}
			if len(f) > 2 {
				fmt.Fprintf(os.Stderr, "?usage: tags [prefix]\n")
				continue
			}
			tags, err := repo.Tags(prefix)
			if err != nil {
				fmt.Fprintf(os.Stderr, "?%s\n", err)
				continue
			}
			for _, tag := range tags {
				fmt.Printf("%s\n", tag)
			}

		case "stat":
			if len(f) != 2 {
				fmt.Fprintf(os.Stderr, "?usage: stat rev\n")
				continue
			}
			info, err := repo.Stat(f[1])

stderr '^go: added toolchain go1.999testmod$'
grep 'go 1.21' go.mod
grep 'toolchain go1.999testmod' go.mod

# Bug fixes.

# go get go@garbage should fail but not crash
! go get go@garbage
! stderr panic
stderr '^go: invalid go version garbage$'

# go get go@go1.21.0 is OK - we silently correct to 1.21.0
go get go@1.19
go get go@go1.21.0
stderr '^go: upgraded go 1.19 => 1.21.0'

	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	if err := json.Unmarshal(b1, &t1); err != nil  {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

	var t2 time.Time
	b2, err := os.ReadFile(os.Args[2])
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	if err := json.Unmarshal(b2, &t2); err != nil  {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}

stderr '^go: parsing \$GOFLAGS: non-flag "--"'

env GOFLAGS=---oops
! go list runtime
stderr '^go: parsing \$GOFLAGS: non-flag "---oops"'

env GOFLAGS=-=noname
! go list runtime
stderr '^go: parsing \$GOFLAGS: non-flag "-=noname"'

env GOFLAGS=-f
! go list runtime
stderr '^go: flag needs an argument: -f \(from (\$GOFLAGS|%GOFLAGS%)\)$'

env GOFLAGS=-e=asdf
! go list runtime

# explicit get should report errors about bad names
! go get appengine
stderr '^go: malformed module path "appengine": missing dot in first path element$'
! go get x/y.z
stderr 'malformed module path "x/y.z": missing dot in first path element'


# 'go list -m' should report errors about module names, never GOROOT.
! go list -m -versions appengine
stderr 'malformed module path "appengine": missing dot in first path element'

env GOTOOLCHAIN=go1.9999x
! go version
stderr 'go: download go1.9999x for .*: toolchain not available'

# GOTOOLCHAIN from network
[!exec:/bin/sh] stop 'the fake proxy serves shell scripts instead of binaries'
env GOTOOLCHAIN=go1.999testmod
go version
stderr 'go: downloading go1.999testmod \(.*/.*\)'

# GOTOOLCHAIN cached from network
go version
! stderr downloading
stdout go1.999testmod

go list -C ../strings
stdout strings
! go list -C ../nonexist
stderr 'chdir.*nonexist'

# check for -C in subcommands with custom flag parsing
# cmd/go/chdir_test.go handles the normal ones more directly.

# go doc
go doc -C ../strings HasPrefix

# go env
go env -C $OLD/custom GOMOD
stdout 'custom[\\/]go.mod'
! go env -C ../nonexist
stderr '^go: chdir ../nonexist: '

# go test
go test -C ../strings -n

# Only allow //go:cgo_ldflag .* in cgo-generated code
[compiler:gc] cp x_gc.go.txt x.go
[compiler:gc] ! go build x
[compiler:gc] stderr '//go:cgo_ldflag .* only allowed in cgo-generated code'

# Ignore _* files
rm x.go
! go build .
stderr 'no Go files'
cp cgo_yy.go.txt _cgo_yy.go
! go build .
stderr 'no Go files' #_* files are ignored...

[compiler:gc] ! go build _cgo_yy.go # ... but if forced, the comment is rejected

	out, err := cmd.CombinedOutput()
	if err != nil {
		fmt.Fprintf(os.Stderr, "%s env GOROOT: %v, %s\n", exe, err, out)
		os.Exit(1)
	}
	goroot, err := filepath.EvalSymlinks(strings.TrimSpace(string(out)))
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	want, err = filepath.EvalSymlinks(want)
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	if !strings.EqualFold(goroot, want) {

! go get rsc.io/badfile1 rsc.io/badfile2 rsc.io/badfile3 rsc.io/badfile4 rsc.io/badfile5
! stderr 'unzip.*badfile1'
stderr 'unzip.*badfile2[\\/]@v[\\/]v1.0.0.zip:.*malformed file path "☺.go": invalid char ''☺'''
stderr 'unzip.*badfile3[\\/]@v[\\/]v1.0.0.zip: rsc.io[\\/]badfile3@v1.0.0[\\/]x\?y.go: malformed file path "x\?y.go": invalid char ''\?'''