build: move package sources from src/pkg to src

Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.

4 files changed, 1323 insertions, 0 deletions

diff --git a/src/flag/example_test.go b/src/flag/example_test.go
new file mode 100644
index 000000000..04a0d20ee
--- /dev/null
+++ b/src/flag/example_test.go
@@ -0,0 +1,83 @@
+// Copyright 2012 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.
+
+// These examples demonstrate more intricate uses of the flag package.
+package flag_test
+
+import (
+	"errors"
+	"flag"
+	"fmt"
+	"strings"
+	"time"
+)
+
+// Example 1: A single string flag called "species" with default value "gopher".
+var species = flag.String("species", "gopher", "the species we are studying")
+
+// Example 2: Two flags sharing a variable, so we can have a shorthand.
+// The order of initialization is undefined, so make sure both use the
+// same default value. They must be set up with an init function.
+var gopherType string
+
+func init() {
+	const (
+		defaultGopher = "pocket"
+		usage         = "the variety of gopher"
+	)
+	flag.StringVar(&gopherType, "gopher_type", defaultGopher, usage)
+	flag.StringVar(&gopherType, "g", defaultGopher, usage+" (shorthand)")
+}
+
+// Example 3: A user-defined flag type, a slice of durations.
+type interval []time.Duration
+
+// String is the method to format the flag's value, part of the flag.Value interface.
+// The String method's output will be used in diagnostics.
+func (i *interval) String() string {
+	return fmt.Sprint(*i)
+}
+
+// Set is the method to set the flag value, part of the flag.Value interface.
+// Set's argument is a string to be parsed to set the flag.
+// It's a comma-separated list, so we split it.
+func (i *interval) Set(value string) error {
+	// If we wanted to allow the flag to be set multiple times,
+	// accumulating values, we would delete this if statement.
+	// That would permit usages such as
+	//	-deltaT 10s -deltaT 15s
+	// and other combinations.
+	if len(*i) > 0 {
+		return errors.New("interval flag already set")
+	}
+	for _, dt := range strings.Split(value, ",") {
+		duration, err := time.ParseDuration(dt)
+		if err != nil {
+			return err
+		}
+		*i = append(*i, duration)
+	}
+	return nil
+}
+
+// Define a flag to accumulate durations. Because it has a special type,
+// we need to use the Var function and therefore create the flag during
+// init.
+
+var intervalFlag interval
+
+func init() {
+	// Tie the command-line flag to the intervalFlag variable and
+	// set a usage message.
+	flag.Var(&intervalFlag, "deltaT", "comma-separated list of intervals to use between events")
+}
+
+func Example() {
+	// All the interesting pieces are with the variables declared above, but
+	// to enable the flag package to see the flags defined there, one must
+	// execute, typically at the start of main (not init!):
+	//	flag.Parse()
+	// We don't run it here because this is not a main function and
+	// the testing suite has already parsed the flags.
+}
diff --git a/src/flag/export_test.go b/src/flag/export_test.go
new file mode 100644
index 000000000..56cda58b3
--- /dev/null
+++ b/src/flag/export_test.go
@@ -0,0 +1,17 @@
+// Copyright 2010 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 flag
+
+import "os"
+
+// Additional routines compiled into the package only during testing.
+
+// ResetForTesting clears all flag state and sets the usage function as directed.
+// After calling ResetForTesting, parse errors in flag handling will not
+// exit the program.
+func ResetForTesting(usage func()) {
+	CommandLine = NewFlagSet(os.Args[0], ContinueOnError)
+	Usage = usage
+}
diff --git a/src/flag/flag.go b/src/flag/flag.go
new file mode 100644
index 000000000..de2d91f8b
--- /dev/null
+++ b/src/flag/flag.go
@@ -0,0 +1,854 @@
+// Copyright 2009 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 flag implements command-line flag parsing.
+
+	Usage:
+
+	Define flags using flag.String(), Bool(), Int(), etc.
+
+	This declares an integer flag, -flagname, stored in the pointer ip, with type *int.
+		import "flag"
+		var ip = flag.Int("flagname", 1234, "help message for flagname")
+	If you like, you can bind the flag to a variable using the Var() functions.
+		var flagvar int
+		func init() {
+			flag.IntVar(&flagvar, "flagname", 1234, "help message for flagname")
+		}
+	Or you can create custom flags that satisfy the Value interface (with
+	pointer receivers) and couple them to flag parsing by
+		flag.Var(&flagVal, "name", "help message for flagname")
+	For such flags, the default value is just the initial value of the variable.
+
+	After all flags are defined, call
+		flag.Parse()
+	to parse the command line into the defined flags.
+
+	Flags may then be used directly. If you're using the flags themselves,
+	they are all pointers; if you bind to variables, they're values.
+		fmt.Println("ip has value ", *ip)
+		fmt.Println("flagvar has value ", flagvar)
+
+	After parsing, the arguments after the flag are available as the
+	slice flag.Args() or individually as flag.Arg(i).
+	The arguments are indexed from 0 through flag.NArg()-1.
+
+	Command line flag syntax:
+		-flag
+		-flag=x
+		-flag x  // non-boolean flags only
+	One or two minus signs may be used; they are equivalent.
+	The last form is not permitted for boolean flags because the
+	meaning of the command
+		cmd -x *
+	will change if there is a file called 0, false, etc.  You must
+	use the -flag=false form to turn off a boolean flag.
+
+	Flag parsing stops just before the first non-flag argument
+	("-" is a non-flag argument) or after the terminator "--".
+
+	Integer flags accept 1234, 0664, 0x1234 and may be negative.
