			case reference.Canonical:

-				digested = true

-			default:

-				ref, err = reference.WithTag(ref, reference.DefaultTag)

-				if err != nil {

-					return nil, nil, err

-				}

-			}

-

-			if !digested && isTrusted() {

-				trustedRef, err := translator(ref.(reference.NamedTagged))

+			ref = reference.WithDefaultTag(ref)

+			if ref, ok := ref.(reference.NamedTagged); ok && isTrusted() {

+				trustedRef, err := translator(ref)

 				if err != nil {

 					return nil, nil, err

 				}

@@ -544,7 +532,7 @@ func rewriteDockerfileFrom(dockerfileName string, translator func(reference.Name

 				line = dockerfileFromLinePattern.ReplaceAllLiteralString(line, fmt.Sprintf("FROM %s", trustedRef.String()))

 				resolvedTags = append(resolvedTags, &resolvedTag{

 					digestRef: trustedRef,

-					tagRef:    ref.(reference.NamedTagged),

+					tagRef:    ref,

 				})

 			}

 		}

@@ -25,14 +25,11 @@ func (cli *DockerCli) pullImageCustomOut(image string, out io.Writer) error {

 	}

 	var tag string

-	switch x := ref.(type) {

+	switch x := reference.WithDefaultTag(ref).(type) {

 	case reference.Canonical:

 		tag = x.Digest().String()

 	case reference.NamedTagged:

 		tag = x.Tag()

-	default:

-		// pull only the image tagged 'latest' if no tag was specified

-		tag = reference.DefaultTag

 	}

 	// Resolve the Repository name from fqn to RepositoryInfo

@@ -97,24 +94,13 @@ func (cli *DockerCli) createContainer(config *runconfig.Config, hostConfig *runc

 	if err != nil {

 		return nil, err

 	}

-

-	isCanonical := false

-	switch ref.(type) {

-	case reference.NamedTagged:

-	case reference.Canonical:

-		isCanonical = true

-	default:

-		ref, err = reference.WithTag(ref, reference.DefaultTag)

-		if err != nil {

-			return nil, err

-		}

-	}

+	ref = reference.WithDefaultTag(ref)

 	var trustedRef reference.Canonical

-	if isTrusted() && !isCanonical {

+	if ref, ok := ref.(reference.NamedTagged); ok && isTrusted() {

 		var err error

-		trustedRef, err = cli.trustedReference(ref.(reference.NamedTagged))

+		trustedRef, err = cli.trustedReference(ref)

 		if err != nil {

 			return nil, err

 		}

@@ -132,8 +118,8 @@ func (cli *DockerCli) createContainer(config *runconfig.Config, hostConfig *runc

 			if err = cli.pullImageCustomOut(config.Image, cli.err); err != nil {

 				return nil, err

 			}

-			if trustedRef != nil && !isCanonical {

-				if err := cli.tagTrusted(trustedRef, ref.(reference.NamedTagged)); err != nil {

+			if ref, ok := ref.(reference.NamedTagged); ok && trustedRef != nil {

+				if err := cli.tagTrusted(trustedRef, ref); err != nil {

 					return nil, err

 				}

 			}

@@ -59,7 +59,6 @@ func (cli *DockerCli) CmdImport(args ...string) error {

 		}

 		defer file.Close()

 		in = file

-

 	}

 	options := types.ImageImportOptions{

@@ -13,8 +13,6 @@ import (

 	"github.com/docker/docker/registry"

 )

-var errTagCantBeUsed = errors.New("tag can't be used with --all-tags/-a")

-

 // CmdPull pulls an image or a repository from the registry.

 //

 // Usage: docker pull [OPTIONS] IMAGENAME[:TAG|@DIGEST]

@@ -31,28 +29,21 @@ func (cli *DockerCli) CmdPull(args ...string) error {

 	if err != nil {

 		return err

 	}

+	if *allTags && !reference.IsNameOnly(distributionRef) {

+		return errors.New("tag can't be used with --all-tags/-a")

+	}

+

+	if !*allTags && reference.IsNameOnly(distributionRef) {

+		distributionRef = reference.WithDefaultTag(distributionRef)

+		fmt.Fprintf(cli.out, "Using default tag: %s\n", reference.DefaultTag)

+	}

 	var tag string

 	switch x := distributionRef.(type) {

 	case reference.Canonical:

-		if *allTags {

-			return errTagCantBeUsed

-		}

 		tag = x.Digest().String()

 	case reference.NamedTagged:

