tools: replace references to obsolete package ioutils

ioutil defines 7 functions. 6 of these are replaced by
functions in io or os with the same signature.
ReadDir is deprecated, but the suggested replacement has a different
signature.

These changes were generated by a program, with some manual adjutments.
The program replaces ReadDir with a call to a function named ioutilReadDir
that has the same signature. The code for this function
is added to files if necessary. The program replaces all the others
with their new versions. The program removes the 'io/ioutil' import
and adds, as necessary, 'os', 'io', and 'io/fs', the latter being
needed for the signature of ioutilReadDir.

The automatic process fails in a few ways:
1. ReadFile occurs only in a comment but the program adds an unneeded import.
2. ioutilReadDir is added to more than one file in the same package
Both of these could be viewed as bugs and fixed by looking harder.

After manual adjustment, two tests failed:
1. gopls/internal/lsp/regtesg/mis:TestGenerateProgress. The reason
	 was a use of ioutil in a txtar constant. The calls were changed,
	 but the code is not smart enough to change the import inside the
	 string constant. (Or it's not smart enough not to change the
	 contents of a string.)
2. gopls/internal/lsp/analysis/deprecated, which wants to see a use
	 of ioutil

These tests were adjused by hand, and all tests (-short) pass.

Change-Id: If9efe40bbb0edda36173d9a88afaf71245db8e79
Reviewed-on: https://go-review.googlesource.com/c/tools/+/527675
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Peter Weinberger <pjw@google.com>
Reviewed-by: Heschi Kreinick <heschi@google.com>

cmd/auth/netrcauth/netrcauth.go

@@ -16,7 +16,6 @@ package main
 
 import (
 	"fmt"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"net/url"
@@ -41,7 +40,7 @@ func main() {
 
 	path := os.Args[1]
 
-	data, err := ioutil.ReadFile(path)
+	data, err := os.ReadFile(path)
 	if err != nil {
 		if os.IsNotExist(err) {
 			return

cmd/bundle/main.go

@@ -79,7 +79,6 @@ import (
 	"go/printer"
 	"go/token"
 	"go/types"
-	"io/ioutil"
 	"log"
 	"os"
 	"strconv"
@@ -149,7 +148,7 @@ func main() {
 		log.Fatal(err)
 	}
 	if *outputFile != "" {
-		err := ioutil.WriteFile(*outputFile, code, 0666)
+		err := os.WriteFile(*outputFile, code, 0666)
 		if err != nil {
 			log.Fatal(err)
 		}

cmd/bundle/main_test.go

@@ -6,7 +6,6 @@ package main
 
 import (
 	"bytes"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"runtime"
@@ -18,7 +17,7 @@ import (
 func TestBundle(t *testing.T) { packagestest.TestAll(t, testBundle) }
 func testBundle(t *testing.T, x packagestest.Exporter) {
 	load := func(name string) string {
-		data, err := ioutil.ReadFile(name)
+		data, err := os.ReadFile(name)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -53,7 +52,7 @@ func testBundle(t *testing.T, x packagestest.Exporter) {
 	if got, want := string(out), load("testdata/out.golden"); got != want {
 		t.Errorf("-- got --\n%s\n-- want --\n%s\n-- diff --", got, want)
 
-		if err := ioutil.WriteFile("testdata/out.got", out, 0644); err != nil {
+		if err := os.WriteFile("testdata/out.got", out, 0644); err != nil {
 			t.Fatal(err)
 		}
 		t.Log(diff("testdata/out.golden", "testdata/out.got"))

cmd/compilebench/main.go

@@ -81,7 +81,6 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -388,7 +387,7 @@ func (c compile) run(name string, count int) error {
 	opath := pkg.Dir + "/_compilebench_.o"
 	if *flagObj {
 		// TODO(josharian): object files are big; just read enough to find what we seek.
-		data, err := ioutil.ReadFile(opath)
+		data, err := os.ReadFile(opath)
 		if err != nil {
 			log.Print(err)
 		}
@@ -498,7 +497,7 @@ func runBuildCmd(name string, count int, dir, tool string, args []string) error
 	haveAllocs, haveRSS := false, false
 	var allocs, allocbytes, rssbytes int64
 	if *flagAlloc || *flagMemprofile != "" {
-		out, err := ioutil.ReadFile(dir + "/_compilebench_.memprof")
+		out, err := os.ReadFile(dir + "/_compilebench_.memprof")
 		if err != nil {
 			log.Print("cannot find memory profile after compilation")
 		}
@@ -531,23 +530,23 @@ func runBuildCmd(name string, count int, dir, tool string, args []string) error
 			if *flagCount != 1 {
 				outpath = fmt.Sprintf("%s_%d", outpath, count)
 			}
-			if err := ioutil.WriteFile(outpath, out, 0666); err != nil {
+			if err := os.WriteFile(outpath, out, 0666); err != nil {
 				log.Print(err)
 			}
 		}
 		os.Remove(dir + "/_compilebench_.memprof")
 	}
 