+	Boolean flags may be:
+		1, 0, t, f, T, F, true, false, TRUE, FALSE, True, False
+	Duration flags accept any input valid for time.ParseDuration.
+
+	The default set of command-line flags is controlled by
+	top-level functions.  The FlagSet type allows one to define
+	independent sets of flags, such as to implement subcommands
+	in a command-line interface. The methods of FlagSet are
+	analogous to the top-level functions for the command-line
+	flag set.
+*/
+package flag
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strconv"
+	"time"
+)
+
+// ErrHelp is the error returned if the -help or -h flag is invoked
+// but no such flag is defined.
+var ErrHelp = errors.New("flag: help requested")
+
+// -- bool Value
+type boolValue bool
+
+func newBoolValue(val bool, p *bool) *boolValue {
+	*p = val
+	return (*boolValue)(p)
+}
+
+func (b *boolValue) Set(s string) error {
+	v, err := strconv.ParseBool(s)
+	*b = boolValue(v)
+	return err
+}
+
+func (b *boolValue) Get() interface{} { return bool(*b) }
+
+func (b *boolValue) String() string { return fmt.Sprintf("%v", *b) }
+
+func (b *boolValue) IsBoolFlag() bool { return true }
+
+// optional interface to indicate boolean flags that can be
+// supplied without "=value" text
+type boolFlag interface {
+	Value
+	IsBoolFlag() bool
+}
+
+// -- int Value
+type intValue int
+
+func newIntValue(val int, p *int) *intValue {
+	*p = val
+	return (*intValue)(p)
+}
+
+func (i *intValue) Set(s string) error {
+	v, err := strconv.ParseInt(s, 0, 64)
+	*i = intValue(v)
+	return err
+}
+
+func (i *intValue) Get() interface{} { return int(*i) }
+
+func (i *intValue) String() string { return fmt.Sprintf("%v", *i) }
+
+// -- int64 Value
+type int64Value int64
+
+func newInt64Value(val int64, p *int64) *int64Value {
+	*p = val
+	return (*int64Value)(p)
+}
+
+func (i *int64Value) Set(s string) error {
+	v, err := strconv.ParseInt(s, 0, 64)
+	*i = int64Value(v)
+	return err
+}
+
+func (i *int64Value) Get() interface{} { return int64(*i) }
+
+func (i *int64Value) String() string { return fmt.Sprintf("%v", *i) }
+
+// -- uint Value
+type uintValue uint
+
+func newUintValue(val uint, p *uint) *uintValue {
+	*p = val
+	return (*uintValue)(p)
+}
+
+func (i *uintValue) Set(s string) error {
+	v, err := strconv.ParseUint(s, 0, 64)
+	*i = uintValue(v)
+	return err
+}
+
+func (i *uintValue) Get() interface{} { return uint(*i) }
+
+func (i *uintValue) String() string { return fmt.Sprintf("%v", *i) }
+
+// -- uint64 Value
+type uint64Value uint64
+
+func newUint64Value(val uint64, p *uint64) *uint64Value {
+	*p = val
+	return (*uint64Value)(p)
+}
+
+func (i *uint64Value) Set(s string) error {
+	v, err := strconv.ParseUint(s, 0, 64)
+	*i = uint64Value(v)
+	return err
+}
+
+func (i *uint64Value) Get() interface{} { return uint64(*i) }
+
+func (i *uint64Value) String() string { return fmt.Sprintf("%v", *i) }
+
+// -- string Value
+type stringValue string
+
+func newStringValue(val string, p *string) *stringValue {
+	*p = val
+	return (*stringValue)(p)
+}
+
+func (s *stringValue) Set(val string) error {
+	*s = stringValue(val)
+	return nil
+}
+
+func (s *stringValue) Get() interface{} { return string(*s) }
+
+func (s *stringValue) String() string { return fmt.Sprintf("%s", *s) }
+
+// -- float64 Value
+type float64Value float64
+
+func newFloat64Value(val float64, p *float64) *float64Value {
+	*p = val
+	return (*float64Value)(p)
+}
+
+func (f *float64Value) Set(s string) error {
+	v, err := strconv.ParseFloat(s, 64)
+	*f = float64Value(v)
+	return err
+}
+
+func (f *float64Value) Get() interface{} { return float64(*f) }
+
+func (f *float64Value) String() string { return fmt.Sprintf("%v", *f) }
+
+// -- time.Duration Value
+type durationValue time.Duration
+
+func newDurationValue(val time.Duration, p *time.Duration) *durationValue {
+	*p = val
+	return (*durationValue)(p)
+}
+
+func (d *durationValue) Set(s string) error {
+	v, err := time.ParseDuration(s)
+	*d = durationValue(v)
+	return err
+}
+
+func (d *durationValue) Get() interface{} { return time.Duration(*d) }
+
+func (d *durationValue) String() string { return (*time.Duration)(d).String() }
+
+// Value is the interface to the dynamic value stored in a flag.
+// (The default value is represented as a string.)
+//
+// If a Value has an IsBoolFlag() bool method returning true,
+// the command-line parser makes -name equivalent to -name=true
+// rather than using the next command-line argument.
+type Value interface {
+	String() string
+	Set(string) error
+}
+
+// Getter is an interface that allows the contents of a Value to be retrieved.
+// It wraps the Value interface, rather than being part of it, because it
+// appeared after Go 1 and its compatibility rules. All Value types provided
+// by this package satisfy the Getter interface.
+type Getter interface {
+	Value
+	Get() interface{}
+}
+
+// ErrorHandling defines how to handle flag parsing errors.
+type ErrorHandling int
+
+const (
+	ContinueOnError ErrorHandling = iota
+	ExitOnError
+	PanicOnError
+)
+
+// A FlagSet represents a set of defined flags.  The zero value of a FlagSet
+// has no name and has ContinueOnError error handling.
