all: update to use os.ReadFile, os.WriteFile, os.CreateTemp, os.MkdirTemp

As part of #42026, these helpers from io/ioutil were moved to os.
(ioutil.TempFile and TempDir became os.CreateTemp and MkdirTemp.)

Update the Go tree to use the preferred names.

As usual, code compiled with the Go 1.4 bootstrap toolchain
and code vendored from other sources is excluded.

ReadDir changes are in a separate CL, because they are not a
simple search and replace.

For #42026.

Change-Id: If318df0216d57e95ea0c4093b89f65e5b0ababb3
Reviewed-on: https://go-review.googlesource.com/c/go/+/266365
Trust: Russ Cox <rsc@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

79 files changed, 193 insertions, 258 deletions

diff --git a/src/cmd/addr2line/addr2line_test.go b/src/cmd/addr2line/addr2line_test.go
index 7973aa2fe1..992d7ac11e 100644
--- a/src/cmd/addr2line/addr2line_test.go
+++ b/src/cmd/addr2line/addr2line_test.go
@@ -8,7 +8,6 @@ import (
 	"bufio"
 	"bytes"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -98,8 +97,8 @@ func testAddr2Line(t *testing.T, exepath, addr string) {
 	if !os.SameFile(fi1, fi2) {
 		t.Fatalf("addr2line_test.go and %s are not same file", srcPath)
 	}
-	if srcLineNo != "107" {
-		t.Fatalf("line number = %v; want 107", srcLineNo)
+	if srcLineNo != "106" {
+		t.Fatalf("line number = %v; want 106", srcLineNo)
 	}
 }
 
@@ -107,7 +106,7 @@ func testAddr2Line(t *testing.T, exepath, addr string) {
 func TestAddr2Line(t *testing.T) {
 	testenv.MustHaveGoBuild(t)
 
-	tmpDir, err := ioutil.TempDir("", "TestAddr2Line")
+	tmpDir, err := os.MkdirTemp("", "TestAddr2Line")
 	if err != nil {
 		t.Fatal("TempDir failed: ", err)
 	}
diff --git a/src/cmd/api/goapi.go b/src/cmd/api/goapi.go
index b14d57c236..ba42812fa6 100644
--- a/src/cmd/api/goapi.go
+++ b/src/cmd/api/goapi.go
@@ -17,7 +17,6 @@ import (
 	"go/token"
 	"go/types"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -342,7 +341,7 @@ func fileFeatures(filename string) []string {
 	if filename == "" {
 		return nil
 	}
-	bs, err := ioutil.ReadFile(filename)
+	bs, err := os.ReadFile(filename)
 	if err != nil {
 		log.Fatalf("Error reading file %s: %v", filename, err)
 	}
diff --git a/src/cmd/api/goapi_test.go b/src/cmd/api/goapi_test.go
index 24620a94af..16e0058e5e 100644
--- a/src/cmd/api/goapi_test.go
+++ b/src/cmd/api/goapi_test.go
@@ -9,7 +9,6 @@ import (
 	"flag"
 	"fmt"
 	"go/build"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -75,7 +74,7 @@ func TestGolden(t *testing.T) {
 			f.Close()
 		}
 
-		bs, err := ioutil.ReadFile(goldenFile)
+		bs, err := os.ReadFile(goldenFile)
 		if err != nil {
 			t.Fatalf("opening golden.txt for package %q: %v", fi.Name(), err)
 		}
diff --git a/src/cmd/cover/cover.go b/src/cmd/cover/cover.go
index 360f9aeb06..7ee000861b 100644
--- a/src/cmd/cover/cover.go
+++ b/src/cmd/cover/cover.go
@@ -12,7 +12,6 @@ import (
 	"go/parser"
 	"go/token"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"sort"
@@ -304,7 +303,7 @@ func (f *File) Visit(node ast.Node) ast.Visitor {
 
 func annotate(name string) {
 	fset := token.NewFileSet()
-	content, err := ioutil.ReadFile(name)
+	content, err := os.ReadFile(name)
 	if err != nil {
 		log.Fatalf("cover: %s: %s", name, err)
 	}
diff --git a/src/cmd/cover/cover_test.go b/src/cmd/cover/cover_test.go
index 1c252e6e45..86c95d15c5 100644
--- a/src/cmd/cover/cover_test.go
+++ b/src/cmd/cover/cover_test.go
@@ -13,7 +13,6 @@ import (
 	"go/parser"
 	"go/token"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -81,7 +80,7 @@ var debug = flag.Bool("debug", false, "keep rewritten files for debugging")
 // We use TestMain to set up a temporary directory and remove it when
 // the tests are done.
 func TestMain(m *testing.M) {
-	dir, err := ioutil.TempDir("", "go-testcover")
+	dir, err := os.MkdirTemp("", "go-testcover")
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
@@ -173,7 +172,7 @@ func TestCover(t *testing.T) {
 	buildCover(t)
 
 	// Read in the test file (testTest) and write it, with LINEs specified, to coverInput.
-	file, err := ioutil.ReadFile(testTest)
+	file, err := os.ReadFile(testTest)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -192,7 +191,7 @@ func TestCover(t *testing.T) {
 		[]byte("}"))
 	lines = append(lines, []byte("func unFormatted2(b bool) {if b{}else{}}"))
 
-	if err := ioutil.WriteFile(coverInput, bytes.Join(lines, []byte("\n")), 0666); err != nil {
+	if err := os.WriteFile(coverInput, bytes.Join(lines, []byte("\n")), 0666); err != nil {
 		t.Fatal(err)
 	}
 
@@ -208,11 +207,11 @@ func TestCover(t *testing.T) {
 
 	// Copy testmain to testTempDir, so that it is in the same directory
 	// as coverOutput.
-	b, err := ioutil.ReadFile(testMain)
+	b, err := os.ReadFile(testMain)
 	if err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(tmpTestMain, b, 0444); err != nil {
+	if err := os.WriteFile(tmpTestMain, b, 0444); err != nil {
 		t.Fatal(err)
 	}
 
@@ -220,7 +219,7 @@ func TestCover(t *testing.T) {
 	cmd = exec.Command(testenv.GoToolPath(t), "run", tmpTestMain, coverOutput)
 	run(cmd, t)
 
-	file, err = ioutil.ReadFile(coverOutput)
+	file, err = os.ReadFile(coverOutput)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -251,7 +250,7 @@ func TestDirectives(t *testing.T) {
 	// Read the source file and find all the directives. We'll keep
 	// track of whether each one has been seen in the output.
 	testDirectives := filepath.Join(testdata, "directives.go")
-	source, err := ioutil.ReadFile(testDirectives)
+	source, err := os.ReadFile(testDirectives)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -398,7 +397,7 @@ func TestCoverHTML(t *testing.T) {
 
 	// Extract the parts of the HTML with comment markers,
 	// and compare against a golden file.
-	entireHTML, err := ioutil.ReadFile(htmlHTML)
+	entireHTML, err := os.ReadFile(htmlHTML)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -420,7 +419,7 @@ func TestCoverHTML(t *testing.T) {
 	if scan.Err() != nil {
 		t.Error(scan.Err())
 	}
-	golden, err := ioutil.ReadFile(htmlGolden)
+	golden, err := os.ReadFile(htmlGolden)
 	if err != nil {
 		t.Fatalf("reading golden file: %v", err)
 	}
@@ -457,7 +456,7 @@ func TestHtmlUnformatted(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := ioutil.WriteFile(filepath.Join(htmlUDir, "go.mod"), []byte("module htmlunformatted\n"), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(htmlUDir, "go.mod"), []byte("module htmlunformatted\n"), 0666); err != nil {
 		t.Fatal(err)
 	}
 
@@ -474,10 +473,10 @@ lab:
 
 	const htmlUTestContents = `package htmlunformatted`
 
-	if err := ioutil.WriteFile(htmlU, []byte(htmlUContents), 0444); err != nil {
+	if err := os.WriteFile(htmlU, []byte(htmlUContents), 0444); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(htmlUTest, []byte(htmlUTestContents), 0444); err != nil {
+	if err := os.WriteFile(htmlUTest, []byte(htmlUTestContents), 0444); err != nil {
 		t.Fatal(err)
 	}
 
@@ -540,13 +539,13 @@ func TestFuncWithDuplicateLines(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	if err := ioutil.WriteFile(filepath.Join(lineDupDir, "go.mod"), []byte("module linedup\n"), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(lineDupDir, "go.mod"), []byte("module linedup\n"), 0666); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(lineDupGo, []byte(lineDupContents), 0444); err != nil {
+	if err := os.WriteFile(lineDupGo, []byte(lineDupContents), 0444); err != nil {
 		t.Fatal(err)
 	}
-	if err := ioutil.WriteFile(lineDupTestGo, []byte(lineDupTestContents), 0444); err != nil {
+	if err := os.WriteFile(lineDupTestGo, []byte(lineDupTestContents), 0444); err != nil {
 		t.Fatal(err)
 	}
 
diff --git a/src/cmd/cover/html.go b/src/cmd/cover/html.go
index f76ea03cf5..b2865c427c 100644
--- a/src/cmd/cover/html.go
+++ b/src/cmd/cover/html.go
@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"html/template"
 	"io"
-	"io/ioutil"
 	"math"
 	"os"
 	"path/filepath"
@@ -43,7 +42,7 @@ func htmlOutput(profile, outfile string) error {
 		if err != nil {
 			return err
 		}
-		src, err := ioutil.ReadFile(file)
+		src, err := os.ReadFile(file)
 		if err != nil {
 			return fmt.Errorf("can't read %q: %v", fn, err)
 		}
@@ -62,7 +61,7 @@ func htmlOutput(profile, outfile string) error {
 	var out *os.File
 	if outfile == "" {
 		var dir string
-		dir, err = ioutil.TempDir("", "cover")
+		dir, err = os.MkdirTemp("", "cover")
 		if err != nil {
 			return err
 		}
diff --git a/src/cmd/fix/main.go b/src/cmd/fix/main.go
index 1cedf992cf..d055929aac 100644
--- a/src/cmd/fix/main.go
+++ b/src/cmd/fix/main.go
@@ -15,7 +15,6 @@ import (
 	"go/token"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -217,7 +216,7 @@ func processFile(filename string, useStdin bool) error {
 		return nil
 	}
 
-	return ioutil.WriteFile(f.Name(), newSrc, 0)
+	return os.WriteFile(f.Name(), newSrc, 0)
 }
 
 func gofmt(n interface{}) string {
diff --git a/src/cmd/fix/typecheck.go b/src/cmd/fix/typecheck.go
index f45155b06d..40b2287f26 100644
--- a/src/cmd/fix/typecheck.go
+++ b/src/cmd/fix/typecheck.go
@@ -9,7 +9,6 @@ import (
 	"go/ast"
 	"go/parser"
 	"go/token"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -162,12 +161,12 @@ func typecheck(cfg *TypeConfig, f *ast.File) (typeof map[interface{}]string, ass
 			if err != nil {
 				return err
 			}
-			dir, err := ioutil.TempDir(os.TempDir(), "fix_cgo_typecheck")
+			dir, err := os.MkdirTemp(os.TempDir(), "fix_cgo_typecheck")
 			if err != nil {
 				return err
 			}
 			defer os.RemoveAll(dir)
-			err = ioutil.WriteFile(filepath.Join(dir, "in.go"), txt, 0600)
+			err = os.WriteFile(filepath.Join(dir, "in.go"), txt, 0600)
 			if err != nil {
 				return err
 			}
@@ -176,7 +175,7 @@ func typecheck(cfg *TypeConfig, f *ast.File) (typeof map[interface{}]string, ass
 			if err != nil {
 				return err
 			}
-			out, err := ioutil.ReadFile(filepath.Join(dir, "_cgo_gotypes.go"))
+			out, err := os.ReadFile(filepath.Join(dir, "_cgo_gotypes.go"))
 			if err != nil {
 				return err
 			}
diff --git a/src/cmd/go/go_test.go b/src/cmd/go/go_test.go
index 1b8a21ecfa..19764bfc60 100644
--- a/src/cmd/go/go_test.go
+++ b/src/cmd/go/go_test.go
@@ -17,7 +17,6 @@ import (
 	"internal/testenv"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -100,7 +99,7 @@ func TestMain(m *testing.M) {
 
