cmd/go/internal/toolchain: revert "make a best effort to parse 'go ru…

…n' and 'go install' flags"

This caused other problems, and for the purposes of the Go 1.22
release, we can just roll back to the Go 1.21 behavior and then
decide in January what the correct path forward is.

Revert of CL 546635.

Unfixes #64282.
Fixes #64738.
For #57001.

This reverts commit e44b8b1.

Change-Id: I78753c76dcd0bc6dbc90caa17f73248c42e5f64a
Reviewed-on: https://go-review.googlesource.com/c/go/+/551215
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Than McIntosh <thanm@google.com>

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

@@ -88,7 +88,7 @@ type boolFlag interface {
 }
 
 // SetFromGOFLAGS sets the flags in the given flag set using settings in $GOFLAGS.
-func SetFromGOFLAGS(flags *flag.FlagSet, ignoreErrors bool) {
+func SetFromGOFLAGS(flags *flag.FlagSet) {
 	InitGOFLAGS()
 
 	// This loop is similar to flag.Parse except that it ignores
@@ -121,22 +121,22 @@ func SetFromGOFLAGS(flags *flag.FlagSet, ignoreErrors bool) {
 
 		if fb, ok := f.Value.(boolFlag); ok && fb.IsBoolFlag() {
 			if hasValue {
-				if err := flags.Set(f.Name, value); err != nil && !ignoreErrors {
+				if err := flags.Set(f.Name, value); err != nil {
 					fmt.Fprintf(flags.Output(), "go: invalid boolean value %q for flag %s (from %s): %v\n", value, name, where, err)
 					flags.Usage()
 				}
 			} else {
-				if err := flags.Set(f.Name, "true"); err != nil && !ignoreErrors {
+				if err := flags.Set(f.Name, "true"); err != nil {
 					fmt.Fprintf(flags.Output(), "go: invalid boolean flag %s (from %s): %v\n", name, where, err)
 					flags.Usage()
 				}
 			}
 		} else {
-			if !hasValue && !ignoreErrors {
+			if !hasValue {
 				fmt.Fprintf(flags.Output(), "go: flag needs an argument: %s (from %s)\n", name, where)
 				flags.Usage()
 			}
-			if err := flags.Set(f.Name, value); err != nil && !ignoreErrors {
+			if err := flags.Set(f.Name, value); err != nil {
 				fmt.Fprintf(flags.Output(), "go: invalid value %q for flag %s (from %s): %v\n", value, name, where, err)
 				flags.Usage()
 			}

src/cmd/go/internal/modfetch/fetch.go

@@ -525,7 +525,7 @@ func readGoSum(dst map[module.Version][]string, file string, data []byte) {
 				// ignore malformed line so that go mod tidy can fix go.sum
 				continue
 			} else {
-				base.Fatalf("go: malformed go.sum:\n%s:%d: wrong number of fields %v\n", file, lineno, len(f))
+				base.Fatalf("malformed go.sum:\n%s:%d: wrong number of fields %v\n", file, lineno, len(f))
 			}
 		}
 		if f[2] == emptyGoModHash {
@@ -574,32 +574,32 @@ func checkMod(ctx context.Context, mod module.Version) {
 	// Do the file I/O before acquiring the go.sum lock.
 	ziphash, err := CachePath(ctx, mod, "ziphash")
 	if err != nil {
-		base.Fatalf("go: verifying %v", module.VersionError(mod, err))
+		base.Fatalf("verifying %v", module.VersionError(mod, err))
 	}
 	data, err := lockedfile.Read(ziphash)
 	if err != nil {
-		base.Fatalf("go: verifying %v", module.VersionError(mod, err))
+		base.Fatalf("verifying %v", module.VersionError(mod, err))
 	}
 	data = bytes.TrimSpace(data)
 	if !isValidSum(data) {
 		// Recreate ziphash file from zip file and use that to check the mod sum.
 		zip, err := CachePath(ctx, mod, "zip")
 		if err != nil {
-			base.Fatalf("go: verifying %v", module.VersionError(mod, err))
+			base.Fatalf("verifying %v", module.VersionError(mod, err))
 		}
 		err = hashZip(mod, zip, ziphash)
 		if err != nil {
-			base.Fatalf("go: verifying %v", module.VersionError(mod, err))
+			base.Fatalf("verifying %v", module.VersionError(mod, err))
 		}
 		return
 	}
 	h := string(data)
 	if !strings.HasPrefix(h, "h1:") {
-		base.Fatalf("go: verifying %v", module.VersionError(mod, fmt.Errorf("unexpected ziphash: %q", h)))
+		base.Fatalf("verifying %v", module.VersionError(mod, fmt.Errorf("unexpected ziphash: %q", h)))
 	}
 
 	if err := checkModSum(mod, h); err != nil {
-		base.Fatal(err)
+		base.Fatalf("%s", err)
 	}
 }
 
