Bug in greenpack generator

greenpack-bug.go

package gpbug

type I64 uint64
type Str1 string

type Struct1 struct {
	I I64  // `zid:"0"`
	S Str1 // `zid:"1"`
}

type Struct2 struct {
	S Struct1
}

greenpack-bug_gen.go.patch

--- greenpack-bug_gen.go.1	2018-04-16 16:27:45.681013175 +0200
+++ greenpack-bug_gen.go	2018-04-16 16:27:45.693013210 +0200
@@ -278,7 +278,7 @@
 		return 1
 	}
 	var fieldsInUse uint32 = 1
-	isempty[0] = false // struct values are never empty
+	isempty[0] = false
 	if isempty[0] {
 		fieldsInUse--
 	}
@@ -302,24 +302,10 @@
 	if !empty[0] {
 		// string "S"
 		o = append(o, 0xa1, 0x53)
-
-		// honor the omitempty tags
-		var empty [2]bool
-		fieldsInUse := z.S.fieldsNotEmpty(empty[:])
-		o = msgp.AppendMapHeader(o, fieldsInUse)
-
-		if !empty[0] {
-			// string "I"
-			o = append(o, 0xa1, 0x49)
-			o = msgp.AppendUint64(o, uint64(z.S.I))
-		}
-
-		if !empty[1] {
-			// string "S"
-			o = append(o, 0xa1, 0x53)
-			o = msgp.AppendString(o, string(z.S.S))
+		o, err = z.S.MarshalMsg(o) // not is.iface, gen/marshal.go:243
+		if err != nil {
+			return
 		}
-
 	}
 