 	// Run with a temporary TMPDIR to check that the tests don't
 	// leave anything behind.
-	topTmpdir, err := ioutil.TempDir("", "cmd-go-test-")
+	topTmpdir, err := os.MkdirTemp("", "cmd-go-test-")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -109,7 +108,7 @@ func TestMain(m *testing.M) {
 	}
 	os.Setenv(tempEnvName(), topTmpdir)
 
-	dir, err := ioutil.TempDir(topTmpdir, "tmpdir")
+	dir, err := os.MkdirTemp(topTmpdir, "tmpdir")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -616,7 +615,7 @@ func (tg *testgoData) makeTempdir() {
 	tg.t.Helper()
 	if tg.tempdir == "" {
 		var err error
-		tg.tempdir, err = ioutil.TempDir("", "gotest")
+		tg.tempdir, err = os.MkdirTemp("", "gotest")
 		tg.must(err)
 	}
 }
@@ -633,7 +632,7 @@ func (tg *testgoData) tempFile(path, contents string) {
 			bytes = formatted
 		}
 	}
-	tg.must(ioutil.WriteFile(filepath.Join(tg.tempdir, path), bytes, 0644))
+	tg.must(os.WriteFile(filepath.Join(tg.tempdir, path), bytes, 0644))
 }
 
 // tempDir adds a temporary directory for a run of testgo.
@@ -833,7 +832,7 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 					return err
 				}
 				dest := filepath.Join("goroot", copydir, srcrel)
-				data, err := ioutil.ReadFile(path)
+				data, err := os.ReadFile(path)
 				if err != nil {
 					return err
 				}
@@ -850,18 +849,18 @@ func TestNewReleaseRebuildsStalePackagesInGOPATH(t *testing.T) {
 	tg.setenv("GOROOT", tg.path("goroot"))
 
 	addVar := func(name string, idx int) (restore func()) {
-		data, err := ioutil.ReadFile(name)
+		data, err := os.ReadFile(name)
 		if err != nil {
 			t.Fatal(err)
 		}
 		old := data
 		data = append(data, fmt.Sprintf("var DummyUnusedVar%d bool\n", idx)...)
-		if err := ioutil.WriteFile(name, append(data, '\n'), 0666); err != nil {
+		if err := os.WriteFile(name, append(data, '\n'), 0666); err != nil {
 			t.Fatal(err)
 		}
 		tg.sleep()
 		return func() {
-			if err := ioutil.WriteFile(name, old, 0666); err != nil {
+			if err := os.WriteFile(name, old, 0666); err != nil {
 				t.Fatal(err)
 			}
 		}
@@ -2674,7 +2673,7 @@ echo $* >>`+tg.path("pkg-config.out"))
 	tg.setenv("GOPATH", tg.path("."))
 	tg.setenv("PKG_CONFIG", tg.path("pkg-config.sh"))
 	tg.run("build", "x")
-	out, err := ioutil.ReadFile(tg.path("pkg-config.out"))
+	out, err := os.ReadFile(tg.path("pkg-config.out"))
 	tg.must(err)
 	out = bytes.TrimSpace(out)
 	want := "--cflags --static --static -- a a\n--libs --static --static -- a a"
diff --git a/src/cmd/go/go_windows_test.go b/src/cmd/go/go_windows_test.go
index 02634f19f5..3094212bae 100644
--- a/src/cmd/go/go_windows_test.go
+++ b/src/cmd/go/go_windows_test.go
@@ -5,7 +5,6 @@
 package main_test
 
 import (
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -20,14 +19,14 @@ func TestAbsolutePath(t *testing.T) {
 	defer tg.cleanup()
 	tg.parallel()
 
-	tmp, err := ioutil.TempDir("", "TestAbsolutePath")
+	tmp, err := os.MkdirTemp("", "TestAbsolutePath")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer robustio.RemoveAll(tmp)
 
 	file := filepath.Join(tmp, "a.go")
-	err = ioutil.WriteFile(file, []byte{}, 0644)
+	err = os.WriteFile(file, []byte{}, 0644)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/help_test.go b/src/cmd/go/help_test.go
index 78d63ff05e..abfc3db993 100644
--- a/src/cmd/go/help_test.go
+++ b/src/cmd/go/help_test.go
@@ -6,7 +6,7 @@ package main_test
 
 import (
 	"bytes"
-	"io/ioutil"
+	"os"
 	"testing"
 
 	"cmd/go/internal/help"
@@ -23,7 +23,7 @@ func TestDocsUpToDate(t *testing.T) {
 	buf := new(bytes.Buffer)
 	// Match the command in mkalldocs.sh that generates alldocs.go.
 	help.Help(buf, []string{"documentation"})
-	data, err := ioutil.ReadFile("alldocs.go")
+	data, err := os.ReadFile("alldocs.go")
 	if err != nil {
 		t.Fatalf("error reading alldocs.go: %v", err)
 	}
diff --git a/src/cmd/go/internal/auth/netrc.go b/src/cmd/go/internal/auth/netrc.go
index 7a9bdbb72c..0107f20d7a 100644
--- a/src/cmd/go/internal/auth/netrc.go
+++ b/src/cmd/go/internal/auth/netrc.go
@@ -5,7 +5,6 @@
 package auth
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -99,7 +98,7 @@ func readNetrc() {
 		return
 	}
 
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		if !os.IsNotExist(err) {
 			netrcErr = err
diff --git a/src/cmd/go/internal/bug/bug.go b/src/cmd/go/internal/bug/bug.go
index 07e3516855..1085feaaee 100644
--- a/src/cmd/go/internal/bug/bug.go
+++ b/src/cmd/go/internal/bug/bug.go
@@ -10,7 +10,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	urlpkg "net/url"
 	"os"
 	"os/exec"
@@ -117,7 +116,7 @@ func printOSDetails(w io.Writer) {
 	case "illumos", "solaris":
 		// Be sure to use the OS-supplied uname, in "/usr/bin":
 		printCmdOut(w, "uname -srv: ", "/usr/bin/uname", "-srv")
-		out, err := ioutil.ReadFile("/etc/release")
+		out, err := os.ReadFile("/etc/release")
 		if err == nil {
 			fmt.Fprintf(w, "/etc/release: %s\n", out)
 		} else {
@@ -177,7 +176,7 @@ func printGlibcVersion(w io.Writer) {
 	src := []byte(`int main() {}`)
 	srcfile := filepath.Join(tempdir, "go-bug.c")
 	outfile := filepath.Join(tempdir, "go-bug")
-	err := ioutil.WriteFile(srcfile, src, 0644)
+	err := os.WriteFile(srcfile, src, 0644)
 	if err != nil {
 		return
 	}
diff --git a/src/cmd/go/internal/cache/cache.go b/src/cmd/go/internal/cache/cache.go
index 5464fe5685..41f921641d 100644
--- a/src/cmd/go/internal/cache/cache.go
+++ b/src/cmd/go/internal/cache/cache.go
@@ -13,7 +13,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strconv"
@@ -239,7 +238,7 @@ func (c *Cache) GetBytes(id ActionID) ([]byte, Entry, error) {
 	if err != nil {
 		return nil, entry, err
 	}
-	data, _ := ioutil.ReadFile(c.OutputFile(entry.OutputID))
+	data, _ := os.ReadFile(c.OutputFile(entry.OutputID))
 	if sha256.Sum256(data) != entry.OutputID {
 		return nil, entry, &entryNotFoundError{Err: errors.New("bad checksum")}
 	}
@@ -378,7 +377,7 @@ func (c *Cache) putIndexEntry(id ActionID, out OutputID, size int64, allowVerify
 		// Truncate the file only *after* writing it.
 		// (This should be a no-op, but truncate just in case of previous corruption.)
 		//
-		// This differs from ioutil.WriteFile, which truncates to 0 *before* writing
+		// This differs from os.WriteFile, which truncates to 0 *before* writing
 		// via os.O_TRUNC. Truncating only after writing ensures that a second write
 		// of the same content to the same file is idempotent, and does not — even
 		// temporarily! — undo the effect of the first write.
diff --git a/src/cmd/go/internal/cache/cache_test.go b/src/cmd/go/internal/cache/cache_test.go
index 1988c34502..a865b97018 100644
--- a/src/cmd/go/internal/cache/cache_test.go
+++ b/src/cmd/go/internal/cache/cache_test.go
@@ -8,7 +8,6 @@ import (
 	"bytes"
 	"encoding/binary"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -20,7 +19,7 @@ func init() {
 }
 
 func TestBasic(t *testing.T) {
-	dir, err := ioutil.TempDir("", "cachetest-")
+	dir, err := os.MkdirTemp("", "cachetest-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -65,7 +64,7 @@ func TestBasic(t *testing.T) {
 }
 
 func TestGrowth(t *testing.T) {
-	dir, err := ioutil.TempDir("", "cachetest-")
+	dir, err := os.MkdirTemp("", "cachetest-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -118,7 +117,7 @@ func TestVerifyPanic(t *testing.T) {
 		t.Fatal("initEnv did not set verify")
 	}
 
-	dir, err := ioutil.TempDir("", "cachetest-")
+	dir, err := os.MkdirTemp("", "cachetest-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -151,7 +150,7 @@ func dummyID(x int) [HashSize]byte {
 }
 
 func TestCacheTrim(t *testing.T) {
-	dir, err := ioutil.TempDir("", "cachetest-")
+	dir, err := os.MkdirTemp("", "cachetest-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -207,7 +206,7 @@ func TestCacheTrim(t *testing.T) {
 		t.Fatal(err)
 	}
 	c.OutputFile(entry.OutputID)
-	data, err := ioutil.ReadFile(filepath.Join(dir, "trim.txt"))
+	data, err := os.ReadFile(filepath.Join(dir, "trim.txt"))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -220,7 +219,7 @@ func TestCacheTrim(t *testing.T) {
 		t.Fatal(err)
 	}
 	c.OutputFile(entry.OutputID)
-	data2, err := ioutil.ReadFile(filepath.Join(dir, "trim.txt"))
+	data2, err := os.ReadFile(filepath.Join(dir, "trim.txt"))
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/cache/default.go b/src/cmd/go/internal/cache/default.go
index 9f8dd8af4b..0b1c1e0c20 100644
--- a/src/cmd/go/internal/cache/default.go
+++ b/src/cmd/go/internal/cache/default.go
@@ -6,7 +6,6 @@ package cache
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sync"
@@ -49,7 +48,7 @@ func initDefaultCache() {
 	}
 	if _, err := os.Stat(filepath.Join(dir, "README")); err != nil {
 		// Best effort.
-		ioutil.WriteFile(filepath.Join(dir, "README"), []byte(cacheREADME), 0666)
+		os.WriteFile(filepath.Join(dir, "README"), []byte(cacheREADME), 0666)
 	}
 
 	c, err := Open(dir)
diff --git a/src/cmd/go/internal/cache/hash_test.go b/src/cmd/go/internal/cache/hash_test.go
index 3bf7143039..a0356771ca 100644
--- a/src/cmd/go/internal/cache/hash_test.go
+++ b/src/cmd/go/internal/cache/hash_test.go
@@ -6,7 +6,6 @@ package cache
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"testing"
 )
@@ -28,7 +27,7 @@ func TestHash(t *testing.T) {
 }
 
