Fix enum values.

flags.go

@@ -41,13 +41,13 @@ func (f *flagGroup) init() error {
 
 func (f *flagGroup) parse(tokens tokens, ignoreRequired bool) (tokens, error) {
 	// Track how many required flags we've seen.
-	required := make(map[string]struct{})
+	required := make(map[string]bool)
 	// Keep track of any flags that we need to initialise with defaults.
-	defaults := make(map[string]struct{})
+	defaults := make(map[string]bool)
 	for k, flag := range f.long {
-		defaults[k] = struct{}{}
+		defaults[k] = true
 		if !ignoreRequired && flag.needsValue() {
-			required[k] = struct{}{}
+			required[k] = true
 		}
 	}
 

parsers.go

@@ -264,11 +264,11 @@ func (p *parserMixin) URLListVar(target *[]*url.URL) {
 // Enum allows a value from a set of options.
 func (p *parserMixin) Enum(options ...string) (target *string) {
 	target = new(string)
-	p.EnumVar(target, options...)
+	p.EnumVar(&target, options...)
 	return
 }
 
 // EnumVar allows a value from a set of options.
-func (p *parserMixin) EnumVar(target *string, options ...string) {
+func (p *parserMixin) EnumVar(target **string, options ...string) {
 	p.SetValue(newEnumFlag(target, options...))
 }

values.go

@@ -420,16 +420,15 @@ type enumValue struct {
 	options []string
 }
 
-func newEnumFlag(target *string, options ...string) *enumValue {
-	value := new(string)
+func newEnumFlag(target **string, options ...string) *enumValue {
 	return &enumValue{
-		value:   value,
+		value:   *target,
 		options: options,
 	}
 }
 
 func (a *enumValue) String() string {
-	return *a.value + " [" + strings.Join(a.options, "|") + "]"
+	return *a.value
 }
 
 func (a *enumValue) Set(value string) error {