go/neo/proto/msgpack: Fix case where Compression == None

'Compression' is py type 'Optional[int]'. Before this patch only 'int' was
supported. Now NEO/go also understands 'Compression' with value 'Nil'.

go/neo/proto/protogen.go

@@ -1148,8 +1148,21 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		v = fmt.Sprintf("%s(v)", typeName(userType))
 	}
 
+	// optional emits optional value of int/float
+	optional := func(optionalValue string) {
+		if optionalValue != "" {
+			d.emit("  tail, err = msgp.ReadNilBytes(data)")
+			d.emit("  if err != nil {")
+			d.emit("    return 0, mdecodeErr(%q, err)", d.pathName(assignto))
+			d.emit("  }")
+			d.emit("v = %v", optionalValue)
+		} else {
+			d.emit("  return 0, mdecodeErr(%q, err)", d.pathName(assignto))
+		}
+	}
+
 	// mgetint emits assignto = mget<kind>int<size>()
-	mgetint := func(kind string, size int) {
+	mgetint := func(kind string, size int, optionalValue string) {
 		// we are going to go into msgp - flush previously queued
 		// overflow checks; put place for next overflow check after
 		// msgp is done.
@@ -1164,7 +1177,7 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		d.emit("{")
 		d.emit("v, tail, err := msgp.Read%snt%dBytes(data)", KI, size)
 		d.emit("if err != nil {")
-		d.emit("  return 0, mdecodeErr(%q, err)", d.pathName(assignto))
+		optional(optionalValue)
 		d.emit("}")
 		d.emit("%s= %s", assignto, v)
 		d.emit("%v += uint64(len(data) - len(tail))", d.var_("nread"))
@@ -1182,15 +1195,7 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		d.emit("{")
 		d.emit("v, tail, err := msgp.ReadFloat%dBytes(data)", size)
 		d.emit("if err != nil {")
-		if optionalValue != "" {
-			d.emit("  tail, err = msgp.ReadNilBytes(data)")
-			d.emit("    if err != nil {")
-			d.emit("      return 0, mdecodeErr(%q, err)", d.pathName(assignto))
-			d.emit("  }")
-			d.emit("v = %v", optionalValue)
-		} else {
-			d.emit("  return 0, mdecodeErr(%q, err)", d.pathName(assignto))
-		}
+		optional(optionalValue)
 		d.emit("}")
 		d.emit("%s= %s", assignto, v)
 		d.emit("%v += uint64(len(data) - len(tail))", d.var_("nread"))
@@ -1206,6 +1211,13 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		return
 	}
 
+	// Compression can be nil ('None'), this means the same as
+	// no compression ('py/NoneType.__bool__' is 'False').
+	if typeName(userType) == "Compression" {
+		mgetint("u", 64, "0")
+		return
+	}
+
 	switch typ.Kind() {
 	case types.Bool:
 		d.emit("switch op := msgpack.Op(data[%v]); op {", d.n)
@@ -1217,15 +1229,15 @@ func (d *decoderM) genBasic(assignto string, typ *types.Basic, userType types.Ty
 		d.n++
 		d.overflow.Add(1)
 
-	case types.Int8:	mgetint("", 8)
-	case types.Int16:	mgetint("", 16)
-	case types.Int32:	mgetint("", 32)
-	case types.Int64:	mgetint("", 64)
+	case types.Int8:	mgetint("", 8, "")
+	case types.Int16:	mgetint("", 16, "")
+	case types.Int32:	mgetint("", 32, "")
+	case types.Int64:	mgetint("", 64, "")
 
-	case types.Uint8:	mgetint("u", 8)
-	case types.Uint16:	mgetint("u", 16)
-	case types.Uint32:	mgetint("u", 32)
-	case types.Uint64:	mgetint("u", 64)
+	case types.Uint8:	mgetint("u", 8, "")
+	case types.Uint16:	mgetint("u", 16, "")
+	case types.Uint32:	mgetint("u", 32, "")
+	case types.Uint64:	mgetint("u", 64, "")
 
 	case types.Float64:	mgetfloat(64, "")
 	}

go/neo/proto/zproto-marshal.go

@@ -4956,7 +4956,11 @@ func (p *AnswerRebaseObject) neoMsgDecodeM(data []byte) (int, error) {
 	{
 		v, tail, err := msgp.ReadUint64Bytes(data)
 		if err != nil {
-			return 0, mdecodeErr("AnswerRebaseObject.Compression", err)
+			tail, err = msgp.ReadNilBytes(data)
+			if err != nil {
+				return 0, mdecodeErr("AnswerRebaseObject.Compression", err)
+			}
+			v = 0
 		}
 		p.Compression = Compression(v)
 		nread += uint64(len(data) - len(tail))
@@ -5169,7 +5173,11 @@ func (p *StoreObject) neoMsgDecodeM(data []byte) (int, error) {
 	{
 		v, tail, err := msgp.ReadUint64Bytes(data)
 		if err != nil {
-			return 0, mdecodeErr("StoreObject.Compression", err)
+			tail, err = msgp.ReadNilBytes(data)
+			if err != nil {
+				return 0, mdecodeErr("StoreObject.Compression", err)
+			}
+			v = 0
 		}
 		p.Compression = Compression(v)
 		nread += uint64(len(data) - len(tail))
@@ -6212,7 +6220,11 @@ func (p *AnswerObject) neoMsgDecodeM(data []byte) (int, error) {
 	{
 		v, tail, err := msgp.ReadUint64Bytes(data)
 		if err != nil {
-			return 0, mdecodeErr("AnswerObject.Compression", err)
+			tail, err = msgp.ReadNilBytes(data)
+			if err != nil {
+				return 0, mdecodeErr("AnswerObject.Compression", err)
+			}
+			v = 0
 		}
 		p.Compression = Compression(v)
 		nread += uint64(len(data) - len(tail))
@@ -13153,7 +13165,11 @@ func (p *AddObject) neoMsgDecodeM(data []byte) (int, error) {
 	{
 		v, tail, err := msgp.ReadUint64Bytes(data)
 		if err != nil {
-			return 0, mdecodeErr("AddObject.Compression", err)
+			tail, err = msgp.ReadNilBytes(data)
+			if err != nil {
+				return 0, mdecodeErr("AddObject.Compression", err)
+			}
+			v = 0
 		}
 		p.Compression = Compression(v)
 		nread += uint64(len(data) - len(tail))