+type FlagSet struct {
+	// Usage is the function called when an error occurs while parsing flags.
+	// The field is a function (not a method) that may be changed to point to
+	// a custom error handler.
+	Usage func()
+
+	name          string
+	parsed        bool
+	actual        map[string]*Flag
+	formal        map[string]*Flag
+	args          []string // arguments after flags
+	errorHandling ErrorHandling
+	output        io.Writer // nil means stderr; use out() accessor
+}
+
+// A Flag represents the state of a flag.
+type Flag struct {
+	Name     string // name as it appears on command line
+	Usage    string // help message
+	Value    Value  // value as set
+	DefValue string // default value (as text); for usage message
+}
+
+// sortFlags returns the flags as a slice in lexicographical sorted order.
+func sortFlags(flags map[string]*Flag) []*Flag {
+	list := make(sort.StringSlice, len(flags))
+	i := 0
+	for _, f := range flags {
+		list[i] = f.Name
+		i++
+	}
+	list.Sort()
+	result := make([]*Flag, len(list))
+	for i, name := range list {
+		result[i] = flags[name]
+	}
+	return result
+}
+
+func (f *FlagSet) out() io.Writer {
+	if f.output == nil {
+		return os.Stderr
+	}
+	return f.output
+}
+
+// SetOutput sets the destination for usage and error messages.
+// If output is nil, os.Stderr is used.
+func (f *FlagSet) SetOutput(output io.Writer) {
+	f.output = output
+}
+
+// VisitAll visits the flags in lexicographical order, calling fn for each.
+// It visits all flags, even those not set.
+func (f *FlagSet) VisitAll(fn func(*Flag)) {
+	for _, flag := range sortFlags(f.formal) {
+		fn(flag)
+	}
+}
+
+// VisitAll visits the command-line flags in lexicographical order, calling
+// fn for each.  It visits all flags, even those not set.
+func VisitAll(fn func(*Flag)) {
+	CommandLine.VisitAll(fn)
+}
+
+// Visit visits the flags in lexicographical order, calling fn for each.
+// It visits only those flags that have been set.
+func (f *FlagSet) Visit(fn func(*Flag)) {
+	for _, flag := range sortFlags(f.actual) {
+		fn(flag)
+	}
+}
+
+// Visit visits the command-line flags in lexicographical order, calling fn
+// for each.  It visits only those flags that have been set.
+func Visit(fn func(*Flag)) {
+	CommandLine.Visit(fn)
+}
+
+// Lookup returns the Flag structure of the named flag, returning nil if none exists.
+func (f *FlagSet) Lookup(name string) *Flag {
+	return f.formal[name]
+}
+
+// Lookup returns the Flag structure of the named command-line flag,
+// returning nil if none exists.
+func Lookup(name string) *Flag {
+	return CommandLine.formal[name]
+}
+
+// Set sets the value of the named flag.
+func (f *FlagSet) Set(name, value string) error {
+	flag, ok := f.formal[name]
+	if !ok {
+		return fmt.Errorf("no such flag -%v", name)
+	}
+	err := flag.Value.Set(value)
+	if err != nil {
+		return err
+	}
+	if f.actual == nil {
+		f.actual = make(map[string]*Flag)
+	}
+	f.actual[name] = flag
+	return nil
+}
+
+// Set sets the value of the named command-line flag.
+func Set(name, value string) error {
+	return CommandLine.Set(name, value)
+}
+
+// PrintDefaults prints, to standard error unless configured
+// otherwise, the default values of all defined flags in the set.
+func (f *FlagSet) PrintDefaults() {
+	f.VisitAll(func(flag *Flag) {
+		format := "  -%s=%s: %s\n"
+		if _, ok := flag.Value.(*stringValue); ok {
+			// put quotes on the value
+			format = "  -%s=%q: %s\n"
+		}
+		fmt.Fprintf(f.out(), format, flag.Name, flag.DefValue, flag.Usage)
+	})
+}
+
+// PrintDefaults prints to standard error the default values of all defined command-line flags.
+func PrintDefaults() {
+	CommandLine.PrintDefaults()
+}
+
+// defaultUsage is the default function to print a usage message.
+func defaultUsage(f *FlagSet) {
+	if f.name == "" {
+		fmt.Fprintf(f.out(), "Usage:\n")
+	} else {
+		fmt.Fprintf(f.out(), "Usage of %s:\n", f.name)
+	}
+	f.PrintDefaults()
+}
+
+// NOTE: Usage is not just defaultUsage(CommandLine)
+// because it serves (via godoc flag Usage) as the example
+// for how to write your own usage function.
+
+// Usage prints to standard error a usage message documenting all defined command-line flags.
+// The function is a variable that may be changed to point to a custom function.
+var Usage = func() {
+	fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
+	PrintDefaults()
+}
+
+// NFlag returns the number of flags that have been set.
+func (f *FlagSet) NFlag() int { return len(f.actual) }
+
+// NFlag returns the number of command-line flags that have been set.
+func NFlag() int { return len(CommandLine.actual) }
+
+// Arg returns the i'th argument.  Arg(0) is the first remaining argument
+// after flags have been processed.
+func (f *FlagSet) Arg(i int) string {
+	if i < 0 || i >= len(f.args) {
+		return ""
+	}
+	return f.args[i]
+}
+
+// Arg returns the i'th command-line argument.  Arg(0) is the first remaining argument
+// after flags have been processed.
+func Arg(i int) string {
+	return CommandLine.Arg(i)
+}
+
+// NArg is the number of arguments remaining after flags have been processed.