 	if *flagCpuprofile != "" {
-		out, err := ioutil.ReadFile(dir + "/_compilebench_.cpuprof")
+		out, err := os.ReadFile(dir + "/_compilebench_.cpuprof")
 		if err != nil {
 			log.Print(err)
 		}
 		outpath := *flagCpuprofile
 		if *flagCount != 1 {
 			outpath = fmt.Sprintf("%s_%d", outpath, count)
 		}
-		if err := ioutil.WriteFile(outpath, out, 0666); err != nil {
+		if err := os.WriteFile(outpath, out, 0666); err != nil {
 			log.Print(err)
 		}
 		os.Remove(dir + "/_compilebench_.cpuprof")

cmd/eg/eg.go

@@ -15,7 +15,6 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
@@ -77,7 +76,7 @@ func doMain() error {
 	if err != nil {
 		return err
 	}
-	template, err := ioutil.ReadFile(tAbs)
+	template, err := os.ReadFile(tAbs)
 	if err != nil {
 		return err
 	}

cmd/file2fuzz/main.go

@@ -25,7 +25,6 @@ import (
 	"flag"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -51,7 +50,7 @@ func dirWriter(dir string) func([]byte) error {
 		if err := os.MkdirAll(dir, 0777); err != nil {
 			return err
 		}
-		if err := ioutil.WriteFile(name, b, 0666); err != nil {
+		if err := os.WriteFile(name, b, 0666); err != nil {
 			os.Remove(name)
 			return err
 		}
@@ -98,14 +97,14 @@ func convert(inputArgs []string, outputArg string) error {
 				output = dirWriter(outputArg)
 			} else {
 				output = func(b []byte) error {
-					return ioutil.WriteFile(outputArg, b, 0666)
+					return os.WriteFile(outputArg, b, 0666)
 				}
 			}
 		}
 	}
 
 	for _, f := range input {
-		b, err := ioutil.ReadAll(f)
+		b, err := io.ReadAll(f)
 		if err != nil {
 			return fmt.Errorf("unable to read input: %s", err)
 		}

cmd/file2fuzz/main_test.go

@@ -5,7 +5,6 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -118,9 +117,9 @@ func TestFile2Fuzz(t *testing.T) {
 
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			tmp, err := ioutil.TempDir(os.TempDir(), "file2fuzz")
+			tmp, err := os.MkdirTemp(os.TempDir(), "file2fuzz")
 			if err != nil {
-				t.Fatalf("ioutil.TempDir failed: %s", err)
+				t.Fatalf("os.MkdirTemp failed: %s", err)
 			}
 			defer os.RemoveAll(tmp)
 			for _, f := range tc.inputFiles {
@@ -129,7 +128,7 @@ func TestFile2Fuzz(t *testing.T) {
 						t.Fatalf("failed to create test directory: %s", err)
 					}
 				} else {
-					if err := ioutil.WriteFile(filepath.Join(tmp, f.name), []byte(f.content), 0666); err != nil {
+					if err := os.WriteFile(filepath.Join(tmp, f.name), []byte(f.content), 0666); err != nil {
 						t.Fatalf("failed to create test input file: %s", err)
 					}
 				}
@@ -146,7 +145,7 @@ func TestFile2Fuzz(t *testing.T) {
 			}
 
 			for _, f := range tc.expectedFiles {
-				c, err := ioutil.ReadFile(filepath.Join(tmp, f.name))
+				c, err := os.ReadFile(filepath.Join(tmp, f.name))
 				if err != nil {
 					t.Fatalf("failed to read expected output file %q: %s", f.name, err)
 				}

cmd/fiximports/main.go

@@ -76,7 +76,6 @@ import (
 	"go/parser"
 	"go/token"
 	"io"
-	"io/ioutil"
 	"log"
 	"os"
 	"path"
@@ -100,7 +99,7 @@ var (
 // seams for testing
 var (
 	stderr    io.Writer = os.Stderr
-	writeFile           = ioutil.WriteFile
+	writeFile           = os.WriteFile
 )
 
 const usage = `fiximports: rewrite import paths to use canonical package names.

cmd/getgo/download.go

@@ -15,7 +15,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -51,7 +50,7 @@ func downloadGoVersion(version, ops, arch, dest string) error {
 	}
 	defer resp.Body.Close()
 