 func TestHashFile(t *testing.T) {
-	f, err := ioutil.TempFile("", "cmd-go-test-")
+	f, err := os.CreateTemp("", "cmd-go-test-")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/cfg/cfg.go b/src/cmd/go/internal/cfg/cfg.go
index 9bc48132ae..c48904eacc 100644
--- a/src/cmd/go/internal/cfg/cfg.go
+++ b/src/cmd/go/internal/cfg/cfg.go
@@ -12,7 +12,6 @@ import (
 	"go/build"
 	"internal/cfg"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -187,7 +186,7 @@ func initEnvCache() {
 	if file == "" {
 		return
 	}
-	data, err := ioutil.ReadFile(file)
+	data, err := os.ReadFile(file)
 	if err != nil {
 		return
 	}
diff --git a/src/cmd/go/internal/envcmd/env.go b/src/cmd/go/internal/envcmd/env.go
index 46af36eb11..6937187522 100644
--- a/src/cmd/go/internal/envcmd/env.go
+++ b/src/cmd/go/internal/envcmd/env.go
@@ -10,7 +10,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"go/build"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -452,7 +451,7 @@ func updateEnvFile(add map[string]string, del map[string]bool) {
 	if file == "" {
 		base.Fatalf("go env: cannot find go env config: %v", err)
 	}
-	data, err := ioutil.ReadFile(file)
+	data, err := os.ReadFile(file)
 	if err != nil && (!os.IsNotExist(err) || len(add) == 0) {
 		base.Fatalf("go env: reading go env config: %v", err)
 	}
@@ -506,11 +505,11 @@ func updateEnvFile(add map[string]string, del map[string]bool) {
 	}
 
 	data = []byte(strings.Join(lines, ""))
-	err = ioutil.WriteFile(file, data, 0666)
+	err = os.WriteFile(file, data, 0666)
 	if err != nil {
 		// Try creating directory.
 		os.MkdirAll(filepath.Dir(file), 0777)
-		err = ioutil.WriteFile(file, data, 0666)
+		err = os.WriteFile(file, data, 0666)
 		if err != nil {
 			base.Fatalf("go env: writing go env config: %v", err)
 		}
diff --git a/src/cmd/go/internal/fsys/fsys.go b/src/cmd/go/internal/fsys/fsys.go
index 0264786e5b..7b06c3c7f3 100644
--- a/src/cmd/go/internal/fsys/fsys.go
+++ b/src/cmd/go/internal/fsys/fsys.go
@@ -86,7 +86,7 @@ func Init(wd string) error {
 		return nil
 	}
 
-	b, err := ioutil.ReadFile(OverlayFile)
+	b, err := os.ReadFile(OverlayFile)
 	if err != nil {
 		return fmt.Errorf("reading overlay file: %v", err)
 	}
diff --git a/src/cmd/go/internal/fsys/fsys_test.go b/src/cmd/go/internal/fsys/fsys_test.go
index 90a69de14a..7f175c7031 100644
--- a/src/cmd/go/internal/fsys/fsys_test.go
+++ b/src/cmd/go/internal/fsys/fsys_test.go
@@ -8,7 +8,6 @@ import (
 	"internal/testenv"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -47,7 +46,7 @@ func initOverlay(t *testing.T, config string) {
 		if err := os.MkdirAll(filepath.Dir(name), 0777); err != nil {
 			t.Fatal(err)
 		}
-		if err := ioutil.WriteFile(name, f.Data, 0666); err != nil {
+		if err := os.WriteFile(name, f.Data, 0666); err != nil {
 			t.Fatal(err)
 		}
 	}
diff --git a/src/cmd/go/internal/generate/generate.go b/src/cmd/go/internal/generate/generate.go
index 98c17bba8c..c7401948b8 100644
--- a/src/cmd/go/internal/generate/generate.go
+++ b/src/cmd/go/internal/generate/generate.go
@@ -13,7 +13,6 @@ import (
 	"go/parser"
 	"go/token"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -201,7 +200,7 @@ func runGenerate(ctx context.Context, cmd *base.Command, args []string) {
 
 // generate runs the generation directives for a single file.
 func generate(absFile string) bool {
-	src, err := ioutil.ReadFile(absFile)
+	src, err := os.ReadFile(absFile)
 	if err != nil {
 		log.Fatalf("generate: %s", err)
 	}
diff --git a/src/cmd/go/internal/imports/scan_test.go b/src/cmd/go/internal/imports/scan_test.go
index e424656cae..5ba3201968 100644
--- a/src/cmd/go/internal/imports/scan_test.go
+++ b/src/cmd/go/internal/imports/scan_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"internal/testenv"
 	"io/ioutil"
+	"os"
 	"path"
 	"path/filepath"
 	"runtime"
@@ -66,7 +67,7 @@ func TestScanDir(t *testing.T) {
 			continue
 		}
 		t.Run(dir.Name(), func(t *testing.T) {
-			tagsData, err := ioutil.ReadFile(filepath.Join("testdata", dir.Name(), "tags.txt"))
+			tagsData, err := os.ReadFile(filepath.Join("testdata", dir.Name(), "tags.txt"))
 			if err != nil {
 				t.Fatalf("error reading tags: %v", err)
 			}
@@ -75,7 +76,7 @@ func TestScanDir(t *testing.T) {
 				tags[t] = true
 			}
 
-			wantData, err := ioutil.ReadFile(filepath.Join("testdata", dir.Name(), "want.txt"))
+			wantData, err := os.ReadFile(filepath.Join("testdata", dir.Name(), "want.txt"))
 			if err != nil {
 				t.Fatalf("error reading want: %v", err)
 			}
diff --git a/src/cmd/go/internal/load/pkg.go b/src/cmd/go/internal/load/pkg.go
index cbc683da2b..da3e0b895c 100644
--- a/src/cmd/go/internal/load/pkg.go
+++ b/src/cmd/go/internal/load/pkg.go
@@ -1147,7 +1147,7 @@ var (
 // goModPath returns the module path in the go.mod in dir, if any.
 func goModPath(dir string) (path string) {
 	return goModPathCache.Do(dir, func() interface{} {
-		data, err := ioutil.ReadFile(filepath.Join(dir, "go.mod"))
+		data, err := os.ReadFile(filepath.Join(dir, "go.mod"))
 		if err != nil {
 			return ""
 		}
@@ -1728,7 +1728,7 @@ func (p *Package) load(ctx context.Context, path string, stk *ImportStack, impor
 			// not work for any package that lacks a Target — such as a non-main
 			// package in module mode. We should probably fix that.
 			shlibnamefile := p.Target[:len(p.Target)-2] + ".shlibname"
-			shlib, err := ioutil.ReadFile(shlibnamefile)
+			shlib, err := os.ReadFile(shlibnamefile)
 			if err != nil && !os.IsNotExist(err) {
 				base.Fatalf("reading shlibname: %v", err)
 			}
diff --git a/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go b/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go
index 8301fb6b6e..2ac2052b8f 100644
--- a/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go
+++ b/src/cmd/go/internal/lockedfile/internal/filelock/filelock_test.go
@@ -9,7 +9,6 @@ package filelock_test
 import (
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -51,9 +50,9 @@ func mustTempFile(t *testing.T) (f *os.File, remove func()) {
 	t.Helper()
 
 	base := filepath.Base(t.Name())
-	f, err := ioutil.TempFile("", base)
+	f, err := os.CreateTemp("", base)
 	if err != nil {
-		t.Fatalf(`ioutil.TempFile("", %q) = %v`, base, err)
+		t.Fatalf(`os.CreateTemp("", %q) = %v`, base, err)
 	}
 	t.Logf("fd %d = %s", f.Fd(), f.Name())
 
diff --git a/src/cmd/go/internal/lockedfile/lockedfile_test.go b/src/cmd/go/internal/lockedfile/lockedfile_test.go
index 416c69d83b..34327dd841 100644
--- a/src/cmd/go/internal/lockedfile/lockedfile_test.go
+++ b/src/cmd/go/internal/lockedfile/lockedfile_test.go
@@ -10,7 +10,6 @@ package lockedfile_test
 import (
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -23,7 +22,7 @@ import (
 func mustTempDir(t *testing.T) (dir string, remove func()) {
 	t.Helper()
 
-	dir, err := ioutil.TempDir("", filepath.Base(t.Name()))
+	dir, err := os.MkdirTemp("", filepath.Base(t.Name()))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -155,8 +154,8 @@ func TestCanLockExistingFile(t *testing.T) {
 	defer remove()
 	path := filepath.Join(dir, "existing.txt")
 
-	if err := ioutil.WriteFile(path, []byte("ok"), 0777); err != nil {
-		t.Fatalf("ioutil.WriteFile: %v", err)
+	if err := os.WriteFile(path, []byte("ok"), 0777); err != nil {
+		t.Fatalf("os.WriteFile: %v", err)
 	}
 
 	f, err := lockedfile.Edit(path)
@@ -201,7 +200,7 @@ func TestSpuriousEDEADLK(t *testing.T) {
 		}
 		defer b.Close()
 
-		if err := ioutil.WriteFile(filepath.Join(dir, "locked"), []byte("ok"), 0666); err != nil {
+		if err := os.WriteFile(filepath.Join(dir, "locked"), []byte("ok"), 0666); err != nil {
 			t.Fatal(err)
 		}
 
diff --git a/src/cmd/go/internal/modcmd/vendor.go b/src/cmd/go/internal/modcmd/vendor.go
index 38c473d36b..390a195547 100644
--- a/src/cmd/go/internal/modcmd/vendor.go
+++ b/src/cmd/go/internal/modcmd/vendor.go
@@ -155,7 +155,7 @@ func runVendor(ctx context.Context, cmd *base.Command, args []string) {
 		base.Fatalf("go mod vendor: %v", err)
 	}
 
-	if err := ioutil.WriteFile(filepath.Join(vdir, "modules.txt"), buf.Bytes(), 0666); err != nil {
+	if err := os.WriteFile(filepath.Join(vdir, "modules.txt"), buf.Bytes(), 0666); err != nil {
 		base.Fatalf("go mod vendor: %v", err)
 	}
 }
diff --git a/src/cmd/go/internal/modcmd/verify.go b/src/cmd/go/internal/modcmd/verify.go
index ce24793929..c83e70076a 100644
--- a/src/cmd/go/internal/modcmd/verify.go
+++ b/src/cmd/go/internal/modcmd/verify.go
@@ -10,7 +10,6 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"runtime"
 
@@ -87,7 +86,7 @@ func verifyMod(mod module.Version) []error {
 		_, zipErr = os.Stat(zip)
 	}
 	dir, dirErr := modfetch.DownloadDir(mod)
-	data, err := ioutil.ReadFile(zip + "hash")
+	data, err := os.ReadFile(zip + "hash")
 	if err != nil {
 		if zipErr != nil && errors.Is(zipErr, fs.ErrNotExist) &&
 			dirErr != nil && errors.Is(dirErr, fs.ErrNotExist) {
diff --git a/src/cmd/go/internal/modconv/convert_test.go b/src/cmd/go/internal/modconv/convert_test.go
index faa2b4c606..66b9ff4f38 100644
--- a/src/cmd/go/internal/modconv/convert_test.go
+++ b/src/cmd/go/internal/modconv/convert_test.go
@@ -9,7 +9,6 @@ import (
 	"context"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -37,7 +36,7 @@ func testMain(m *testing.M) int {
 		return 0
 	}
 
