From 880442f110ce33b2981561461841979d58848b78 Mon Sep 17 00:00:00 2001
From: Emil Hessman <c.emil.hessman@gmail.com>
Date: Fri, 3 Jan 2014 10:13:28 -0800
Subject: [PATCH] encoding/json: Fix missing error when trying to unmarshal
 null string into int, for successive ,string option

Fixes #7046.

R=golang-codereviews, bradfitz
CC=golang-codereviews
https://golang.org/cl/47260043
---
 src/pkg/encoding/json/decode.go      |  1 +
 src/pkg/encoding/json/decode_test.go | 19 +++++++++++++++++--
 2 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/pkg/encoding/json/decode.go b/src/pkg/encoding/json/decode.go
index 4db566726e..dde0d78e32 100644
--- a/src/pkg/encoding/json/decode.go
+++ b/src/pkg/encoding/json/decode.go
@@ -561,6 +561,7 @@ func (d *decodeState) object(v reflect.Value) {
 		if destring {
 			d.value(reflect.ValueOf(&d.tempstr))
 			d.literalStore([]byte(d.tempstr), subv, true)
+			d.tempstr = "" // Zero scratch space for successive values.
 		} else {
 			d.value(subv)
 		}
diff --git a/src/pkg/encoding/json/decode_test.go b/src/pkg/encoding/json/decode_test.go
index c5a84ab832..238a87fd66 100644
--- a/src/pkg/encoding/json/decode_test.go
+++ b/src/pkg/encoding/json/decode_test.go
@@ -1060,6 +1060,21 @@ func TestEmptyString(t *testing.T) {
 	}
 }
 
+// Test that the returned error is non-nil when trying to unmarshal null string into int, for successive ,string option
+// Issue 7046
+func TestNullString(t *testing.T) {
+	type T struct {
+		A int `json:",string"`
+		B int `json:",string"`
+	}
+	data := []byte(`{"A": "1", "B": null}`)
+	var s T
+	err := Unmarshal(data, &s)
+	if err == nil {
+		t.Fatalf("expected error; got %v", s)
+	}
+}
+
 func intp(x int) *int {
 	p := new(int)
 	*p = x
@@ -1110,8 +1125,8 @@ func TestInterfaceSet(t *testing.T) {
 // Issue 2540
 func TestUnmarshalNulls(t *testing.T) {
 	jsonData := []byte(`{
-		"Bool"    : null, 
-		"Int"     : null, 
+		"Bool"    : null,
+		"Int"     : null,
 		"Int8"    : null,
 		"Int16"   : null,
 		"Int32"   : null,
-- 
2.48.1