+func (f *FlagSet) NArg() int { return len(f.args) }
+
+// NArg is the number of arguments remaining after flags have been processed.
+func NArg() int { return len(CommandLine.args) }
+
+// Args returns the non-flag arguments.
+func (f *FlagSet) Args() []string { return f.args }
+
+// Args returns the non-flag command-line arguments.
+func Args() []string { return CommandLine.args }
+
+// BoolVar defines a bool flag with specified name, default value, and usage string.
+// The argument p points to a bool variable in which to store the value of the flag.
+func (f *FlagSet) BoolVar(p *bool, name string, value bool, usage string) {
+	f.Var(newBoolValue(value, p), name, usage)
+}
+
+// BoolVar defines a bool flag with specified name, default value, and usage string.
+// The argument p points to a bool variable in which to store the value of the flag.
+func BoolVar(p *bool, name string, value bool, usage string) {
+	CommandLine.Var(newBoolValue(value, p), name, usage)
+}
+
+// Bool defines a bool flag with specified name, default value, and usage string.
+// The return value is the address of a bool variable that stores the value of the flag.
+func (f *FlagSet) Bool(name string, value bool, usage string) *bool {
+	p := new(bool)
+	f.BoolVar(p, name, value, usage)
+	return p
+}
+
+// Bool defines a bool flag with specified name, default value, and usage string.
+// The return value is the address of a bool variable that stores the value of the flag.
+func Bool(name string, value bool, usage string) *bool {
+	return CommandLine.Bool(name, value, usage)
+}
+
+// IntVar defines an int flag with specified name, default value, and usage string.
+// The argument p points to an int variable in which to store the value of the flag.
+func (f *FlagSet) IntVar(p *int, name string, value int, usage string) {
+	f.Var(newIntValue(value, p), name, usage)
+}
+
+// IntVar defines an int flag with specified name, default value, and usage string.
+// The argument p points to an int variable in which to store the value of the flag.
+func IntVar(p *int, name string, value int, usage string) {
+	CommandLine.Var(newIntValue(value, p), name, usage)
+}
+
+// Int defines an int flag with specified name, default value, and usage string.
+// The return value is the address of an int variable that stores the value of the flag.
+func (f *FlagSet) Int(name string, value int, usage string) *int {
+	p := new(int)
+	f.IntVar(p, name, value, usage)
+	return p
+}
+
+// Int defines an int flag with specified name, default value, and usage string.
+// The return value is the address of an int variable that stores the value of the flag.
+func Int(name string, value int, usage string) *int {
+	return CommandLine.Int(name, value, usage)
+}
+
+// Int64Var defines an int64 flag with specified name, default value, and usage string.
+// The argument p points to an int64 variable in which to store the value of the flag.
+func (f *FlagSet) Int64Var(p *int64, name string, value int64, usage string) {
+	f.Var(newInt64Value(value, p), name, usage)
+}
+
+// Int64Var defines an int64 flag with specified name, default value, and usage string.
+// The argument p points to an int64 variable in which to store the value of the flag.
+func Int64Var(p *int64, name string, value int64, usage string) {
+	CommandLine.Var(newInt64Value(value, p), name, usage)
+}
+
+// Int64 defines an int64 flag with specified name, default value, and usage string.
+// The return value is the address of an int64 variable that stores the value of the flag.
+func (f *FlagSet) Int64(name string, value int64, usage string) *int64 {
+	p := new(int64)
+	f.Int64Var(p, name, value, usage)
+	return p
+}
+
+// Int64 defines an int64 flag with specified name, default value, and usage string.
+// The return value is the address of an int64 variable that stores the value of the flag.
+func Int64(name string, value int64, usage string) *int64 {
+	return CommandLine.Int64(name, value, usage)
+}
+
+// UintVar defines a uint flag with specified name, default value, and usage string.
+// The argument p points to a uint variable in which to store the value of the flag.
+func (f *FlagSet) UintVar(p *uint, name string, value uint, usage string) {
+	f.Var(newUintValue(value, p), name, usage)
+}
+
+// UintVar defines a uint flag with specified name, default value, and usage string.
+// The argument p points to a uint  variable in which to store the value of the flag.
+func UintVar(p *uint, name string, value uint, usage string) {
+	CommandLine.Var(newUintValue(value, p), name, usage)
+}
+
+// Uint defines a uint flag with specified name, default value, and usage string.
+// The return value is the address of a uint  variable that stores the value of the flag.
+func (f *FlagSet) Uint(name string, value uint, usage string) *uint {
+	p := new(uint)
+	f.UintVar(p, name, value, usage)
+	return p
+}
+
+// Uint defines a uint flag with specified name, default value, and usage string.
+// The return value is the address of a uint  variable that stores the value of the flag.
+func Uint(name string, value uint, usage string) *uint {
+	return CommandLine.Uint(name, value, usage)
+}
+
+// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
+// The argument p points to a uint64 variable in which to store the value of the flag.
+func (f *FlagSet) Uint64Var(p *uint64, name string, value uint64, usage string) {
+	f.Var(newUint64Value(value, p), name, usage)
+}
+
+// Uint64Var defines a uint64 flag with specified name, default value, and usage string.
+// The argument p points to a uint64 variable in which to store the value of the flag.
+func Uint64Var(p *uint64, name string, value uint64, usage string) {
+	CommandLine.Var(newUint64Value(value, p), name, usage)
+}
+
+// Uint64 defines a uint64 flag with specified name, default value, and usage string.
+// The return value is the address of a uint64 variable that stores the value of the flag.
+func (f *FlagSet) Uint64(name string, value uint64, usage string) *uint64 {
+	p := new(uint64)
+	f.Uint64Var(p, name, value, usage)
+	return p
+}
+
+// Uint64 defines a uint64 flag with specified name, default value, and usage string.