-	dir, err := ioutil.TempDir("", "modconv-test-")
+	dir, err := os.MkdirTemp("", "modconv-test-")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -167,7 +166,7 @@ func TestConvertLegacyConfig(t *testing.T) {
 
 			for name := range Converters {
 				file := filepath.Join(dir, name)
-				data, err := ioutil.ReadFile(file)
+				data, err := os.ReadFile(file)
 				if err == nil {
 					f := new(modfile.File)
 					f.AddModuleStmt(tt.path)
diff --git a/src/cmd/go/internal/modconv/modconv_test.go b/src/cmd/go/internal/modconv/modconv_test.go
index ccc4f3d576..750525d404 100644
--- a/src/cmd/go/internal/modconv/modconv_test.go
+++ b/src/cmd/go/internal/modconv/modconv_test.go
@@ -7,7 +7,7 @@ package modconv
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 )
@@ -42,7 +42,7 @@ func Test(t *testing.T) {
 			if Converters[extMap[ext]] == nil {
 				t.Fatalf("Converters[%q] == nil", extMap[ext])
 			}
-			data, err := ioutil.ReadFile(test)
+			data, err := os.ReadFile(test)
 			if err != nil {
 				t.Fatal(err)
 			}
@@ -50,7 +50,7 @@ func Test(t *testing.T) {
 			if err != nil {
 				t.Fatal(err)
 			}
-			want, err := ioutil.ReadFile(test[:len(test)-len(ext)] + ".out")
+			want, err := os.ReadFile(test[:len(test)-len(ext)] + ".out")
 			if err != nil {
 				t.Error(err)
 			}
diff --git a/src/cmd/go/internal/modfetch/cache_test.go b/src/cmd/go/internal/modfetch/cache_test.go
index 241c800e69..722c984e37 100644
--- a/src/cmd/go/internal/modfetch/cache_test.go
+++ b/src/cmd/go/internal/modfetch/cache_test.go
@@ -5,14 +5,13 @@
 package modfetch
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
 )
 
 func TestWriteDiskCache(t *testing.T) {
-	tmpdir, err := ioutil.TempDir("", "go-writeCache-test-")
+	tmpdir, err := os.MkdirTemp("", "go-writeCache-test-")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/modfetch/codehost/codehost.go b/src/cmd/go/internal/modfetch/codehost/codehost.go
index 286d3f7220..86c1c14d4a 100644
--- a/src/cmd/go/internal/modfetch/codehost/codehost.go
+++ b/src/cmd/go/internal/modfetch/codehost/codehost.go
@@ -12,7 +12,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -189,7 +188,7 @@ func WorkDir(typ, name string) (dir, lockfile string, err error) {
 	}
 	defer unlock()
 
-	data, err := ioutil.ReadFile(dir + ".info")
+	data, err := os.ReadFile(dir + ".info")
 	info, err2 := os.Stat(dir)
 	if err == nil && err2 == nil && info.IsDir() {
 		// Info file and directory both already exist: reuse.
@@ -211,7 +210,7 @@ func WorkDir(typ, name string) (dir, lockfile string, err error) {
 	if err := os.MkdirAll(dir, 0777); err != nil {
 		return "", "", err
 	}
-	if err := ioutil.WriteFile(dir+".info", []byte(key), 0666); err != nil {
+	if err := os.WriteFile(dir+".info", []byte(key), 0666); err != nil {
 		os.RemoveAll(dir)
 		return "", "", err
 	}
diff --git a/src/cmd/go/internal/modfetch/codehost/git_test.go b/src/cmd/go/internal/modfetch/codehost/git_test.go
index 981e3fe91f..89a73baad9 100644
--- a/src/cmd/go/internal/modfetch/codehost/git_test.go
+++ b/src/cmd/go/internal/modfetch/codehost/git_test.go
@@ -12,7 +12,6 @@ import (
 	"internal/testenv"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -54,7 +53,7 @@ func testMain(m *testing.M) int {
 		return 0
 	}
 
-	dir, err := ioutil.TempDir("", "gitrepo-test-")
+	dir, err := os.MkdirTemp("", "gitrepo-test-")
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/modfetch/codehost/shell.go b/src/cmd/go/internal/modfetch/codehost/shell.go
index b9525adf5e..ce8b501d53 100644
--- a/src/cmd/go/internal/modfetch/codehost/shell.go
+++ b/src/cmd/go/internal/modfetch/codehost/shell.go
@@ -15,7 +15,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"strings"
@@ -124,7 +123,7 @@ func main() {
 			}
 
 			if f[3] != "-" {
-				if err := ioutil.WriteFile(f[3], data, 0666); err != nil {
+				if err := os.WriteFile(f[3], data, 0666); err != nil {
 					fmt.Fprintf(os.Stderr, "?%s\n", err)
 					continue
 				}
diff --git a/src/cmd/go/internal/modfetch/codehost/vcs.go b/src/cmd/go/internal/modfetch/codehost/vcs.go
index e67ee94ad8..c2cca084e3 100644
--- a/src/cmd/go/internal/modfetch/codehost/vcs.go
+++ b/src/cmd/go/internal/modfetch/codehost/vcs.go
@@ -10,7 +10,6 @@ import (
 	"internal/lazyregexp"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -433,7 +432,7 @@ func (r *vcsRepo) ReadZip(rev, subdir string, maxSize int64) (zip io.ReadCloser,
 	if rev == "latest" {
 		rev = r.cmd.latest
 	}
-	f, err := ioutil.TempFile("", "go-readzip-*.zip")
+	f, err := os.CreateTemp("", "go-readzip-*.zip")
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/cmd/go/internal/modfetch/coderepo.go b/src/cmd/go/internal/modfetch/coderepo.go
index b6bcf83f1a..2dcbb99b18 100644
--- a/src/cmd/go/internal/modfetch/coderepo.go
+++ b/src/cmd/go/internal/modfetch/coderepo.go
@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path"
 	"sort"
@@ -966,7 +965,7 @@ func (r *codeRepo) Zip(dst io.Writer, version string) error {
 	subdir = strings.Trim(subdir, "/")
 
 	// Spool to local file.
-	f, err := ioutil.TempFile("", "go-codehost-")
+	f, err := os.CreateTemp("", "go-codehost-")
 	if err != nil {
 		dl.Close()
 		return err
diff --git a/src/cmd/go/internal/modfetch/coderepo_test.go b/src/cmd/go/internal/modfetch/coderepo_test.go
index 53b048dbdf..02e399f352 100644
--- a/src/cmd/go/internal/modfetch/coderepo_test.go
+++ b/src/cmd/go/internal/modfetch/coderepo_test.go
@@ -11,7 +11,6 @@ import (
 	"hash"
 	"internal/testenv"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"reflect"
@@ -38,7 +37,7 @@ func testMain(m *testing.M) int {
 	// code, bypass the sum database.
 	cfg.GOSUMDB = "off"
 
-	dir, err := ioutil.TempDir("", "gitrepo-test-")
+	dir, err := os.MkdirTemp("", "gitrepo-test-")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -424,7 +423,7 @@ var codeRepoTests = []codeRepoTest{
 func TestCodeRepo(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 
-	tmpdir, err := ioutil.TempDir("", "modfetch-test-")
+	tmpdir, err := os.MkdirTemp("", "modfetch-test-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -491,9 +490,9 @@ func TestCodeRepo(t *testing.T) {
 
 					needHash := !testing.Short() && (tt.zipFileHash != "" || tt.zipSum != "")
 					if tt.zip != nil || tt.zipErr != "" || needHash {
-						f, err := ioutil.TempFile(tmpdir, tt.version+".zip.")
+						f, err := os.CreateTemp(tmpdir, tt.version+".zip.")
 						if err != nil {
-							t.Fatalf("ioutil.TempFile: %v", err)
+							t.Fatalf("os.CreateTemp: %v", err)
 						}
 						zipfile := f.Name()
 						defer func() {
@@ -655,7 +654,7 @@ var codeRepoVersionsTests = []struct {
 func TestCodeRepoVersions(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 
-	tmpdir, err := ioutil.TempDir("", "vgo-modfetch-test-")
+	tmpdir, err := os.MkdirTemp("", "vgo-modfetch-test-")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -729,7 +728,7 @@ var latestTests = []struct {
 func TestLatest(t *testing.T) {
 	testenv.MustHaveExternalNetwork(t)
 
-	tmpdir, err := ioutil.TempDir("", "vgo-modfetch-test-")
+	tmpdir, err := os.MkdirTemp("", "vgo-modfetch-test-")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/modfetch/fetch.go b/src/cmd/go/internal/modfetch/fetch.go
index 2ee78de5b2..debeb3f319 100644
--- a/src/cmd/go/internal/modfetch/fetch.go
+++ b/src/cmd/go/internal/modfetch/fetch.go
@@ -12,7 +12,6 @@ import (
 	"fmt"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sort"
@@ -136,7 +135,7 @@ func download(ctx context.Context, mod module.Version) (dir string, err error) {
 	if err := os.MkdirAll(parentDir, 0777); err != nil {
 		return "", err
 	}
-	if err := ioutil.WriteFile(partialPath, nil, 0666); err != nil {
+	if err := os.WriteFile(partialPath, nil, 0666); err != nil {
 		return "", err
 	}
 	if err := modzip.Unzip(dir, mod, zipfile); err != nil {
@@ -223,7 +222,7 @@ func downloadZip(ctx context.Context, mod module.Version, zipfile string) (err e
 	// contents of the file (by hashing it) before we commit it. Because the file
 	// is zip-compressed, we need an actual file — or at least an io.ReaderAt — to
 	// validate it: we can't just tee the stream as we write it.
-	f, err := ioutil.TempFile(filepath.Dir(zipfile), filepath.Base(renameio.Pattern(zipfile)))
+	f, err := os.CreateTemp(filepath.Dir(zipfile), filepath.Base(renameio.Pattern(zipfile)))
 	if err != nil {
 		return err
 	}
diff --git a/src/cmd/go/internal/modfetch/zip_sum_test/zip_sum_test.go b/src/cmd/go/internal/modfetch/zip_sum_test/zip_sum_test.go
index 82398ebfed..d9ba8ef2da 100644
--- a/src/cmd/go/internal/modfetch/zip_sum_test/zip_sum_test.go
+++ b/src/cmd/go/internal/modfetch/zip_sum_test/zip_sum_test.go
@@ -24,7 +24,6 @@ import (
 	"fmt"
 	"internal/testenv"
 	"io"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -81,7 +80,7 @@ func TestZipSums(t *testing.T) {
 	if *modCacheDir != "" {
 		cfg.BuildContext.GOPATH = *modCacheDir
 	} else {
-		tmpDir, err := ioutil.TempDir("", "TestZipSums")
+		tmpDir, err := os.MkdirTemp("", "TestZipSums")
 		if err != nil {
 			t.Fatal(err)
 		}
diff --git a/src/cmd/go/internal/modload/init.go b/src/cmd/go/internal/modload/init.go
index 1c31a5f90a..6a2cea668d 100644
--- a/src/cmd/go/internal/modload/init.go
+++ b/src/cmd/go/internal/modload/init.go
@@ -632,7 +632,7 @@ func setDefaultBuildMod() {
 func convertLegacyConfig(modPath string) (from string, err error) {
 	for _, name := range altConfigs {
 		cfg := filepath.Join(modRoot, name)
-		data, err := ioutil.ReadFile(cfg)
+		data, err := os.ReadFile(cfg)
 		if err == nil {
 			convert := modconv.Converters[name]
 			if convert == nil {
@@ -753,7 +753,7 @@ func findModulePath(dir string) (string, error) {
 	}
 
