go/types: unsafe.Pointer is not an alias

Change-Id: Ieb0808caa24c9a5e599084183ba5ee8a6536f7d8
Reviewed-on: https://go-review.googlesource.com/36622
Reviewed-by: Robert Griesemer <gri@golang.org>

src/go/types/object.go

@@ -164,6 +164,10 @@ func (obj *TypeName) IsAlias() bool {
 	case nil:
 		return false
 	case *Basic:
+		// unsafe.Pointer is not an alias.
+		if obj.pkg == Unsafe {
+			return false
+		}
 		// Any user-defined type name for a basic type is an alias for a
 		// basic type (because basic types are pre-declared in the Universe
 		// scope, outside any package scope), and so is any type name with

src/go/types/object_test.go

@@ -14,6 +14,7 @@ func TestIsAlias(t *testing.T) {
 	}
 
 	// predeclared types
+	check(Unsafe.Scope().Lookup("Pointer").(*TypeName), false)
 	for _, name := range Universe.Names() {
 		if obj, _ := Universe.Lookup(name).(*TypeName); obj != nil {
 			check(obj, name == "byte" || name == "rune")