+// The return value is the address of a uint64 variable that stores the value of the flag.
+func Uint64(name string, value uint64, usage string) *uint64 {
+	return CommandLine.Uint64(name, value, usage)
+}
+
+// StringVar defines a string flag with specified name, default value, and usage string.
+// The argument p points to a string variable in which to store the value of the flag.
+func (f *FlagSet) StringVar(p *string, name string, value string, usage string) {
+	f.Var(newStringValue(value, p), name, usage)
+}
+
+// StringVar defines a string flag with specified name, default value, and usage string.
+// The argument p points to a string variable in which to store the value of the flag.
+func StringVar(p *string, name string, value string, usage string) {
+	CommandLine.Var(newStringValue(value, p), name, usage)
+}
+
+// String defines a string flag with specified name, default value, and usage string.
+// The return value is the address of a string variable that stores the value of the flag.
+func (f *FlagSet) String(name string, value string, usage string) *string {
+	p := new(string)
+	f.StringVar(p, name, value, usage)
+	return p
+}
+
+// String defines a string flag with specified name, default value, and usage string.
+// The return value is the address of a string variable that stores the value of the flag.
+func String(name string, value string, usage string) *string {
+	return CommandLine.String(name, value, usage)
+}
+
+// Float64Var defines a float64 flag with specified name, default value, and usage string.
+// The argument p points to a float64 variable in which to store the value of the flag.
+func (f *FlagSet) Float64Var(p *float64, name string, value float64, usage string) {
+	f.Var(newFloat64Value(value, p), name, usage)
+}
+
+// Float64Var defines a float64 flag with specified name, default value, and usage string.
+// The argument p points to a float64 variable in which to store the value of the flag.
+func Float64Var(p *float64, name string, value float64, usage string) {
+	CommandLine.Var(newFloat64Value(value, p), name, usage)
+}
+
+// Float64 defines a float64 flag with specified name, default value, and usage string.
+// The return value is the address of a float64 variable that stores the value of the flag.
+func (f *FlagSet) Float64(name string, value float64, usage string) *float64 {
+	p := new(float64)
+	f.Float64Var(p, name, value, usage)
+	return p
+}
+
+// Float64 defines a float64 flag with specified name, default value, and usage string.
+// The return value is the address of a float64 variable that stores the value of the flag.
+func Float64(name string, value float64, usage string) *float64 {
+	return CommandLine.Float64(name, value, usage)
+}
+
+// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
+// The argument p points to a time.Duration variable in which to store the value of the flag.
+// The flag accepts a value acceptable to time.ParseDuration.
+func (f *FlagSet) DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
+	f.Var(newDurationValue(value, p), name, usage)
+}
+
+// DurationVar defines a time.Duration flag with specified name, default value, and usage string.
+// The argument p points to a time.Duration variable in which to store the value of the flag.
+// The flag accepts a value acceptable to time.ParseDuration.
+func DurationVar(p *time.Duration, name string, value time.Duration, usage string) {
+	CommandLine.Var(newDurationValue(value, p), name, usage)
+}
+
+// Duration defines a time.Duration flag with specified name, default value, and usage string.
+// The return value is the address of a time.Duration variable that stores the value of the flag.
+// The flag accepts a value acceptable to time.ParseDuration.
+func (f *FlagSet) Duration(name string, value time.Duration, usage string) *time.Duration {
+	p := new(time.Duration)
+	f.DurationVar(p, name, value, usage)
+	return p
+}
+
+// Duration defines a time.Duration flag with specified name, default value, and usage string.
+// The return value is the address of a time.Duration variable that stores the value of the flag.
+// The flag accepts a value acceptable to time.ParseDuration.
+func Duration(name string, value time.Duration, usage string) *time.Duration {
+	return CommandLine.Duration(name, value, usage)
+}
+
+// Var defines a flag with the specified name and usage string. The type and
+// value of the flag are represented by the first argument, of type Value, which
+// typically holds a user-defined implementation of Value. For instance, the
+// caller could create a flag that turns a comma-separated string into a slice
+// of strings by giving the slice the methods of Value; in particular, Set would
+// decompose the comma-separated string into the slice.
+func (f *FlagSet) Var(value Value, name string, usage string) {
+	// Remember the default value as a string; it won't change.
+	flag := &Flag{name, usage, value, value.String()}
+	_, alreadythere := f.formal[name]
+	if alreadythere {
+		var msg string
+		if f.name == "" {
+			msg = fmt.Sprintf("flag redefined: %s", name)
+		} else {
+			msg = fmt.Sprintf("%s flag redefined: %s", f.name, name)
+		}
+		fmt.Fprintln(f.out(), msg)
+		panic(msg) // Happens only if flags are declared with identical names
+	}
+	if f.formal == nil {
+		f.formal = make(map[string]*Flag)
+	}
+	f.formal[name] = flag
+}
+
+// Var defines a flag with the specified name and usage string. The type and
+// value of the flag are represented by the first argument, of type Value, which
+// typically holds a user-defined implementation of Value. For instance, the
+// caller could create a flag that turns a comma-separated string into a slice
+// of strings by giving the slice the methods of Value; in particular, Set would
+// decompose the comma-separated string into the slice.
+func Var(value Value, name string, usage string) {
+	CommandLine.Var(value, name, usage)
+}
+
+// failf prints to standard error a formatted error and usage message and
+// returns the error.
+func (f *FlagSet) failf(format string, a ...interface{}) error {
+	err := fmt.Errorf(format, a...)
+	fmt.Fprintln(f.out(), err)
+	f.usage()
+	return err
+}
+
+// usage calls the Usage method for the flag set, or the usage function if
+// the flag set is CommandLine.