 	// Look for Godeps.json declaring import path.
-	data, _ := ioutil.ReadFile(filepath.Join(dir, "Godeps/Godeps.json"))
+	data, _ := os.ReadFile(filepath.Join(dir, "Godeps/Godeps.json"))
 	var cfg1 struct{ ImportPath string }
 	json.Unmarshal(data, &cfg1)
 	if cfg1.ImportPath != "" {
@@ -761,7 +761,7 @@ func findModulePath(dir string) (string, error) {
 	}
 
 	// Look for vendor.json declaring import path.
-	data, _ = ioutil.ReadFile(filepath.Join(dir, "vendor/vendor.json"))
+	data, _ = os.ReadFile(filepath.Join(dir, "vendor/vendor.json"))
 	var cfg2 struct{ RootPath string }
 	json.Unmarshal(data, &cfg2)
 	if cfg2.RootPath != "" {
@@ -813,7 +813,7 @@ var (
 )
 
 func findImportComment(file string) string {
-	data, err := ioutil.ReadFile(file)
+	data, err := os.ReadFile(file)
 	if err != nil {
 		return ""
 	}
diff --git a/src/cmd/go/internal/modload/query_test.go b/src/cmd/go/internal/modload/query_test.go
index 777a56b977..e225a0e71e 100644
--- a/src/cmd/go/internal/modload/query_test.go
+++ b/src/cmd/go/internal/modload/query_test.go
@@ -7,7 +7,6 @@ package modload
 import (
 	"context"
 	"internal/testenv"
-	"io/ioutil"
 	"log"
 	"os"
 	"path"
@@ -27,7 +26,7 @@ func TestMain(m *testing.M) {
 func testMain(m *testing.M) int {
 	cfg.GOPROXY = "direct"
 
-	dir, err := ioutil.TempDir("", "modload-test-")
+	dir, err := os.MkdirTemp("", "modload-test-")
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/modload/vendor.go b/src/cmd/go/internal/modload/vendor.go
index ab29d4d014..80d49053c6 100644
--- a/src/cmd/go/internal/modload/vendor.go
+++ b/src/cmd/go/internal/modload/vendor.go
@@ -8,7 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io/fs"
-	"io/ioutil"
+	"os"
 	"path/filepath"
 	"strings"
 	"sync"
@@ -40,7 +40,7 @@ func readVendorList() {
 		vendorPkgModule = make(map[string]module.Version)
 		vendorVersion = make(map[string]string)
 		vendorMeta = make(map[module.Version]vendorMetadata)
-		data, err := ioutil.ReadFile(filepath.Join(ModRoot(), "vendor/modules.txt"))
+		data, err := os.ReadFile(filepath.Join(ModRoot(), "vendor/modules.txt"))
 		if err != nil {
 			if !errors.Is(err, fs.ErrNotExist) {
 				base.Fatalf("go: %s", err)
diff --git a/src/cmd/go/internal/renameio/renameio.go b/src/cmd/go/internal/renameio/renameio.go
index 60a7138a76..9788171d6e 100644
--- a/src/cmd/go/internal/renameio/renameio.go
+++ b/src/cmd/go/internal/renameio/renameio.go
@@ -25,7 +25,7 @@ func Pattern(filename string) string {
 	return filepath.Join(filepath.Dir(filename), filepath.Base(filename)+patternSuffix)
 }
 
-// WriteFile is like ioutil.WriteFile, but first writes data to an arbitrary
+// WriteFile is like os.WriteFile, but first writes data to an arbitrary
 // file in the same directory as filename, then renames it atomically to the
 // final name.
 //
@@ -67,7 +67,7 @@ func WriteToFile(filename string, data io.Reader, perm fs.FileMode) (err error)
 	return robustio.Rename(f.Name(), filename)
 }
 
-// ReadFile is like ioutil.ReadFile, but on Windows retries spurious errors that
+// ReadFile is like os.ReadFile, but on Windows retries spurious errors that
 // may occur if the file is concurrently replaced.
 //
 // Errors are classified heuristically and retries are bounded, so even this
diff --git a/src/cmd/go/internal/renameio/renameio_test.go b/src/cmd/go/internal/renameio/renameio_test.go
index e6d2025a0e..5b2ed83624 100644
--- a/src/cmd/go/internal/renameio/renameio_test.go
+++ b/src/cmd/go/internal/renameio/renameio_test.go
@@ -10,7 +10,6 @@ import (
 	"encoding/binary"
 	"errors"
 	"internal/testenv"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"path/filepath"
@@ -30,7 +29,7 @@ func TestConcurrentReadsAndWrites(t *testing.T) {
 		testenv.SkipFlaky(t, 33041)
 	}
 
-	dir, err := ioutil.TempDir("", "renameio")
+	dir, err := os.MkdirTemp("", "renameio")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/renameio/umask_test.go b/src/cmd/go/internal/renameio/umask_test.go
index 19e217c548..65e4fa587b 100644
--- a/src/cmd/go/internal/renameio/umask_test.go
+++ b/src/cmd/go/internal/renameio/umask_test.go
@@ -8,7 +8,6 @@ package renameio
 
 import (
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"syscall"
@@ -16,7 +15,7 @@ import (
 )
 
 func TestWriteFileModeAppliesUmask(t *testing.T) {
-	dir, err := ioutil.TempDir("", "renameio")
+	dir, err := os.MkdirTemp("", "renameio")
 	if err != nil {
 		t.Fatalf("Failed to create temporary directory: %v", err)
 	}
diff --git a/src/cmd/go/internal/robustio/robustio.go b/src/cmd/go/internal/robustio/robustio.go
index 76e47ad1ff..ce3dbbde6d 100644
--- a/src/cmd/go/internal/robustio/robustio.go
+++ b/src/cmd/go/internal/robustio/robustio.go
@@ -22,7 +22,7 @@ func Rename(oldpath, newpath string) error {
 	return rename(oldpath, newpath)
 }
 
-// ReadFile is like ioutil.ReadFile, but on Windows retries errors that may
+// ReadFile is like os.ReadFile, but on Windows retries errors that may
 // occur if the file is concurrently replaced.
 //
 // (See golang.org/issue/31247 and golang.org/issue/32188.)
diff --git a/src/cmd/go/internal/robustio/robustio_flaky.go b/src/cmd/go/internal/robustio/robustio_flaky.go
index d4cb7e6457..5bd44bd345 100644
--- a/src/cmd/go/internal/robustio/robustio_flaky.go
+++ b/src/cmd/go/internal/robustio/robustio_flaky.go
@@ -8,7 +8,6 @@ package robustio
 
 import (
 	"errors"
-	"io/ioutil"
 	"math/rand"
 	"os"
 	"syscall"
@@ -70,11 +69,11 @@ func rename(oldpath, newpath string) (err error) {
 	})
 }
 
-// readFile is like ioutil.ReadFile, but retries ephemeral errors.
+// readFile is like os.ReadFile, but retries ephemeral errors.
 func readFile(filename string) ([]byte, error) {
 	var b []byte
 	err := retry(func() (err error, mayRetry bool) {
-		b, err = ioutil.ReadFile(filename)
+		b, err = os.ReadFile(filename)
 
 		// Unlike in rename, we do not retry errFileNotFound here: it can occur
 		// as a spurious error, but the file may also genuinely not exist, so the
diff --git a/src/cmd/go/internal/robustio/robustio_other.go b/src/cmd/go/internal/robustio/robustio_other.go
index 907b556858..6fe7b7e4e4 100644
--- a/src/cmd/go/internal/robustio/robustio_other.go
+++ b/src/cmd/go/internal/robustio/robustio_other.go
@@ -7,7 +7,6 @@
 package robustio
 
 import (
-	"io/ioutil"
 	"os"
 )
 
@@ -16,7 +15,7 @@ func rename(oldpath, newpath string) error {
 }
 
 func readFile(filename string) ([]byte, error) {
-	return ioutil.ReadFile(filename)
+	return os.ReadFile(filename)
 }
 
 func removeAll(path string) error {
diff --git a/src/cmd/go/internal/test/test.go b/src/cmd/go/internal/test/test.go
index 24601dc061..401b67c260 100644
--- a/src/cmd/go/internal/test/test.go
+++ b/src/cmd/go/internal/test/test.go
@@ -884,7 +884,7 @@ func builderTest(b *work.Builder, ctx context.Context, p *load.Package) (buildAc
 	if !cfg.BuildN {
 		// writeTestmain writes _testmain.go,
 		// using the test description gathered in t.
-		if err := ioutil.WriteFile(testDir+"_testmain.go", *pmain.Internal.TestmainGo, 0666); err != nil {
+		if err := os.WriteFile(testDir+"_testmain.go", *pmain.Internal.TestmainGo, 0666); err != nil {
 			return nil, nil, nil, err
 		}
 	}
@@ -1616,7 +1616,7 @@ func (c *runCache) saveOutput(a *work.Action) {
 	}
 
 	// See comment about two-level lookup in tryCacheWithID above.
-	testlog, err := ioutil.ReadFile(a.Objdir + "testlog.txt")
+	testlog, err := os.ReadFile(a.Objdir + "testlog.txt")
 	if err != nil || !bytes.HasPrefix(testlog, testlogMagic) || testlog[len(testlog)-1] != '\n' {
 		if cache.DebugTest {
 			if err != nil {
diff --git a/src/cmd/go/internal/txtar/archive.go b/src/cmd/go/internal/txtar/archive.go
index c384f33bdf..1796684877 100644
--- a/src/cmd/go/internal/txtar/archive.go
+++ b/src/cmd/go/internal/txtar/archive.go
@@ -34,7 +34,7 @@ package txtar
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 )
 
@@ -66,7 +66,7 @@ func Format(a *Archive) []byte {
 
 // ParseFile parses the named file as an archive.
 func ParseFile(file string) (*Archive, error) {
-	data, err := ioutil.ReadFile(file)
+	data, err := os.ReadFile(file)
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/cmd/go/internal/vcs/vcs_test.go b/src/cmd/go/internal/vcs/vcs_test.go
index 72d74a01e3..c5c7a3283b 100644
--- a/src/cmd/go/internal/vcs/vcs_test.go
+++ b/src/cmd/go/internal/vcs/vcs_test.go
@@ -7,7 +7,6 @@ package vcs
 import (
 	"errors"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"path"
 	"path/filepath"
@@ -208,7 +207,7 @@ func TestRepoRootForImportPath(t *testing.T) {
 
 // Test that vcsFromDir correctly inspects a given directory and returns the right VCS and root.
 func TestFromDir(t *testing.T) {
-	tempDir, err := ioutil.TempDir("", "vcstest")
+	tempDir, err := os.MkdirTemp("", "vcstest")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/web/file_test.go b/src/cmd/go/internal/web/file_test.go
index a1bb080e07..3734df5c4e 100644
--- a/src/cmd/go/internal/web/file_test.go
+++ b/src/cmd/go/internal/web/file_test.go
@@ -7,7 +7,6 @@ package web
 import (
 	"errors"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -16,7 +15,7 @@ import (
 func TestGetFileURL(t *testing.T) {
 	const content = "Hello, file!\n"
 
