Cleanup context.go

flag.go

@@ -1,6 +1,7 @@
 package cli
 
 import (
+	"errors"
 	"flag"
 	"fmt"
 	"io/ioutil"
@@ -130,6 +131,48 @@ func flagSet(name string, flags []Flag) (*flag.FlagSet, error) {
 	return set, nil
 }
 
+func copyFlag(name string, ff *flag.Flag, set *flag.FlagSet) {
+	switch ff.Value.(type) {
+	case Serializer:
+		_ = set.Set(name, ff.Value.(Serializer).Serialize())
+	default:
+		_ = set.Set(name, ff.Value.String())
+	}
+}
+
+func normalizeFlags(flags []Flag, set *flag.FlagSet) error {
+	visited := make(map[string]bool)
+	set.Visit(func(f *flag.Flag) {
+		visited[f.Name] = true
+	})
+	for _, f := range flags {
+		parts := f.Names()
+		if len(parts) == 1 {
+			continue
+		}
+		var ff *flag.Flag
+		for _, name := range parts {
+			name = strings.Trim(name, " ")
+			if visited[name] {
+				if ff != nil {
+					return errors.New("Cannot use two forms of the same flag: " + name + " " + ff.Name)
+				}
+				ff = set.Lookup(name)
+			}
+		}
+		if ff == nil {
+			continue
+		}
+		for _, name := range parts {
+			name = strings.Trim(name, " ")
+			if !visited[name] {
+				copyFlag(name, ff, set)
+			}
+		}
+	}
+	return nil
+}
+
 func visibleFlags(fl []Flag) []Flag {
 	var visible []Flag
 	for _, f := range fl {