+func (f *FlagSet) usage() {
+	if f == CommandLine {
+		Usage()
+	} else if f.Usage == nil {
+		defaultUsage(f)
+	} else {
+		f.Usage()
+	}
+}
+
+// parseOne parses one flag. It reports whether a flag was seen.
+func (f *FlagSet) parseOne() (bool, error) {
+	if len(f.args) == 0 {
+		return false, nil
+	}
+	s := f.args[0]
+	if len(s) == 0 || s[0] != '-' || len(s) == 1 {
+		return false, nil
+	}
+	num_minuses := 1
+	if s[1] == '-' {
+		num_minuses++
+		if len(s) == 2 { // "--" terminates the flags
+			f.args = f.args[1:]
+			return false, nil
+		}
+	}
+	name := s[num_minuses:]
+	if len(name) == 0 || name[0] == '-' || name[0] == '=' {
+		return false, f.failf("bad flag syntax: %s", s)
+	}
+
+	// it's a flag. does it have an argument?
+	f.args = f.args[1:]
+	has_value := false
+	value := ""
+	for i := 1; i < len(name); i++ { // equals cannot be first
+		if name[i] == '=' {
+			value = name[i+1:]
+			has_value = true
+			name = name[0:i]
+			break
+		}
+	}
+	m := f.formal
+	flag, alreadythere := m[name] // BUG
+	if !alreadythere {
+		if name == "help" || name == "h" { // special case for nice help message.
+			f.usage()
+			return false, ErrHelp
+		}
+		return false, f.failf("flag provided but not defined: -%s", name)
+	}
+	if fv, ok := flag.Value.(boolFlag); ok && fv.IsBoolFlag() { // special case: doesn't need an arg
+		if has_value {
+			if err := fv.Set(value); err != nil {
+				return false, f.failf("invalid boolean value %q for -%s: %v", value, name, err)
+			}
+		} else {
+			fv.Set("true")
+		}
+	} else {
+		// It must have a value, which might be the next argument.
+		if !has_value && len(f.args) > 0 {
+			// value is the next arg
+			has_value = true
+			value, f.args = f.args[0], f.args[1:]
+		}
+		if !has_value {
+			return false, f.failf("flag needs an argument: -%s", name)
+		}
+		if err := flag.Value.Set(value); err != nil {
+			return false, f.failf("invalid value %q for flag -%s: %v", value, name, err)
+		}
+	}
+	if f.actual == nil {
+		f.actual = make(map[string]*Flag)
+	}
+	f.actual[name] = flag
+	return true, nil
+}
+
+// Parse parses flag definitions from the argument list, which should not
+// include the command name.  Must be called after all flags in the FlagSet
+// are defined and before flags are accessed by the program.
+// The return value will be ErrHelp if -help or -h were set but not defined.
+func (f *FlagSet) Parse(arguments []string) error {
+	f.parsed = true
+	f.args = arguments
+	for {
+		seen, err := f.parseOne()
+		if seen {
+			continue
+		}
+		if err == nil {
+			break
+		}
+		switch f.errorHandling {
+		case ContinueOnError:
+			return err
+		case ExitOnError:
+			os.Exit(2)
+		case PanicOnError:
+			panic(err)
+		}
+	}
+	return nil
+}
+
+// Parsed reports whether f.Parse has been called.
+func (f *FlagSet) Parsed() bool {
+	return f.parsed
+}
+
+// Parse parses the command-line flags from os.Args[1:].  Must be called
+// after all flags are defined and before flags are accessed by the program.
+func Parse() {
+	// Ignore errors; CommandLine is set for ExitOnError.
+	CommandLine.Parse(os.Args[1:])
+}
+
+// Parsed returns true if the command-line flags have been parsed.
+func Parsed() bool {
+	return CommandLine.Parsed()
+}
+
+// CommandLine is the default set of command-line flags, parsed from os.Args.
+// The top-level functions such as BoolVar, Arg, and so on are wrappers for the
+// methods of CommandLine.
+var CommandLine = NewFlagSet(os.Args[0], ExitOnError)
+
+// NewFlagSet returns a new, empty flag set with the specified name and
+// error handling property.
+func NewFlagSet(name string, errorHandling ErrorHandling) *FlagSet {
+	f := &FlagSet{
+		name:          name,
+		errorHandling: errorHandling,
+	}
+	return f
+}
+
+// Init sets the name and error handling property for a flag set.
+// By default, the zero FlagSet uses an empty name and the
+// ContinueOnError error handling policy.
