all: update references to symbols moved from os to io/fs

The old os references are still valid, but update our code
to reflect best practices and get used to the new locations.

Code compiled with the bootstrap toolchain
(cmd/asm, cmd/dist, cmd/compile, debug/elf)
must remain Go 1.4-compatible and is excluded.

For #41190.

Change-Id: I8f9526977867c10a221e2f392f78d7dec073f1bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/243907
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>

3 files changed, 14 insertions, 13 deletions

diff --git a/src/errors/errors.go b/src/errors/errors.go
index d923ad4b70..f2fabacd4e 100644
--- a/src/errors/errors.go
+++ b/src/errors/errors.go
@@ -27,30 +27,30 @@
 // second. It reports whether it finds a match. It should be used in preference to
 // simple equality checks:
 //
-//	if errors.Is(err, os.ErrExist)
+//	if errors.Is(err, fs.ErrExist)
 //
 // is preferable to
 //
-//	if err == os.ErrExist
+//	if err == fs.ErrExist
 //
-// because the former will succeed if err wraps os.ErrExist.
+// because the former will succeed if err wraps fs.ErrExist.
 //
 // As unwraps its first argument sequentially looking for an error that can be
 // assigned to its second argument, which must be a pointer. If it succeeds, it
 // performs the assignment and returns true. Otherwise, it returns false. The form
 //
-//	var perr *os.PathError
+//	var perr *fs.PathError
 //	if errors.As(err, &perr) {
 //		fmt.Println(perr.Path)
 //	}
 //
 // is preferable to
 //
-//	if perr, ok := err.(*os.PathError); ok {
+//	if perr, ok := err.(*fs.PathError); ok {
 //		fmt.Println(perr.Path)
 //	}
 //
-// because the former will succeed if err wraps an *os.PathError.
+// because the former will succeed if err wraps an *fs.PathError.
 package errors
 
 // New returns an error that formats as the given text.
diff --git a/src/errors/wrap.go b/src/errors/wrap.go
index b82ca34b46..7928fe673e 100644
--- a/src/errors/wrap.go
+++ b/src/errors/wrap.go
@@ -32,9 +32,9 @@ func Unwrap(err error) error {
 // An error type might provide an Is method so it can be treated as equivalent
 // to an existing error. For example, if MyError defines
 //
-//	func (m MyError) Is(target error) bool { return target == os.ErrExist }
+//	func (m MyError) Is(target error) bool { return target == fs.ErrExist }
 //
-// then Is(MyError{}, os.ErrExist) returns true. See syscall.Errno.Is for
+// then Is(MyError{}, fs.ErrExist) returns true. See syscall.Errno.Is for
 // an example in the standard library.
 func Is(err, target error) bool {
 	if target == nil {
diff --git a/src/errors/wrap_test.go b/src/errors/wrap_test.go
index 4a4a732c9b..6f66e99c4a 100644
--- a/src/errors/wrap_test.go
+++ b/src/errors/wrap_test.go
@@ -7,6 +7,7 @@ package errors_test
 import (
 	"errors"
 	"fmt"
+	"io/fs"
 	"os"
 	"reflect"
 	"testing"
@@ -61,7 +62,7 @@ type poser struct {
 	f   func(error) bool
 }
 
-var poserPathErr = &os.PathError{Op: "poser"}
+var poserPathErr = &fs.PathError{Op: "poser"}
 
 func (p *poser) Error() string     { return p.msg }
 func (p *poser) Is(err error) bool { return p.f(err) }
@@ -71,7 +72,7 @@ func (p *poser) As(err interface{}) bool {
 		*x = p
 	case *errorT:
 		*x = errorT{"poser"}
-	case **os.PathError:
+	case **fs.PathError:
 		*x = poserPathErr
 	default:
 		return false
@@ -81,7 +82,7 @@ func (p *poser) As(err interface{}) bool {
 
 func TestAs(t *testing.T) {
 	var errT errorT
-	var errP *os.PathError
+	var errP *fs.PathError
 	var timeout interface{ Timeout() bool }
 	var p *poser
 	_, errF := os.Open("non-existing")
@@ -240,7 +241,7 @@ func (errorUncomparable) Is(target error) bool {
 
 func ExampleIs() {
 	if _, err := os.Open("non-existing"); err != nil {
-		if errors.Is(err, os.ErrNotExist) {
+		if errors.Is(err, fs.ErrNotExist) {
 			fmt.Println("file does not exist")
 		} else {
 			fmt.Println(err)
@@ -253,7 +254,7 @@ func ExampleIs() {
 
 func ExampleAs() {
 	if _, err := os.Open("non-existing"); err != nil {
-		var pathError *os.PathError
+		var pathError *fs.PathError
 		if errors.As(err, &pathError) {
 			fmt.Println("Failed at path:", pathError.Path)
 		} else {