Merge remote-tracking branch 'origin/master' into v2-merge

context.go

@@ -3,6 +3,8 @@ package cli
 import (
 	"errors"
 	"flag"
+	"os"
+	"reflect"
 	"strings"
 )
 
@@ -42,8 +44,44 @@ func (c *Context) IsSet(name string) bool {
 				isSet = true
 			}
 		})
-		return isSet
+		if isSet {
+			return true
+		}
 	}
+
+	// XXX hack to support IsSet for flags with EnvVar
+	//
+	// There isn't an easy way to do this with the current implementation since
+	// whether a flag was set via an environment variable is very difficult to
+	// determine here. Instead, we intend to introduce a backwards incompatible
+	// change in version 2 to add `IsSet` to the Flag interface to push the
+	// responsibility closer to where the information required to determine
+	// whether a flag is set by non-standard means such as environment
+	// variables is avaliable.
+	//
+	// See https://github.com/urfave/cli/issues/294 for additional discussion
+	f := lookupFlag(name, c)
+	if f == nil {
+		return false
+	}
+
+	val := reflect.ValueOf(f)
+	if val.Kind() == reflect.Ptr {
+		val = val.Elem()
+	}
+
+	envVarValues := val.FieldByName("EnvVars")
+	if !envVarValues.IsValid() {
+		return false
+	}
+
+	for _, envVar := range envVarValues.Interface().([]string) {
+		envVar = strings.TrimSpace(envVar)
+		if envVal := os.Getenv(envVar); envVal != "" {
+			continue
+		}
+	}
+
 	return false
 }
 
@@ -87,6 +125,34 @@ func (c *Context) NArg() int {
 	return c.Args().Len()
 }
 
+func lookupFlag(name string, ctx *Context) Flag {
+	for _, c := range ctx.Lineage() {
+		if c.Command == nil {
+			continue
+		}
+
+		for _, f := range c.Command.Flags {
+			for _, n := range f.Names() {
+				if n == name {
+					return f
+				}
+			}
+		}
+	}
+
+	if ctx.App != nil {
+		for _, f := range ctx.App.Flags {
+			for _, n := range f.Names() {
+				if n == name {
+					return f
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
 func lookupFlagSet(name string, ctx *Context) *flag.FlagSet {
 	for _, c := range ctx.Lineage() {
 		if f := c.flagSet.Lookup(name); f != nil {