-	f, err := ioutil.TempFile("", "web-TestGetFileURL")
+	f, err := os.CreateTemp("", "web-TestGetFileURL")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/internal/work/action.go b/src/cmd/go/internal/work/action.go
index f461c5780f..9d141ae233 100644
--- a/src/cmd/go/internal/work/action.go
+++ b/src/cmd/go/internal/work/action.go
@@ -14,7 +14,6 @@ import (
 	"debug/elf"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -253,7 +252,7 @@ func (b *Builder) Init() {
 	if cfg.BuildN {
 		b.WorkDir = "$WORK"
 	} else {
-		tmp, err := ioutil.TempDir(cfg.Getenv("GOTMPDIR"), "go-build")
+		tmp, err := os.MkdirTemp(cfg.Getenv("GOTMPDIR"), "go-build")
 		if err != nil {
 			base.Fatalf("go: creating work dir: %v", err)
 		}
diff --git a/src/cmd/go/internal/work/build_test.go b/src/cmd/go/internal/work/build_test.go
index e941729734..eaf2639e9e 100644
--- a/src/cmd/go/internal/work/build_test.go
+++ b/src/cmd/go/internal/work/build_test.go
@@ -8,7 +8,6 @@ import (
 	"bytes"
 	"fmt"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
@@ -170,7 +169,7 @@ func TestSharedLibName(t *testing.T) {
 	for _, data := range testData {
 		func() {
 			if data.rootedAt != "" {
-				tmpGopath, err := ioutil.TempDir("", "gopath")
+				tmpGopath, err := os.MkdirTemp("", "gopath")
 				if err != nil {
 					t.Fatal(err)
 				}
@@ -238,7 +237,7 @@ func TestRespectSetgidDir(t *testing.T) {
 		return cmdBuf.WriteString(fmt.Sprint(a...))
 	}
 
-	setgiddir, err := ioutil.TempDir("", "SetGroupID")
+	setgiddir, err := os.MkdirTemp("", "SetGroupID")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -258,9 +257,9 @@ func TestRespectSetgidDir(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	pkgfile, err := ioutil.TempFile("", "pkgfile")
+	pkgfile, err := os.CreateTemp("", "pkgfile")
 	if err != nil {
-		t.Fatalf("ioutil.TempFile(\"\", \"pkgfile\"): %v", err)
+		t.Fatalf("os.CreateTemp(\"\", \"pkgfile\"): %v", err)
 	}
 	defer os.Remove(pkgfile.Name())
 	defer pkgfile.Close()
diff --git a/src/cmd/go/internal/work/buildid.go b/src/cmd/go/internal/work/buildid.go
index 3c7be5a3e3..d76988145b 100644
--- a/src/cmd/go/internal/work/buildid.go
+++ b/src/cmd/go/internal/work/buildid.go
@@ -7,7 +7,6 @@ package work
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"strings"
@@ -344,7 +343,7 @@ func (b *Builder) gccgoBuildIDFile(a *Action) (string, error) {
 		}
 	}
 
-	if err := ioutil.WriteFile(sfile, buf.Bytes(), 0666); err != nil {
+	if err := os.WriteFile(sfile, buf.Bytes(), 0666); err != nil {
 		return "", err
 	}
 
diff --git a/src/cmd/go/internal/work/exec.go b/src/cmd/go/internal/work/exec.go
index 6ce56dd6f4..336751df27 100644
--- a/src/cmd/go/internal/work/exec.go
+++ b/src/cmd/go/internal/work/exec.go
@@ -16,7 +16,6 @@ import (
 	"internal/lazyregexp"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"log"
 	"math/rand"
 	"os"
@@ -94,7 +93,7 @@ func (b *Builder) Do(ctx context.Context, root *Action) {
 				base.Fatalf("go: refusing to write action graph to %v\n", file)
 			}
 			js := actionGraphJSON(root)
-			if err := ioutil.WriteFile(file, []byte(js), 0666); err != nil {
+			if err := os.WriteFile(file, []byte(js), 0666); err != nil {
 				fmt.Fprintf(os.Stderr, "go: writing action graph: %v\n", err)
 				base.SetExitStatus(1)
 			}
@@ -636,7 +635,7 @@ OverlayLoop:
 			sfiles, gccfiles = filter(sfiles, sfiles[:0], gccfiles)
 		} else {
 			for _, sfile := range sfiles {
-				data, err := ioutil.ReadFile(filepath.Join(a.Package.Dir, sfile))
+				data, err := os.ReadFile(filepath.Join(a.Package.Dir, sfile))
 				if err == nil {
 					if bytes.HasPrefix(data, []byte("TEXT")) || bytes.Contains(data, []byte("\nTEXT")) ||
 						bytes.HasPrefix(data, []byte("DATA")) || bytes.Contains(data, []byte("\nDATA")) ||
@@ -1471,7 +1470,7 @@ func (b *Builder) installShlibname(ctx context.Context, a *Action) error {
 
 	// TODO: BuildN
 	a1 := a.Deps[0]
-	err := ioutil.WriteFile(a.Target, []byte(filepath.Base(a1.Target)+"\n"), 0666)
+	err := os.WriteFile(a.Target, []byte(filepath.Base(a1.Target)+"\n"), 0666)
 	if err != nil {
 		return err
 	}
@@ -1788,7 +1787,7 @@ func (b *Builder) writeFile(file string, text []byte) error {
 	if cfg.BuildN {
 		return nil
 	}
-	return ioutil.WriteFile(file, text, 0666)
+	return os.WriteFile(file, text, 0666)
 }
 
 // Install the cgo export header file, if there is one.
@@ -2537,7 +2536,7 @@ func (b *Builder) gccSupportsFlag(compiler []string, flag string) bool {
 
 	tmp := os.DevNull
 	if runtime.GOOS == "windows" {
-		f, err := ioutil.TempFile(b.WorkDir, "")
+		f, err := os.CreateTemp(b.WorkDir, "")
 		if err != nil {
 			return false
 		}
@@ -2840,7 +2839,7 @@ func (b *Builder) cgo(a *Action, cgoExe, objdir string, pcCFLAGS, pcLDFLAGS, cgo
 				continue
 			}
 
-			src, err := ioutil.ReadFile(f)
+			src, err := os.ReadFile(f)
 			if err != nil {
 				return nil, nil, err
 			}
@@ -3070,7 +3069,7 @@ func (b *Builder) swigDoIntSize(objdir string) (intsize string, err error) {
 		return "$INTBITS", nil
 	}
 	src := filepath.Join(b.WorkDir, "swig_intsize.go")
-	if err = ioutil.WriteFile(src, []byte(swigIntSizeCode), 0666); err != nil {
+	if err = os.WriteFile(src, []byte(swigIntSizeCode), 0666); err != nil {
 		return
 	}
 	srcs := []string{src}
@@ -3230,7 +3229,7 @@ func passLongArgsInResponseFiles(cmd *exec.Cmd) (cleanup func()) {
 		return
 	}
 
-	tf, err := ioutil.TempFile("", "args")
+	tf, err := os.CreateTemp("", "args")
 	if err != nil {
 		log.Fatalf("error writing long arguments to response file: %v", err)
 	}
diff --git a/src/cmd/go/internal/work/gc.go b/src/cmd/go/internal/work/gc.go
index 3a53c714e3..cc4e2b2b2b 100644
--- a/src/cmd/go/internal/work/gc.go
+++ b/src/cmd/go/internal/work/gc.go
@@ -9,7 +9,6 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -426,11 +425,11 @@ func toolVerify(a *Action, b *Builder, p *load.Package, newTool string, ofile st
 	if err := b.run(a, p.Dir, p.ImportPath, nil, newArgs...); err != nil {
 		return err
 	}
-	data1, err := ioutil.ReadFile(ofile)
+	data1, err := os.ReadFile(ofile)
 	if err != nil {
 		return err
 	}
-	data2, err := ioutil.ReadFile(ofile + ".new")
+	data2, err := os.ReadFile(ofile + ".new")
 	if err != nil {
 		return err
 	}
@@ -580,7 +579,7 @@ func pluginPath(a *Action) string {
 	}
 	fmt.Fprintf(h, "build ID: %s\n", buildID)
 	for _, file := range str.StringList(p.GoFiles, p.CgoFiles, p.SFiles) {
-		data, err := ioutil.ReadFile(filepath.Join(p.Dir, file))
+		data, err := os.ReadFile(filepath.Join(p.Dir, file))
 		if err != nil {
 			base.Fatalf("go: %s", err)
 		}
diff --git a/src/cmd/go/internal/work/gccgo.go b/src/cmd/go/internal/work/gccgo.go
index 01d2b89159..3ffd01c473 100644
--- a/src/cmd/go/internal/work/gccgo.go
+++ b/src/cmd/go/internal/work/gccgo.go
@@ -6,7 +6,6 @@ package work
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -271,7 +270,7 @@ func (tools gccgoToolchain) link(b *Builder, root *Action, out, importcfg string
 	}
 
 	readCgoFlags := func(flagsFile string) error {
-		flags, err := ioutil.ReadFile(flagsFile)
+		flags, err := os.ReadFile(flagsFile)
 		if err != nil {
 			return err
 		}
diff --git a/src/cmd/go/script_test.go b/src/cmd/go/script_test.go
index aee3742f13..dfaa40548e 100644
--- a/src/cmd/go/script_test.go
+++ b/src/cmd/go/script_test.go
@@ -15,7 +15,6 @@ import (
 	"go/build"
 	"internal/testenv"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -220,7 +219,7 @@ func (ts *testScript) run() {
 	for _, f := range a.Files {
 		name := ts.mkabs(ts.expand(f.Name, false))
 		ts.check(os.MkdirAll(filepath.Dir(name), 0777))
-		ts.check(ioutil.WriteFile(name, f.Data, 0666))
+		ts.check(os.WriteFile(name, f.Data, 0666))
 	}
 
 	// With -v or -testwork, start log with full environment.
@@ -377,19 +376,19 @@ var (
 
 func isCaseSensitive(t *testing.T) bool {
 	onceCaseSensitive.Do(func() {
-		tmpdir, err := ioutil.TempDir("", "case-sensitive")
+		tmpdir, err := os.MkdirTemp("", "case-sensitive")
 		if err != nil {
 			t.Fatal("failed to create directory to determine case-sensitivity:", err)
 		}
 		defer os.RemoveAll(tmpdir)
 
 		fcap := filepath.Join(tmpdir, "FILE")
-		if err := ioutil.WriteFile(fcap, []byte{}, 0644); err != nil {
+		if err := os.WriteFile(fcap, []byte{}, 0644); err != nil {
 			t.Fatal("error writing file to determine case-sensitivity:", err)
 		}
 
 		flow := filepath.Join(tmpdir, "file")
-		_, err = ioutil.ReadFile(flow)
+		_, err = os.ReadFile(flow)
 		switch {
 		case err == nil:
 			caseSensitive = false
@@ -450,9 +449,9 @@ func (ts *testScript) cmdAddcrlf(want simpleStatus, args []string) {
 
 	for _, file := range args {
 		file = ts.mkabs(file)
-		data, err := ioutil.ReadFile(file)
+		data, err := os.ReadFile(file)
 		ts.check(err)
-		ts.check(ioutil.WriteFile(file, bytes.ReplaceAll(data, []byte("\n"), []byte("\r\n")), 0666))
+		ts.check(os.WriteFile(file, bytes.ReplaceAll(data, []byte("\n"), []byte("\r\n")), 0666))
 	}
 }
 
@@ -557,12 +556,12 @@ func (ts *testScript) doCmdCmp(args []string, env, quiet bool) {
 	} else if name1 == "stderr" {
 		text1 = ts.stderr
 	} else {
-		data, err := ioutil.ReadFile(ts.mkabs(name1))
+		data, err := os.ReadFile(ts.mkabs(name1))
 		ts.check(err)
 		text1 = string(data)
 	}
 
-	data, err := ioutil.ReadFile(ts.mkabs(name2))
+	data, err := os.ReadFile(ts.mkabs(name2))
 	ts.check(err)
 	text2 = string(data)
 
