4 files changed, 19 insertions, 13 deletions
diff --git a/src/pkg/json/decode.go b/src/pkg/json/decode.go
index e78b60ccb..35a06b0f9 100644
--- a/src/pkg/json/decode.go
+++ b/src/pkg/json/decode.go
@@ -482,7 +482,7 @@ func (d *decodeState) object(v reflect.Value) {
 			if isValidTag(key) {
 				for i := 0; i < sv.NumField(); i++ {
 					f = st.Field(i)
-					if f.Tag == key {
+					if f.Tag.Get("json") == key {
 						ok = true
 						break
 					}
diff --git a/src/pkg/json/decode_test.go b/src/pkg/json/decode_test.go
index bf8bf10bf..9b84bc76c 100644
--- a/src/pkg/json/decode_test.go
+++ b/src/pkg/json/decode_test.go
@@ -42,8 +42,9 @@ var (
 
 type badTag struct {
 	X string
-	Y string "y"
-	Z string "@#*%(#@"
+	Y string `json:"y"`
+	Z string `x:"@#*%(#@"`
+	W string `json:"@#$@#$"`
 }
 
 type unmarshalTest struct {
@@ -68,7 +69,7 @@ var unmarshalTests = []unmarshalTest{
 	{`{"x": 1}`, new(tx), tx{}, &UnmarshalFieldError{"x", txType, txType.Field(0)}},
 
 	// skip invalid tags
-	{`{"X":"a", "y":"b", "Z":"c"}`, new(badTag), badTag{"a", "b", "c"}, nil},
+	{`{"X":"a", "y":"b", "Z":"c", "W":"d"}`, new(badTag), badTag{"a", "b", "c", "d"}, nil},
 
 	// syntax errors
 	{`{"X": "foo", "Y"}`, nil, nil, &SyntaxError{"invalid character '}' after object key", 17}},
@@ -250,7 +251,7 @@ type All struct {
 	Float32 float32
 	Float64 float64
 
-	Foo string "bar"
+	Foo string `json:"bar"`
 
 	PBool    *bool
 	PInt     *int
diff --git a/src/pkg/json/encode.go b/src/pkg/json/encode.go
index ec0a14a6a..adc0f0f37 100644
--- a/src/pkg/json/encode.go
+++ b/src/pkg/json/encode.go
@@ -36,11 +36,13 @@ import (
 // Array and slice values encode as JSON arrays, except that
 // []byte encodes as a base64-encoded string.
 //
-// Struct values encode as JSON objects.  Each struct field becomes
-// a member of the object.  By default the object's key name is the
-// struct field name.  If the struct field has a non-empty tag consisting
-// of only Unicode letters, digits, and underscores, that tag will be used
-// as the name instead.  Only exported fields will be encoded.
+// Struct values encode as JSON objects.  Each exported struct field
+// becomes a member of the object.  By default the object's key string
+// is the struct field name.  If the struct field's tag has a "json" key with a
+// value that is a non-empty string consisting of only Unicode letters,
+// digits, and underscores, that value will be used as the object key.
+// For example, the field tag `json:"myName"` says to use "myName"
+// as the object key.
 //
 // Map values encode as JSON objects.
 // The map's key type must be string; the object keys are used directly
@@ -236,8 +238,8 @@ func (e *encodeState) reflectValue(v reflect.Value) {
 			} else {
 				e.WriteByte(',')
 			}
-			if isValidTag(f.Tag) {
-				e.string(f.Tag)
+			if tag := f.Tag.Get("json"); tag != "" && isValidTag(tag) {
+				e.string(tag)
 			} else {
 				e.string(f.Name)
 			}
diff --git a/src/pkg/json/scanner_test.go b/src/pkg/json/scanner_test.go
index 0d4de3246..023e7c81e 100644
--- a/src/pkg/json/scanner_test.go
+++ b/src/pkg/json/scanner_test.go
@@ -252,7 +252,10 @@ func genArray(n int) []interface{} {
 	if f > n {
 		f = n
 	}
-	x := make([]interface{}, int(f))
+	if n > 0 && f == 0 {
+		f = 1
+	}
+	x := make([]interface{}, f)
 	for i := range x {
 		x[i] = genValue(((i+1)*n)/f - (i*n)/f)
 	}