4 files changed, 14 insertions, 21 deletions

diff --git a/src/cmd/go/internal/modcmd/download.go b/src/cmd/go/internal/modcmd/download.go
index 050a2e0e12..e2e8ba6825 100644
--- a/src/cmd/go/internal/modcmd/download.go
+++ b/src/cmd/go/internal/modcmd/download.go
@@ -87,7 +87,7 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 	if len(args) == 0 {
 		args = []string{"all"}
 	} else if modload.HasModRoot() {
-		modload.InitMod(ctx) // to fill Target
+		modload.LoadModFile(ctx) // to fill Target
 		targetAtLatest := modload.Target.Path + "@latest"
 		targetAtUpgrade := modload.Target.Path + "@upgrade"
 		targetAtPatch := modload.Target.Path + "@patch"
diff --git a/src/cmd/go/internal/modcmd/init.go b/src/cmd/go/internal/modcmd/init.go
index 7cfc0e6f5b..7384f3f293 100644
--- a/src/cmd/go/internal/modcmd/init.go
+++ b/src/cmd/go/internal/modcmd/init.go
@@ -10,8 +10,6 @@ import (
 	"cmd/go/internal/base"
 	"cmd/go/internal/modload"
 	"context"
-	"os"
-	"strings"
 )
 
 var cmdInit = &base.Command{
@@ -33,21 +31,14 @@ func init() {
 }
 
 func runInit(ctx context.Context, cmd *base.Command, args []string) {
-	modload.CmdModInit = true
 	if len(args) > 1 {
 		base.Fatalf("go mod init: too many arguments")
 	}
+	var modPath string
 	if len(args) == 1 {
-		modload.CmdModModule = args[0]
+		modPath = args[0]
 	}
+
 	modload.ForceUseModules = true
-	modFilePath := modload.ModFilePath()
-	if _, err := os.Stat(modFilePath); err == nil {
-		base.Fatalf("go mod init: go.mod already exists")
-	}
-	if strings.Contains(modload.CmdModModule, "@") {
-		base.Fatalf("go mod init: module path must not contain '@'")
-	}
-	modload.InitMod(ctx) // does all the hard work
-	modload.WriteGoMod()
+	modload.CreateModFile(ctx, modPath) // does all the hard work
 }
diff --git a/src/cmd/go/internal/modcmd/vendor.go b/src/cmd/go/internal/modcmd/vendor.go
index 1bc4ab3def..1b9ce60529 100644
--- a/src/cmd/go/internal/modcmd/vendor.go
+++ b/src/cmd/go/internal/modcmd/vendor.go
@@ -9,6 +9,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"io/fs"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -232,7 +233,7 @@ var metaPrefixes = []string{
 }
 
 // matchMetadata reports whether info is a metadata file.
-func matchMetadata(dir string, info os.FileInfo) bool {
+func matchMetadata(dir string, info fs.FileInfo) bool {
 	name := info.Name()
 	for _, p := range metaPrefixes {
 		if strings.HasPrefix(name, p) {
@@ -243,7 +244,7 @@ func matchMetadata(dir string, info os.FileInfo) bool {
 }
 
 // matchPotentialSourceFile reports whether info may be relevant to a build operation.
-func matchPotentialSourceFile(dir string, info os.FileInfo) bool {
+func matchPotentialSourceFile(dir string, info fs.FileInfo) bool {
 	if strings.HasSuffix(info.Name(), "_test.go") {
 		return false
 	}
@@ -269,7 +270,7 @@ func matchPotentialSourceFile(dir string, info os.FileInfo) bool {
 }
 
 // copyDir copies all regular files satisfying match(info) from src to dst.
-func copyDir(dst, src string, match func(dir string, info os.FileInfo) bool) {
+func copyDir(dst, src string, match func(dir string, info fs.FileInfo) bool) {
 	files, err := ioutil.ReadDir(src)
 	if 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 bd591d3f32..ce24793929 100644
--- a/src/cmd/go/internal/modcmd/verify.go
+++ b/src/cmd/go/internal/modcmd/verify.go
@@ -9,6 +9,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"io/fs"
 	"io/ioutil"
 	"os"
 	"runtime"
@@ -88,8 +89,8 @@ func verifyMod(mod module.Version) []error {
 	dir, dirErr := modfetch.DownloadDir(mod)
 	data, err := ioutil.ReadFile(zip + "hash")
 	if err != nil {
-		if zipErr != nil && errors.Is(zipErr, os.ErrNotExist) &&
-			dirErr != nil && errors.Is(dirErr, os.ErrNotExist) {
+		if zipErr != nil && errors.Is(zipErr, fs.ErrNotExist) &&
+			dirErr != nil && errors.Is(dirErr, fs.ErrNotExist) {
 			// Nothing downloaded yet. Nothing to verify.
 			return nil
 		}
@@ -98,7 +99,7 @@ func verifyMod(mod module.Version) []error {
 	}
 	h := string(bytes.TrimSpace(data))
 
-	if zipErr != nil && errors.Is(zipErr, os.ErrNotExist) {
+	if zipErr != nil && errors.Is(zipErr, fs.ErrNotExist) {
 		// ok
 	} else {
 		hZ, err := dirhash.HashZip(zip, dirhash.DefaultHash)
@@ -109,7 +110,7 @@ func verifyMod(mod module.Version) []error {
 			errs = append(errs, fmt.Errorf("%s %s: zip has been modified (%v)", mod.Path, mod.Version, zip))
 		}
 	}
-	if dirErr != nil && errors.Is(dirErr, os.ErrNotExist) {
+	if dirErr != nil && errors.Is(dirErr, fs.ErrNotExist) {
 		// ok
 	} else {
 		hD, err := dirhash.HashDir(dir, mod.Path+"@"+mod.Version, dirhash.DefaultHash)