@@ -614,14 +613,14 @@ func (ts *testScript) cmdCp(want simpleStatus, args []string) {
 			info, err := os.Stat(src)
 			ts.check(err)
 			mode = info.Mode() & 0777
-			data, err = ioutil.ReadFile(src)
+			data, err = os.ReadFile(src)
 			ts.check(err)
 		}
 		targ := dst
 		if dstDir {
 			targ = filepath.Join(dst, filepath.Base(src))
 		}
-		err := ioutil.WriteFile(targ, data, mode)
+		err := os.WriteFile(targ, data, mode)
 		switch want {
 		case failure:
 			if err == nil {
@@ -897,7 +896,7 @@ func scriptMatch(ts *testScript, want simpleStatus, args []string, text, name st
 	isGrep := name == "grep"
 	if isGrep {
 		name = args[1] // for error messages
-		data, err := ioutil.ReadFile(ts.mkabs(args[1]))
+		data, err := os.ReadFile(ts.mkabs(args[1]))
 		ts.check(err)
 		text = string(data)
 	}
diff --git a/src/cmd/go/testdata/addmod.go b/src/cmd/go/testdata/addmod.go
index 71ac47fdc1..58376b7ed4 100644
--- a/src/cmd/go/testdata/addmod.go
+++ b/src/cmd/go/testdata/addmod.go
@@ -23,7 +23,6 @@ import (
 	"flag"
 	"fmt"
 	"io/fs"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -58,7 +57,7 @@ func main() {
 	log.SetFlags(0)
 
 	var err error
-	tmpdir, err = ioutil.TempDir("", "addmod-")
+	tmpdir, err = os.MkdirTemp("", "addmod-")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -82,7 +81,7 @@ func main() {
 
 	exitCode := 0
 	for _, arg := range flag.Args() {
-		if err := ioutil.WriteFile(filepath.Join(tmpdir, "go.mod"), []byte("module m\n"), 0666); err != nil {
+		if err := os.WriteFile(filepath.Join(tmpdir, "go.mod"), []byte("module m\n"), 0666); err != nil {
 			fatalf("%v", err)
 		}
 		run(goCmd, "get", "-d", arg)
@@ -98,13 +97,13 @@ func main() {
 			continue
 		}
 		path, vers, dir := f[0], f[1], f[2]
-		mod, err := ioutil.ReadFile(filepath.Join(gopath, "pkg/mod/cache/download", path, "@v", vers+".mod"))
+		mod, err := os.ReadFile(filepath.Join(gopath, "pkg/mod/cache/download", path, "@v", vers+".mod"))
 		if err != nil {
 			log.Printf("%s: %v", arg, err)
 			exitCode = 1
 			continue
 		}
-		info, err := ioutil.ReadFile(filepath.Join(gopath, "pkg/mod/cache/download", path, "@v", vers+".info"))
+		info, err := os.ReadFile(filepath.Join(gopath, "pkg/mod/cache/download", path, "@v", vers+".info"))
 		if err != nil {
 			log.Printf("%s: %v", arg, err)
 			exitCode = 1
@@ -128,7 +127,7 @@ func main() {
 			}
 			name := info.Name()
 			if name == "go.mod" || strings.HasSuffix(name, ".go") {
-				data, err := ioutil.ReadFile(path)
+				data, err := os.ReadFile(path)
 				if err != nil {
 					return err
 				}
@@ -144,7 +143,7 @@ func main() {
 
 		data := txtar.Format(a)
 		target := filepath.Join("mod", strings.ReplaceAll(path, "/", "_")+"_"+vers+".txt")
-		if err := ioutil.WriteFile(target, data, 0666); err != nil {
+		if err := os.WriteFile(target, data, 0666); err != nil {
 			log.Printf("%s: %v", arg, err)
 			exitCode = 1
 			continue
diff --git a/src/cmd/go/testdata/savedir.go b/src/cmd/go/testdata/savedir.go
index 75895ee279..d469c31a91 100644
--- a/src/cmd/go/testdata/savedir.go
+++ b/src/cmd/go/testdata/savedir.go
@@ -18,7 +18,6 @@ import (
 	"flag"
 	"fmt"
 	"io/fs"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -63,7 +62,7 @@ func main() {
 		if !info.Type().IsRegular() {
 			return nil
 		}
-		data, err := ioutil.ReadFile(path)
+		data, err := os.ReadFile(path)
 		if err != nil {
 			log.Fatal(err)
 		}
diff --git a/src/cmd/go/testdata/script/build_issue6480.txt b/src/cmd/go/testdata/script/build_issue6480.txt
index ae99c60d99..cf1e9ea6c2 100644
--- a/src/cmd/go/testdata/script/build_issue6480.txt
+++ b/src/cmd/go/testdata/script/build_issue6480.txt
@@ -81,7 +81,6 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"time"
 )
@@ -100,7 +99,7 @@ func truncateLike(t, p time.Time) time.Time {
 
 func main() {
 	var t1 time.Time
-	b1, err := ioutil.ReadFile(os.Args[1])
+	b1, err := os.ReadFile(os.Args[1])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
@@ -111,7 +110,7 @@ func main() {
 	}
 
 	var t2 time.Time
-	b2, err := ioutil.ReadFile(os.Args[2])
+	b2, err := os.ReadFile(os.Args[2])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
diff --git a/src/cmd/go/testdata/script/build_trimpath.txt b/src/cmd/go/testdata/script/build_trimpath.txt
index 2c3bee8fdc..e1ea0a48b2 100644
--- a/src/cmd/go/testdata/script/build_trimpath.txt
+++ b/src/cmd/go/testdata/script/build_trimpath.txt
@@ -121,7 +121,6 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -131,7 +130,7 @@ import (
 
 func main() {
 	exe := os.Args[1]
-	data, err := ioutil.ReadFile(exe)
+	data, err := os.ReadFile(exe)
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/src/cmd/go/testdata/script/cover_error.txt b/src/cmd/go/testdata/script/cover_error.txt
index 4abdf1137a..583a664237 100644
--- a/src/cmd/go/testdata/script/cover_error.txt
+++ b/src/cmd/go/testdata/script/cover_error.txt
@@ -54,7 +54,6 @@ func Test(t *testing.T) {}
 package main
 
 import (
-	"io/ioutil"
 	"log"
 	"os"
 	"strings"
@@ -62,13 +61,13 @@ import (
 
 func main() {
 	log.SetFlags(0)
-	b, err := ioutil.ReadFile(os.Args[1])
+	b, err := os.ReadFile(os.Args[1])
 	if err != nil {
 		log.Fatal(err)
 	}
 	s := strings.ReplaceAll(string(b), "p.go:4:2:", "p.go:4:")
 	s = strings.ReplaceAll(s, "p1.go:6:2:", "p1.go:6:")
-	ioutil.WriteFile(os.Args[1], []byte(s), 0644)
+	os.WriteFile(os.Args[1], []byte(s), 0644)
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/src/cmd/go/testdata/script/gopath_moved_repo.txt b/src/cmd/go/testdata/script/gopath_moved_repo.txt
index 869980da7c..99d80bff5d 100644
--- a/src/cmd/go/testdata/script/gopath_moved_repo.txt
+++ b/src/cmd/go/testdata/script/gopath_moved_repo.txt
@@ -45,7 +45,6 @@ package main
 
 import (
 	"bytes"
-	"io/ioutil"
 	"log"
 	"os"
 )
@@ -57,11 +56,11 @@ func main() {
 
 	base := []byte(os.Args[1])
 	path := os.Args[2]
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		log.Fatal(err)
 	}
-	err = ioutil.WriteFile(path, bytes.ReplaceAll(data, base, append(base, "XXX"...)), 0644)
+	err = os.WriteFile(path, bytes.ReplaceAll(data, base, append(base, "XXX"...)), 0644)
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/src/cmd/go/testdata/script/mod_download_concurrent_read.txt b/src/cmd/go/testdata/script/mod_download_concurrent_read.txt
index caf105c6e5..231babd0c0 100644
--- a/src/cmd/go/testdata/script/mod_download_concurrent_read.txt
+++ b/src/cmd/go/testdata/script/mod_download_concurrent_read.txt
@@ -25,7 +25,6 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -45,7 +44,7 @@ func main() {
 // don't need to clean the cache or synchronize closing files after each
 // iteration.
 func run() (err error) {
-	tmpDir, err := ioutil.TempDir("", "")
+	tmpDir, err := os.MkdirTemp("", "")
 	if err != nil {
 		return err
 	}
diff --git a/src/cmd/go/testdata/script/mod_modinfo.txt b/src/cmd/go/testdata/script/mod_modinfo.txt
index d9e9fdec21..8d77e224a5 100644
--- a/src/cmd/go/testdata/script/mod_modinfo.txt
+++ b/src/cmd/go/testdata/script/mod_modinfo.txt
@@ -69,7 +69,6 @@ package main
 import (
 	"bytes"
 	"encoding/hex"
-	"io/ioutil"
 	"log"
 	"os"
 
@@ -77,7 +76,7 @@ import (
 )
 
 func main() {
-	b, err := ioutil.ReadFile(os.Args[0])
+	b, err := os.ReadFile(os.Args[0])
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/src/cmd/go/testdata/script/mod_test_cached.txt b/src/cmd/go/testdata/script/mod_test_cached.txt
index ffd573c02a..3da4358fa1 100644
--- a/src/cmd/go/testdata/script/mod_test_cached.txt
+++ b/src/cmd/go/testdata/script/mod_test_cached.txt
@@ -51,26 +51,25 @@ bar
 package foo_test
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
 )
 
 func TestWriteTmp(t *testing.T) {
-	dir, err := ioutil.TempDir("", "")
+	dir, err := os.MkdirTemp("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
 	defer os.RemoveAll(dir)
-	err = ioutil.WriteFile(filepath.Join(dir, "x"), nil, 0666)
+	err = os.WriteFile(filepath.Join(dir, "x"), nil, 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
 }
 
 func TestReadTestdata(t *testing.T) {
-	_, err := ioutil.ReadFile("testdata/foo.txt")
+	_, err := os.ReadFile("testdata/foo.txt")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/testdata/script/test_compile_tempfile.txt b/src/cmd/go/testdata/script/test_compile_tempfile.txt
index 912410814f..05f721a800 100644
--- a/src/cmd/go/testdata/script/test_compile_tempfile.txt
+++ b/src/cmd/go/testdata/script/test_compile_tempfile.txt
@@ -1,7 +1,7 @@
 [short] skip
 
 # Ensure that the target of 'go build -o' can be an existing, empty file so that
-# its name can be reserved using ioutil.TempFile or the 'mktemp` command.
+# its name can be reserved using os.CreateTemp or the 'mktemp` command.
 