-	tmpf, err := ioutil.TempFile("", "go")
+	tmpf, err := os.CreateTemp("", "go")
 	if err != nil {
 		return err
 	}
@@ -75,7 +74,7 @@ func downloadGoVersion(version, ops, arch, dest string) error {
 		return fmt.Errorf("Downloading Go sha256 from %s.sha256 failed with HTTP status %s", uri, sresp.Status)
 	}
 
-	shasum, err := ioutil.ReadAll(sresp.Body)
+	shasum, err := io.ReadAll(sresp.Body)
 	if err != nil {
 		return err
 	}
@@ -174,7 +173,7 @@ func getLatestGoVersion() (string, error) {
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
-		b, _ := ioutil.ReadAll(io.LimitReader(resp.Body, 1024))
+		b, _ := io.ReadAll(io.LimitReader(resp.Body, 1024))
 		return "", fmt.Errorf("Could not get current Go release: HTTP %d: %q", resp.StatusCode, b)
 	}
 	var releases []struct {

cmd/getgo/download_test.go

@@ -8,7 +8,6 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"testing"
@@ -19,7 +18,7 @@ func TestDownloadGoVersion(t *testing.T) {
 		t.Skipf("Skipping download in short mode")
 	}
 
-	tmpd, err := ioutil.TempDir("", "go")
+	tmpd, err := os.MkdirTemp("", "go")
 	if err != nil {
 		t.Fatal(err)
 	}

cmd/getgo/main_test.go

@@ -10,7 +10,6 @@ package main
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"testing"
@@ -37,7 +36,7 @@ func TestMain(m *testing.M) {
 }
 
 func createTmpHome(t *testing.T) string {
-	tmpd, err := ioutil.TempDir("", "testgetgo")
+	tmpd, err := os.MkdirTemp("", "testgetgo")
 	if err != nil {
 		t.Fatalf("creating test tempdir failed: %v", err)
 	}
@@ -86,7 +85,7 @@ func TestCommandVerbose(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	b, err := ioutil.ReadFile(shellConfig)
+	b, err := os.ReadFile(shellConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -122,7 +121,7 @@ func TestCommandPathExists(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	b, err := ioutil.ReadFile(shellConfig)
+	b, err := os.ReadFile(shellConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -146,7 +145,7 @@ export PATH=$PATH:%s/go/bin
 		t.Fatal(err)
 	}
 
-	b, err = ioutil.ReadFile(shellConfig)
+	b, err = os.ReadFile(shellConfig)
 	if err != nil {
 		t.Fatal(err)
 	}

cmd/getgo/path_test.go

@@ -8,15 +8,14 @@
 package main
 
 import (
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
 	"testing"
 )
 
 func TestAppendPath(t *testing.T) {
-	tmpd, err := ioutil.TempDir("", "go")
+	tmpd, err := os.MkdirTemp("", "go")
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -35,7 +34,7 @@ func TestAppendPath(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	b, err := ioutil.ReadFile(shellConfig)
+	b, err := os.ReadFile(shellConfig)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -49,7 +48,7 @@ func TestAppendPath(t *testing.T) {
 	if err := appendToPATH(filepath.Join(GOPATH, "bin")); err != nil {
 		t.Fatal(err)
 	}
-	b, err = ioutil.ReadFile(shellConfig)
+	b, err = os.ReadFile(shellConfig)
 	if err != nil {
 		t.Fatal(err)
 	}

cmd/go-contrib-init/contrib.go

@@ -14,7 +14,6 @@ import (
 	"fmt"
 	"go/build"
 	exec "golang.org/x/sys/execabs"
-	"io/ioutil"
 	"log"
 	"os"
 	"path/filepath"
@@ -66,7 +65,7 @@ func detectrepo() string {
 var googleSourceRx = regexp.MustCompile(`(?m)^(go|go-review)?\.googlesource.com\b`)
 
 func checkCLA() {
-	slurp, err := ioutil.ReadFile(cookiesFile())
+	slurp, err := os.ReadFile(cookiesFile())
 	if err != nil && !os.IsNotExist(err) {
 		log.Fatal(err)
 	}
@@ -135,7 +134,7 @@ func checkGoroot() {
 				"your GOROOT or set it to the path of your development version\n"+
 				"of Go.", v)
 		}
-		slurp, err := ioutil.ReadFile(filepath.Join(v, "VERSION"))
+		slurp, err := os.ReadFile(filepath.Join(v, "VERSION"))
 		if err == nil {
 			slurp = bytes.TrimSpace(slurp)
 			log.Fatalf("Your GOROOT environment variable is set to %q\n"+