From 305e858ea121708b055918fed395068c0916a91d Mon Sep 17 00:00:00 2001
From: Masaaki Goshima <goccy54@gmail.com>
Date: Fri, 22 Jan 2021 13:28:33 +0900
Subject: [PATCH] Fix encoding with nil pointer type of implementing
 MarshalJSON

---
 encode_vm.go                | 6 ++++++
 encode_vm_escaped.go        | 6 ++++++
 encode_vm_escaped_indent.go | 6 ++++++
 encode_vm_indent.go         | 6 ++++++
 4 files changed, 24 insertions(+)

diff --git a/encode_vm.go b/encode_vm.go
index 01f3fa0..9d783c6 100644
--- a/encode_vm.go
+++ b/encode_vm.go
@@ -267,6 +267,12 @@ func (e *Encoder) run(ctx *encodeRuntimeContext, b []byte, code *opcode) ([]byte
 			code = code.next
 		case opMarshalJSON:
 			ptr := load(ctxptr, code.idx)
+			if ptr == 0 {
+				b = encodeNull(b)
+				b = encodeComma(b)
+				code = code.next
+				break
+			}
 			v := e.ptrToInterface(code, ptr)
 			bb, err := v.(Marshaler).MarshalJSON()
 			if err != nil {
diff --git a/encode_vm_escaped.go b/encode_vm_escaped.go
index 0345338..416d1eb 100644
--- a/encode_vm_escaped.go
+++ b/encode_vm_escaped.go
@@ -229,6 +229,12 @@ func (e *Encoder) runEscaped(ctx *encodeRuntimeContext, b []byte, code *opcode)
 			code = code.next
 		case opMarshalJSON:
 			ptr := load(ctxptr, code.idx)
+			if ptr == 0 {
+				b = encodeNull(b)
+				b = encodeComma(b)
+				code = code.next
+				break
+			}
 			v := e.ptrToInterface(code, ptr)
 			bb, err := v.(Marshaler).MarshalJSON()
 			if err != nil {
diff --git a/encode_vm_escaped_indent.go b/encode_vm_escaped_indent.go
index 785c0a2..5adf19e 100644
--- a/encode_vm_escaped_indent.go
+++ b/encode_vm_escaped_indent.go
@@ -242,6 +242,12 @@ func (e *Encoder) runEscapedIndent(ctx *encodeRuntimeContext, b []byte, code *op
 			code = code.next
 		case opMarshalJSON:
 			ptr := load(ctxptr, code.idx)
+			if ptr == 0 {
+				b = encodeNull(b)
+				b = encodeIndentComma(b)
+				code = code.next
+				break
+			}
 			v := e.ptrToInterface(code, ptr)
 			bb, err := v.(Marshaler).MarshalJSON()
 			if err != nil {
diff --git a/encode_vm_indent.go b/encode_vm_indent.go
index 3507a46..ad9c30e 100644
--- a/encode_vm_indent.go
+++ b/encode_vm_indent.go
@@ -242,6 +242,12 @@ func (e *Encoder) runIndent(ctx *encodeRuntimeContext, b []byte, code *opcode) (
 			code = code.next
 		case opMarshalJSON:
 			ptr := load(ctxptr, code.idx)
+			if ptr == 0 {
+				b = encodeNull(b)
+				b = encodeIndentComma(b)
+				code = code.next
+				break
+			}
 			v := e.ptrToInterface(code, ptr)
 			bb, err := v.(Marshaler).MarshalJSON()
 			if err != nil {