 go build -o empty-file$GOEXE main.go
 
diff --git a/src/cmd/go/testdata/script/test_generated_main.txt b/src/cmd/go/testdata/script/test_generated_main.txt
index 75ffa9cde2..2e991a5797 100644
--- a/src/cmd/go/testdata/script/test_generated_main.txt
+++ b/src/cmd/go/testdata/script/test_generated_main.txt
@@ -12,7 +12,6 @@ package x
 import (
 	"os"
 	"path/filepath"
-	"io/ioutil"
 	"regexp"
 	"testing"
 )
@@ -23,7 +22,7 @@ func Test(t *testing.T) {
 		t.Fatal(err)
 	}
 	testmainPath := filepath.Join(filepath.Dir(exePath), "_testmain.go")
-	source, err := ioutil.ReadFile(testmainPath)
+	source, err := os.ReadFile(testmainPath)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/go/testdata/script/test_race_install_cgo.txt b/src/cmd/go/testdata/script/test_race_install_cgo.txt
index 82f00f2086..3f4eb90e3f 100644
--- a/src/cmd/go/testdata/script/test_race_install_cgo.txt
+++ b/src/cmd/go/testdata/script/test_race_install_cgo.txt
@@ -29,7 +29,6 @@ go 1.16
 package main
 
 import (
-	"io/ioutil"
 	"encoding/json"
 	"fmt"
 	"os"
@@ -37,7 +36,7 @@ import (
 )
 
 func main() {
-	b, err := ioutil.ReadFile(os.Args[1])
+	b, err := os.ReadFile(os.Args[1])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
@@ -59,7 +58,6 @@ package main
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"time"
 )
@@ -67,7 +65,7 @@ import (
 
 func main() {
 	var t1 time.Time
-	b1, err := ioutil.ReadFile(os.Args[1])
+	b1, err := os.ReadFile(os.Args[1])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
@@ -78,7 +76,7 @@ func main() {
 	}
 
 	var t2 time.Time
-	b2, err := ioutil.ReadFile(os.Args[2])
+	b2, err := os.ReadFile(os.Args[2])
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
diff --git a/src/cmd/gofmt/gofmt.go b/src/cmd/gofmt/gofmt.go
index 719c681a3e..2793c2c2a4 100644
--- a/src/cmd/gofmt/gofmt.go
+++ b/src/cmd/gofmt/gofmt.go
@@ -15,7 +15,6 @@ import (
 	"go/token"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -137,7 +136,7 @@ func processFile(filename string, in io.Reader, out io.Writer, stdin bool) error
 			if err != nil {
 				return err
 			}
-			err = ioutil.WriteFile(filename, res, perm)
+			err = os.WriteFile(filename, res, perm)
 			if err != nil {
 				os.Rename(bakname, filename)
 				return err
@@ -278,7 +277,7 @@ const chmodSupported = runtime.GOOS != "windows"
 // the chosen file name.
 func backupFile(filename string, data []byte, perm fs.FileMode) (string, error) {
 	// create backup file
-	f, err := ioutil.TempFile(filepath.Dir(filename), filepath.Base(filename))
+	f, err := os.CreateTemp(filepath.Dir(filename), filepath.Base(filename))
 	if err != nil {
 		return "", err
 	}
diff --git a/src/cmd/gofmt/gofmt_test.go b/src/cmd/gofmt/gofmt_test.go
index 98d3eb7eb2..bf2adfe64c 100644
--- a/src/cmd/gofmt/gofmt_test.go
+++ b/src/cmd/gofmt/gofmt_test.go
@@ -7,7 +7,6 @@ package main
 import (
 	"bytes"
 	"flag"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -93,7 +92,7 @@ func runTest(t *testing.T, in, out string) {
 		return
 	}
 
-	expected, err := ioutil.ReadFile(out)
+	expected, err := os.ReadFile(out)
 	if err != nil {
 		t.Error(err)
 		return
@@ -102,7 +101,7 @@ func runTest(t *testing.T, in, out string) {
 	if got := buf.Bytes(); !bytes.Equal(got, expected) {
 		if *update {
 			if in != out {
-				if err := ioutil.WriteFile(out, got, 0666); err != nil {
+				if err := os.WriteFile(out, got, 0666); err != nil {
 					t.Error(err)
 				}
 				return
@@ -116,7 +115,7 @@ func runTest(t *testing.T, in, out string) {
 		if err == nil {
 			t.Errorf("%s", d)
 		}
-		if err := ioutil.WriteFile(in+".gofmt", got, 0666); err != nil {
+		if err := os.WriteFile(in+".gofmt", got, 0666); err != nil {
 			t.Error(err)
 		}
 	}
@@ -157,7 +156,7 @@ func TestCRLF(t *testing.T) {
 	const input = "testdata/crlf.input"   // must contain CR/LF's
 	const golden = "testdata/crlf.golden" // must not contain any CR's
 
-	data, err := ioutil.ReadFile(input)
+	data, err := os.ReadFile(input)
 	if err != nil {
 		t.Error(err)
 	}
@@ -165,7 +164,7 @@ func TestCRLF(t *testing.T) {
 		t.Errorf("%s contains no CR/LF's", input)
 	}
 
-	data, err = ioutil.ReadFile(golden)
+	data, err = os.ReadFile(golden)
 	if err != nil {
 		t.Error(err)
 	}
@@ -175,7 +174,7 @@ func TestCRLF(t *testing.T) {
 }
 
 func TestBackupFile(t *testing.T) {
-	dir, err := ioutil.TempDir("", "gofmt_test")
+	dir, err := os.MkdirTemp("", "gofmt_test")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/nm/nm_test.go b/src/cmd/nm/nm_test.go
index 382446e9fe..0d51b07a44 100644
--- a/src/cmd/nm/nm_test.go
+++ b/src/cmd/nm/nm_test.go
@@ -8,7 +8,6 @@ import (
 	"fmt"
 	"internal/obscuretestdata"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -31,7 +30,7 @@ func testMain(m *testing.M) int {
 		return 0
 	}
 
-	tmpDir, err := ioutil.TempDir("", "TestNM")
+	tmpDir, err := os.MkdirTemp("", "TestNM")
 	if err != nil {
 		fmt.Println("TempDir failed:", err)
 		return 2
@@ -88,7 +87,7 @@ func TestNonGoExecs(t *testing.T) {
 
 func testGoExec(t *testing.T, iscgo, isexternallinker bool) {
 	t.Parallel()
-	tmpdir, err := ioutil.TempDir("", "TestGoExec")
+	tmpdir, err := os.MkdirTemp("", "TestGoExec")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -222,7 +221,7 @@ func TestGoExec(t *testing.T) {
 
 func testGoLib(t *testing.T, iscgo bool) {
 	t.Parallel()
-	tmpdir, err := ioutil.TempDir("", "TestGoLib")
+	tmpdir, err := os.MkdirTemp("", "TestGoLib")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -245,7 +244,7 @@ func testGoLib(t *testing.T, iscgo bool) {
 		err = e
 	}
 	if err == nil {
-		err = ioutil.WriteFile(filepath.Join(libpath, "go.mod"), []byte("module mylib\n"), 0666)
+		err = os.WriteFile(filepath.Join(libpath, "go.mod"), []byte("module mylib\n"), 0666)
 	}
 	if err != nil {
 		t.Fatal(err)
diff --git a/src/cmd/objdump/objdump_test.go b/src/cmd/objdump/objdump_test.go
index cb692e7a81..edaca774f7 100644
--- a/src/cmd/objdump/objdump_test.go
+++ b/src/cmd/objdump/objdump_test.go
@@ -10,7 +10,6 @@ import (
 	"fmt"
 	"go/build"
 	"internal/testenv"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -39,7 +38,7 @@ func TestMain(m *testing.M) {
 
 func buildObjdump() error {
 	var err error
-	tmp, err = ioutil.TempDir("", "TestObjDump")
+	tmp, err = os.MkdirTemp("", "TestObjDump")
 	if err != nil {
 		return fmt.Errorf("TempDir failed: %v", err)
 	}
@@ -320,7 +319,7 @@ func TestGoobjFileNumber(t *testing.T) {
 
 	t.Parallel()
 
-	tmpdir, err := ioutil.TempDir("", "TestGoobjFileNumber")
+	tmpdir, err := os.MkdirTemp("", "TestGoobjFileNumber")
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/pack/pack_test.go b/src/cmd/pack/pack_test.go
index 9f65705def..218c7acda6 100644
--- a/src/cmd/pack/pack_test.go
+++ b/src/cmd/pack/pack_test.go
@@ -12,7 +12,6 @@ import (
 	"internal/testenv"
 	"io"
 	"io/fs"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -22,7 +21,7 @@ import (
 
 // tmpDir creates a temporary directory and returns its name.
 func tmpDir(t *testing.T) string {
-	name, err := ioutil.TempDir("", "pack")
+	name, err := os.MkdirTemp("", "pack")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -158,7 +157,7 @@ func TestExtract(t *testing.T) {
 	ar = openArchive(name, os.O_RDONLY, []string{goodbyeFile.name})
 	ar.scan(ar.extractContents)
 	ar.a.File().Close()
-	data, err := ioutil.ReadFile(goodbyeFile.name)
+	data, err := os.ReadFile(goodbyeFile.name)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -183,7 +182,7 @@ func TestHello(t *testing.T) {
 			println("hello world")
 		}
 	`
-	err := ioutil.WriteFile(hello, []byte(prog), 0666)
+	err := os.WriteFile(hello, []byte(prog), 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -251,7 +250,7 @@ func TestLargeDefs(t *testing.T) {
 			println("ok")
 		}
 	`
-	err = ioutil.WriteFile(main, []byte(prog), 0666)
+	err = os.WriteFile(main, []byte(prog), 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -281,13 +280,13 @@ func TestIssue21703(t *testing.T) {
 	defer os.RemoveAll(dir)
 
 	const aSrc = `package a; const X = "\n!\n"`
-	err := ioutil.WriteFile(filepath.Join(dir, "a.go"), []byte(aSrc), 0666)
+	err := os.WriteFile(filepath.Join(dir, "a.go"), []byte(aSrc), 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
 
 	const bSrc = `package b; import _ "a"`
-	err = ioutil.WriteFile(filepath.Join(dir, "b.go"), []byte(bSrc), 0666)
+	err = os.WriteFile(filepath.Join(dir, "b.go"), []byte(bSrc), 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
diff --git a/src/cmd/trace/annotations_test.go b/src/cmd/trace/annotations_test.go
index a9068d53c1..9c2d027366 100644
--- a/src/cmd/trace/annotations_test.go
+++ b/src/cmd/trace/annotations_test.go
@@ -12,7 +12,7 @@ import (
 	"flag"
 	"fmt"
 	traceparser "internal/trace"
-	"io/ioutil"
+	"os"
 	"reflect"
 	"runtime/debug"
 	"runtime/trace"
@@ -386,7 +386,7 @@ func saveTrace(buf *bytes.Buffer, name string) {
 	if !*saveTraces {
 		return
 	}
-	if err := ioutil.WriteFile(name+".trace", buf.Bytes(), 0600); err != nil {
+	if err := os.WriteFile(name+".trace", buf.Bytes(), 0600); err != nil {
 		panic(fmt.Errorf("failed to write trace file: %v", err))
 	}
 }
diff --git a/src/cmd/trace/pprof.go b/src/cmd/trace/pprof.go
index a31d71b013..a73ff5336a 100644
--- a/src/cmd/trace/pprof.go
+++ b/src/cmd/trace/pprof.go
@@ -11,7 +11,6 @@ import (
 	"fmt"
 	"internal/trace"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"os/exec"
@@ -294,7 +293,7 @@ func serveSVGProfile(prof func(w io.Writer, r *http.Request) error) http.Handler
 			return
 		}
 
-		blockf, err := ioutil.TempFile("", "block")
+		blockf, err := os.CreateTemp("", "block")
 		if err != nil {
 			http.Error(w, fmt.Sprintf("failed to create temp file: %v", err), http.StatusInternalServerError)
 			return
diff --git a/src/cmd/vet/vet_test.go b/src/cmd/vet/vet_test.go
index 5d8139d977..d15d1ce377 100644
--- a/src/cmd/vet/vet_test.go
+++ b/src/cmd/vet/vet_test.go
@@ -9,7 +9,6 @@ import (
 	"errors"
 	"fmt"
 	"internal/testenv"
-	"io/ioutil"
 	"log"
 	"os"
 	"os/exec"
@@ -32,7 +31,7 @@ func TestMain(m *testing.M) {
 }
 
 func testMain(m *testing.M) int {
-	dir, err := ioutil.TempDir("", "vet_test")
+	dir, err := os.MkdirTemp("", "vet_test")
 	if err != nil {
 		fmt.Fprintln(os.Stderr, err)
 		return 1
@@ -345,7 +344,7 @@ var (
 func wantedErrors(file, short string) (errs []wantedError) {
 	cache := make(map[string]*regexp.Regexp)
 
-	src, err := ioutil.ReadFile(file)
+	src, err := os.ReadFile(file)
 	if err != nil {
 		log.Fatal(err)
 	}