switched to go-mod, updated codegangsta/cli -> urfave/cli

vendor/github.com/fatih/structs/field.go

@@ -25,7 +25,7 @@ func (f *Field) Tag(key string) string {
 	return f.field.Tag.Get(key)
 }
 
-// Value returns the underlying value of of the field. It panics if the field
+// Value returns the underlying value of the field. It panics if the field
 // is not exported.
 func (f *Field) Value() interface{} {
 	return f.value.Interface()
@@ -41,7 +41,7 @@ func (f *Field) IsExported() bool {
 	return f.field.PkgPath == ""
 }
 
-// IsZero returns true if the given field is not initalized (has a zero value).
+// IsZero returns true if the given field is not initialized (has a zero value).
 // It panics if the field is not exported.
 func (f *Field) IsZero() bool {
 	zero := reflect.Zero(f.value.Type()).Interface()
@@ -60,8 +60,8 @@ func (f *Field) Kind() reflect.Kind {
 	return f.value.Kind()
 }
 
-// Set sets the field to given value v. It retuns an error if the field is not
-// settable (not addresable or not exported) or if the given value's type
+// Set sets the field to given value v. It returns an error if the field is not
+// settable (not addressable or not exported) or if the given value's type
 // doesn't match the fields type.
 func (f *Field) Set(val interface{}) error {
 	// we can't set unexported fields, so be sure this field is exported
@@ -84,6 +84,13 @@ func (f *Field) Set(val interface{}) error {
 	return nil
 }
 
+// Zero sets the field to its zero value. It returns an error if the field is not
+// settable (not addressable or not exported).
+func (f *Field) Zero() error {
+	zero := reflect.Zero(f.value.Type()).Interface()
+	return f.Set(zero)
+}
+
 // Fields returns a slice of Fields. This is particular handy to get the fields
 // of a nested struct . A struct tag with the content of "-" ignores the
 // checking of that particular field. Example:
@@ -107,11 +114,19 @@ func (f *Field) Field(name string) *Field {
 	return field
 }
 
-// Field returns the field from a nested struct. The boolean returns true if
-// the field was found. It panics if the nested struct is not exported or if
-// the field was not found.
+// FieldOk returns the field from a nested struct. The boolean returns whether
+// the field was found (true) or not (false).
 func (f *Field) FieldOk(name string) (*Field, bool) {
-	v := strctVal(f.value.Interface())
+	value := &f.value
+	// value must be settable so we need to make sure it holds the address of the
+	// variable and not a copy, so we can pass the pointer to strctVal instead of a
+	// copy (which is not assigned to any variable, hence not settable).
+	// see "https://blog.golang.org/laws-of-reflection#TOC_8."
+	if f.value.Kind() != reflect.Ptr {
+		a := f.value.Addr()
+		value = &a
+	}
+	v := strctVal(value.Interface())
 	t := v.Type()
 
 	field, ok := t.FieldByName(name)