interp: do not export RealFS, used internally only

interp/interp.go

@@ -312,7 +312,7 @@ type Options struct {
 // New returns a new interpreter.
 func New(options Options) *Interpreter {
 	i := Interpreter{
-		opt:      opt{context: build.Default, filesystem: &RealFS{}},
+		opt:      opt{context: build.Default, filesystem: &realFS{}},
 		frame:    newFrame(nil, 0, 0),
 		fset:     token.NewFileSet(),
 		universe: initUniverse(),

interp/realfs.go

@@ -5,14 +5,14 @@ import (
 	"os"
 )
 
-// RealFS complies with the fs.FS interface (go 1.16 onwards)
+// realFS complies with the fs.FS interface (go 1.16 onwards)
 // We use this rather than os.DirFS as DirFS has no concept of
 // what the current working directory is, whereas this simple
 // passthru to os.Open knows about working dir automagically.
-type RealFS struct{}
+type realFS struct{}
 
 // Open complies with the fs.FS interface.
-func (dir RealFS) Open(name string) (fs.File, error) {
+func (dir realFS) Open(name string) (fs.File, error) {
 	f, err := os.Open(name)
 	if err != nil {
 		return nil, err

interp/src_test.go

@@ -163,7 +163,7 @@ func Test_pkgDir(t *testing.T) {
 
 	interp := &Interpreter{
 		opt: opt{
-			filesystem: &RealFS{},
+			filesystem: &realFS{},
 		},
 	}
 
@@ -251,7 +251,7 @@ func Test_previousRoot(t *testing.T) {
 			} else {
 				rootPath = vendor
 			}
-			p, err := previousRoot(&RealFS{}, rootPath, test.root)
+			p, err := previousRoot(&realFS{}, rootPath, test.root)
 			if err != nil {
 				t.Error(err)
 			}