-		if *allTags {

-			return errTagCantBeUsed

-		}

 		tag = x.Tag()

-	default:

-		if !*allTags {

-			tag = reference.DefaultTag

-			distributionRef, err = reference.WithTag(distributionRef, tag)

-			if err != nil {

-				return err

-			}

-			fmt.Fprintf(cli.out, "Using default tag: %s\n", tag)

-		}

 	}

 	ref := registry.ParseReference(tag)

@@ -28,9 +28,8 @@ func (cli *DockerCli) CmdTag(args ...string) error {

 		return errors.New("refusing to create a tag with a digest reference")

 	}

-	tag := ""

-	tagged, isTagged := ref.(reference.NamedTagged)

-	if isTagged {

+	var tag string

+	if tagged, isTagged := ref.(reference.NamedTagged); isTagged {

 		tag = tagged.Tag()

 	}

@@ -334,9 +334,11 @@ func (cli *DockerCli) trustedPull(repoInfo *registry.RepositoryInfo, ref registr

 				return err

 			}

 			trustedRef, err := reference.WithDigest(repoInfo, r.digest)

+			if err != nil {

+				return err

+			}

 			if err := cli.tagTrusted(trustedRef, tagged); err != nil {

 				return err

-

 			}

 		}

 	}

@@ -154,8 +154,7 @@ func (s *router) postImagesCreate(ctx context.Context, w http.ResponseWriter, r

 				return err

 			}

-			switch newRef.(type) {

-			case reference.Canonical:

+			if _, isCanonical := newRef.(reference.Canonical); isCanonical {

 				return errors.New("cannot import digest reference")

 			}

@@ -496,15 +495,12 @@ func sanitizeRepoAndTags(names []string) ([]reference.Named, error) {

 		if err != nil {

 			return nil, err

 		}

+		ref = reference.WithDefaultTag(ref)

 		if _, isCanonical := ref.(reference.Canonical); isCanonical {

 			return nil, errors.New("build tag cannot contain a digest")

 		}

-		if _, isTagged := ref.(reference.NamedTagged); !isTagged {

-			ref, err = reference.WithTag(ref, reference.DefaultTag)

-		}

-

 		nameWithTag := ref.String()

 		if _, exists := uniqNames[nameWithTag]; !exists {

@@ -41,15 +41,7 @@ func (d Docker) Pull(name string) (*image.Image, error) {

 	if err != nil {

 		return nil, err

 	}

-	switch ref.(type) {

-	case reference.NamedTagged:

-	case reference.Canonical:

-	default:

-		ref, err = reference.WithTag(ref, "latest")

-		if err != nil {

-			return nil, err

-		}

-	}

+	ref = reference.WithDefaultTag(ref)

 	pullRegistryAuth := &types.AuthConfig{}

 	if len(d.AuthConfigs) > 0 {

@@ -149,17 +149,7 @@ func (daemon *Daemon) getContainerUsingImage(imageID image.ID) *container.Contai

 // optional tag or digest reference. If tag or digest is omitted, the default

 // tag is used. Returns the resolved image reference and an error.

 func (daemon *Daemon) removeImageRef(ref reference.Named) (reference.Named, error) {

-	switch ref.(type) {

-	case reference.NamedTagged:

-	case reference.Canonical:

-	default:

-		var err error

-		ref, err = reference.WithTag(ref, reference.DefaultTag)

-		if err != nil {

-			return nil, err

-		}

-	}

-

+	ref = reference.WithDefaultTag(ref)

 	// Ignore the boolean value returned, as far as we're concerned, this

 	// is an idempotent operation and it's okay if the reference didn't

 	// exist in the first place.

@@ -54,10 +54,7 @@ func (p *v2Puller) Pull(ctx context.Context, ref reference.Named) (fallback bool

 func (p *v2Puller) pullV2Repository(ctx context.Context, ref reference.Named) (err error) {

 	var refs []reference.Named

-	taggedName := ref

-	if _, isTagged := ref.(reference.NamedTagged); isTagged {

-		refs = []reference.Named{ref}

-	} else if _, isCanonical := ref.(reference.Canonical); isCanonical {

+	if !reference.IsNameOnly(ref) {

 		refs = []reference.Named{ref}

 	} else {

 		manSvc, err := p.repo.Manifests(ctx)

