take advantage of Go 1.22

cmp.Or and no longer needing to shallow copy range loop vars.

While here, remove an unused parameter as spotted by gopls.

goproxytest/proxy.go

@@ -24,6 +24,7 @@ package goproxytest
 import (
 	"archive/zip"
 	"bytes"
+	"cmp"
 	"encoding/json"
 	"fmt"
 	"io/fs"
@@ -76,12 +77,8 @@ func NewServer(dir, addr string) (*Server, error) {
 }
 
 func newServer(dir, addr string, logf func(string, ...any)) (*Server, error) {
-	if addr == "" {
-		addr = "localhost:0"
-	}
-	if dir == "" {
-		dir = "testmod"
-	}
+	addr = cmp.Or(addr, "localhost:0")
+	dir = cmp.Or(dir, "testmod")
 	srv := Server{dir: dir, logf: logf}
 	if err := srv.readModList(); err != nil {
 		return nil, fmt.Errorf("cannot read modules: %v", err)

imports/scan.go

@@ -85,6 +85,7 @@ Files:
 
 var ErrNoGo = fmt.Errorf("no Go source files")
 
+// TODO: replace with maps.Keys from go1.23
 func keys(m map[string]bool) []string {
 	var list []string
 	for k := range m {

internal/os/execpath/lp_unix.go

@@ -7,6 +7,7 @@
 package execpath
 
 import (
+	"cmp"
 	"os"
 	"path/filepath"
 	"strings"
@@ -45,10 +46,8 @@ func Look(file string, getenv func(string) string) (string, error) {
 	}
 	path := getenv("PATH")
 	for _, dir := range filepath.SplitList(path) {
-		if dir == "" {
-			// Unix shell semantics: path element "" means "."
-			dir = "."
-		}
+		// Unix shell semantics: path element "" means "."
+		dir = cmp.Or(dir, ".")
 		path := filepath.Join(dir, file)
 		if err := findExecutable(path); err == nil {
 			return path, nil

testscript/exe.go

@@ -75,7 +75,6 @@ func RunMain(m TestingM, commands map[string]func() int) (exitCode int) {
 
 		// We're not in a subcommand.
 		for name := range commands {
-			name := name
 			// Set up this command in the directory we added to $PATH.
 			binfile := filepath.Join(bindir, name)
 			if runtime.GOOS == "windows" {

testscript/testscript.go

@@ -320,7 +320,6 @@ func RunT(t T, p Params) {
 	refCount := int32(len(files))
 	names := make(map[string]bool)
 	for _, file := range files {
-		file := file
 		name := filepath.Base(file)
 		if name1, ok := strings.CutSuffix(name, ".txt"); ok {
 			name = name1
@@ -737,13 +736,13 @@ func (ts *TestScript) runLine(line string) (runOK bool) {
 			ts.Fatalf("unknown command %q", args[0])
 		}
 	}
-	ts.callBuiltinCmd(args[0], func() {
+	ts.callBuiltinCmd(func() {
 		cmd(ts, neg, args[1:])
 	})
 	return true
 }
 
-func (ts *TestScript) callBuiltinCmd(cmd string, runCmd func()) {
+func (ts *TestScript) callBuiltinCmd(runCmd func()) {
 	ts.runningBuiltin = true
 	defer func() {
 		r := recover()