+func (f *FlagSet) Init(name string, errorHandling ErrorHandling) {
+	f.name = name
+	f.errorHandling = errorHandling
+}
diff --git a/src/flag/flag_test.go b/src/flag/flag_test.go
new file mode 100644
index 000000000..2c0387269
--- /dev/null
+++ b/src/flag/flag_test.go
@@ -0,0 +1,369 @@
+// Copyright 2009 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 flag_test
+
+import (
+	"bytes"
+	. "flag"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+	"testing"
+	"time"
+)
+
+func boolString(s string) string {
+	if s == "0" {
+		return "false"
+	}
+	return "true"
+}
+
+func TestEverything(t *testing.T) {
+	ResetForTesting(nil)
+	Bool("test_bool", false, "bool value")
+	Int("test_int", 0, "int value")
+	Int64("test_int64", 0, "int64 value")
+	Uint("test_uint", 0, "uint value")
+	Uint64("test_uint64", 0, "uint64 value")
+	String("test_string", "0", "string value")
+	Float64("test_float64", 0, "float64 value")
+	Duration("test_duration", 0, "time.Duration value")
+
+	m := make(map[string]*Flag)
+	desired := "0"
+	visitor := func(f *Flag) {
+		if len(f.Name) > 5 && f.Name[0:5] == "test_" {
+			m[f.Name] = f
+			ok := false
+			switch {
+			case f.Value.String() == desired:
+				ok = true
+			case f.Name == "test_bool" && f.Value.String() == boolString(desired):
+				ok = true
+			case f.Name == "test_duration" && f.Value.String() == desired+"s":
+				ok = true
+			}
+			if !ok {
+				t.Error("Visit: bad value", f.Value.String(), "for", f.Name)
+			}
+		}
+	}
+	VisitAll(visitor)
+	if len(m) != 8 {
+		t.Error("VisitAll misses some flags")
+		for k, v := range m {
+			t.Log(k, *v)
+		}
+	}
+	m = make(map[string]*Flag)
+	Visit(visitor)
+	if len(m) != 0 {
+		t.Errorf("Visit sees unset flags")
+		for k, v := range m {
+			t.Log(k, *v)
+		}
+	}
+	// Now set all flags
+	Set("test_bool", "true")
+	Set("test_int", "1")
+	Set("test_int64", "1")
+	Set("test_uint", "1")
+	Set("test_uint64", "1")
+	Set("test_string", "1")
+	Set("test_float64", "1")
+	Set("test_duration", "1s")
+	desired = "1"
+	Visit(visitor)
+	if len(m) != 8 {
+		t.Error("Visit fails after set")
+		for k, v := range m {
+			t.Log(k, *v)
+		}
+	}
+	// Now test they're visited in sort order.
+	var flagNames []string
+	Visit(func(f *Flag) { flagNames = append(flagNames, f.Name) })
+	if !sort.StringsAreSorted(flagNames) {
+		t.Errorf("flag names not sorted: %v", flagNames)
+	}
+}
+
+func TestGet(t *testing.T) {
+	ResetForTesting(nil)
+	Bool("test_bool", true, "bool value")
+	Int("test_int", 1, "int value")
+	Int64("test_int64", 2, "int64 value")
+	Uint("test_uint", 3, "uint value")
+	Uint64("test_uint64", 4, "uint64 value")
+	String("test_string", "5", "string value")
+	Float64("test_float64", 6, "float64 value")
+	Duration("test_duration", 7, "time.Duration value")
+
+	visitor := func(f *Flag) {
+		if len(f.Name) > 5 && f.Name[0:5] == "test_" {
+			g, ok := f.Value.(Getter)
+			if !ok {
+				t.Errorf("Visit: value does not satisfy Getter: %T", f.Value)
+				return
+			}
+			switch f.Name {
+			case "test_bool":
+				ok = g.Get() == true
+			case "test_int":
+				ok = g.Get() == int(1)
+			case "test_int64":
+				ok = g.Get() == int64(2)
+			case "test_uint":
+				ok = g.Get() == uint(3)
+			case "test_uint64":
+				ok = g.Get() == uint64(4)
+			case "test_string":
+				ok = g.Get() == "5"
+			case "test_float64":
+				ok = g.Get() == float64(6)
+			case "test_duration":
+				ok = g.Get() == time.Duration(7)
+			}
+			if !ok {
+				t.Errorf("Visit: bad value %T(%v) for %s", g.Get(), g.Get(), f.Name)
+			}
+		}
+	}
+	VisitAll(visitor)
+}
+
+func TestUsage(t *testing.T) {
+	called := false
+	ResetForTesting(func() { called = true })
+	if CommandLine.Parse([]string{"-x"}) == nil {
+		t.Error("parse did not fail for unknown flag")
+	}
+	if !called {
+		t.Error("did not call Usage for unknown flag")
+	}
+}
+
+func testParse(f *FlagSet, t *testing.T) {
+	if f.Parsed() {
+		t.Error("f.Parse() = true before Parse")
+	}
+	boolFlag := f.Bool("bool", false, "bool value")
+	bool2Flag := f.Bool("bool2", false, "bool2 value")
+	intFlag := f.Int("int", 0, "int value")
+	int64Flag := f.Int64("int64", 0, "int64 value")
+	uintFlag := f.Uint("uint", 0, "uint value")
+	uint64Flag := f.Uint64("uint64", 0, "uint64 value")
+	stringFlag := f.String("string", "0", "string value")
+	float64Flag := f.Float64("float64", 0, "float64 value")
+	durationFlag := f.Duration("duration", 5*time.Second, "time.Duration value")
+	extra := "one-extra-argument"
+	args := []string{
+		"-bool",
+		"-bool2=true",
+		"--int", "22",
+		"--int64", "0x23",
+		"-uint", "24",
+		"--uint64", "25",
+		"-string", "hello",
+		"-float64", "2718e28",
+		"-duration", "2m",
+		extra,
+	}
+	if err := f.Parse(args); err != nil {
+		t.Fatal(err)
+	}
+	if !f.Parsed() {
+		t.Error("f.Parse() = false after Parse")
+	}
+	if *boolFlag != true {
+		t.Error("bool flag should be true, is ", *boolFlag)
+	}
+	if *bool2Flag != true {
+		t.Error("bool2 flag should be true, is ", *bool2Flag)
+	}
+	if *intFlag != 22 {
+		t.Error("int flag should be 22, is ", *intFlag)
+	}
+	if *int64Flag != 0x23 {
+		t.Error("int64 flag should be 0x23, is ", *int64Flag)
+	}
+	if *uintFlag != 24 {
+		t.Error("uint flag should be 24, is ", *uintFlag)
+	}
+	if *uint64Flag != 25 {
+		t.Error("uint64 flag should be 25, is ", *uint64Flag)
+	}
+	if *stringFlag != "hello" {
+		t.Error("string flag should be `hello`, is ", *stringFlag)
+	}
+	if *float64Flag != 2718e28 {
+		t.Error("float64 flag should be 2718e28, is ", *float64Flag)
+	}
+	if *durationFlag != 2*time.Minute {
+		t.Error("duration flag should be 2m, is ", *durationFlag)
+	}
+	if len(f.Args()) != 1 {
+		t.Error("expected one argument, got", len(f.Args()))
+	} else if f.Args()[0] != extra {
+		t.Errorf("expected argument %q got %q", extra, f.Args()[0])
+	}
+}
+
+func TestParse(t *testing.T) {
+	ResetForTesting(func() { t.Error("bad parse") })
+	testParse(CommandLine, t)
+}
+
+func TestFlagSetParse(t *testing.T) {
+	testParse(NewFlagSet("test", ContinueOnError), t)
+}
+
+// Declare a user-defined flag type.