@@ -92,7 +89,7 @@ func (p *v2Puller) pullV2Repository(ctx context.Context, ref reference.Named) (e

 		layersDownloaded = layersDownloaded || pulledNew

 	}

-	writeStatus(taggedName.String(), p.config.ProgressOutput, layersDownloaded)

+	writeStatus(ref.String(), p.config.ProgressOutput, layersDownloaded)

 	return nil

 }

@@ -81,21 +81,19 @@ func (l *tarexporter) parseNames(names []string) (map[image.ID]*imageDescriptor,

 			addAssoc(imgID, nil)

 			continue

 		}

-		if _, ok := ref.(reference.Canonical); !ok {

-			if _, ok := ref.(reference.NamedTagged); !ok {

-				assocs := l.rs.ReferencesByName(ref)

-				for _, assoc := range assocs {

-					addAssoc(assoc.ImageID, assoc.Ref)

-				}

-				if len(assocs) == 0 {

-					imgID, err := l.is.Search(name)

-					if err != nil {

-						return nil, err

-					}

-					addAssoc(imgID, nil)

+		if reference.IsNameOnly(ref) {

+			assocs := l.rs.ReferencesByName(ref)

+			for _, assoc := range assocs {

+				addAssoc(assoc.ImageID, assoc.Ref)

+			}

+			if len(assocs) == 0 {

+				imgID, err := l.is.Search(name)

+				if err != nil {

+					return nil, err

 				}

-				continue

+				addAssoc(imgID, nil)

 			}

+			continue

 		}

 		var imgID image.ID

 		if imgID, err = l.rs.Get(ref); err != nil {

@@ -132,6 +132,25 @@ func (r *canonicalRef) Digest() digest.Digest {

 	return r.namedRef.Named.(distreference.Canonical).Digest()

 }

+// WithDefaultTag adds a default tag to a reference if it only has a repo name.

+func WithDefaultTag(ref Named) Named {

+	if IsNameOnly(ref) {

+		ref, _ = WithTag(ref, DefaultTag)

+	}

+	return ref

+}

+

+// IsNameOnly returns true if reference only contains a repo name.

+func IsNameOnly(ref Named) bool {

+	if _, ok := ref.(NamedTagged); ok {

+		return false

+	}

+	if _, ok := ref.(Canonical); ok {

+		return false

+	}

+	return true

+}

+

 // splitHostname splits a repository name to hostname and remotename string.

 // If no valid hostname is found, the default hostname is used. Repository name

 // needs to be already validated before.

@@ -64,19 +64,6 @@ func (a lexicalAssociations) Len() int           { return len(a) }

 func (a lexicalAssociations) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

 func (a lexicalAssociations) Less(i, j int) bool { return a[i].Ref.String() < a[j].Ref.String() }

-func defaultTagIfNameOnly(ref Named) Named {

-	switch ref.(type) {

-	case NamedTagged:

-		return ref

-	case Canonical:

-		return ref

-	default:

-		// Should never fail

-		ref, _ = WithTag(ref, DefaultTag)

-		return ref

-	}

-}

-

 // NewReferenceStore creates a new reference store, tied to a file path where

 // the set of references are serialized in JSON format.

 func NewReferenceStore(jsonPath string) (Store, error) {

@@ -107,7 +94,7 @@ func (store *store) AddTag(ref Named, id image.ID, force bool) error {

 	if _, isCanonical := ref.(Canonical); isCanonical {

 		return errors.New("refusing to create a tag with a digest reference")

 	}

-	return store.addReference(defaultTagIfNameOnly(ref), id, force)

+	return store.addReference(WithDefaultTag(ref), id, force)

 }

 // AddDigest adds a digest reference to the store.

@@ -162,7 +149,7 @@ func (store *store) addReference(ref Named, id image.ID, force bool) error {

 // Delete deletes a reference from the store. It returns true if a deletion

 // happened, or false otherwise.

 func (store *store) Delete(ref Named) (bool, error) {

-	ref = defaultTagIfNameOnly(ref)

+	ref = WithDefaultTag(ref)

 	store.mu.Lock()

 	defer store.mu.Unlock()

@@ -194,7 +181,7 @@ func (store *store) Delete(ref Named) (bool, error) {

 // Get retrieves an item from the store by

 func (store *store) Get(ref Named) (image.ID, error) {

-	ref = defaultTagIfNameOnly(ref)

+	ref = WithDefaultTag(ref)

 	store.mu.RLock()

 	defer store.mu.RUnlock()