cmd/go: remove work directory on usage error

Ensure that cmd/go consistently calls base.Exit rather than os.Exit,
so that we don't incorrectly leave the work directory around on exit.

Test this by modifying the testsuite to run all the tests with TMPDIR
set to a temporary directory, and then check that no files are left
behind in that temporary directory. Adjust a couple of tests to make
this approach work.

Updates #30500
Updates https://gcc.gnu.org/PR89406

Change-Id: Ib6a5fc8a288a6cf4713022baa2b8dfefad62ba34
Reviewed-on: https://go-review.googlesource.com/c/163237
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/cmd/go/go_test.go

@@ -146,7 +146,18 @@ func TestMain(m *testing.M) {
 		select {}
 	}
 
-	dir, err := ioutil.TempDir(os.Getenv("GOTMPDIR"), "cmd-go-test-")
+	// Run with a temporary TMPDIR to check that the tests don't
+	// leave anything behind.
+	topTmpdir, err := ioutil.TempDir("", "cmd-go-test-")
+	if err != nil {
+		log.Fatal(err)
+	}
+	if !*testWork {
+		defer removeAll(topTmpdir)
+	}
+	os.Setenv(tempEnvName(), topTmpdir)
+
+	dir, err := ioutil.TempDir(topTmpdir, "tmpdir")
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -258,6 +269,23 @@ func TestMain(m *testing.M) {
 		removeAll(testTmpDir) // os.Exit won't run defer
 	}
 
+	if !*testWork {
+		// There shouldn't be anything left in topTmpdir.
+		dirf, err := os.Open(topTmpdir)
+		if err != nil {
+			log.Fatal(err)
+		}
+		names, err := dirf.Readdirnames(0)
+		if err != nil {
+			log.Fatal(err)
+		}
+		if len(names) > 0 {
+			log.Fatalf("unexpected files left in tmpdir: %v", names)
+		}
+
+		removeAll(topTmpdir)
+	}
+
 	os.Exit(r)
 }
 
@@ -5059,7 +5087,8 @@ func TestExecBuildX(t *testing.T) {
 	obj := tg.path("main")
 	tg.run("build", "-x", "-o", obj, src)
 	sh := tg.path("test.sh")
-	err := ioutil.WriteFile(sh, []byte("set -e\n"+tg.getStderr()), 0666)
+	cmds := tg.getStderr()
+	err := ioutil.WriteFile(sh, []byte("set -e\n"+cmds), 0666)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -5090,6 +5119,12 @@ func TestExecBuildX(t *testing.T) {
 	if string(out) != "hello" {
 		t.Fatalf("got %q; want %q", out, "hello")
 	}
+
+	matches := regexp.MustCompile(`^WORK=(.*)\n`).FindStringSubmatch(cmds)
+	if len(matches) == 0 {
+		t.Fatal("no WORK directory")
+	}
+	tg.must(os.RemoveAll(matches[1]))
 }
 
 func TestParallelNumber(t *testing.T) {

src/cmd/go/internal/base/base.go

@@ -82,7 +82,8 @@ func (c *Command) Name() string {
 func (c *Command) Usage() {
 	fmt.Fprintf(os.Stderr, "usage: %s\n", c.UsageLine)
 	fmt.Fprintf(os.Stderr, "Run 'go help %s' for details.\n", c.LongName())
-	os.Exit(2)
+	SetExitStatus(2)
+	Exit()
 }
 
 // Runnable reports whether the command can be run; otherwise

src/cmd/go/internal/cmdflag/flag.go

@@ -66,7 +66,8 @@ func SyntaxError(cmd, msg string) {
 	} else {
 		fmt.Fprintf(os.Stderr, `run "go help %s" for more information`+"\n", cmd)
 	}
-	os.Exit(2)
+	base.SetExitStatus(2)
+	base.Exit()
 }
 
 // AddKnownFlags registers the flags in defns with base.AddKnownFlag.

src/cmd/go/internal/help/help.go

@@ -63,7 +63,8 @@ Args:
 			helpSuccess = " " + strings.Join(args[:i], " ")
 		}
 		fmt.Fprintf(os.Stderr, "go help %s: unknown help topic. Run '%s'.\n", strings.Join(args, " "), helpSuccess)
-		os.Exit(2) // failed at 'go help cmd'
+		base.SetExitStatus(2) // failed at 'go help cmd'
+		base.Exit()
 	}
 
 	if len(cmd.Commands) > 0 {
@@ -167,7 +168,8 @@ func tmpl(w io.Writer, text string, data interface{}) {
 	if ew.err != nil {
 		// I/O error writing. Ignore write on closed pipe.
 		if strings.Contains(ew.err.Error(), "pipe") {
-			os.Exit(1)
+			base.SetExitStatus(1)
+			base.Exit()
 		}
 		base.Fatalf("writing output: %v", ew.err)
 	}

src/cmd/go/internal/vet/vetflag.go

@@ -76,7 +76,8 @@ func vetFlags(usage func(), args []string) (passToVet, packageNames []string) {
 	vetcmd.Stdout = out
 	if err := vetcmd.Run(); err != nil {
 		fmt.Fprintf(os.Stderr, "go vet: can't execute %s -flags: %v\n", tool, err)
-		os.Exit(2)
+		base.SetExitStatus(2)
+		base.Exit()
 	}
 	var analysisFlags []struct {
 		Name  string
@@ -85,7 +86,8 @@ func vetFlags(usage func(), args []string) (passToVet, packageNames []string) {
 	}
 	if err := json.Unmarshal(out.Bytes(), &analysisFlags); err != nil {
 		fmt.Fprintf(os.Stderr, "go vet: can't unmarshal JSON from %s -flags: %v", tool, err)
-		os.Exit(2)
+		base.SetExitStatus(2)
+		base.Exit()
 	}
 
