//	go test -x math
func testFlags(args []string) (packageNames, passToTest []string) {
	base.SetFromGOFLAGS(&CmdTest.Flag)
	addFromGOFLAGS := map[string]bool{}
	CmdTest.Flag.Visit(func(f *flag.Flag) {
		if short := strings.TrimPrefix(f.Name, "test."); passFlagToTest[short] {
			addFromGOFLAGS[f.Name] = true
		}
	})

	// firstUnknownFlag helps us report an error when flags not known to 'go

	cmdEdit.Run = runEditwork // break init cycle

	cmdEdit.Flag.Var(flagFunc(flagEditworkGodebug), "godebug", "")
	cmdEdit.Flag.Var(flagFunc(flagEditworkDropGodebug), "dropgodebug", "")
	cmdEdit.Flag.Var(flagFunc(flagEditworkUse), "use", "")
	cmdEdit.Flag.Var(flagFunc(flagEditworkDropUse), "dropuse", "")
	cmdEdit.Flag.Var(flagFunc(flagEditworkReplace), "replace", "")
	cmdEdit.Flag.Var(flagFunc(flagEditworkDropReplace), "dropreplace", "")

func init() {
	// break init cycle
	CmdClean.Run = runClean

	CmdClean.Flag.BoolVar(&cleanI, "i", false, "")
	CmdClean.Flag.BoolVar(&cleanR, "r", false, "")
	CmdClean.Flag.BoolVar(&cleanCache, "cache", false, "")
	CmdClean.Flag.BoolVar(&cleanFuzzcache, "fuzzcache", false, "")
	CmdClean.Flag.BoolVar(&cleanModcache, "modcache", false, "")
	CmdClean.Flag.BoolVar(&cleanTestcache, "testcache", false, "")

	// -n and -x are important enough to be

	if phase == "intrinsics" {
		switch flag {
		case "on":
			IntrinsicsDisable = val == 0
		case "off":
			IntrinsicsDisable = val != 0
		case "debug":
			IntrinsicsDebug = val
		default:
			return fmt.Sprintf("Did not find a flag matching %s in -d=ssa/%s debug option (expected ssa/intrinsics/{on,off,debug})", flag, phase)
		}
		return ""
	}
	if phase == "build" {
		switch flag {
		case "debug":

			verb = verb[:i]
		}
		flag := pragmaFlag(verb)
		const runtimePragmas = ir.Systemstack | ir.Nowritebarrier | ir.Nowritebarrierrec | ir.Yeswritebarrierrec
		if !base.Flag.CompilingRuntime && flag&runtimePragmas != 0 {
			p.error(syntax.Error{Pos: pos, Msg: fmt.Sprintf("//%s only allowed in runtime", verb)})
		}
		if flag == ir.UintptrKeepAlive && !base.Flag.Std {

package main

import (
	"bytes"
	"flag"
	"fmt"
	"go/build"
	"go/token"
	"io"
	"log"
	"os"
	"path"
	"path/filepath"
	"strings"

	"cmd/internal/telemetry"
)

var (
	unexported bool   // -u flag
	matchCase  bool   // -c flag
	chdir      string // -C flag
	showAll    bool   // -all flag
	showCmd    bool   // -cmd flag
	showSrc    bool   // -src flag
	short      bool   // -short flag
)

)

var (
	// main operation modes
	list        = flag.Bool("l", false, "list files whose formatting differs from gofmt's")
	write       = flag.Bool("w", false, "write result to (source) file instead of stdout")
	rewriteRule = flag.String("r", "", "rewrite rule (e.g., 'a[b:len(a)] -> a[b:]')")
	simplifyAST = flag.Bool("s", false, "simplify code")
	doDiff      = flag.Bool("d", false, "display diffs instead of rewriting files")

)

func init() {
	cmdDownload.Run = runDownload // break init cycle

	// TODO(jayconrod): https://golang.org/issue/35849 Apply -x to other 'go mod' commands.
	cmdDownload.Flag.BoolVar(&cfg.BuildX, "x", false, "")
	base.AddChdirFlag(&cmdDownload.Flag)
	base.AddModCommonFlags(&cmdDownload.Flag)
}

// A ModuleJSON describes the result of go mod download.
type ModuleJSON struct {

		}

		// Write the extended header file.
		var name string
		var flag byte
		if isGlobal {
			name = realName
			if name == "" {
				name = "GlobalHead.0.0"
			}
			flag = TypeXGlobalHeader
		} else {
			dir, file := path.Split(realName)
			name = path.Join(dir, "PaxHeaders.0", file)
			flag = TypeXHeader
		}
		data := buf.String()
		if len(data) > maxSpecialFileSize {

The -changed flag prints only those settings whose effective
value differs from the default value that would be obtained in
an empty environment with no prior uses of the -w flag.

For more about environment variables, see 'go help environment'.
	`,
}

func init() {
	CmdEnv.Run = runEnv // break init cycle
	base.AddChdirFlag(&CmdEnv.Flag)
	base.AddBuildFlagsNX(&CmdEnv.Flag)
}

var (