 	return
@@ -392,89 +378,10 @@
 
 		case "S":
 			found6zgensym_1452b2c984fe1b1a_7[0] = true
-			const maxFields8zgensym_1452b2c984fe1b1a_9 = 2
-
-			// -- templateUnmarshalMsg starts here--
-			var totalEncodedFields8zgensym_1452b2c984fe1b1a_9 uint32
-			if !nbs.AlwaysNil {
-				totalEncodedFields8zgensym_1452b2c984fe1b1a_9, bts, err = nbs.ReadMapHeaderBytes(bts)
-				if err != nil {
-					return
-				}
-			}
-			encodedFieldsLeft8zgensym_1452b2c984fe1b1a_9 := totalEncodedFields8zgensym_1452b2c984fe1b1a_9
-			missingFieldsLeft8zgensym_1452b2c984fe1b1a_9 := maxFields8zgensym_1452b2c984fe1b1a_9 - totalEncodedFields8zgensym_1452b2c984fe1b1a_9
-
-			var nextMiss8zgensym_1452b2c984fe1b1a_9 int32 = -1
-			var found8zgensym_1452b2c984fe1b1a_9 [maxFields8zgensym_1452b2c984fe1b1a_9]bool
-			var curField8zgensym_1452b2c984fe1b1a_9 string
-
-		doneWithStruct8zgensym_1452b2c984fe1b1a_9:
-			// First fill all the encoded fields, then
-			// treat the remaining, missing fields, as Nil.
-			for encodedFieldsLeft8zgensym_1452b2c984fe1b1a_9 > 0 || missingFieldsLeft8zgensym_1452b2c984fe1b1a_9 > 0 {
-				//fmt.Printf("encodedFieldsLeft: %v, missingFieldsLeft: %v, found: '%v', fields: '%#v'\n", encodedFieldsLeft8zgensym_1452b2c984fe1b1a_9, missingFieldsLeft8zgensym_1452b2c984fe1b1a_9, msgp.ShowFound(found8zgensym_1452b2c984fe1b1a_9[:]), unmarshalMsgFieldOrder8zgensym_1452b2c984fe1b1a_9)
-				if encodedFieldsLeft8zgensym_1452b2c984fe1b1a_9 > 0 {
-					encodedFieldsLeft8zgensym_1452b2c984fe1b1a_9--
-					field, bts, err = nbs.ReadMapKeyZC(bts)
-					if err != nil {
-						return
-					}
-					curField8zgensym_1452b2c984fe1b1a_9 = msgp.UnsafeString(field)
-				} else {
-					//missing fields need handling
-					if nextMiss8zgensym_1452b2c984fe1b1a_9 < 0 {
-						// set bts to contain just mnil (0xc0)
-						bts = nbs.PushAlwaysNil(bts)
-						nextMiss8zgensym_1452b2c984fe1b1a_9 = 0
-					}
-					for nextMiss8zgensym_1452b2c984fe1b1a_9 < maxFields8zgensym_1452b2c984fe1b1a_9 && (found8zgensym_1452b2c984fe1b1a_9[nextMiss8zgensym_1452b2c984fe1b1a_9] || unmarshalMsgFieldSkip8zgensym_1452b2c984fe1b1a_9[nextMiss8zgensym_1452b2c984fe1b1a_9]) {
-						nextMiss8zgensym_1452b2c984fe1b1a_9++
-					}
-					if nextMiss8zgensym_1452b2c984fe1b1a_9 == maxFields8zgensym_1452b2c984fe1b1a_9 {
-						// filled all the empty fields!
-						break doneWithStruct8zgensym_1452b2c984fe1b1a_9
-					}
-					missingFieldsLeft8zgensym_1452b2c984fe1b1a_9--
-					curField8zgensym_1452b2c984fe1b1a_9 = unmarshalMsgFieldOrder8zgensym_1452b2c984fe1b1a_9[nextMiss8zgensym_1452b2c984fe1b1a_9]
-				}
-				//fmt.Printf("switching on curField: '%v'\n", curField8zgensym_1452b2c984fe1b1a_9)
-				switch curField8zgensym_1452b2c984fe1b1a_9 {
-				// -- templateUnmarshalMsg ends here --
-
-				case "I":
-					found8zgensym_1452b2c984fe1b1a_9[0] = true
-					{
-						var zgensym_1452b2c984fe1b1a_10 uint64
-						zgensym_1452b2c984fe1b1a_10, bts, err = nbs.ReadUint64Bytes(bts)
-
-						if err != nil {
-							return
-						}
-						z.S.I = I64(zgensym_1452b2c984fe1b1a_10)
-					}
-				case "S":
-					found8zgensym_1452b2c984fe1b1a_9[1] = true
-					{
-						var zgensym_1452b2c984fe1b1a_11 string
-						zgensym_1452b2c984fe1b1a_11, bts, err = nbs.ReadStringBytes(bts)
-
-						if err != nil {
-							return
-						}
-						z.S.S = Str1(zgensym_1452b2c984fe1b1a_11)
-					}
-				default:
-					bts, err = msgp.Skip(bts)
-					if err != nil {
-						return
-					}
-				}
-			}
-			if nextMiss8zgensym_1452b2c984fe1b1a_9 != -1 {
-				bts = nbs.PopAlwaysNil()
+			bts, err = z.S.UnmarshalMsg(bts)
+			if err != nil {
+				return
 			}
-
 		default:
 			bts, err = msgp.Skip(bts)
 			if err != nil {
@@ -502,13 +409,8 @@
 
 var unmarshalMsgFieldSkip6zgensym_1452b2c984fe1b1a_7 = []bool{false}
 
-// fields of Struct1
-var unmarshalMsgFieldOrder8zgensym_1452b2c984fe1b1a_9 = []string{"I", "S"}
-
-var unmarshalMsgFieldSkip8zgensym_1452b2c984fe1b1a_9 = []bool{false, false}
-
 // Msgsize returns an upper bound estimate of the number of bytes occupied by the serialized message
 func (z *Struct2) Msgsize() (s int) {
-	s = 1 + 2 + 1 + 2 + msgp.Uint64Size + 2 + msgp.StringPrefixSize + len(string(z.S.S))
+	s = 1 + 2 + z.S.Msgsize()
 	return
 }