Properly encode struct fields having toml tags without a name

Fixes BurntSushi#122.

encode.go

@@ -347,15 +347,14 @@ func (enc *Encoder) eStruct(key Key, rv reflect.Value) {
 				continue
 			}
 
-			keyName := sft.Tag.Get("toml")
-			if keyName == "-" {
+			tag := sft.Tag.Get("toml")
+			if tag == "-" {
 				continue
 			}
+			keyName, opts := getOptions(tag)
 			if keyName == "" {
 				keyName = sft.Name
 			}
-
-			keyName, opts := getOptions(keyName)
 			if _, ok := opts["omitempty"]; ok && isEmpty(sf) {
 				continue
 			} else if _, ok := opts["omitzero"]; ok && isZero(sf) {

encode_test.go

@@ -505,6 +505,16 @@ unsigned = 5
 	encodeExpected(t, "simple with omitzero, non-zero", value, expected, nil)
 }
 
+func TestEncodeOmitemptyWithEmptyName(t *testing.T) {
+	type simple struct {
+		S []int `toml:",omitempty"`
+	}
+	v := simple{[]int{1, 2, 3}}
+	expected := "S = [1, 2, 3]\n"
+	encodeExpected(t, "simple with omitempty, no name, non-empty field",
+		v, expected, nil)
+}
+
 func TestEncodeAnonymousStructPointerField(t *testing.T) {
 	type Sub struct{}
 	type simple struct {