[dev.typealias] go/types: export TypeName.IsAlias so clients can use it

For #18130.

Change-Id: I634eaaeaa11e92fc31219d70419fdb4a7aa6e0b4
Reviewed-on: https://go-review.googlesource.com/35099
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/go/types/object.go

@@ -163,7 +163,7 @@ func NewTypeName(pos token.Pos, pkg *Package, name string, typ Type) *TypeName {
 	return &TypeName{object{nil, pos, pkg, name, typ, 0, token.NoPos}}
 }
 
-func (obj *TypeName) isAlias() bool {
+func (obj *TypeName) IsAlias() bool {
 	switch t := obj.typ.(type) {
 	case nil:
 		return false
@@ -330,11 +330,11 @@ func writeObject(buf *bytes.Buffer, obj Object, qf Qualifier) {
 	if tname != nil {
 		// We have a type object: Don't print anything more for
 		// basic types since there's no more information (names
-		// are the same; see also comment in TypeName.isAlias).
+		// are the same; see also comment in TypeName.IsAlias).
 		if _, ok := typ.(*Basic); ok {
 			return
 		}
-		if tname.isAlias() {
+		if tname.IsAlias() {
 			buf.WriteString(" =")
 		} else {
 			typ = typ.Underlying()

src/go/types/object_test.go

@@ -8,8 +8,8 @@ import "testing"
 
 func TestIsAlias(t *testing.T) {
 	check := func(obj *TypeName, want bool) {
-		if got := obj.isAlias(); got != want {
-			t.Errorf("%v: got isAlias = %v; want %v", obj, got, want)
+		if got := obj.IsAlias(); got != want {
+			t.Errorf("%v: got IsAlias = %v; want %v", obj, got, want)
 		}
 	}
 

src/go/types/predicates.go

@@ -139,7 +139,7 @@ func identical(x, y Type, cmpTags bool, p *ifacePair) bool {
 	case *Basic:
 		// Basic types are singletons except for the rune and byte
 		// aliases, thus we cannot solely rely on the x == y check
-		// above. See also comment in TypeName.isAlias.
+		// above. See also comment in TypeName.IsAlias.
 		if y, ok := y.(*Basic); ok {
 			return x.kind == y.kind
 		}