@@ -684,7 +684,7 @@ func haveModSumLocked(mod module.Version, h string) bool {
 			return true
 		}
 		if strings.HasPrefix(vh, "h1:") {
-			base.Fatalf("go: verifying %s@%s: checksum mismatch\n\tdownloaded: %v\n\t%s:     %v"+goSumMismatch, mod.Path, mod.Version, h, sumFileName, vh)
+			base.Fatalf("verifying %s@%s: checksum mismatch\n\tdownloaded: %v\n\t%s:     %v"+goSumMismatch, mod.Path, mod.Version, h, sumFileName, vh)
 		}
 	}
 	// Also check workspace sums.
@@ -696,7 +696,7 @@ func haveModSumLocked(mod module.Version, h string) bool {
 			if h == vh {
 				foundMatch = true
 			} else if strings.HasPrefix(vh, "h1:") {
-				base.Fatalf("go: verifying %s@%s: checksum mismatch\n\tdownloaded: %v\n\t%s:     %v"+goSumMismatch, mod.Path, mod.Version, h, goSumFile, vh)
+				base.Fatalf("verifying %s@%s: checksum mismatch\n\tdownloaded: %v\n\t%s:     %v"+goSumMismatch, mod.Path, mod.Version, h, goSumFile, vh)
 			}
 		}
 	}
@@ -895,7 +895,7 @@ func TrimGoSum(keep map[module.Version]bool) {
 	defer goSum.mu.Unlock()
 	inited, err := initGoSum()
 	if err != nil {
-		base.Fatal(err)
+		base.Fatalf("%s", err)
 	}
 	if !inited {
 		return

src/cmd/go/internal/test/testflag.go

@@ -222,7 +222,7 @@ func (f *shuffleFlag) Set(value string) error {
 //	go test fmt -custom-flag-for-fmt-test
 //	go test -x math
 func testFlags(args []string) (packageNames, passToTest []string) {
-	base.SetFromGOFLAGS(&CmdTest.Flag, false)
+	base.SetFromGOFLAGS(&CmdTest.Flag)
 	addFromGOFLAGS := map[string]bool{}
 	CmdTest.Flag.Visit(func(f *flag.Flag) {
 		if short := strings.TrimPrefix(f.Name, "test."); passFlagToTest[short] {

src/cmd/go/internal/toolchain/exec.go

@@ -44,12 +44,12 @@ func execGoToolchain(gotoolchain, dir, exe string) {
 				if e.ProcessState.Exited() {
 					os.Exit(e.ProcessState.ExitCode())
 				}
-				base.Fatalf("go: exec %s: %s", gotoolchain, e.ProcessState)
+				base.Fatalf("exec %s: %s", gotoolchain, e.ProcessState)
 			}
-			base.Fatalf("go: exec %s: %s", exe, err)
+			base.Fatalf("exec %s: %s", exe, err)
 		}
 		os.Exit(0)
 	}
 	err := syscall.Exec(exe, os.Args, os.Environ())
-	base.Fatalf("go: exec %s: %v", gotoolchain, err)
+	base.Fatalf("exec %s: %v", gotoolchain, err)
 }

src/cmd/go/internal/toolchain/select.go

@@ -8,10 +8,10 @@ package toolchain
 import (
 	"context"
 	"errors"
-	"flag"
 	"fmt"
 	"go/build"
 	"io/fs"
+	"log"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -20,12 +20,10 @@ import (
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
-	"cmd/go/internal/cmdflag"
 	"cmd/go/internal/gover"
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/run"
-	"cmd/go/internal/work"
 