 	// Add vet's flags to vetflagDefn.
@@ -134,7 +136,8 @@ func vetFlags(usage func(), args []string) (passToVet, packageNames []string) {
 		if f == nil {
 			fmt.Fprintf(os.Stderr, "vet: flag %q not defined\n", args[i])
 			fmt.Fprintf(os.Stderr, "Run \"go help vet\" for more information\n")
-			os.Exit(2)
+			base.SetExitStatus(2)
+			base.Exit()
 		}
 		if f.Value != nil {
 			if err := f.Value.Set(value); err != nil {
@@ -182,5 +185,6 @@ func usage() {
 	}
 	fmt.Fprintf(os.Stderr, "Run '%s -help' for the vet tool's flags.\n", cmd)
 
-	os.Exit(2)
+	base.SetExitStatus(2)
+	base.Exit()
 }

src/cmd/go/internal/work/action.go

@@ -248,12 +248,14 @@ func (b *Builder) Init() {
 
 	if _, ok := cfg.OSArchSupportsCgo[cfg.Goos+"/"+cfg.Goarch]; !ok && cfg.BuildContext.Compiler == "gc" {
 		fmt.Fprintf(os.Stderr, "cmd/go: unsupported GOOS/GOARCH pair %s/%s\n", cfg.Goos, cfg.Goarch)
-		os.Exit(2)
+		base.SetExitStatus(2)
+		base.Exit()
 	}
 	for _, tag := range cfg.BuildContext.BuildTags {
 		if strings.Contains(tag, ",") {
 			fmt.Fprintf(os.Stderr, "cmd/go: -tags space-separated list contains comma\n")
-			os.Exit(2)
+			base.SetExitStatus(2)
+			base.Exit()
 		}
 	}
 }

src/cmd/go/internal/work/exec.go

@@ -2327,7 +2327,7 @@ func (b *Builder) gccSupportsFlag(compiler []string, flag string) bool {
 	// version of GCC, so some systems have frozen on it.
 	// Now we pass an empty file on stdin, which should work at least for
 	// GCC and clang.
-	cmdArgs := str.StringList(compiler, flag, "-c", "-x", "c", "-")
+	cmdArgs := str.StringList(compiler, flag, "-c", "-x", "c", "-", "-o", os.DevNull)
 	if cfg.BuildN || cfg.BuildX {
 		b.Showcmd(b.WorkDir, "%s || true", joinUnambiguously(cmdArgs))
 		if cfg.BuildN {

src/cmd/go/internal/work/gccgo.go

@@ -56,7 +56,8 @@ func checkGccgoBin() {
 		return
 	}
 	fmt.Fprintf(os.Stderr, "cmd/go: gccgo: %s\n", gccgoErr)
-	os.Exit(2)
+	base.SetExitStatus(2)
+	base.Exit()
 }
 
 func (tools gccgoToolchain) gc(b *Builder, a *Action, archive string, importcfg []byte, symabis string, asmhdr bool, gofiles []string) (ofile string, output []byte, err error) {

src/cmd/go/internal/work/init.go

@@ -29,7 +29,8 @@ func BuildInit() {
 		p, err := filepath.Abs(cfg.BuildPkgdir)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "go %s: evaluating -pkgdir: %v\n", flag.Args()[0], err)
-			os.Exit(2)
+			base.SetExitStatus(2)
+			base.Exit()
 		}
 		cfg.BuildPkgdir = p
 	}
@@ -41,16 +42,19 @@ func instrumentInit() {
 	}
 	if cfg.BuildRace && cfg.BuildMSan {
 		fmt.Fprintf(os.Stderr, "go %s: may not use -race and -msan simultaneously\n", flag.Args()[0])
-		os.Exit(2)
+		base.SetExitStatus(2)
+		base.Exit()
 	}
 	if cfg.BuildMSan && !sys.MSanSupported(cfg.Goos, cfg.Goarch) {
 		fmt.Fprintf(os.Stderr, "-msan is not supported on %s/%s\n", cfg.Goos, cfg.Goarch)
-		os.Exit(2)
+		base.SetExitStatus(2)
+		base.Exit()
 	}
 	if cfg.BuildRace {
 		if !sys.RaceDetectorSupported(cfg.Goos, cfg.Goarch) {
 			fmt.Fprintf(os.Stderr, "go %s: -race is only supported on linux/amd64, linux/ppc64le, linux/arm64, freebsd/amd64, netbsd/amd64, darwin/amd64 and windows/amd64\n", flag.Args()[0])
-			os.Exit(2)
+			base.SetExitStatus(2)
+			base.Exit()
 		}
 	}
 	mode := "race"
@@ -61,7 +65,8 @@ func instrumentInit() {
 
 	if !cfg.BuildContext.CgoEnabled {
 		fmt.Fprintf(os.Stderr, "go %s: %s requires cgo; enable cgo by setting CGO_ENABLED=1\n", flag.Args()[0], modeFlag)
-		os.Exit(2)
+		base.SetExitStatus(2)
+		base.Exit()
 	}
 	forcedGcflags = append(forcedGcflags, modeFlag)
 	forcedLdflags = append(forcedLdflags, modeFlag)

src/cmd/go/script_test.go

@@ -399,6 +399,7 @@ func (ts *testScript) cmdCc(neg bool, args []string) {
 	var b work.Builder
 	b.Init()
 	ts.cmdExec(neg, append(b.GccCmd(".", ""), args...))
+	os.RemoveAll(b.WorkDir)
 }
 
 // cd changes to a different directory.