cmd/go: don't crash when running "go version" in deleted directory

If the go command is executed on Linux in a deleted directory,
it fails. This behavior is reasonable for commands which depend on
the CWD, but it's unexpected for commands like `go version`.
This change delays initialization of a global CWD variable.

Fixed #34499

Change-Id: I7302fb84a3b7f5f149a123d277abd5b9b5bc95b2
Reviewed-on: https://go-review.googlesource.com/c/go/+/268261
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Trust: Bryan C. Mills <bcmills@google.com>
Trust: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Go Bot <gobot@golang.org>

1 files changed, 16 insertions, 9 deletions

diff --git a/src/cmd/go/internal/test/testflag.go b/src/cmd/go/internal/test/testflag.go
index 6ed96a36d0..08f1efa2c0 100644
--- a/src/cmd/go/internal/test/testflag.go
+++ b/src/cmd/go/internal/test/testflag.go
@@ -62,7 +62,7 @@ func init() {
 	cf.String("memprofilerate", "", "")
 	cf.StringVar(&testMutexProfile, "mutexprofile", "", "")
 	cf.String("mutexprofilefraction", "", "")
-	cf.Var(outputdirFlag{&testOutputDir}, "outputdir", "")
+	cf.Var(&testOutputDir, "outputdir", "")
 	cf.Int("parallel", 0, "")
 	cf.String("run", "", "")
 	cf.Bool("short", false, "")
@@ -71,7 +71,7 @@ func init() {
 	cf.BoolVar(&testV, "v", false, "")
 	cf.Var(&testShuffle, "shuffle", "")
 
-	for name, _ := range passFlagToTest {
+	for name := range passFlagToTest {
 		cf.Var(cf.Lookup(name).Value, "test."+name, "")
 	}
 }
@@ -128,19 +128,26 @@ func (f stringFlag) Set(value string) error {
 // outputdirFlag implements the -outputdir flag.
 // It interprets an empty value as the working directory of the 'go' command.
 type outputdirFlag struct {
-	resolved *string
+	abs string
 }
 
-func (f outputdirFlag) String() string { return *f.resolved }
-func (f outputdirFlag) Set(value string) (err error) {
+func (f *outputdirFlag) String() string {
+	return f.abs
+}
+func (f *outputdirFlag) Set(value string) (err error) {
 	if value == "" {
-		// The empty string implies the working directory of the 'go' command.
-		*f.resolved = base.Cwd
+		f.abs = ""
 	} else {
-		*f.resolved, err = filepath.Abs(value)
+		f.abs, err = filepath.Abs(value)
 	}
 	return err
 }
+func (f *outputdirFlag) getAbs() string {
+	if f.abs == "" {
+		return base.Cwd()
+	}
+	return f.abs
+}
 
 // vetFlag implements the special parsing logic for the -vet flag:
 // a comma-separated list, with a distinguished value "off" and
@@ -404,7 +411,7 @@ func testFlags(args []string) (packageNames, passToTest []string) {
 	// command. Set it explicitly if it is needed due to some other flag that
 	// requests output.
 	if testProfile() != "" && !outputDirSet {
-		injectedFlags = append(injectedFlags, "-test.outputdir="+testOutputDir)
+		injectedFlags = append(injectedFlags, "-test.outputdir="+testOutputDir.getAbs())
 	}
 
 	// If the user is explicitly passing -help or -h, show output