 	"golang.org/x/mod/module"
 )
@@ -87,6 +85,9 @@ func FilterEnv(env []string) []string {
 // It must be called early in startup.
 // See https://go.dev/doc/toolchain#select.
 func Select() {
+	log.SetPrefix("go: ")
+	defer log.SetPrefix("")
+
 	if !modload.WillBeEnabled() {
 		return
 	}
@@ -132,15 +133,15 @@ func Select() {
 			v := gover.FromToolchain(min)
 			if v == "" {
 				if plus {
-					base.Fatalf("go: invalid GOTOOLCHAIN %q: invalid minimum toolchain %q", gotoolchain, min)
+					base.Fatalf("invalid GOTOOLCHAIN %q: invalid minimum toolchain %q", gotoolchain, min)
 				}
-				base.Fatalf("go: invalid GOTOOLCHAIN %q", gotoolchain)
+				base.Fatalf("invalid GOTOOLCHAIN %q", gotoolchain)
 			}
 			minToolchain = min
 			minVers = v
 		}
 		if plus && suffix != "auto" && suffix != "path" {
-			base.Fatalf("go: invalid GOTOOLCHAIN %q: only version suffixes are +auto and +path", gotoolchain)
+			base.Fatalf("invalid GOTOOLCHAIN %q: only version suffixes are +auto and +path", gotoolchain)
 		}
 		mode = suffix
 	}
@@ -171,7 +172,7 @@ func Select() {
 				// has a suffix like "go1.21.1-foo" and toolchain is "go1.21.1".)
 				toolVers := gover.FromToolchain(toolchain)
 				if toolVers == "" || (!strings.HasPrefix(toolchain, "go") && !strings.Contains(toolchain, "-go")) {
-					base.Fatalf("go: invalid toolchain %q in %s", toolchain, base.ShortPath(file))
+					base.Fatalf("invalid toolchain %q in %s", toolchain, base.ShortPath(file))
 				}
 				if gover.Compare(toolVers, minVers) > 0 {
 					gotoolchain = toolchain
@@ -193,7 +194,7 @@ func Select() {
 	// so that we have initialized gover.Startup for use in error messages.
 	if target := os.Getenv(targetEnv); target != "" && TestVersionSwitch != "loop" {
 		if gover.LocalToolchain() != target {
-			base.Fatalf("go: toolchain %v invoked to provide %v", gover.LocalToolchain(), target)
+			base.Fatalf("toolchain %v invoked to provide %v", gover.LocalToolchain(), target)
 		}
 		os.Unsetenv(targetEnv)
 
@@ -224,7 +225,7 @@ func Select() {
 	// We want to disallow mistakes / bad ideas like GOTOOLCHAIN=bash,
 	// since we will find that in the path lookup.
 	if !strings.HasPrefix(gotoolchain, "go1") && !strings.Contains(gotoolchain, "-go1") {
-		base.Fatalf("go: invalid GOTOOLCHAIN %q", gotoolchain)
+		base.Fatalf("invalid GOTOOLCHAIN %q", gotoolchain)
 	}
 
 	Exec(gotoolchain)
@@ -243,14 +244,16 @@ var TestVersionSwitch string
 // as a source of Go toolchains. Otherwise Exec tries the PATH but then downloads
 // a toolchain if necessary.
 func Exec(gotoolchain string) {
+	log.SetPrefix("go: ")
+
 	writeBits = sysWriteBits()
 
 	count, _ := strconv.Atoi(os.Getenv(countEnv))
 	if count >= maxSwitch-10 {
 		fmt.Fprintf(os.Stderr, "go: switching from go%v to %v [depth %d]\n", gover.Local(), gotoolchain, count)
 	}
 	if count >= maxSwitch {
-		base.Fatalf("go: too many toolchain switches")
+		base.Fatalf("too many toolchain switches")
 	}
 	os.Setenv(countEnv, fmt.Sprint(count+1))
 
@@ -273,7 +276,7 @@ func Exec(gotoolchain string) {
 	case "loop", "mismatch":
 		exe, err := os.Executable()
 		if err != nil {
-			base.Fatal(err)
+			base.Fatalf("%v", err)
 		}
 		execGoToolchain(gotoolchain, os.Getenv("GOROOT"), exe)
 	}
@@ -288,7 +291,7 @@ func Exec(gotoolchain string) {
 	// GOTOOLCHAIN=auto looks in PATH and then falls back to download.
 	// GOTOOLCHAIN=path only looks in PATH.
 	if pathOnly {
-		base.Fatalf("go: cannot find %q in PATH", gotoolchain)
+		base.Fatalf("cannot find %q in PATH", gotoolchain)
 	}
 
 	// Set up modules without an explicit go.mod, to download distribution.
@@ -307,9 +310,9 @@ func Exec(gotoolchain string) {
 	dir, err := modfetch.Download(context.Background(), m)
 	if err != nil {
 		if errors.Is(err, fs.ErrNotExist) {
-			base.Fatalf("go: download %s for %s/%s: toolchain not available", gotoolchain, runtime.GOOS, runtime.GOARCH)
+			base.Fatalf("download %s for %s/%s: toolchain not available", gotoolchain, runtime.GOOS, runtime.GOARCH)
 		}
-		base.Fatalf("go: download %s: %v", gotoolchain, err)
+		base.Fatalf("download %s: %v", gotoolchain, err)
 	}
 
