fix: check flags for indirection

encoder/assembler_amd64.go

@@ -1022,7 +1022,7 @@ func (self *_Assembler) _asm_OP_recurse(p *_Instr) {
     self.Emit("MOVQ", _AX, jit.Ptr(_SP, 8))     // MOVQ AX, 8(SP)
 
     /* check for indirection */
-    if p.vk() == reflect.Ptr {
+    if (p.vf() & rt.F_direct) != 0 {
         self.Emit("MOVQ", _SP_p, _AX)               // MOVQ SP.p, AX
     } else {
         self.Emit("MOVQ", _SP_p, jit.Ptr(_SP, 48))  // MOVQ SP.p, 48(SP)

encoder/compiler.go

@@ -224,6 +224,10 @@ func (self _Instr) vi() int {
     return rt.UnpackInt(self.u)
 }
 
+func (self _Instr) vf() uint8 {
+    return (*rt.GoType)(self.p).KindFlags
+}
+
 func (self _Instr) vs() (v string) {
     (*rt.GoString)(unsafe.Pointer(&v)).Ptr = self.p
     (*rt.GoString)(unsafe.Pointer(&v)).Len = self.vi()

issue76_test.go

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2021 ByteDance Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package sonic
+
+import (
+    `encoding/json`
+    `fmt`
+    `testing`
+
+    `github.com/davecgh/go-spew/spew`
+)
+
+type SingleMapField struct {
+    Z *int
+}
+
+type SingleMapFieldOuter struct {
+    Y *SingleMapField
+}
+
+type SingleMapFieldOuterContainer struct {
+    X *SingleMapFieldOuter
+}
+
+func TestIssue76_MarshalSingleMapField(t *testing.T) {
+    data := `{"X": {"Y": {"Z": 1}}}`
+    obj := new(SingleMapFieldOuterContainer)
+    if err := json.Unmarshal([]byte(data), obj); err != nil {
+        t.Fatal(err)
+    }
+    spew.Dump(obj)
+    buf, err := Marshal(obj)
+    if err != nil {
+        t.Fatal(err)
+    }
+    fmt.Println(string(buf))
+}