From f810369f2d91ab47b97b0f82adc1a92344d56d89 Mon Sep 17 00:00:00 2001
From: Masaaki Goshima <goccy54@gmail.com>
Date: Tue, 11 Jan 2022 15:11:17 +0900
Subject: [PATCH] Fix encoding of MarshalText operation with head offset

---
 encode_test.go                         | 31 ++++++++++++++++++++++++++
 internal/cmd/generator/vm.go.tmpl      | 17 +++++++++-----
 internal/encoder/vm/vm.go              | 17 +++++++++-----
 internal/encoder/vm_color/vm.go        | 17 +++++++++-----
 internal/encoder/vm_color_indent/vm.go | 17 +++++++++-----
 internal/encoder/vm_indent/vm.go       | 17 +++++++++-----
 6 files changed, 86 insertions(+), 30 deletions(-)

diff --git a/encode_test.go b/encode_test.go
index 1b88d52..ce6a336 100644
--- a/encode_test.go
+++ b/encode_test.go
@@ -2308,3 +2308,34 @@ func TestMarshalIndent(t *testing.T) {
 		t.Fatalf("expected: %q but got %q", expected, got)
 	}
 }
+
+type issue318Embedded struct {
+	_ [64]byte
+}
+
+type issue318 struct {
+	issue318Embedded `json:"-"`
+	ID               issue318MarshalText `json:"id,omitempty"`
+}
+
+type issue318MarshalText struct {
+	ID string
+}
+
+func (i issue318MarshalText) MarshalText() ([]byte, error) {
+	return []byte(i.ID), nil
+}
+
+func TestIssue318(t *testing.T) {
+	v := issue318{
+		ID: issue318MarshalText{ID: "1"},
+	}
+	b, err := json.Marshal(v)
+	if err != nil {
+		t.Fatal(err)
+	}
+	expected := `{"id":"1"}`
+	if string(b) != expected {
+		t.Fatalf("failed to encode. expected %s but got %s", expected, string(b))
+	}
+}
diff --git a/internal/cmd/generator/vm.go.tmpl b/internal/cmd/generator/vm.go.tmpl
index fb1ec4d..91b11e1 100644
--- a/internal/cmd/generator/vm.go.tmpl
+++ b/internal/cmd/generator/vm.go.tmpl
@@ -705,14 +705,15 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
-			u64 := ptrToUint64(p+uintptr(code.Offset), code.NumBitSize)
+			p += uintptr(code.Offset)
+			u64 := ptrToUint64(p, code.NumBitSize)
 			v := u64 & ((1 << code.NumBitSize) - 1)
 			if v == 0 {
 				code = code.NextField
 			} else {
 				b = appendStructKey(ctx, code, b)
 				b = append(b, '"')
-				b = appendInt(ctx, b, p+uintptr(code.Offset), code)
+				b = appendInt(ctx, b, p, code)
 				b = append(b, '"')
 				b = appendComma(ctx, b)
 				code = code.Next
@@ -2953,9 +2954,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -2994,9 +2996,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			iface := ptrToInterface(code, p)
@@ -3114,9 +3117,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -3155,9 +3159,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
diff --git a/internal/encoder/vm/vm.go b/internal/encoder/vm/vm.go
index fb1ec4d..91b11e1 100644
--- a/internal/encoder/vm/vm.go
+++ b/internal/encoder/vm/vm.go
@@ -705,14 +705,15 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
-			u64 := ptrToUint64(p+uintptr(code.Offset), code.NumBitSize)
+			p += uintptr(code.Offset)
+			u64 := ptrToUint64(p, code.NumBitSize)
 			v := u64 & ((1 << code.NumBitSize) - 1)
 			if v == 0 {
 				code = code.NextField
 			} else {
 				b = appendStructKey(ctx, code, b)
 				b = append(b, '"')
-				b = appendInt(ctx, b, p+uintptr(code.Offset), code)
+				b = appendInt(ctx, b, p, code)
 				b = append(b, '"')
 				b = appendComma(ctx, b)
 				code = code.Next
@@ -2953,9 +2954,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -2994,9 +2996,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			iface := ptrToInterface(code, p)
@@ -3114,9 +3117,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -3155,9 +3159,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
diff --git a/internal/encoder/vm_color/vm.go b/internal/encoder/vm_color/vm.go
index 1ce3fc1..5c6c52c 100644