 	// On first use after download, set the execute bits on the commands
@@ -318,7 +321,7 @@ func Exec(gotoolchain string) {
 	if runtime.GOOS != "windows" {
 		info, err := os.Stat(filepath.Join(dir, "bin/go"))
 		if err != nil {
-			base.Fatalf("go: download %s: %v", gotoolchain, err)
+			base.Fatalf("download %s: %v", gotoolchain, err)
 		}
 		if info.Mode()&0111 == 0 {
 			// allowExec sets the exec permission bits on all files found in dir.
@@ -339,7 +342,7 @@ func Exec(gotoolchain string) {
 					return nil
 				})
 				if err != nil {
-					base.Fatalf("go: download %s: %v", gotoolchain, err)
+					base.Fatalf("download %s: %v", gotoolchain, err)
 				}
 			}
 
@@ -381,7 +384,7 @@ func Exec(gotoolchain string) {
 			err = raceSafeCopy(srcUGoMod, srcGoMod)
 		}
 		if err != nil {
-			base.Fatalf("go: download %s: %v", gotoolchain, err)
+			base.Fatalf("download %s: %v", gotoolchain, err)
 		}
 	}
 
@@ -472,7 +475,7 @@ func modGoToolchain() (file, goVers, toolchain string) {
 
 	data, err := os.ReadFile(file)
 	if err != nil {
-		base.Fatal(err)
+		base.Fatalf("%v", err)
 	}
 	return file, gover.GoModLookup(data, "go"), gover.GoModLookup(data, "toolchain")
 }
@@ -489,7 +492,6 @@ func goInstallVersion() bool {
 
 	// Check for pkg@version.
 	var arg string
-	var cmdFlags *flag.FlagSet
 	switch os.Args[1] {
 	default:
 		return false
@@ -498,15 +500,13 @@ func goInstallVersion() bool {
 		// across a toolchain switch. To make that work, assume the pkg@version
 		// is the last argument and skip the flag parsing.
 		arg = os.Args[len(os.Args)-1]
-		cmdFlags = &work.CmdInstall.Flag
 	case "run":
 		// For run, the pkg@version can be anywhere on the command line,
 		// because it is preceded by run flags and followed by arguments to the
 		// program being run. To handle that precisely, we have to interpret the
 		// flags a little bit, to know whether each flag takes an optional argument.
 		// We can still allow unknown flags as long as they have an explicit =value.
 		args := os.Args[2:]
-		cmdFlags = &run.CmdRun.Flag
 		for i := 0; i < len(args); i++ {
 			a := args[i]
 			if !strings.HasPrefix(a, "-") {
@@ -554,20 +554,6 @@ func goInstallVersion() bool {
 		return false
 	}
 
-	// Make a best effort to parse flags so that module flags like -modcacherw
-	// will take effect (see https://go.dev/issue/64282).
-	args := os.Args[2:]
-	for len(args) > 0 {
-		var err error
-		_, args, err = cmdflag.ParseOne(cmdFlags, args)
-		if errors.Is(err, cmdflag.ErrFlagTerminator) {
-			break
-		}
-		// Ignore all other errors: they may be new flags — or updated syntax for
-		// existing flags — intended for a newer Go toolchain.
-	}
-	base.SetFromGOFLAGS(cmdFlags, true)
-
 	// It would be correct to simply return true here, bypassing use
 	// of the current go.mod or go.work, and let "go run" or "go install"
 	// do the rest, including a toolchain switch.

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

@@ -116,7 +116,7 @@ func vetFlags(args []string) (passToVet, packageNames []string) {
 
 	// Record the set of vet tool flags set by GOFLAGS. We want to pass them to
 	// the vet tool, but only if they aren't overridden by an explicit argument.
-	base.SetFromGOFLAGS(&CmdVet.Flag, false)
+	base.SetFromGOFLAGS(&CmdVet.Flag)
 	addFromGOFLAGS := map[string]bool{}
 	CmdVet.Flag.Visit(func(f *flag.Flag) {
 		if isVetFlag[f.Name] {

src/cmd/go/main.go

@@ -234,7 +234,7 @@ func invoke(cmd *base.Command, args []string) {
 	if cmd.CustomFlags {
 		args = args[1:]
 	} else {
-		base.SetFromGOFLAGS(&cmd.Flag, false)
+		base.SetFromGOFLAGS(&cmd.Flag)
 		cmd.Flag.Parse(args[1:])
 		args = cmd.Flag.Args()
 	}