1 files changed, 18 insertions, 9 deletions

diff --git a/libgo/go/flag/flag.go b/libgo/go/flag/flag.go
index cd2a165be19..60aef5d806c 100644
--- a/libgo/go/flag/flag.go
+++ b/libgo/go/flag/flag.go
@@ -73,7 +73,8 @@ import (
 	"time"
 )
 
-// ErrHelp is the error returned if the flag -help is invoked but no such flag is defined.
+// 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
@@ -405,6 +406,7 @@ func defaultUsage(f *FlagSet) {
 // for how to write your own usage function.
 
 // Usage prints to standard error a usage message documenting all defined command-line flags.
+// It is called when an error occurs while parsing 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])
@@ -628,18 +630,21 @@ func Float64(name string, value float64, usage string) *float64 {
 
 // 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)
@@ -648,6 +653,7 @@ func (f *FlagSet) Duration(name string, value time.Duration, usage string) *time
 
 // 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)
 }
@@ -697,13 +703,15 @@ func (f *FlagSet) failf(format string, a ...interface{}) error {
 	return err
 }
 
-// usage calls the Usage method for the flag set, or the usage function if
-// the flag set is CommandLine.
+// usage calls the Usage method for the flag set if one is specified,
+// or the appropriate default usage function otherwise.
 func (f *FlagSet) usage() {
-	if f == CommandLine {
-		Usage()
-	} else if f.Usage == nil {
-		defaultUsage(f)
+	if f.Usage == nil {
+		if f == CommandLine {
+			Usage()
+		} else {
+			defaultUsage(f)
+		}
 	} else {
 		f.Usage()
 	}
@@ -752,6 +760,7 @@ func (f *FlagSet) parseOne() (bool, error) {
 		}
 		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 {
@@ -784,7 +793,7 @@ func (f *FlagSet) parseOne() (bool, error) {
 // 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 was set but not defined.
+// 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
@@ -826,7 +835,7 @@ func Parsed() bool {
 }
 
 // CommandLine is the default set of command-line flags, parsed from os.Args.
-// The top-level functions such as BoolVar, Arg, and on are wrappers for the
+// 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)