+type flagVar []string
+
+func (f *flagVar) String() string {
+	return fmt.Sprint([]string(*f))
+}
+
+func (f *flagVar) Set(value string) error {
+	*f = append(*f, value)
+	return nil
+}
+
+func TestUserDefined(t *testing.T) {
+	var flags FlagSet
+	flags.Init("test", ContinueOnError)
+	var v flagVar
+	flags.Var(&v, "v", "usage")
+	if err := flags.Parse([]string{"-v", "1", "-v", "2", "-v=3"}); err != nil {
+		t.Error(err)
+	}
+	if len(v) != 3 {
+		t.Fatal("expected 3 args; got ", len(v))
+	}
+	expect := "[1 2 3]"
+	if v.String() != expect {
+		t.Errorf("expected value %q got %q", expect, v.String())
+	}
+}
+
+// Declare a user-defined boolean flag type.
+type boolFlagVar struct {
+	count int
+}
+
+func (b *boolFlagVar) String() string {
+	return fmt.Sprintf("%d", b.count)
+}
+
+func (b *boolFlagVar) Set(value string) error {
+	if value == "true" {
+		b.count++
+	}
+	return nil
+}
+
+func (b *boolFlagVar) IsBoolFlag() bool {
+	return b.count < 4
+}
+
+func TestUserDefinedBool(t *testing.T) {
+	var flags FlagSet
+	flags.Init("test", ContinueOnError)
+	var b boolFlagVar
+	var err error
+	flags.Var(&b, "b", "usage")
+	if err = flags.Parse([]string{"-b", "-b", "-b", "-b=true", "-b=false", "-b", "barg", "-b"}); err != nil {
+		if b.count < 4 {
+			t.Error(err)
+		}
+	}
+
+	if b.count != 4 {
+		t.Errorf("want: %d; got: %d", 4, b.count)
+	}
+
+	if err == nil {
+		t.Error("expected error; got none")
+	}
+}
+
+func TestSetOutput(t *testing.T) {
+	var flags FlagSet
+	var buf bytes.Buffer
+	flags.SetOutput(&buf)
+	flags.Init("test", ContinueOnError)
+	flags.Parse([]string{"-unknown"})
+	if out := buf.String(); !strings.Contains(out, "-unknown") {
+		t.Logf("expected output mentioning unknown; got %q", out)
+	}
+}
+
+// This tests that one can reset the flags. This still works but not well, and is
+// superseded by FlagSet.
+func TestChangingArgs(t *testing.T) {
+	ResetForTesting(func() { t.Fatal("bad parse") })
+	oldArgs := os.Args
+	defer func() { os.Args = oldArgs }()
+	os.Args = []string{"cmd", "-before", "subcmd", "-after", "args"}
+	before := Bool("before", false, "")
+	if err := CommandLine.Parse(os.Args[1:]); err != nil {
+		t.Fatal(err)
+	}
+	cmd := Arg(0)
+	os.Args = Args()
+	after := Bool("after", false, "")
+	Parse()
+	args := Args()
+
+	if !*before || cmd != "subcmd" || !*after || len(args) != 1 || args[0] != "args" {
+		t.Fatalf("expected true subcmd true [args] got %v %v %v %v", *before, cmd, *after, args)
+	}
+}
+
+// Test that -help invokes the usage message and returns ErrHelp.
+func TestHelp(t *testing.T) {
+	var helpCalled = false
+	fs := NewFlagSet("help test", ContinueOnError)
+	fs.Usage = func() { helpCalled = true }
+	var flag bool
+	fs.BoolVar(&flag, "flag", false, "regular flag")
+	// Regular flag invocation should work
+	err := fs.Parse([]string{"-flag=true"})
+	if err != nil {
+		t.Fatal("expected no error; got ", err)
+	}
+	if !flag {
+		t.Error("flag was not set by -flag")
+	}
+	if helpCalled {
+		t.Error("help called for regular flag")
+		helpCalled = false // reset for next test
+	}
+	// Help flag should work as expected.
+	err = fs.Parse([]string{"-help"})
+	if err == nil {
+		t.Fatal("error expected")
+	}
+	if err != ErrHelp {
+		t.Fatal("expected ErrHelp; got ", err)
+	}
+	if !helpCalled {
+		t.Fatal("help was not called")
+	}
+	// If we define a help flag, that should override.
+	var help bool
+	fs.BoolVar(&help, "help", false, "help flag")
+	helpCalled = false
+	err = fs.Parse([]string{"-help"})
+	if err != nil {
+		t.Fatal("expected no error for defined -help; got ", err)
+	}
+	if helpCalled {
+		t.Fatal("help was called; should not have been for defined help flag")
+	}
+}