--- a/internal/encoder/vm_color/vm.go
+++ b/internal/encoder/vm_color/vm.go
@@ -705,14 +705,15 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
-			u64 := ptrToUint64(p+uintptr(code.Offset), code.NumBitSize)
+			p += uintptr(code.Offset)
+			u64 := ptrToUint64(p, code.NumBitSize)
 			v := u64 & ((1 << code.NumBitSize) - 1)
 			if v == 0 {
 				code = code.NextField
 			} else {
 				b = appendStructKey(ctx, code, b)
 				b = append(b, '"')
-				b = appendInt(ctx, b, p+uintptr(code.Offset), code)
+				b = appendInt(ctx, b, p, code)
 				b = append(b, '"')
 				b = appendComma(ctx, b)
 				code = code.Next
@@ -2953,9 +2954,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -2994,9 +2996,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			iface := ptrToInterface(code, p)
@@ -3114,9 +3117,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -3155,9 +3159,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
diff --git a/internal/encoder/vm_color_indent/vm.go b/internal/encoder/vm_color_indent/vm.go
index 506c10c..42dc11c 100644
--- a/internal/encoder/vm_color_indent/vm.go
+++ b/internal/encoder/vm_color_indent/vm.go
@@ -705,14 +705,15 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
-			u64 := ptrToUint64(p+uintptr(code.Offset), code.NumBitSize)
+			p += uintptr(code.Offset)
+			u64 := ptrToUint64(p, code.NumBitSize)
 			v := u64 & ((1 << code.NumBitSize) - 1)
 			if v == 0 {
 				code = code.NextField
 			} else {
 				b = appendStructKey(ctx, code, b)
 				b = append(b, '"')
-				b = appendInt(ctx, b, p+uintptr(code.Offset), code)
+				b = appendInt(ctx, b, p, code)
 				b = append(b, '"')
 				b = appendComma(ctx, b)
 				code = code.Next
@@ -2953,9 +2954,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -2994,9 +2996,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			iface := ptrToInterface(code, p)
@@ -3114,9 +3117,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -3155,9 +3159,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
diff --git a/internal/encoder/vm_indent/vm.go b/internal/encoder/vm_indent/vm.go
index 5e17673..dfe0cc6 100644
--- a/internal/encoder/vm_indent/vm.go
+++ b/internal/encoder/vm_indent/vm.go
@@ -705,14 +705,15 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
-			u64 := ptrToUint64(p+uintptr(code.Offset), code.NumBitSize)
+			p += uintptr(code.Offset)
+			u64 := ptrToUint64(p, code.NumBitSize)
 			v := u64 & ((1 << code.NumBitSize) - 1)
 			if v == 0 {
 				code = code.NextField
 			} else {
 				b = appendStructKey(ctx, code, b)
 				b = append(b, '"')
-				b = appendInt(ctx, b, p+uintptr(code.Offset), code)
+				b = appendInt(ctx, b, p, code)
 				b = append(b, '"')
 				b = appendComma(ctx, b)
 				code = code.Next
@@ -2953,9 +2954,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -2994,9 +2996,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalJSON {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			iface := ptrToInterface(code, p)
@@ -3114,9 +3117,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 				b = appendStructHead(ctx, b)
 			}
 			b = appendStructKey(ctx, code, b)
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {
@@ -3155,9 +3159,10 @@ func Run(ctx *encoder.RuntimeContext, b []byte, codeSet *encoder.OpcodeSet) ([]b
 			if code.Flags&encoder.AnonymousHeadFlags == 0 {
 				b = appendStructHead(ctx, b)
 			}
+			p += uintptr(code.Offset)
 			if (code.Flags & encoder.IsNilableTypeFlags) != 0 {
 				if (code.Flags&encoder.IndirectFlags) != 0 || code.Op == encoder.OpStructPtrHeadOmitEmptyMarshalText {
-					p = ptrToPtr(p + uintptr(code.Offset))
+					p = ptrToPtr(p)
 				}
 			}
 			if p == 0 && (code.Flags&encoder.NilCheckFlags) != 0 {