1 files changed, 152 insertions, 0 deletions
diff --git a/libgo/go/cmd/go/internal/base/goflags.go b/libgo/go/cmd/go/internal/base/goflags.go
new file mode 100644
index 00000000000..2f50b50bfcf
--- /dev/null
+++ b/libgo/go/cmd/go/internal/base/goflags.go
@@ -0,0 +1,152 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package base
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"runtime"
+	"strings"
+
+	"cmd/go/internal/cfg"
+)
+
+var (
+	goflags   []string                // cached $GOFLAGS list; can be -x or --x form
+	knownFlag = make(map[string]bool) // flags allowed to appear in $GOFLAGS; no leading dashes
+)
+
+// AddKnownFlag adds name to the list of known flags for use in $GOFLAGS.
+func AddKnownFlag(name string) {
+	knownFlag[name] = true
+}
+
+// GOFLAGS returns the flags from $GOFLAGS.
+// The list can be assumed to contain one string per flag,
+// with each string either beginning with -name or --name.
+func GOFLAGS() []string {
+	InitGOFLAGS()
+	return goflags
+}
+
+// InitGOFLAGS initializes the goflags list from $GOFLAGS.
+// If goflags is already initialized, it does nothing.
+func InitGOFLAGS() {
+	if goflags != nil { // already initialized
+		return
+	}
+
+	// Build list of all flags for all commands.
+	// If no command has that flag, then we report the problem.
+	// This catches typos while still letting users record flags in GOFLAGS
+	// that only apply to a subset of go commands.
+	// Commands using CustomFlags can report their flag names
+	// by calling AddKnownFlag instead.
+	var walkFlags func(*Command)
+	walkFlags = func(cmd *Command) {
+		for _, sub := range cmd.Commands {
+			walkFlags(sub)
+		}
+		cmd.Flag.VisitAll(func(f *flag.Flag) {
+			knownFlag[f.Name] = true
+		})
+	}
+	walkFlags(Go)
+
+	// Ignore bad flag in go env and go bug, because
+	// they are what people reach for when debugging
+	// a problem, and maybe they're debugging GOFLAGS.
+	// (Both will show the GOFLAGS setting if let succeed.)
+	hideErrors := cfg.CmdName == "env" || cfg.CmdName == "bug"
+
+	goflags = strings.Fields(os.Getenv("GOFLAGS"))
+	if goflags == nil {
+		goflags = []string{} // avoid work on later InitGOFLAGS call
+	}
+
+	// Each of the words returned by strings.Fields must be its own flag.
+	// To set flag arguments use -x=value instead of -x value.
+	// For boolean flags, -x is fine instead of -x=true.
+	for _, f := range goflags {
+		// Check that every flag looks like -x --x -x=value or --x=value.
+		if !strings.HasPrefix(f, "-") || f == "-" || f == "--" || strings.HasPrefix(f, "---") || strings.HasPrefix(f, "-=") || strings.HasPrefix(f, "--=") {
+			if hideErrors {
+				continue
+			}
+			Fatalf("go: parsing $GOFLAGS: non-flag %q", f)
+		}
+
+		name := f[1:]
+		if name[0] == '-' {
+			name = name[1:]
+		}
+		if i := strings.Index(name, "="); i >= 0 {
+			name = name[:i]
+		}
+		if !knownFlag[name] {
+			if hideErrors {
+				continue
+			}
+			Fatalf("go: parsing $GOFLAGS: unknown flag -%s", name)
+		}
+	}
+}
+
+// boolFlag is the optional interface for flag.Value known to the flag package.
+// (It is not clear why package flag does not export this interface.)
+type boolFlag interface {
+	flag.Value
+	IsBoolFlag() bool
+}
+
+// SetFromGOFLAGS sets the flags in the given flag set using settings in $GOFLAGS.
+func SetFromGOFLAGS(flags flag.FlagSet) {
+	InitGOFLAGS()
+
+	// This loop is similar to flag.Parse except that it ignores
+	// unknown flags found in goflags, so that setting, say, GOFLAGS=-ldflags=-w
+	// does not break commands that don't have a -ldflags.
+	// It also adjusts the output to be clear that the reported problem is from $GOFLAGS.
+	where := "$GOFLAGS"
+	if runtime.GOOS == "windows" {
+		where = "%GOFLAGS%"
+	}
+	for _, goflag := range goflags {
+		name, value, hasValue := goflag, "", false
+		if i := strings.Index(goflag, "="); i >= 0 {
+			name, value, hasValue = goflag[:i], goflag[i+1:], true
+		}
+		if strings.HasPrefix(name, "--") {
+			name = name[1:]
+		}
+		f := flags.Lookup(name[1:])
+		if f == nil {
+			continue
+		}
+		if fb, ok := f.Value.(boolFlag); ok && fb.IsBoolFlag() {
+			if hasValue {
+				if err := fb.Set(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 := fb.Set("true"); err != nil {
+					fmt.Fprintf(flags.Output(), "go: invalid boolean flag %s (from %s): %v\n", name, where, err)
+					flags.Usage()
+				}
+			}
+		} else {
+			if !hasValue {
+				fmt.Fprintf(flags.Output(), "go: flag needs an argument: %s (from %s)\n", name, where)
+				flags.Usage()
+			}
+			if err := f.Value.Set(value); err != nil {
+				fmt.Fprintf(flags.Output(), "go: invalid value %q for flag %s (from %s): %v\n", value, name, where, err)
+				flags.Usage()
+			}
+		}
+	}
+}