Merge pull request #22 from idrarig/private-map-fix

Do not panic on private map properties

merge.go

@@ -53,6 +53,9 @@ func deepMerge(dst, src reflect.Value, visited map[uintptr]*visit, depth int, ov
 				}
 				fallthrough
 			default:
+				if !srcElement.CanInterface() {
+					continue
+				}
 				switch reflect.TypeOf(srcElement.Interface()).Kind() {
 				case reflect.Struct:
 					fallthrough

mergo_test.go

@@ -6,11 +6,12 @@
 package mergo
 
 import (
-	"gopkg.in/yaml.v1"
 	"io/ioutil"
 	"reflect"
 	"testing"
 	"time"
+
+	"gopkg.in/yaml.v1"
 )
 
 type simpleTest struct {
@@ -499,3 +500,26 @@ func loadYAML(path string) (m map[string]interface{}) {
 	_ = yaml.Unmarshal(raw, &m)
 	return
 }
+
+type structWithMap struct {
+	m map[string]structWithUnexportedProperty
+}
+
+type structWithUnexportedProperty struct {
+	s string
+}
+
+func TestUnexportedProperty(t *testing.T) {
+	a := structWithMap{map[string]structWithUnexportedProperty{
+		"key": structWithUnexportedProperty{"hello"},
+	}}
+	b := structWithMap{map[string]structWithUnexportedProperty{
+		"key": structWithUnexportedProperty{"hi"},
+	}}
+	defer func() {
+		if r := recover(); r != nil {
+			t.Errorf("Should not have panicked")
+		}
+	}()
+	Merge(&a, b)
+}