all: update references to symbols moved from io/ioutil to io

The old ioutil 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.
Also excluded vendored code.

For #41190.

Change-Id: I6d86f2bf7bc37a9d904b6cee3fe0c7af6d94d5b1
Reviewed-on: https://go-review.googlesource.com/c/go/+/263142
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>

1 files changed, 9 insertions, 10 deletions

diff --git a/src/bufio/bufio_test.go b/src/bufio/bufio_test.go
index cb68f3ba23..75086f1f24 100644
--- a/src/bufio/bufio_test.go
+++ b/src/bufio/bufio_test.go
@@ -10,7 +10,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"strings"
 	"testing"
 	"testing/iotest"
@@ -886,7 +885,7 @@ func TestReadEmptyBuffer(t *testing.T) {
 
 func TestLinesAfterRead(t *testing.T) {
 	l := NewReaderSize(bytes.NewReader([]byte("foo")), minReadBufferSize)
-	_, err := ioutil.ReadAll(l)
+	_, err := io.ReadAll(l)
 	if err != nil {
 		t.Error(err)
 		return
@@ -1130,7 +1129,7 @@ func TestWriterReadFromCounts(t *testing.T) {
 	}
 }
 
-// A writeCountingDiscard is like ioutil.Discard and counts the number of times
+// A writeCountingDiscard is like io.Discard and counts the number of times
 // Write is called on it.
 type writeCountingDiscard int
 
@@ -1300,7 +1299,7 @@ func TestReaderReset(t *testing.T) {
 		t.Errorf("buf = %q; want foo", buf)
 	}
 	r.Reset(strings.NewReader("bar bar"))
-	all, err := ioutil.ReadAll(r)
+	all, err := io.ReadAll(r)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1645,13 +1644,13 @@ func BenchmarkReaderWriteToOptimal(b *testing.B) {
 	buf := make([]byte, bufSize)
 	r := bytes.NewReader(buf)
 	srcReader := NewReaderSize(onlyReader{r}, 1<<10)
-	if _, ok := ioutil.Discard.(io.ReaderFrom); !ok {
-		b.Fatal("ioutil.Discard doesn't support ReaderFrom")
+	if _, ok := io.Discard.(io.ReaderFrom); !ok {
+		b.Fatal("io.Discard doesn't support ReaderFrom")
 	}
 	for i := 0; i < b.N; i++ {
 		r.Seek(0, io.SeekStart)
 		srcReader.Reset(onlyReader{r})
-		n, err := srcReader.WriteTo(ioutil.Discard)
+		n, err := srcReader.WriteTo(io.Discard)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -1722,7 +1721,7 @@ func BenchmarkReaderEmpty(b *testing.B) {
 	str := strings.Repeat("x", 16<<10)
 	for i := 0; i < b.N; i++ {
 		br := NewReader(strings.NewReader(str))
-		n, err := io.Copy(ioutil.Discard, br)
+		n, err := io.Copy(io.Discard, br)
 		if err != nil {
 			b.Fatal(err)
 		}
@@ -1737,7 +1736,7 @@ func BenchmarkWriterEmpty(b *testing.B) {
 	str := strings.Repeat("x", 1<<10)
 	bs := []byte(str)
 	for i := 0; i < b.N; i++ {
-		bw := NewWriter(ioutil.Discard)
+		bw := NewWriter(io.Discard)
 		bw.Flush()
 		bw.WriteByte('a')
 		bw.Flush()
@@ -1752,7 +1751,7 @@ func BenchmarkWriterEmpty(b *testing.B) {
 
 func BenchmarkWriterFlush(b *testing.B) {
 	b.ReportAllocs()
-	bw := NewWriter(ioutil.Discard)
+	bw := NewWriter(io.Discard)
 	str := strings.Repeat("x", 50)
 	for i := 0; i < b.N; i++ {
 		bw.WriteString(str)